Mybatis第一个入门案例

1.导入Jar包

mybatis-3.4.4.jar

mysql-connector-java-8.0.11.jar

2.编写Mybatis的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!-- 这个是配置数据库的信息 -->
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///dt48_mybatis?serverTimezone=GMT"/>
                <property name="username" value="root"/>
                <property name="password" value="zhangpn"/>
            </dataSource>
        </environment>
    </environments>
    
    
    <!-- 关联局部配置文件 -->
    <mappers>
        <mapper resource="cn/java/dao/impl/UserDaoImpl.xml"/>
    </mappers>
</configuration>

3.创建一个pojo类

 1 /**
 2  * Project Name:dt48_mybatis1
 3  * File Name:User.java
 4  * Package Name:cn.java.entity
 5  * Date:下午4:03:45
 6  * Copyright (c) 2017, bluemobi All Rights Reserved.
 7  *
 8 */
 9 
10 package cn.java.entity;
11 
12 public class User {
13     private Long id;// 主键
14 
15     private String username;// 用户名
16 
17     private String password;// 密码
18 
19     public Long getId() {
20         return id;
21     }
22 
23     public void setId(Long id) {
24         this.id = id;
25     }
26 
27     public String getUsername() {
28         return username;
29     }
30 
31     public void setUsername(String username) {
32         this.username = username;
33     }
34 
35     public String getPassword() {
36         return password;
37     }
38 
39     public void setPassword(String password) {
40         this.password = password;
41     }
42 
43     @Override
44     public String toString() {
45         return "User [id=" + id + ", username=" + username + ", password=" + password + "]";
46     }
47 }

User的POJO类

4.编写一个局部配置文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE mapper
 3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 
 6 <mapper namespace="cn.java.dao.impl.UserDaoImpl">
 7 
 8     <select id="getAllUser" resultType="cn.java.entity.User">
 9         SELECT * FROM users
10     </select>
11     
12     <!-- 
13         select语句返回List<Map<String,Object>
14      -->
15     <select id="getAllUser22" resultType="Map">
16         SELECT * FROM users
17     </select>
18 </mapper>

5.调用执行测试结果

/**
 * Project Name:dt48_mybatis1
 * File Name:UserDaoImpl.java
 * Package Name:cn.java.dao.impl
 * Date:下午3:39:43
 * Copyright (c) 2017, bluemobi All Rights Reserved.
 *
*/

package cn.java.dao.impl;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Map;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import cn.java.entity.User;
import sun.applet.Main;

/**
 * Description: <br/>
 * Date: 下午3:39:43 <br/>
 * 
 * @author dingP
 * @version
 * @see
 */
public class UserDaoImpl {
	
	
	public static void main(String[] args) throws IOException {
        SqlSessionFactoryBuilder sfb = new SqlSessionFactoryBuilder();
        // 将mybatis.xml文件转化成流
        InputStream ins = Resources.getResourceAsStream("mybatis.xml");
        SqlSessionFactory ssf = sfb.build(ins);
        SqlSession session = ssf.openSession();
        // 2、调用局部配置文件中的sql语句
        List<User> userList = session.selectList("cn.java.dao.impl.UserDaoImpl.getAllUser");
        for (User user : userList) {
            System.out.println(user);
        }
	}
	
	
    public void getAllUser() throws IOException {
        // 1、启动mybatis框架
        // SqlSession---->SqlSessionFactory---->SqlSessionFactoryBuilder
        SqlSessionFactoryBuilder sfb = new SqlSessionFactoryBuilder();
        // 将mybatis.xml文件转化成流
        InputStream ins = Resources.getResourceAsStream("mybatis.xml");
        SqlSessionFactory ssf = sfb.build(ins);
        SqlSession session = ssf.openSession();
        // 2、调用局部配置文件中的sql语句
        List<User> userList = session.selectList("cn.java.dao.impl.UserDaoImpl.getAllUser");
        for (User user : userList) {
            System.out.println(user);
        }
    }

    public void getAllUser22() throws IOException {
        // 1、启动mybatis框架
        // SqlSession---->SqlSessionFactory---->SqlSessionFactoryBuilder
        SqlSessionFactoryBuilder sfb = new SqlSessionFactoryBuilder();
        // 将mybatis.xml文件转化成流
        InputStream ins = Resources.getResourceAsStream("mybatis.xml");
        SqlSessionFactory ssf = sfb.build(ins);
        SqlSession session = ssf.openSession();
        // 2、调用局部配置文件中的sql语句
        List<Map<String, Object>> userList = session.selectList("cn.java.dao.impl.UserDaoImpl.getAllUser22");
        for (Map<String, Object> map : userList) {
            System.out.println(map);
        }
    }
}