做業2

時間 2019-12-11

原文原文鏈接

stored procedure connector/j 8.0 Developer guide7.3存儲過程的實驗。實驗報告形式寫博客java

使用JDBC `CallableStatements`執行存儲過程

CallableStatement的全部超級接口爲PreparedStatement、Statement、Wrapper。其中繼承自PreparedStatement接口。CallableStatement主要是調用數據庫中的存儲過程。在使用CallableStatement時能夠接收存儲過程的返回值。CallableStatement對象爲全部的DBMS提供了一種標準的形式去調用數據庫中已存在的存儲過程。對數據庫中存儲過程的調用是CallableStatement對象所含的內容。有兩種形式：1：形式帶結果參數；2：形式不帶結果參數。結果參數是一種輸出參數(存儲過程當中的輸出OUT參數)，是存儲過程的返回值。兩種形式都有帶有數量可變的輸入、輸出、輸入和輸出的參數。用問號作佔位符。mysql

形式帶結果參數語法格式：{ ? = call 存儲過程名[(?, ?, ?, ...)]};sql

形式不帶結果參數語法格式：{ call 存儲過程名[(?, ?, ?, ...)]};PS方括號裏面的內容無關緊要。數據庫

CallableStatement接口中經常使用的方法。app

1：getInt(int parameterIndex)、getInt(String parameterName)、還有getString、getBigDecimal、getString、getDate、getURL等等都相似和PreparedStatement與Statement中的用法相似。ide

2：registerOutParameter(int parameterIndex, int sqlType):按順序位置parameterIndex將OUT參數註冊爲JDBC類型sqlType。測試

3：wasNull():查詢最後一個讀取的OUT參數是否爲SQL Null。等等還有不少方法，感興趣的讀者能夠自行查閱JDK API文檔。ui

講解了那麼多，不如一個例子來的痛快。下面經過一個例子讓讀者更清楚的看到CallableStatement的用法。this

首先在原先的t_employee表中添加表示幹了多少年的tyear字段。spa

    alter table t_employee add tyear int;

在數據庫中編寫存儲過程統計指定id的userName的人，輸出一下他一共賺了多少錢。

JDBC代碼：

package com.panli.dbutil;
/**
 * 鏈接數據庫
 */
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
public class DbUtil {
	//數據庫驅動名字
	private static String jdbcName = "com.mysql.jdbc.Driver";
	//數據庫協議地址
	private static String dbUrl = "jdbc:mysql://localhost:3306/db_user";
	//數據庫用戶名
	private static String dbUser = "root";
	//數據庫密碼
	private static String dbPassword = "123456";
	
	
	/**
	 * 獲取鏈接
	 * @return
	 * @throws Exception
	 */
	public static Connection getCon() throws Exception{
		Class.forName(jdbcName);
		Connection conn = DriverManager.getConnection(dbUrl, dbUser, dbPassword);
		return conn;
	}
	
	/**
	 * 關閉鏈接
	 * @param stmt
	 * @param conn
	 * @throws Exception
	 */
	public static void close(Statement stmt,Connection conn) throws Exception{
		if(stmt!=null){
			stmt.close();
			if(conn!=null){
				conn.close();
			}
		}
	}
	
	/**
	 * 關閉鏈接
	 * @param cstmt
	 * @param conn
	 * @throws Exception
	 */
	public static void close(CallableStatement cstmt, Connection conn) throws Exception{
		if(cstmt!=null){
			cstmt.close();
			if(conn!=null){
				conn.close();
			}
		}
	}
	
	
	/**
	 * 關閉鏈接
	 * @param pstmt
	 * @param conn
	 * @throws SQLException
	 */
	public static void close(PreparedStatement pstmt, Connection conn) throws SQLException{
		if(pstmt!=null){
			pstmt.close();
			if(conn!=null){
				conn.close();
			}
		}
	}
	
	
	/**
	 * 重載關閉方法
	 * @param pstmt
	 * @param conn
	 * @throws Exception
	 */
	public void close(ResultSet rs,PreparedStatement pstmt, Connection conn) throws Exception{
		if(rs!=null){
			rs.close();
			if(pstmt!=null){
				pstmt.close();
				if(conn!=null){
					conn.close();
				}
				
			}
		}
		
	}
}

package com.panli.model;
 
import java.io.File;
 
/**
 * model包下的cemployee類,對每一個字段進行建模
 * @author Peter
 *
 */
public class CEmployee {
	private int id;
	private String userName;
	private double salary;
	private String job;
	private int jobTypeId;
	private File context;
	private File pic;
	private double counts;
	/**
	 * 默認的構造方法
	 */
	public CEmployee() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	/**
	 * 帶一個參數的構造方法
	 * @param id
	 */
	public CEmployee(int id) {
		super();
		this.id = id;
	}
	
	/**
	 * 兩個參數的構造方法
	 * @param counts
	 * @param userNames
	 */
	public CEmployee(double counts, String userName) {
		// TODO Auto-generated constructor stub
		this.counts = counts;
		this.userName = userName;
	}
 
	/**
	 * 重寫toString()方法
	 */
	@Override
	public String toString(){
		return userName+"一共賺了"+counts+"錢";
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public double getSalary() {
		return salary;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}
	public String getJob() {
		return job;
	}
	public void setJob(String job) {
		this.job = job;
	}
	public int getJobTypeId() {
		return jobTypeId;
	}
	public void setJobTypeId(int jobTypeId) {
		this.jobTypeId = jobTypeId;
	}
 
	public File getContext() {
		return context;
	}
 
	public void setContext(File context) {
		this.context = context;
	}
 
	public File getPic() {
		return pic;
	}
 
	public void setPic(File pic) {
		this.pic = pic;
	}
 
	public double getCounts() {
		return counts;
	}
 
	public void setCounts(double counts) {
		this.counts = counts;
	}
	
}

package com.panli.dao;
 
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.Types;
import java.util.ArrayList;
import java.util.List;
 
import com.panli.dbutil.DbUtil;
import com.panli.model.CEmployee;
 
public class CountsEmployeeDao {
	private static DbUtil dbUtil = new DbUtil();
	/**
	 * 調用存儲過程獲得指定ID用戶的一共賺了多少錢
	 * @param employee
	 * @return
	 * @throws Exception
	 */
	public static List getCountsById(CEmployee cemployee)throws Exception{
		List list = new ArrayList();
		Connection conn = dbUtil.getCon();
		String sql = "{call pro_getCountById(?, ?, ?)}";
		CallableStatement cstmt = conn.prepareCall(sql);
		cstmt.setInt(1, cemployee.getId());
		cstmt.registerOutParameter(2, Types.DOUBLE);
		cstmt.registerOutParameter(3, Types.VARCHAR);
		cstmt.execute();
		double counts = cstmt.getDouble("counts");
		String userNames = cstmt.getString("userNames");
		CEmployee emp = new CEmployee(counts, userNames);
		list.add(emp);
		dbUtil.close(cstmt, conn);
		return list;
	}
	/**
	 * 作測試的主方法
	 * @param args
	 */
	public static void main(String[] args)throws Exception {
		
		CEmployee cemployee = new CEmployee(1);
		List list = getCountsById(cemployee);
		for(CEmployee cemp: list){
			System.out.println(cemp);
		}
	}
}

建立的存儲過程爲：

delimiter &&
create procedure pro_getCountById(in tid int, out counts double, out userNames varchar(20))
begin
  select salary*tyear into counts from t_employee where id = tid;
  select userName into userNames from t_employee where id = tid;
end
&&
 
測試：
call pro_getCountById(1, @counts, @userNames);
select @counts, @userNames;