JDBC_通用增删改操作

原视频地址:https://www.bilibili.com/video/av67955358?p=17

使用Statement操作数据表的弊端:

1.存在拼串操作,比较繁琐

2.存在SQL注入问题

PreparedStatement是Statement的子接口

先将资源关闭与获取的方式封装到一个类中:

package day1;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

import org.junit.jupiter.api.Test;



public class JUnittext {
    
     @Test
     public void connectiontest1() throws SQLException {
         Driver driver = new com.mysql.jdbc.Driver();
        
        String url = "jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8";
        Properties info = new Properties();
        info.setProperty("user", "root");
        info.setProperty("password", "sqw991017");
        
        Connection conn = driver.connect(url, info);
        
        
        System.out.println(conn);
     }
     
    @Test
     public void connectiontest2() throws Exception {
          Class clazz = Class.forName("com.mysql.jdbc.Driver");
          Driver driver = (Driver) clazz.getDeclaredConstructor().newInstance();
            
          String url = "jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8";
          Properties info = new Properties();
          info.setProperty("user", "root");
          info.setProperty("password", "sqw991017");
            
           Connection conn = driver.connect(url, info);
            
            
           System.out.println(conn);
     }
    
    @Test
    public void connectiontest3() throws Exception {
        
        /*
         * Class clazz = Class.forName("com.mysql.jdbc.Driver"); Driver driver =
         * (Driver) clazz.getDeclaredConstructor().newInstance(); //注册驱动
         * DriverManager.registerDriver(driver);
         */
        
        String url = "jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8";
        String user = "root";
        String password = "sqw991017";
        
        Connection conn = DriverManager.getConnection(url, user, password);
        System.out.println(conn);
        
        
    }
    
    @Test
    public void connectiontest4() throws Exception {
        //读取配置文件的4个基本信息
        
        InputStream is = JUnittext.class.getClassLoader().getResourceAsStream("jdbc_properties");
        
        Properties pros = new Properties();
        pros.load(is);
        
        String user = pros.getProperty("user");
        String password = pros.getProperty("password");
        String url = pros.getProperty("url");
        String driverClass = pros.getProperty("driverClass");
        
        //2.加载驱动
        Class.forName(driverClass);
        
        
        //3 获取链接
        Connection conn = DriverManager.getConnection(url, user, password);
        
        System.out.println(conn);
        
    }
}

通用的增删改操作:

//1.获取链接

//2.预编译sql语句

//3.填充占位符

//4.执行

//5.关闭资源

@Test
    public void  testcommonupdatetest() {
        //Object test1 = new Object[]{3};
        String sql="delete from customers where id = ?";
        Update(sql,3);
    }
    



    //通用的增删改操作
    public void Update(String sql,Object ...args) {
        //1.获取链接
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            conn = JDBCutils.getConnection();
            
            //2.预编译sql语句
            ps = conn.prepareStatement(sql);
            
            //3.填充占位符
            for(int i=0;i<args.length;i++) {
                ps.setObject(i+1, args[i]);
            }
            
            //4.执行
            ps.execute();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            //5.关闭资源    
            JDBCutils.closeResource(conn, ps);
        }
        
    }

JDBC_通用增删改操作

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