最简便的java-jdbc-mysql

0x001        环境介绍

编写环境：win10

编写工具:eclipse neon

jdk:1.8

数据库：mysql

数据表创建语句:

CREATE TABLE `score` (
   `id` int(11) NOT NULL AUTO_INCREMENT,
   `teacher_id` varchar(10) NOT NULL,
   `student_id` varchar(10) NOT NULL,
   `subject_id` varchar(10) NOT NULL,
   `score` int(11) DEFAULT NULL,
   PRIMARY KEY (`id`)
 ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8

0x002    这是案例代码

//这是help工具类

package com.utills.jdbc;
 
import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.mysql.jdbc.MySQLConnection;
import com.mysql.jdbc.StringUtils;

/*
 * jdbc
 * mybatis
 * */
public class MysqlHelper {	
	
	//先放这里，要做成注解配置文件的模式
	//不然这里有很多冗余代码 和 代码固化问题
	//没有写成实体类的模式
	static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
	//reacherdb 数据库名字
	static final String DB_URL = "jdbc:mysql://localhost:3306/reacherdb";
    // 数据库的用户名与密码，需要根据自己的设置
    static final String USER = "root";
    static final String PASS = "admin";
	
    private Connection conn;
    private Statement  smt;
 
    
    //初始化
	public MysqlHelper() throws SQLException {
		// TODO Auto-generated constructor stub
		conn = DriverManager.getConnection(DB_URL,USER,PASS);
		smt = conn.createStatement();
		
	}
	
	//写死的查询
	/* 
	public Object GetSelect(String sql) throws SQLException
	{
		if(StringUtils.isNullOrEmpty(sql))
		{
			return null;
		}
 
		List list = new ArrayList();
		ResultSet rs = smt.executeQuery(sql);
        while (rs.next()) {
              
             list.add(rs.getString("id"));
             list.add(rs.getString("teacher_id"));
             list.add(rs.getString("student_id"));
             list.add(rs.getString("subject_id"));
             list.add(rs.getString("score"));
         }
              
		return list;     
	}*/
	
	
	//可以写一个实体类进行获取
	//返回类型可以是list 或 map
	public List GetSelect1(String sql) throws SQLException
	{
		List list = new ArrayList();
		ResultSet rs = smt.executeQuery(sql);
		
        ResultSetMetaData md = rs.getMetaData();
        int columnCount = md.getColumnCount();

        while (rs.next()) {

            Map rowData = new HashMap();
            for (int i = 1; i <= columnCount; i++) {
            	
                rowData.put(md.getColumnName(i), rs.getObject(i));
            }

            list.add(rowData); 
        }

        return list;    //map 数据格式：{subject_id=2, score=75, teacher_id=2, student_id=2, id=1}
	}
	
	
	/*
	 * 执行update delete insert
	 * 这个只是一种写法
	 * */
	public int SqlExecute(String sql) throws SQLException
	{
		int retStatus = -1;
		
		if(StringUtils.isNullOrEmpty(sql))
		{
			return -1;
		}
	
		//返回执行条目数
		retStatus = smt.executeUpdate(sql);
		
		return retStatus;
	}
	
	//分页没做
	
	//做回收功能
	public void finalize(){
	     
	}
	
}

//测试主函数

package com.http.test;


 
import java.sql.SQLException;
import java.util.*;

import com.mysql.jdbc.SocketMetadata.Helper;
import com.utills.jdbc.*;;
 
public class HttpFunc {
	
    public static void main(String[] args) throws SQLException {  
    	 
    	MysqlHelper mysql = new MysqlHelper();
    	
    	String sql = "select * from reacherdb.score";
    	//List list = (List) mysql.GetSelect(sql);
    	List list = mysql.GetSelect1(sql);
    	
    	for(int i = 0; i < list.size(); i++)
    	{
    		System.out.println(list.get(i));
    	}
    	
    	//{subject_id=2, score=75, teacher_id=2, student_id=2, id=1}
    	String insertSql = "delete from reacherdb.score where teacher_id = 5";
    	//约定好返回值，这样才能更好的确认sql执行情况
    	int status = mysql.SqlExecute(insertSql);
    	if(-1 == status)
    	{
    		System.out.println("语句失败!");
    	}else{
    		System.out.println(status);
    	}
    }  
  
}