增删改查——QueryRunner类

Posted 2022-08-07 zhai1997

 

利用QueryRunner类实现对数据库的增删改查操作，需要先导入jar包：commons-dbutils-1.6。利用QueryRunner类可以实现对数据步骤的简化。

1、添加

 

运用JDBC工具类实现连接：

package JDBCUtils;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JDBCUtils 
    private static Connection con;
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    static // 静态代码块只执行一次，获取一次信息即可
        try 
            readConfig();
            Class.forName(driver);
            con = DriverManager.getConnection(url, username, password);
         catch (Exception ex) 
            throw new RuntimeException("数据库连接失败");
        
    
/*
 * getClassLoader();返回该类的加载器
 * getResourceAsStream();查找具有给定名称的资源 
 */
    private static void readConfig() 
        InputStream in = JDBCUtils.class.getClassLoader().getResourceAsStream("JDBC.properties");
        Properties pro = new Properties();
        try 
            pro.load(in);
         catch (IOException e) 
            e.printStackTrace();
        
        driver = pro.getProperty("driver");
        url = pro.getProperty("url");
        username = pro.getProperty("username");
        password = pro.getProperty("password");
    

    public static Connection getConnection() 
        return con;
    
    public static void close(Connection con) 

        if (con != null) 
            try 
                con.close();
             catch (SQLException e) 
                e.printStackTrace();
                System.out.println("con流关闭异常！");
            
        

    
    public static void close(Connection con, Statement stat) 

        if (stat != null) 
            try 
                stat.close();
             catch (SQLException e) 
                e.printStackTrace();
                System.out.println("stat流关闭异常！");
            
        

        if (con != null) 
            try 
                con.close();
             catch (SQLException e) 
                e.printStackTrace();
                System.out.println("con流关闭异常！");
            
        

    

    public static void close(Connection con, Statement stat, ResultSet rs) 
        if (rs != null) 
            try 
                rs.close();
             catch (SQLException e) 
                e.printStackTrace();
                System.out.println("rs流关闭异常！");
            
        

        if (stat != null) 
            try 
                stat.close();
             catch (SQLException e) 
                e.printStackTrace();
                System.out.println("stat流关闭异常！");
            
        

        if (con != null) 
            try 
                con.close();
             catch (SQLException e) 
                e.printStackTrace();
                System.out.println("con流关闭异常！");
            
        

import java.sql.Connection;
import java.sql.SQLException;
import org.apache.commons.dbutils.QueryRunner;

import JDBCUtils.JDBCUtils;

public class add 

    public static void main(String[] args) 
        Connection con = null;
        try 
            con = JDBCUtils.getConnection();
            QueryRunner qr = new QueryRunner();
            String sql = "INSERT INTO student(studentno,sname,sex,birthday,classno,point,phone,email) VALUES(?,?,?,?,?,?,?,?)";
            Object[] params =  "20191811", "Jack", "男", "1988-12-01",
                    "201901", "239", "16623540978", "[e-mail]" ;

            int num = qr.update(con, sql, params);
            System.out.println("添加了" + num + "行");

         catch (SQLException e) 
            throw new RuntimeException(e);
        
        JDBCUtils.close(con);
    

2、删除

import java.sql.Connection;
import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;

import JDBCUtils.JDBCUtils;

public class DeleteDemo 
    public static void main(String[] args) 
        Connection con = null;
        try 
            con = JDBCUtils.getConnection();
            QueryRunner qr = new QueryRunner();
            String sql = "DELETE from Student where sname =?";
            Object[] delete =  "Tom" ;
            qr.update(con, sql, delete);

         catch (SQLException e) 
            throw new RuntimeException(e);
        
        JDBCUtils.close(con);
    

3、修改

import java.sql.Connection;
import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;

import JDBCUtils.JDBCUtils;

public class UpdateDemo 
    public static void main(String[] args) 
        Connection con = null;
        try 
            con = JDBCUtils.getConnection();
            QueryRunner qr = new QueryRunner();
            String sql = "Update Student set classno=? Where sname=‘韩吟秋‘";
            Object[] update =  "201901" ;
            qr.update(con, sql, update);

         catch (SQLException e) 
            throw new RuntimeException(e);
        
        JDBCUtils.close(con);
    

4、查询

（1）

 ArrayHandler： 将结果集的第一行存储到Object[]数组中

ArrayListHandler： 将结果集的每一行存储到Object[]数组中

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayListHandler;

import JDBCUtils.JDBCUtils;

public class SeleteDemo 
    public static void main(String[] args) 
        Connection con = null;
        try 
            con = JDBCUtils.getConnection();
            QueryRunner qr = new QueryRunner();
            String sql = "Select * from Student where studentno=?";
            Object[] select =  20191811 ;
            List<Object[]> list = qr.query(con, sql, new ArrayListHandler(),
                    select);
            // 将记录封装到一个装有Object[]的List集合中
            for (Object[] arr : list) 
                System.out.println(Arrays.toString(arr));
            

         catch (SQLException e) 
            throw new RuntimeException(e);
        
        JDBCUtils.close(con);
    

（2）

BeanHandler：结果集中第一条记录封装到一个指定的javaBean中。

BeanListHandler：结果集中每一条记录封装到javaBean中，再将javaBean封装到list集合中。