存儲過程的實驗

時間 2019-11-13

標籤存儲過程實驗简体版

原文原文鏈接

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。java

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

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。sql

CallableStatement接口中經常使用的方法。數據庫

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。app

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

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。測試

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

1 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。code

JDBC代碼：

  1 package com.panli.dbutil;
  2 /**
  3  * 鏈接數據庫
  4  */
  5 import java.sql.CallableStatement;
  6 import java.sql.Connection;
  7 import java.sql.DriverManager;
  8 import java.sql.PreparedStatement;
  9 import java.sql.ResultSet;
 10 import java.sql.SQLException;
 11 import java.sql.Statement;
 12   
 13 public class DbUtil {
 14     //數據庫驅動名字
 15     private static String jdbcName = "com.mysql.jdbc.Driver";
 16     //數據庫協議地址
 17     private static String dbUrl = "jdbc:mysql://localhost:3306/db_user";
 18     //數據庫用戶名
 19     private static String dbUser = "root";
 20     //數據庫密碼
 21     private static String dbPassword = "123456";
 22      
 23      
 24     /**
 25      * 獲取鏈接
 26      * @return
 27      * @throws Exception
 28      */
 29     public static Connection getCon() throws Exception{
 30         Class.forName(jdbcName);
 31         Connection conn = DriverManager.getConnection(dbUrl, dbUser, dbPassword);
 32         return conn;
 33     }
 34      
 35     /**
 36      * 關閉鏈接
 37      * @param stmt
 38      * @param conn
 39      * @throws Exception
 40      */
 41     public static void close(Statement stmt,Connection conn) throws Exception{
 42         if(stmt!=null){
 43             stmt.close();
 44             if(conn!=null){
 45                 conn.close();
 46             }
 47         }
 48     }
 49      
 50     /**
 51      * 關閉鏈接
 52      * @param cstmt
 53      * @param conn
 54      * @throws Exception
 55      */
 56     public static void close(CallableStatement cstmt, Connection conn) throws Exception{
 57         if(cstmt!=null){
 58             cstmt.close();
 59             if(conn!=null){
 60                 conn.close();
 61             }
 62         }
 63     }
 64      
 65      
 66     /**
 67      * 關閉鏈接
 68      * @param pstmt
 69      * @param conn
 70      * @throws SQLException
 71      */
 72     public static void close(PreparedStatement pstmt, Connection conn) throws SQLException{
 73         if(pstmt!=null){
 74             pstmt.close();
 75             if(conn!=null){
 76                 conn.close();
 77             }
 78         }
 79     }
 80      
 81      
 82     /**
 83      * 重載關閉方法
 84      * @param pstmt
 85      * @param conn
 86      * @throws Exception
 87      */
 88     public void close(ResultSet rs,PreparedStatement pstmt, Connection conn) throws Exception{
 89         if(rs!=null){
 90             rs.close();
 91             if(pstmt!=null){
 92                 pstmt.close();
 93                 if(conn!=null){
 94                     conn.close();
 95                 }
 96                  
 97             }
 98         }
 99          
100     }
101 }

  1 package com.panli.model;
  2   
  3 import java.io.File;
  4   
  5 /**
  6  * model包下的cemployee類,對每一個字段進行建模
  7  * @author Peter
  8  *
  9  */
 10 public class CEmployee {
 11     private int id;
 12     private String userName;
 13     private double salary;
 14     private String job;
 15     private int jobTypeId;
 16     private File context;
 17     private File pic;
 18     private double counts;
 19     /**
 20      * 默認的構造方法
 21      */
 22     public CEmployee() {
 23         super();
 24         // TODO Auto-generated constructor stub
 25     }
 26      
 27     /**
 28      * 帶一個參數的構造方法
 29      * @param id
 30      */
 31     public CEmployee(int id) {
 32         super();
 33         this.id = id;
 34     }
 35      
 36     /**
 37      * 兩個參數的構造方法
 38      * @param counts
 39      * @param userNames
 40      */
 41     public CEmployee(double counts, String userName) {
 42         // TODO Auto-generated constructor stub
 43         this.counts = counts;
 44         this.userName = userName;
 45     }
 46   
 47     /**
 48      * 重寫toString()方法
 49      */
 50     @Override
 51     public String toString(){
 52         return userName+"一共賺了"+counts+"錢";
 53     }
 54     public int getId() {
 55         return id;
 56     }
 57     public void setId(int id) {
 58         this.id = id;
 59     }
 60     public String getUserName() {
 61         return userName;
 62     }
 63     public void setUserName(String userName) {
 64         this.userName = userName;
 65     }
 66     public double getSalary() {
 67         return salary;
 68     }
 69     public void setSalary(double salary) {
 70         this.salary = salary;
 71     }
 72     public String getJob() {
 73         return job;
 74     }
 75     public void setJob(String job) {
 76         this.job = job;
 77     }
 78     public int getJobTypeId() {
 79         return jobTypeId;
 80     }
 81     public void setJobTypeId(int jobTypeId) {
 82         this.jobTypeId = jobTypeId;
 83     }
 84   
 85     public File getContext() {
 86         return context;
 87     }
 88   
 89     public void setContext(File context) {
 90         this.context = context;
 91     }
 92   
 93     public File getPic() {
 94         return pic;
 95     }
 96   
 97     public void setPic(File pic) {
 98         this.pic = pic;
 99     }
100   
101     public double getCounts() {
102         return counts;
103     }
104   
105     public void setCounts(double counts) {
106         this.counts = counts;
107     }
108      
109 }

 1 package com.panli.dao;
 2   
 3 import java.sql.CallableStatement;
 4 import java.sql.Connection;
 5 import java.sql.Types;
 6 import java.util.ArrayList;
 7 import java.util.List;
 8   
 9 import com.panli.dbutil.DbUtil;
10 import com.panli.model.CEmployee;
11   
12 public class CountsEmployeeDao {
13     private static DbUtil dbUtil = new DbUtil();
14     /**
15      * 調用存儲過程獲得指定ID用戶的一共賺了多少錢
16      * @param employee
17      * @return
18      * @throws Exception
19      */
20     public static List getCountsById(CEmployee cemployee)throws Exception{
21         List list = new ArrayList();
22         Connection conn = dbUtil.getCon();
23         String sql = "{call pro_getCountById(?, ?, ?)}";
24         CallableStatement cstmt = conn.prepareCall(sql);
25         cstmt.setInt(1, cemployee.getId());
26         cstmt.registerOutParameter(2, Types.DOUBLE);
27         cstmt.registerOutParameter(3, Types.VARCHAR);
28         cstmt.execute();
29         double counts = cstmt.getDouble("counts");
30         String userNames = cstmt.getString("userNames");
31         CEmployee emp = new CEmployee(counts, userNames);
32         list.add(emp);
33         dbUtil.close(cstmt, conn);
34         return list;
35     }
36     /**
37      * 作測試的主方法
38      * @param args
39      */
40     public static void main(String[] args)throws Exception {
41          
42         CEmployee cemployee = new CEmployee(1);
43         List list = getCountsById(cemployee);
44         for(CEmployee cemp: list){
45             System.out.println(cemp);
46         }
47     }
48 }

建立的存儲過程爲：

 1 delimiter &&
 2 create procedure pro_getCountById(in tid int, out counts double, out userNames varchar(20))
 3 begin
 4   select salary*tyear into counts from t_employee where id = tid;
 5   select userName into userNames from t_employee where id = tid;
 6 end
 7 &&
 8   
 9 測試：
10 call pro_getCountById(1, @counts, @userNames);
11 select @counts, @userNames;