JDBC 配置工具类，以及增删改查(一)

序一：先导入mysql驱动jar包，创建数据库jdbc,建表user（字段：id，name）
1.创建一个jdbc.properties文件
driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/jdbc
user=root
password=12345

2.创建jdbcUtils工具类
package com.xdl.jdbc.hello;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ResourceBundle;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;

public class jdbcUtils {
static final String DRIVERCLASS;
static final String URL;
static final String USER;
static final String PASSWORD;
static {
//获取ResourceBunle
ResourceBundle bundle = ResourceBundle.getBundle("jdbc");
//获取指定的内容
DRIVERCLASS=bundle.getString("driverClass");
URL=bundle.getString("url");
USER=bundle.getString("user");
PASSWORD=bundle.getString("password");

}
static {
    //注册驱动
    try {
        Class.forName(DRIVERCLASS);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
}
//获取连接
public static Connection getConnection() throws Exception {
    //获取连接
    return (Connection) DriverManager.getConnection(URL,USER,PASSWORD);
}
/**
 * 释放资源
 * @param conn 连接
 * @param st 语句执行者
 * @param rs 结果集
 */
public static void closeResource(Connection conn,Statement st,ResultSet rs) {
    closeResultSet(rs);
    closeStatement(st);
    closeConn(conn);
}
//释放连接
public static void  closeConn(Connection conn) {
    if(conn!=null) {
        try {
            conn.close();
        } catch (SQLException e) {
            
            e.printStackTrace();
        }
        conn=null;
    }
}
//释放语句执行者
public static void  closeStatement(Statement st) {
    if(st!=null) {
        try {
            st.close();
        } catch (SQLException e) {  
            e.printStackTrace();
        }
            st=null;
    }
}
//释放結果集
public static void  closeResultSet(ResultSet rs) {
    if(rs!=null) {
        try {
            rs.close();
        } catch (SQLException e) {
                
            e.printStackTrace();
        }
        rs=null;
    }
}

}

3.创建测试类
package com.xdl.jdbc.hello;
import java.sql.DriverManager;
import java.sql.ResultSet;
import org.junit.Test;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;

public class hello {
@Test
public void insert() throws Exception {//增加操作
Connection conn=null;
ResultSet rs=null;
PreparedStatement st=null;
try {
//获取连接
conn=jdbcUtils.getConnection();
//编写sql
String sql="insert into user(id,name) values(?,?)";
//获取语句执行者
st= (PreparedStatement)conn.prepareStatement(sql);
//设置参数
st.setString(1, "008");
st.setString(2, "测试");
//执行sql
int i=st.executeUpdate();
System.out.println(i);
//处理结果
if(i==1) {
System.out.println("执行成功");
}else {
System.out.println("执行失败");
}
} catch (Exception e) {
e.printStackTrace();
}finally {
jdbcUtils.closeResource(conn, st, rs);
}

}

@Test
public void update() {
Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;

    try {
        conn=jdbcUtils.getConnection();
        String sql="update user set name= ? where id= ?";
        st=(PreparedStatement) conn.prepareStatement(sql);
        st.setString(1, "手机");//赋给第一个问号name的值
        st.setString(2, "003");//赋给第二个问号id的值
        int i=st.executeUpdate();
        if(i==1) {
            System.out.println("执行成功");
        }else {
            System.out.println("执行失败");
        }
    } catch (Exception e) {
        e.printStackTrace();
    }finally{
        //释放资源
        jdbcUtils.closeResource(conn, st, rs);
    }
}

@Test
public void delete() {//删除
Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;

    try {
        conn=jdbcUtils.getConnection();
        String sql="delete from user where id= ? ";
        st=(PreparedStatement) conn.prepareStatement(sql);
        st.setString(1, "003");//赋给id的值
        int i=st.executeUpdate();
        if(i==1) {
            System.out.println("执行成功");
        }else {
            System.out.println("执行失败");
        }
    } catch (Exception e) {
        e.printStackTrace();
    }finally{
        //释放资源
        jdbcUtils.closeResource(conn, st, rs);
    }
}

}
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