玩轉JDBC打造數據庫操做萬能工具類JDBCUtil，加入了高效的數據庫鏈接池，利用了參數綁定有效防止SQL注入

時間 2019-11-16

標籤 jdbc 打造數據庫萬能工具 jdbcutil 加入高效鏈接利用參數綁定有效防止 sql 注入欄目 Java 简体版

原文原文鏈接

轉載請註明出處：http://blog.csdn.net/linglongxin24/article/details/53750584
本文出自【DylanAndroid的博客】 javascript

玩轉JDBC打造數據庫操做萬能工具類JDBCUtil，加入了高效的數據庫鏈接池，利用了參數綁定有效防止SQL注入

在以前學習了MySQL和Oracle以後，那麼，如和在Java種去鏈接這兩種數據庫。在這個輕量級的工具類當中，使用了數據庫鏈接池
去提升數據庫鏈接的高效性，而且使用了PreparedStatement來執行對SQL的預編譯，可以有效防止SQL注入問題。java

一.準備在配置文件配置:配置數據庫鏈接屬性文件：在項目新建config包下創建jdbc-mysql.properties並加入如下配置

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/test?characterEncoding=utf8
jdbc.username=root
jdbc.password=root複製代碼

二.準備數據庫鏈接池對象：單例

package util;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.mchange.v2.c3p0.DataSources;

import java.beans.PropertyVetoException;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

/** * 數據庫鏈接對象 * Created by yuandl on 2016-12-16. */
public class DBConnectionPool {
    private static volatile DBConnectionPool dbConnection;
    private ComboPooledDataSource cpds;

    /** * 在構造函數初始化的時候獲取數據庫鏈接 */
    private DBConnectionPool() {
        try {
            /**經過屬性文件獲取數據庫鏈接的參數值**/
            Properties properties = new Properties();
            FileInputStream fileInputStream = new FileInputStream("src/config/jdbc-mysql.properties");
            properties.load(fileInputStream);
            /**獲取屬性文件中的值**/
            String driverClassName = properties.getProperty("jdbc.driverClassName");
            String url = properties.getProperty("jdbc.url");
            String username = properties.getProperty("jdbc.username");
            String password = properties.getProperty("jdbc.password");

            /**數據庫鏈接池對象**/
            cpds = new ComboPooledDataSource();

            /**設置數據庫鏈接驅動**/
            cpds.setDriverClass(driverClassName);
            /**設置數據庫鏈接地址**/
            cpds.setJdbcUrl(url);
            /**設置數據庫鏈接用戶名**/
            cpds.setUser(username);
            /**設置數據庫鏈接密碼**/
            cpds.setPassword(password);

            /**初始化時建立的鏈接數,應在minPoolSize與maxPoolSize之間取值.默認爲3**/
            cpds.setInitialPoolSize(3);
            /**鏈接池中保留的最大鏈接數據.默認爲15**/
            cpds.setMaxPoolSize(10);
            /**當鏈接池中的鏈接用完時，C3PO一次性建立新的鏈接數目;**/
            cpds.setAcquireIncrement(1);
            /**隔多少秒檢查全部鏈接池中的空閒鏈接,默認爲0表示不檢查;**/
            cpds.setIdleConnectionTestPeriod(60);
            /**最大空閒時間,超過空閒時間的鏈接將被丟棄.爲0或負數據則永不丟棄.默認爲0;**/
            cpds.setMaxIdleTime(3000);

            /**因性能消耗大請只在須要的時候使用它。若是設爲true那麼在每一個connection提交的 時候都將校驗其有效性。建議使用idleConnectionTestPeriod或automaticTestTable 等方法來提高鏈接測試的性能。Default: false**/
            cpds.setTestConnectionOnCheckout(true);

            /**若是設爲true那麼在取得鏈接的同時將校驗鏈接的有效性。Default: false **/
            cpds.setTestConnectionOnCheckin(true);
            /**定義在從數據庫獲取新的鏈接失敗後重復嘗試獲取的次數，默認爲30;**/
            cpds.setAcquireRetryAttempts(30);
            /**兩次鏈接中間隔時間默認爲1000毫秒**/
            cpds.setAcquireRetryDelay(1000);
            /** 獲取鏈接失敗將會引發全部等待獲取鏈接的線程異常, 可是數據源仍有效的保留,並在下次調用getConnection()的時候繼續嘗試獲取鏈接.若是設爲true, 那麼嘗試獲取鏈接失敗後該數據源將申明已經斷開並永久關閉.默認爲false**/
            cpds.setBreakAfterAcquireFailure(true);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (PropertyVetoException e) {
            e.printStackTrace();
        }

    }

    /** * 獲取數據庫鏈接對象，單例 * * @return */
    public static DBConnectionPool getInstance() {
        if (dbConnection == null) {
            synchronized (DBConnectionPool.class) {
                if (dbConnection == null) {
                    dbConnection = new DBConnectionPool();
                }
            }
        }
        return dbConnection;
    }

    /** * 獲取數據庫鏈接 * * @return 數據庫鏈接 */
    public final synchronized Connection getConnection() throws SQLException {
        return cpds.getConnection();
    }

    /** * finalize()方法是在垃圾收集器刪除對象以前對這個對象調用的。 * * @throws Throwable */
    protected void finalize() throws Throwable {
        DataSources.destroy(cpds);
        super.finalize();
    }
}複製代碼

三.實現新增、修改、刪除、查詢操做的兩個核心方法：能夠實現任何複雜的SQL,並且經過數據綁定的方式不會有SQL注入問題

/** * 能夠執行新增，修改，刪除 * * @param sql sql語句 * @param bindArgs 綁定參數 * @return 影響的行數 * @throws SQLException SQL異常 */
    public static int executeUpdate(String sql, Object[] bindArgs) throws SQLException {
        /**影響的行數**/
        int affectRowCount = -1;
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        try {
            /**從數據庫鏈接池中獲取數據庫鏈接**/
            connection = DBConnectionPool.getInstance().getConnection();
            /**執行SQL預編譯**/
            preparedStatement = connection.prepareStatement(sql.toString());
            /**設置不自動提交，以便於在出現異常的時候數據庫回滾**/
            connection.setAutoCommit(false);
            System.out.println(getExecSQL(sql, bindArgs));
            if (bindArgs != null) {
                /**綁定參數設置sql佔位符中的值**/
                for (int i = 0; i < bindArgs.length; i++) {
                    preparedStatement.setObject(i + 1, bindArgs[i]);
                }
            }
            /**執行sql**/
            affectRowCount = preparedStatement.executeUpdate();
            connection.commit();
            String operate;
            if (sql.toUpperCase().indexOf("DELETE FROM") != -1) {
                operate = "刪除";
            } else if (sql.toUpperCase().indexOf("INSERT INTO") != -1) {
                operate = "新增";
            } else {
                operate = "修改";
            }
            System.out.println("成功" + operate + "了" + affectRowCount + "行");
            System.out.println();
        } catch (Exception e) {
            if (connection != null) {
                connection.rollback();
            }
            e.printStackTrace();
            throw e;
        } finally {
            if (preparedStatement != null) {
                preparedStatement.close();
            }
            if (connection != null) {
                connection.close();
            }
        }
        return affectRowCount;
    }


   /** * 執行查詢 * * @param sql 要執行的sql語句 * @param bindArgs 綁定的參數 * @return List<Map<String, Object>>結果集對象 * @throws SQLException SQL執行異常 */
    public static List<Map<String, Object>> executeQuery(String sql, Object[] bindArgs) throws SQLException {
        List<Map<String, Object>> datas = new ArrayList<>();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        try {
            /**獲取數據庫鏈接池中的鏈接**/
            connection = DBConnectionPool.getInstance().getConnection();
            preparedStatement = connection.prepareStatement(sql);
            if (bindArgs != null) {
                /**設置sql佔位符中的值**/
                for (int i = 0; i < bindArgs.length; i++) {
                    preparedStatement.setObject(i + 1, bindArgs[i]);
                }
            }
            System.out.println(getExecSQL(sql, bindArgs));
            /**執行sql語句，獲取結果集**/
            resultSet = preparedStatement.executeQuery();
            getDatas(resultSet);
            System.out.println();
        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        } finally {
            if (resultSet != null) {
                resultSet.close();
            }
            if (preparedStatement != null) {
                preparedStatement.close();
            }
            if (connection != null) {
                connection.close();
            }
        }
        return datas;
    }複製代碼

四.執行新增的簡化操做

/** * 執行數據庫插入操做 * * @param valueMap 插入數據表中key爲列名和value爲列對應的值的Map對象 * @param tableName 要插入的數據庫的表名 * @return 影響的行數 * @throws SQLException SQL異常 */
    public static int insert(String tableName, Map<String, Object> valueMap) throws SQLException {

        /**獲取數據庫插入的Map的鍵值對的值**/
        Set<String> keySet = valueMap.keySet();
        Iterator<String> iterator = keySet.iterator();
        /**要插入的字段sql，其實就是用key拼起來的**/
        StringBuilder columnSql = new StringBuilder();
        /**要插入的字段值，其實就是？**/
        StringBuilder unknownMarkSql = new StringBuilder();
        Object[] bindArgs = new Object[valueMap.size()];
        int i = 0;
        while (iterator.hasNext()) {
            String key = iterator.next();
            columnSql.append(i == 0 ? "" : ",");
            columnSql.append(key);

            unknownMarkSql.append(i == 0 ? "" : ",");
            unknownMarkSql.append("?");
            bindArgs[i] = valueMap.get(key);
            i++;
        }
        /**開始拼插入的sql語句**/
        StringBuilder sql = new StringBuilder();
        sql.append("INSERT INTO ");
        sql.append(tableName);
        sql.append(" (");
        sql.append(columnSql);
        sql.append(" ) VALUES (");
        sql.append(unknownMarkSql);
        sql.append(" )");
        return executeUpdate(sql.toString(), bindArgs);
    }複製代碼

五.執行更新的簡化操做

/** * 執行更新操做 * * @param tableName 表名 * @param valueMap 要更改的值 * @param whereMap 條件 * @return 影響的行數 * @throws SQLException SQL異常 */
    public static int update(String tableName, Map<String, Object> valueMap, Map<String, Object> whereMap) throws SQLException {
        /**獲取數據庫插入的Map的鍵值對的值**/
        Set<String> keySet = valueMap.keySet();
        Iterator<String> iterator = keySet.iterator();
        /**開始拼插入的sql語句**/
        StringBuilder sql = new StringBuilder();
        sql.append("UPDATE ");
        sql.append(tableName);
        sql.append(" SET ");

        /**要更改的的字段sql，其實就是用key拼起來的**/
        StringBuilder columnSql = new StringBuilder();
        int i = 0;
        List<Object> objects = new ArrayList<>();
        while (iterator.hasNext()) {
            String key = iterator.next();
            columnSql.append(i == 0 ? "" : ",");
            columnSql.append(key + " = ? ");
            objects.add(valueMap.get(key));
            i++;
        }
        sql.append(columnSql);

        /**更新的條件:要更改的的字段sql，其實就是用key拼起來的**/
        StringBuilder whereSql = new StringBuilder();
        int j = 0;
        if (whereMap != null && whereMap.size() > 0) {
            whereSql.append(" WHERE ");
            iterator = whereMap.keySet().iterator();
            while (iterator.hasNext()) {
                String key = iterator.next();
                whereSql.append(j == 0 ? "" : " AND ");
                whereSql.append(key + " = ? ");
                objects.add(whereMap.get(key));
                j++;
            }
            sql.append(whereSql);
        }
        return executeUpdate(sql.toString(), objects.toArray());
    }複製代碼

六.執行刪除的簡化操做

/** * 執行刪除操做 * * @param tableName 要刪除的表名 * @param whereMap 刪除的條件 * @return 影響的行數 * @throws SQLException SQL執行異常 */
    public static int delete(String tableName, Map<String, Object> whereMap) throws SQLException {
        /**準備刪除的sql語句**/
        StringBuilder sql = new StringBuilder();
        sql.append("DELETE FROM ");
        sql.append(tableName);

        /**更新的條件:要更改的的字段sql，其實就是用key拼起來的**/
        StringBuilder whereSql = new StringBuilder();
        Object[] bindArgs = null;
        if (whereMap != null && whereMap.size() > 0) {
            bindArgs = new Object[whereMap.size()];
            whereSql.append(" WHERE ");
            /**獲取數據庫插入的Map的鍵值對的值**/
            Set<String> keySet = whereMap.keySet();
            Iterator<String> iterator = keySet.iterator();
            int i = 0;
            while (iterator.hasNext()) {
                String key = iterator.next();
                whereSql.append(i == 0 ? "" : " AND ");
                whereSql.append(key + " = ? ");
                bindArgs[i] = whereMap.get(key);
                i++;
            }
            sql.append(whereSql);
        }
        return executeUpdate(sql.toString(), bindArgs);
    }複製代碼

七.查詢的4種玩法

1.執行sql經過 Map 限定查詢條件查詢 mysql

/** * 1..執行sql經過 Map<String, Object>限定查詢條件查詢 * * @param tableName 表名 * @param whereMap where條件 * @return List<Map<String, Object>> * @throws SQLException */
  public static List<Map<String, Object>> query(String tableName,
                                                Map<String, Object> whereMap) throws SQLException {
      String whereClause = "";
      Object[] whereArgs = null;
      if (whereMap != null && whereMap.size() > 0) {
          Iterator<String> iterator = whereMap.keySet().iterator();
          whereArgs = new Object[whereMap.size()];
          int i = 0;
          while (iterator.hasNext()) {
              String key = iterator.next();
              whereClause += (i == 0 ? "" : " AND ");
              whereClause += (key + " = ? ");
              whereArgs[i] = whereMap.get(key);
              i++;
          }
      }
      return query(tableName, false, null, whereClause, whereArgs, null, null, null, null);
  }複製代碼

2.執行sql條件參數綁定形式的查詢git

/** * 2.執行sql條件參數綁定形式的查詢 * * @param tableName 表名 * @param whereClause where條件的sql * @param whereArgs where條件中佔位符中的值 * @return List<Map<String, Object>> * @throws SQLException */
  public static List<Map<String, Object>> query(String tableName,
                                                String whereClause,
                                                String[] whereArgs) throws SQLException {
      return query(tableName, false, null, whereClause, whereArgs, null, null, null, null);
  }複製代碼

3.包含全部的查詢條件的查詢方法github

/** * 執行所有結構的sql查詢 * * @param tableName 表名 * @param distinct 去重 * @param columns 要查詢的列名 * @param selection where條件 * @param selectionArgs where條件中佔位符中的值 * @param groupBy 分組 * @param having 篩選 * @param orderBy 排序 * @param limit 分頁 * @return List<Map<String, Object>> * @throws SQLException */
   public static List<Map<String, Object>> query(String tableName,
                                                 boolean distinct,
                                                 String[] columns,
                                                 String selection,
                                                 Object[] selectionArgs,
                                                 String groupBy,
                                                 String having,
                                                 String orderBy,
                                                 String limit) throws SQLException {
       String sql = buildQueryString(distinct, tableName, columns, selection, groupBy, having, orderBy, limit);
       return executeQuery(sql, selectionArgs);
     }複製代碼

4.經過單純的sql查詢數據,慎用，會有sql注入問題，只是爲了方便查詢，實際開發中不會去使用這個方法

* 4.經過sql查詢數據,
     * 慎用，會有sql注入問題只是爲了方便查詢，實際開發中不會去使用這個方法
     *
     * @param sql
     * @return 查詢的數據集合
     * @throws SQLException
     */
    public static List<Map<String, Object>> query(String sql) throws SQLException {
        return executeQuery(sql, null);
    }複製代碼

八.DBUtil的完整代碼

package util;

import com.sun.istack.internal.Nullable;

import java.sql.*;
import java.util.*;
import java.util.regex.Pattern;

/** * 數據庫JDBC鏈接工具類 * Created by yuandl on 2016-12-16. */
public class DBUtil {

 /** * 執行數據庫插入操做 * * @param valueMap 插入數據表中key爲列名和value爲列對應的值的Map對象 * @param tableName 要插入的數據庫的表名 * @return 影響的行數 * @throws SQLException SQL異常 */
 public static int insert(String tableName, Map<String, Object> valueMap) throws SQLException {

     /**獲取數據庫插入的Map的鍵值對的值**/
     Set<String> keySet = valueMap.keySet();
     Iterator<String> iterator = keySet.iterator();
     /**要插入的字段sql，其實就是用key拼起來的**/
     StringBuilder columnSql = new StringBuilder();
     /**要插入的字段值，其實就是？**/
     StringBuilder unknownMarkSql = new StringBuilder();
     Object[] bindArgs = new Object[valueMap.size()];
     int i = 0;
     while (iterator.hasNext()) {
         String key = iterator.next();
         columnSql.append(i == 0 ? "" : ",");
         columnSql.append(key);

         unknownMarkSql.append(i == 0 ? "" : ",");
         unknownMarkSql.append("?");
         bindArgs[i] = valueMap.get(key);
         i++;
     }
     /**開始拼插入的sql語句**/
     StringBuilder sql = new StringBuilder();
     sql.append("INSERT INTO ");
     sql.append(tableName);
     sql.append(" (");
     sql.append(columnSql);
     sql.append(" ) VALUES (");
     sql.append(unknownMarkSql);
     sql.append(" )");
     return executeUpdate(sql.toString(), bindArgs);
 }

 /** * 執行更新操做 * * @param tableName 表名 * @param valueMap 要更改的值 * @param whereMap 條件 * @return 影響的行數 * @throws SQLException SQL異常 */
 public static int update(String tableName, Map<String, Object> valueMap, Map<String, Object> whereMap) throws SQLException {
     /**獲取數據庫插入的Map的鍵值對的值**/
     Set<String> keySet = valueMap.keySet();
     Iterator<String> iterator = keySet.iterator();
     /**開始拼插入的sql語句**/
     StringBuilder sql = new StringBuilder();
     sql.append("UPDATE ");
     sql.append(tableName);
     sql.append(" SET ");

     /**要更改的的字段sql，其實就是用key拼起來的**/
     StringBuilder columnSql = new StringBuilder();
     int i = 0;
     List<Object> objects = new ArrayList<>();
     while (iterator.hasNext()) {
         String key = iterator.next();
         columnSql.append(i == 0 ? "" : ",");
         columnSql.append(key + " = ? ");
         objects.add(valueMap.get(key));
         i++;
     }
     sql.append(columnSql);

     /**更新的條件:要更改的的字段sql，其實就是用key拼起來的**/
     StringBuilder whereSql = new StringBuilder();
     int j = 0;
     if (whereMap != null && whereMap.size() > 0) {
         whereSql.append(" WHERE ");
         iterator = whereMap.keySet().iterator();
         while (iterator.hasNext()) {
             String key = iterator.next();
             whereSql.append(j == 0 ? "" : " AND ");
             whereSql.append(key + " = ? ");
             objects.add(whereMap.get(key));
             j++;
         }
         sql.append(whereSql);
     }
     return executeUpdate(sql.toString(), objects.toArray());
 }

 /** * 執行刪除操做 * * @param tableName 要刪除的表名 * @param whereMap 刪除的條件 * @return 影響的行數 * @throws SQLException SQL執行異常 */
 public static int delete(String tableName, Map<String, Object> whereMap) throws SQLException {
     /**準備刪除的sql語句**/
     StringBuilder sql = new StringBuilder();
     sql.append("DELETE FROM ");
     sql.append(tableName);

     /**更新的條件:要更改的的字段sql，其實就是用key拼起來的**/
     StringBuilder whereSql = new StringBuilder();
     Object[] bindArgs = null;
     if (whereMap != null && whereMap.size() > 0) {
         bindArgs = new Object[whereMap.size()];
         whereSql.append(" WHERE ");
         /**獲取數據庫插入的Map的鍵值對的值**/
         Set<String> keySet = whereMap.keySet();
         Iterator<String> iterator = keySet.iterator();
         int i = 0;
         while (iterator.hasNext()) {
             String key = iterator.next();
             whereSql.append(i == 0 ? "" : " AND ");
             whereSql.append(key + " = ? ");
             bindArgs[i] = whereMap.get(key);
             i++;
         }
         sql.append(whereSql);
     }
     return executeUpdate(sql.toString(), bindArgs);
 }

 /** * 能夠執行新增，修改，刪除 * * @param sql sql語句 * @param bindArgs 綁定參數 * @return 影響的行數 * @throws SQLException SQL異常 */
 public static int executeUpdate(String sql, Object[] bindArgs) throws SQLException {
     /**影響的行數**/
     int affectRowCount = -1;
     Connection connection = null;
     PreparedStatement preparedStatement = null;
     try {
         /**從數據庫鏈接池中獲取數據庫鏈接**/
         connection = DBConnectionPool.getInstance().getConnection();
         /**執行SQL預編譯**/
         preparedStatement = connection.prepareStatement(sql.toString());
         /**設置不自動提交，以便於在出現異常的時候數據庫回滾**/
         connection.setAutoCommit(false);
         System.out.println(getExecSQL(sql, bindArgs));
         if (bindArgs != null) {
             /**綁定參數設置sql佔位符中的值**/
             for (int i = 0; i < bindArgs.length; i++) {
                 preparedStatement.setObject(i + 1, bindArgs[i]);
             }
         }
         /**執行sql**/
         affectRowCount = preparedStatement.executeUpdate();
         connection.commit();
         String operate;
         if (sql.toUpperCase().indexOf("DELETE FROM") != -1) {
             operate = "刪除";
         } else if (sql.toUpperCase().indexOf("INSERT INTO") != -1) {
             operate = "新增";
         } else {
             operate = "修改";
         }
         System.out.println("成功" + operate + "了" + affectRowCount + "行");
         System.out.println();
     } catch (Exception e) {
         if (connection != null) {
             connection.rollback();
         }
         e.printStackTrace();
         throw e;
     } finally {
         if (preparedStatement != null) {
             preparedStatement.close();
         }
         if (connection != null) {
             connection.close();
         }
     }
     return affectRowCount;
 }

 /** * 經過sql查詢數據, * 慎用，會有sql注入問題 * * @param sql * @return 查詢的數據集合 * @throws SQLException */
 public static List<Map<String, Object>> query(String sql) throws SQLException {
     return executeQuery(sql, null);
 }

 /** * 執行sql經過 Map<String, Object>限定查詢條件查詢 * * @param tableName 表名 * @param whereMap where條件 * @return List<Map<String, Object>> * @throws SQLException */
 public static List<Map<String, Object>> query(String tableName,
                                               Map<String, Object> whereMap) throws SQLException {
     String whereClause = "";
     Object[] whereArgs = null;
     if (whereMap != null & whereMap.size() > 0) {
         Iterator<String> iterator = whereMap.keySet().iterator();
         whereArgs = new Object[whereMap.size()];
         int i = 0;
         while (iterator.hasNext()) {
             String key = iterator.next();
             whereClause += (i == 0 ? "" : " AND ");
             whereClause += (key + " = ? ");
             whereArgs[i] = whereMap.get(key);
             i++;
         }
     }
     return query(tableName, false, null, whereClause, whereArgs, null, null, null, null);
 }

 /** * 執行sql條件參數綁定形式的查詢 * * @param tableName 表名 * @param whereClause where條件的sql * @param whereArgs where條件中佔位符中的值 * @return List<Map<String, Object>> * @throws SQLException */
 public static List<Map<String, Object>> query(String tableName,
                                               String whereClause,
                                               String[] whereArgs) throws SQLException {
     return query(tableName, false, null, whereClause, whereArgs, null, null, null, null);
 }

 /** * 執行所有結構的sql查詢 * * @param tableName 表名 * @param distinct 去重 * @param columns 要查詢的列名 * @param selection where條件 * @param selectionArgs where條件中佔位符中的值 * @param groupBy 分組 * @param having 篩選 * @param orderBy 排序 * @param limit 分頁 * @return List<Map<String, Object>> * @throws SQLException */
 public static List<Map<String, Object>> query(String tableName,
                                               boolean distinct,
                                               String[] columns,
                                               String selection,
                                               Object[] selectionArgs,
                                               String groupBy,
                                               String having,
                                               String orderBy,
                                               String limit) throws SQLException {
     String sql = buildQueryString(distinct, tableName, columns, selection, groupBy, having, orderBy, limit);
     return executeQuery(sql, selectionArgs);

 }

 /** * 執行查詢 * * @param sql 要執行的sql語句 * @param bindArgs 綁定的參數 * @return List<Map<String, Object>>結果集對象 * @throws SQLException SQL執行異常 */
 public static List<Map<String, Object>> executeQuery(String sql, Object[] bindArgs) throws SQLException {
     List<Map<String, Object>> datas = new ArrayList<>();
     Connection connection = null;
     PreparedStatement preparedStatement = null;
     ResultSet resultSet = null;

     try {
         /**獲取數據庫鏈接池中的鏈接**/
         connection = DBConnectionPool.getInstance().getConnection();
         preparedStatement = connection.prepareStatement(sql);
         if (bindArgs != null) {
             /**設置sql佔位符中的值**/
             for (int i = 0; i < bindArgs.length; i++) {
                 preparedStatement.setObject(i + 1, bindArgs[i]);
             }
         }
         System.out.println(getExecSQL(sql, bindArgs));
         /**執行sql語句，獲取結果集**/
         resultSet = preparedStatement.executeQuery();
         getDatas(resultSet);
         System.out.println();
     } catch (Exception e) {
         e.printStackTrace();
         throw e;
     } finally {
         if (resultSet != null) {
             resultSet.close();
         }
         if (preparedStatement != null) {
             preparedStatement.close();
         }
         if (connection != null) {
             connection.close();
         }
     }
     return datas;
 }


 /** * 將結果集對象封裝成List<Map<String, Object>> 對象 * * @param resultSet 結果多想 * @return 結果的封裝 * @throws SQLException */
 private static List<Map<String, Object>> getDatas(ResultSet resultSet) throws SQLException {
     List<Map<String, Object>> datas = new ArrayList<>();
     /**獲取結果集的數據結構對象**/
     ResultSetMetaData metaData = resultSet.getMetaData();
     while (resultSet.next()) {
         Map<String, Object> rowMap = new HashMap<>();
         for (int i = 1; i <= metaData.getColumnCount(); i++) {
             rowMap.put(metaData.getColumnName(i), resultSet.getObject(i));
         }
         datas.add(rowMap);
     }
     System.out.println("成功查詢到了" + datas.size() + "行數據");
     for (int i = 0; i < datas.size(); i++) {
         Map<String, Object> map = datas.get(i);
         System.out.println("第" + (i + 1) + "行：" + map);
     }
     return datas;
 }


 /** * Build an SQL query string from the given clauses. * * @param distinct true if you want each row to be unique, false otherwise. * @param tables The table names to compile the query against. * @param columns A list of which columns to return. Passing null will * return all columns, which is discouraged to prevent reading * data from storage that isn't going to be used. * @param where A filter declaring which rows to return, formatted as an SQL * WHERE clause (excluding the WHERE itself). Passing null will * return all rows for the given URL. * @param groupBy A filter declaring how to group rows, formatted as an SQL * GROUP BY clause (excluding the GROUP BY itself). Passing null * will cause the rows to not be grouped. * @param having A filter declare which row groups to include in the cursor, * if row grouping is being used, formatted as an SQL HAVING * clause (excluding the HAVING itself). Passing null will cause * all row groups to be included, and is required when row * grouping is not being used. * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause * (excluding the ORDER BY itself). Passing null will use the * default sort order, which may be unordered. * @param limit Limits the number of rows returned by the query, * formatted as LIMIT clause. Passing null denotes no LIMIT clause. * @return the SQL query string */
 private static String buildQueryString( boolean distinct, String tables, String[] columns, String where, String groupBy, String having, String orderBy, String limit) {
     if (isEmpty(groupBy) && !isEmpty(having)) {
         throw new IllegalArgumentException(
                 "HAVING clauses are only permitted when using a groupBy clause");
     }
     if (!isEmpty(limit) && !sLimitPattern.matcher(limit).matches()) {
         throw new IllegalArgumentException("invalid LIMIT clauses:" + limit);
     }

     StringBuilder query = new StringBuilder(120);

     query.append("SELECT ");
     if (distinct) {
         query.append("DISTINCT ");
     }
     if (columns != null && columns.length != 0) {
         appendColumns(query, columns);
     } else {
         query.append(" * ");
     }
     query.append("FROM ");
     query.append(tables);
     appendClause(query, " WHERE ", where);
     appendClause(query, " GROUP BY ", groupBy);
     appendClause(query, " HAVING ", having);
     appendClause(query, " ORDER BY ", orderBy);
     appendClause(query, " LIMIT ", limit);
     return query.toString();
 }

 /** * Add the names that are non-null in columns to s, separating * them with commas. */
 private static void appendColumns(StringBuilder s, String[] columns) {
     int n = columns.length;

     for (int i = 0; i < n; i++) {
         String column = columns[i];

         if (column != null) {
             if (i > 0) {
                 s.append(", ");
             }
             s.append(column);
         }
     }
     s.append(' ');
 }

 /** * addClause * * @param s the add StringBuilder * @param name clauseName * @param clause clauseSelection */
 private static void appendClause(StringBuilder s, String name, String clause) {
     if (!isEmpty(clause)) {
         s.append(name);
         s.append(clause);
     }
 }

 /** * Returns true if the string is null or 0-length. * * @param str the string to be examined * @return true if str is null or zero length */
 private static boolean isEmpty(@Nullable CharSequence str) {
     if (str == null || str.length() == 0)
         return true;
     else
         return false;
 }

 /** * the pattern of limit */
 private static final Pattern sLimitPattern =
         Pattern.compile("\\s*\\d+\\s*(,\\s*\\d+\\s*)?");

 /** * After the execution of the complete SQL statement, not necessarily the actual implementation of the SQL statement * * @param sql SQL statement * @param bindArgs Binding parameters * @return Replace? SQL statement executed after the */
 private static String getExecSQL(String sql, Object[] bindArgs) {
     StringBuilder sb = new StringBuilder(sql);
     if (bindArgs != null && bindArgs.length > 0) {
         int index = 0;
         for (int i = 0; i < bindArgs.length; i++) {
             index = sb.indexOf("?", index);
             sb.replace(index, index + 1, String.valueOf(bindArgs[i]));
         }
     }
     return sb.toString();
 }
}複製代碼

九.用法

測試代碼

import util.DBUtil;

import java.sql.SQLException;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/** * Created by yuandl on 2016-12-16. */
public class DBTest {

public static void main(String[] args) {
    System.out.println("數據庫的原數據");
    testQuery3();
    testInsert();
    System.out.println("執行插入後的數據");
    testQuery3();
    testUpdate();
    System.out.println("執行修改後的數據");
    testQuery3();
    testDelete();
    System.out.println("執行刪除後的數據");
    testQuery3();
    System.out.println("帶條件的查詢1");
    testQuery2();
    System.out.println("帶條件的查詢2");
    testQuery1();
}



/** * 測試插入 */
private static void testInsert() {
    Map<String, Object> map = new HashMap<>();
    map.put("emp_id", 1013);
    map.put("name", "JDBCUtil測試");
    map.put("job", "developer");
    map.put("salary", 10000);
    map.put("hire_date", new java.sql.Date(System.currentTimeMillis()));
    try {
        int count = DBUtil.insert("emp_test", map);
              } catch (SQLException e) {
        e.printStackTrace();
    }
}



/** * 測試更新 */
private static void testUpdate() {
    Map<String, Object> map = new HashMap<>();
    map.put("name", "測試更新");

    Map<String, Object> whereMap = new HashMap<>();
    whereMap.put("emp_id", "1013");
    try {
        int count = DBUtil.update("emp_test", map, whereMap);
    } catch (SQLException e) {
        e.printStackTrace();
    }
}



/** * 測試刪除 */
private static void testDelete() {
    Map<String, Object> whereMap = new HashMap<>();
    whereMap.put("emp_id", 1013);
    whereMap.put("job", "developer");
    try {
        int count = DBUtil.delete("emp_test", whereMap);
    } catch (SQLException e) {
        e.printStackTrace();
    }
}
/** * 查詢方式一 */
public static void testQuery1() {
    Map<String,Object> whereMap=new HashMap<>();
    whereMap.put("salary","10000");
    try {
        DBUtil.query("emp_test",whereMap);
    } catch (SQLException e) {
        e.printStackTrace();
    }
}
/** * 查詢方式二 */
public static void testQuery2() {
    String where = "job = ? AND salary = ? ";
    String[] whereArgs = new String[]{"clerk", "3000"};

    try {
        List<Map<String, Object>> list = DBUtil.query("emp_test", where, whereArgs);

    } catch (SQLException e) {
        e.printStackTrace();
    }
}

/** * 查詢方式三 */
public static void testQuery3() {
    try {
        List<Map<String, Object>> list = DBUtil.query("emp_test", false, null, null, null, null, null, null, null);

    } catch (SQLException e) {
        e.printStackTrace();
    }
}
}複製代碼

打印結果

數據庫的原數據
SELECT  * FROM emp_test
成功查詢到了14行數據
第1行：{DEPT_TEST_ID=10, EMP_ID=1001, SALARY=10000, HIRE_DATE=2010-01-12, BONUS=2000, MANAGER=1005, JOB=Manager, NAME=張無忌}
第2行：{DEPT_TEST_ID=10, EMP_ID=1002, SALARY=8000, HIRE_DATE=2011-01-12, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=劉蒼松}
第3行：{DEPT_TEST_ID=10, EMP_ID=1003, SALARY=9000, HIRE_DATE=2010-02-11, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=李翊}
第4行：{DEPT_TEST_ID=10, EMP_ID=1004, SALARY=5000, HIRE_DATE=2010-02-11, BONUS=null, MANAGER=1001, JOB=Programmer, NAME=郭芙蓉}
第5行：{DEPT_TEST_ID=20, EMP_ID=1005, SALARY=15000, HIRE_DATE=2008-02-15, BONUS=null, MANAGER=null, JOB=President, NAME=張三丰}
第6行：{DEPT_TEST_ID=20, EMP_ID=1006, SALARY=5000, HIRE_DATE=2009-02-01, BONUS=400, MANAGER=1005, JOB=Manager, NAME=燕小六}
第7行：{DEPT_TEST_ID=20, EMP_ID=1007, SALARY=3000, HIRE_DATE=2009-02-01, BONUS=500, MANAGER=1006, JOB=clerk, NAME=陸無雙}
第8行：{DEPT_TEST_ID=30, EMP_ID=1008, SALARY=5000, HIRE_DATE=2009-05-01, BONUS=500, MANAGER=1005, JOB=Manager, NAME=黃蓉}
第9行：{DEPT_TEST_ID=30, EMP_ID=1009, SALARY=4000, HIRE_DATE=2009-02-20, BONUS=null, MANAGER=1008, JOB=salesman, NAME=韋小寶}
第10行：{DEPT_TEST_ID=30, EMP_ID=1010, SALARY=4500, HIRE_DATE=2009-05-10, BONUS=500, MANAGER=1008, JOB=salesman, NAME=郭靖}
第11行：{DEPT_TEST_ID=null, EMP_ID=1011, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=於澤成}
第12行：{DEPT_TEST_ID=null, EMP_ID=1012, SALARY=null, HIRE_DATE=2011-08-10, BONUS=null, MANAGER=null, JOB=null, NAME=amy}
第13行：{DEPT_TEST_ID=null, EMP_ID=1014, SALARY=8000, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=張無忌}
第14行：{DEPT_TEST_ID=20, EMP_ID=1015, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=劉蒼松}

INSERT INTO emp_test (name,hire_date,job,salary,emp_id )  VALUES (JDBCUtil測試,2016-12-17,developer,10000,1013 )
成功新增了1行

執行插入後的數據
SELECT  * FROM emp_test
成功查詢到了15行數據
第1行：{DEPT_TEST_ID=10, EMP_ID=1001, SALARY=10000, HIRE_DATE=2010-01-12, BONUS=2000, MANAGER=1005, JOB=Manager, NAME=張無忌}
第2行：{DEPT_TEST_ID=10, EMP_ID=1002, SALARY=8000, HIRE_DATE=2011-01-12, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=劉蒼松}
第3行：{DEPT_TEST_ID=10, EMP_ID=1003, SALARY=9000, HIRE_DATE=2010-02-11, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=李翊}
第4行：{DEPT_TEST_ID=10, EMP_ID=1004, SALARY=5000, HIRE_DATE=2010-02-11, BONUS=null, MANAGER=1001, JOB=Programmer, NAME=郭芙蓉}
第5行：{DEPT_TEST_ID=20, EMP_ID=1005, SALARY=15000, HIRE_DATE=2008-02-15, BONUS=null, MANAGER=null, JOB=President, NAME=張三丰}
第6行：{DEPT_TEST_ID=20, EMP_ID=1006, SALARY=5000, HIRE_DATE=2009-02-01, BONUS=400, MANAGER=1005, JOB=Manager, NAME=燕小六}
第7行：{DEPT_TEST_ID=20, EMP_ID=1007, SALARY=3000, HIRE_DATE=2009-02-01, BONUS=500, MANAGER=1006, JOB=clerk, NAME=陸無雙}
第8行：{DEPT_TEST_ID=30, EMP_ID=1008, SALARY=5000, HIRE_DATE=2009-05-01, BONUS=500, MANAGER=1005, JOB=Manager, NAME=黃蓉}
第9行：{DEPT_TEST_ID=30, EMP_ID=1009, SALARY=4000, HIRE_DATE=2009-02-20, BONUS=null, MANAGER=1008, JOB=salesman, NAME=韋小寶}
第10行：{DEPT_TEST_ID=30, EMP_ID=1010, SALARY=4500, HIRE_DATE=2009-05-10, BONUS=500, MANAGER=1008, JOB=salesman, NAME=郭靖}
第11行：{DEPT_TEST_ID=null, EMP_ID=1011, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=於澤成}
第12行：{DEPT_TEST_ID=null, EMP_ID=1012, SALARY=null, HIRE_DATE=2011-08-10, BONUS=null, MANAGER=null, JOB=null, NAME=amy}
第13行：{DEPT_TEST_ID=null, EMP_ID=1014, SALARY=8000, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=張無忌}
第14行：{DEPT_TEST_ID=20, EMP_ID=1015, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=劉蒼松}
第15行：{DEPT_TEST_ID=null, EMP_ID=1013, SALARY=10000, HIRE_DATE=2016-12-17, BONUS=null, MANAGER=null, JOB=developer, NAME=JDBCUtil測試}

UPDATE emp_test SET name = 測試更新  WHERE emp_id = 1013 
成功修改了1行

執行修改後的數據
SELECT  * FROM emp_test
成功查詢到了15行數據
第1行：{DEPT_TEST_ID=10, EMP_ID=1001, SALARY=10000, HIRE_DATE=2010-01-12, BONUS=2000, MANAGER=1005, JOB=Manager, NAME=張無忌}
第2行：{DEPT_TEST_ID=10, EMP_ID=1002, SALARY=8000, HIRE_DATE=2011-01-12, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=劉蒼松}
第3行：{DEPT_TEST_ID=10, EMP_ID=1003, SALARY=9000, HIRE_DATE=2010-02-11, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=李翊}
第4行：{DEPT_TEST_ID=10, EMP_ID=1004, SALARY=5000, HIRE_DATE=2010-02-11, BONUS=null, MANAGER=1001, JOB=Programmer, NAME=郭芙蓉}
第5行：{DEPT_TEST_ID=20, EMP_ID=1005, SALARY=15000, HIRE_DATE=2008-02-15, BONUS=null, MANAGER=null, JOB=President, NAME=張三丰}
第6行：{DEPT_TEST_ID=20, EMP_ID=1006, SALARY=5000, HIRE_DATE=2009-02-01, BONUS=400, MANAGER=1005, JOB=Manager, NAME=燕小六}
第7行：{DEPT_TEST_ID=20, EMP_ID=1007, SALARY=3000, HIRE_DATE=2009-02-01, BONUS=500, MANAGER=1006, JOB=clerk, NAME=陸無雙}
第8行：{DEPT_TEST_ID=30, EMP_ID=1008, SALARY=5000, HIRE_DATE=2009-05-01, BONUS=500, MANAGER=1005, JOB=Manager, NAME=黃蓉}
第9行：{DEPT_TEST_ID=30, EMP_ID=1009, SALARY=4000, HIRE_DATE=2009-02-20, BONUS=null, MANAGER=1008, JOB=salesman, NAME=韋小寶}
第10行：{DEPT_TEST_ID=30, EMP_ID=1010, SALARY=4500, HIRE_DATE=2009-05-10, BONUS=500, MANAGER=1008, JOB=salesman, NAME=郭靖}
第11行：{DEPT_TEST_ID=null, EMP_ID=1011, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=於澤成}
第12行：{DEPT_TEST_ID=null, EMP_ID=1012, SALARY=null, HIRE_DATE=2011-08-10, BONUS=null, MANAGER=null, JOB=null, NAME=amy}
第13行：{DEPT_TEST_ID=null, EMP_ID=1014, SALARY=8000, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=張無忌}
第14行：{DEPT_TEST_ID=20, EMP_ID=1015, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=劉蒼松}
第15行：{DEPT_TEST_ID=null, EMP_ID=1013, SALARY=10000, HIRE_DATE=2016-12-17, BONUS=null, MANAGER=null, JOB=developer, NAME=測試更新}

DELETE FROM emp_test WHERE job = developer  AND emp_id = 1013 
成功刪除了1行

執行刪除後的數據
SELECT  * FROM emp_test
成功查詢到了14行數據
第1行：{DEPT_TEST_ID=10, EMP_ID=1001, SALARY=10000, HIRE_DATE=2010-01-12, BONUS=2000, MANAGER=1005, JOB=Manager, NAME=張無忌}
第2行：{DEPT_TEST_ID=10, EMP_ID=1002, SALARY=8000, HIRE_DATE=2011-01-12, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=劉蒼松}
第3行：{DEPT_TEST_ID=10, EMP_ID=1003, SALARY=9000, HIRE_DATE=2010-02-11, BONUS=1000, MANAGER=1001, JOB=Analyst, NAME=李翊}
第4行：{DEPT_TEST_ID=10, EMP_ID=1004, SALARY=5000, HIRE_DATE=2010-02-11, BONUS=null, MANAGER=1001, JOB=Programmer, NAME=郭芙蓉}
第5行：{DEPT_TEST_ID=20, EMP_ID=1005, SALARY=15000, HIRE_DATE=2008-02-15, BONUS=null, MANAGER=null, JOB=President, NAME=張三丰}
第6行：{DEPT_TEST_ID=20, EMP_ID=1006, SALARY=5000, HIRE_DATE=2009-02-01, BONUS=400, MANAGER=1005, JOB=Manager, NAME=燕小六}
第7行：{DEPT_TEST_ID=20, EMP_ID=1007, SALARY=3000, HIRE_DATE=2009-02-01, BONUS=500, MANAGER=1006, JOB=clerk, NAME=陸無雙}
第8行：{DEPT_TEST_ID=30, EMP_ID=1008, SALARY=5000, HIRE_DATE=2009-05-01, BONUS=500, MANAGER=1005, JOB=Manager, NAME=黃蓉}
第9行：{DEPT_TEST_ID=30, EMP_ID=1009, SALARY=4000, HIRE_DATE=2009-02-20, BONUS=null, MANAGER=1008, JOB=salesman, NAME=韋小寶}
第10行：{DEPT_TEST_ID=30, EMP_ID=1010, SALARY=4500, HIRE_DATE=2009-05-10, BONUS=500, MANAGER=1008, JOB=salesman, NAME=郭靖}
第11行：{DEPT_TEST_ID=null, EMP_ID=1011, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=於澤成}
第12行：{DEPT_TEST_ID=null, EMP_ID=1012, SALARY=null, HIRE_DATE=2011-08-10, BONUS=null, MANAGER=null, JOB=null, NAME=amy}
第13行：{DEPT_TEST_ID=null, EMP_ID=1014, SALARY=8000, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=張無忌}
第14行：{DEPT_TEST_ID=20, EMP_ID=1015, SALARY=null, HIRE_DATE=null, BONUS=null, MANAGER=null, JOB=null, NAME=劉蒼松}

帶條件的查詢1
SELECT  * FROM emp_test WHERE job = clerk  AND salary = 3000 
成功查詢到了1行數據
第1行：{DEPT_TEST_ID=20, EMP_ID=1007, SALARY=3000, HIRE_DATE=2009-02-01, BONUS=500, MANAGER=1006, JOB=clerk, NAME=陸無雙}

帶條件的查詢2
SELECT  * FROM emp_test WHERE salary = 10000 
成功查詢到了1行數據
第1行：{DEPT_TEST_ID=10, EMP_ID=1001, SALARY=10000, HIRE_DATE=2010-01-12, BONUS=2000, MANAGER=1005, JOB=Manager, NAME=張無忌}複製代碼