[增删改查] 之 JDBC 基本 CRUD、调用储存过程

继续总结 Java 后台的工作1

前言

对数据库的 CRUD 操作，有一定的历史了
① JDBC -> ② DBUtils -> ③ JdbcTemplate -> ④ -> Hibernate -> ⑤ MyBatis -> ⑥ JPA+SpringData ，.... 等
用了那么多的 dao 层的框架，以亲身体会各自优缺点，寻求项目的 dao 最佳方案。

但框架会用就好，基础才是最重要

Java 后台，从学习，到参赛、做项目，已一年有余。
最近投身于 IT行业 其他有趣的方向，如 人工智能、大数据、爬虫 等

投身后，觉得有必要先对 Java后台 做点小结
也可以供萌新参看，这次是 JDBC

代码

talk is cheap show me the code

package com.cun.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.junit.Test;

/**
 * 通用 CRUD
 * @author linhongcun
 *
 */
public class CRUD {

    /**
     * 连接
     * @return
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    Connection getConnection() throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection(
                // ?useUnicode=true&characterEncoding=utf-8解决中文乱码
                "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8", "root", "123");
        return conn;
    }

    /**
     * 断开
     * @param stat
     * @param conn
     * @throws SQLException
     */
    void close(PreparedStatement stat, Connection conn) throws SQLException {
        stat.close();
        conn.close();
    }

    /**
     * 1、查
     * 模拟定量查询
     * @throws ClassNotFoundException 
     * @throws SQLException 
     */
    @Test
    public void select() throws ClassNotFoundException, SQLException {
        String sql = "select * from t_user limit ?,?";
        Connection conn = getConnection();
        PreparedStatement stat = conn.prepareStatement(sql);
        // 查询从第条记录起3，连续3条记录
        stat.setInt(1, 2);
        stat.setInt(2, 3);
        ResultSet rs = stat.executeQuery();
        while (rs.next()) {
            System.out.println(rs.getString("id") + "-" + rs.getString("user_name") + "-" + rs.getString("password"));
        }
        // 释放资源
        close(stat, conn);
    }

    /**
     * 2、改
     * 模拟重置密码
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    @Test
    public void update() throws ClassNotFoundException, SQLException {
        String sql = "update t_user set password=? where user_name=?";
        Connection conn = getConnection();
        PreparedStatement stat = conn.prepareStatement(sql);
        stat.setString(1, "777");
        stat.setString(2, "张无忌");
        int rs = stat.executeUpdate();
        if (rs != 0) {
            System.out.println("更新成功");
        } else {
            System.out.println("更新失败");
        }
        // 释放资源
        close(stat, conn);
    }

    /**
     * 3、增
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    @Test
    public void add() throws ClassNotFoundException, SQLException {
        String sql = "insert into t_user(user_name,password) values(?,?)";
        Connection conn = getConnection();
        PreparedStatement stat = conn.prepareStatement(sql);
        stat.setString(1, "张无忌");
        stat.setString(2, "456");
        int rs = stat.executeUpdate();
        if (rs == 1) {
            System.out.println("插入成功");
        } else {
            System.out.println("插入失败");
        }
        // 释放资源
        close(stat, conn);
    }

    /**
     * 4、删
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    @Test
    public void delete() throws ClassNotFoundException, SQLException {
        String sql = "delete from t_user where id=2";
        Connection conn = getConnection();
        PreparedStatement stat = conn.prepareStatement(sql);
        int rs = stat.executeUpdate();
        if (rs == 1) {
            System.out.println("删除成功");
        } else {
            System.out.println("删除失败");
        }
        // 释放资源
        close(stat, conn);
    }

    /**
     * 5、批量插入
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    @Test
    public void adds() throws ClassNotFoundException, SQLException {
        Connection conn = getConnection();
        conn.setAutoCommit(false);
        String sql = "insert into t_user(user_name,password) values(?,?)";
        PreparedStatement stat = conn.prepareStatement(sql);
        for (int i = 1; i < 10; i++) {
            stat.setString(1, "令狐冲" + i);
            stat.setInt(2, i);
            stat.addBatch();
        }
        stat.executeBatch();
        conn.commit();
        // 释放资源
        close(stat, conn);
    }

    /**
     * 6、调用储存过程（查）
     * @throws ClassNotFoundException
     * @throws SQLException
     */
    @Test
    public void pro() throws ClassNotFoundException, SQLException {
        Connection conn = getConnection();
        String sql = "CALL `prc_test3`;";
        PreparedStatement stat = conn.prepareStatement(sql);
        ResultSet rs = stat.executeQuery();
        while (rs.next()) {
            System.out.println(rs.getString("id") + "-" + rs.getString("user_name") + "-" + rs.getString("password"));
        }
        // 释放资源
        close(stat, conn);
    }

}

其他

笔者不喜欢长篇议论各个知识及其用法，华而不实。
具体参见代码、注释

涉及到的存储过程（如果是使用 Oracle/sqlserver，语法还是有区别的）

①删除

DROP PROCEDURE IF EXISTS `prc_test3`;

②创建

CREATE  PROCEDURE `prc_test3`()
BEGIN
    select * from t_user;
END;

③执行

CALL `prc_test3`;