【java】jdbc的使用从0开始（一）

1.首先导入jar包

导入后右键点击add library让其添加进去。

2.在src目录下新建file，db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf8&useSSL=true
username=root
password=123456

3.新建jdbc utils工具类

package com.xmut.zeng.lesson01.utils;

import com.mysql.jdbc.Driver;

import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class JdbcUtils {

    private static  String driver =null;
    private static  String url =null;
    private static  String username =null;
    private static  String password =null;
    static {
        try {
           InputStream in = JdbcUtils.class.getClassLoader().getResourceAsStream("db.properties");
            Properties properties = new Properties();
            properties.load(in);

            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            username = properties.getProperty("username");
            password = properties.getProperty("password");

            //加载驱动 驱动只需要加载一次
            Class.forName(driver);


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


    }
    //获取连接
    public static Connection getConnection() throws SQLException {
           return DriverManager.getConnection(url,username,password);
    }

    //释放   要注意顺序  后执行的先关闭
    public static void release(Connection conn, Statement st, ResultSet rs){
        if (rs!=null){
            try {
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (st!=null){
            try {
                st.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (conn!=null){
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }


}

4.新建插入测试类TestInsert.java

package com.xmut.zeng.lesson01;

import com.xmut.zeng.lesson01.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestInsert {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
             conn = JdbcUtils.getConnection();//获取数据库连接
             st =  conn.createStatement();  //获得sql执行对象
             String sql = "INSERT INTO users (`id`,`NAME`,`PASSWORD`,`email`,`birthday`)" +
                     "VALUES (4,'zss','123','123456@qq.com','2001-12-30')";
             int i  = st.executeUpdate(sql);
             if (i>0){
                 System.out.println("插入成功 "+i+" 条数据");
             }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

执行结果：

在数据库中成功插入一条数据

5、新建删除测试类Delete

package com.xmut.zeng.lesson01;

import com.xmut.zeng.lesson01.utils.JdbcUtils;

import javax.swing.plaf.nimbus.State;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestDelete {

    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try{
            conn = JdbcUtils.getConnection();//连接数据库
            st  = conn.createStatement(); //获取sql对象

            String sql = "DELETE FROM users WHERE id=1";  //sql语句
            int i =st.executeUpdate(sql); //执行删除操作
            if (i>0){
                System.out.println("成功删除"+i+"条数据");
            }
        }catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            //释放
            JdbcUtils.release(conn,st,rs);
        }

    }
}

执行结果：


数据库表中id为1的数据已被删除。

6、新建测试类更新update

package com.xmut.zeng.lesson01;

import com.xmut.zeng.lesson01.utils.JdbcUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestUpdate {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            conn = JdbcUtils.getConnection();//连接数据库

            st = conn.createStatement(); //获取sql对象

            String sql = "UPDATE users SET email='111@qq.com' WHERE id=4";
            int i =  st.executeUpdate(sql);
            if (i>0){
                System.out.println("更新成功"+i+"条数据");
            }

        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

执行结果：

6、新建测试类 查询TestSelect

package com.xmut.zeng.lesson01;

import com.xmut.zeng.lesson01.utils.JdbcUtils;

import javax.swing.plaf.nimbus.State;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestSelect {
    public static void main(String[] args) {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;

        try {
            conn = JdbcUtils.getConnection();//数据库的连接

            st = conn.createStatement();
            String sql = "select * from users";
            rs = st.executeQuery(sql);

            while (rs.next()){
                System.out.println(rs.getString("NAME"));
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            JdbcUtils.release(conn,st,rs);
        }
    }
}

执行结果：