使用JDBC CallableStatements执行存储过程

使用JDBC CallableStatements执行存储过程

实验目的：掌握jdbc callableStatements 的执行过程。

实验内容：掌握jdbc callableStatements 的执行过程。

实验过程：

CallableStatement的所有超级接口为PreparedStatement、Statement、Wrapper。其中继承自PreparedStatement接口。CallableStatement主要是调用数据库中的存储过程。在使用CallableStatement时可以接收存储过程的返回值。CallableStatement对象为所有的DBMS提供了一种标准的形式去调用数据库中已存在的存储过程。对数据库中存储过程的调用是CallableStatement对象所含的内容。有两种形式：1：形式带结果参数；2：形式不带结果参数。结果参数是一种输出参数(存储过程中的输出OUT参数)，是存储过程的返回值。两种形式都有带有数量可变的输入、输出、输入和输出的参数。用问号做占位符。

形式带结果参数语法格式：{ ? = call 存储过程名[(?, ?, ?, ...)]};

形式不带结果参数语法格式：{ call 存储过程名[(?, ?, ?, ...)]};PS方括号里面的内容可有可无。

CallableStatement接口中常用的方法。

1：getInt(int parameterIndex)、getInt(String parameterName)、还有getString、getBigDecimal、getString、getDate、getURL等等都类似和PreparedStatement与Statement中的用法类似。

2：registerOutParameter(int parameterIndex, int sqlType):按顺序位置parameterIndex将OUT参数注册为JDBC类型sqlType。

3：wasNull():查询最后一个读取的OUT参数是否为SQL Null。等等还有很多方法，感兴趣的读者可以自行查阅JDK API文档。

讲解了那么多，不如一个例子来的痛快。下面通过一个例子让读者更清楚的看到CallableStatement的用法。

首先在原先的t_employee表中添加表示干了多少年的tyear字段。

alter table t_employee add tyear int;

在数据库中编写存储过程统计指定id的userName的人，输出一下他一共赚了多少钱。

JDBC代码：

 



package com.panli.dbutil;
/**
 * 连接数据库
 */
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 {
    //数据库驱动名字
    private static String jdbcName = "com.mysql.jdbc.Driver";
    //数据库协议地址
    private static String dbUrl = "jdbc:mysql://localhost:3306/db_user";
    //数据库用户名
    private static String dbUser = "root";
    //数据库密码
    private static String dbPassword = "123456";
     
     
    /**
     * 获取连接
     * @return
     * @throws Exception
     */
    public static Connection getCon() throws Exception{
        Class.forName(jdbcName);
        Connection conn = DriverManager.getConnection(dbUrl, dbUser, dbPassword);
        return conn;
    }
     
    /**
     * 关闭连接
     * @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();
            }
        }
    }
     
    /**
     * 关闭连接
     * @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();
            }
        }
    }
     
     
    /**
     * 关闭连接
     * @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();
            }
        }
    }
     
     
    /**
     * 重载关闭方法
     * @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类,对每个字段进行建模
 * @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;
    /**
     * 默认的构造方法
     */
    public CEmployee() {
        super();
        // TODO Auto-generated constructor stub
    }
     
    /**
     * 带一个参数的构造方法
     * @param id
     */
    public CEmployee(int id) {
        super();
        this.id = id;
    }
     
    /**
     * 两个参数的构造方法
     * @param counts
     * @param userNames
     */
    public CEmployee(double counts, String userName) {
        // TODO Auto-generated constructor stub
        this.counts = counts;
        this.userName = userName;
    }
  
    /**
     * 重写toString()方法
     */
    @Override
    public String toString(){
        return userName+"一共赚了"+counts+"钱";
    }
    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();
    /**
     * 调用存储过程得到指定ID用户的一共赚了多少钱
     * @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;
    }
    /**
     * 做测试的主方法
     * @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);
        }
    }
}

创建的存储过程为：

 



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
&&
  
测试：
call pro_getCountById(1, @counts, @userNames);
select @counts, @userNames;

1	`alter table t_employee add tyear` `int;`

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posted on 2019-06-08 17:12 辉夜星阅读(557) 评论(0) 收藏举报