[Articles] MyBatis a simple case .mybatis

Build mybatis

github源码(day52-mybatis)：https://github.com/1196557363/ideaMavenProject.git

1. dependence guide

<!-- junit依赖 -->
<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.11</version>
  <scope>test</scope>
</dependency>

<!-- mybatis依赖 -->
<dependency>
  <groupId>org.mybatis</groupId>
  <artifactId>mybatis</artifactId>
  <version>3.4.5</version>
</dependency>

<!-- MySQL数据库依赖 -->
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>5.1.6</version>
</dependency>

2. Create a table and profiles mybaits.xml

<?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>
    <!--环境-->
    <environments default="dev_mysql">
        <environment id="dev_mysql">
            <!--事务管理器-->
            <transactionManager type="JDBC"></transactionManager>
            <!--mybatis提供的连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis1" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    <!-- 映射接口 -->
    <mappers>
        <mapper resource="wpj/mapper/IUserDao.xml" />
    </mappers>
</configuration>

3. Define bean

public class User {
    private String name;
    private int age;
    public User() {
    }
    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

4. Write Interface

package wpj.dao;

import wpj.bean.*;
import java.util.*;

public interface IUserDao {
   	List<User> selectAllUser();
}

5. Write xml file corresponding to the interface IUserDao.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 命名空间与dao的全路径一致 -->
<mapper namespace="wpj.dao.IUserDao">
	<!-- id与接口中方法名一致 -->
   <select id="selectAllUser" resultType="wpj.bean.User">
       select * from user
   </select>
</mapper>

6. Test

public class MyBatisTest {

    @Test
    public void testAllUser() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2 获取sqlSession实例，能直接执行已经映射的sql语句
        SqlSession openSession = sqlSessionFactory.openSession();
        try {
            //sql唯一标识，sql要用的参数
            List<User> userList = openSession.selectList("wpj.dao.IUserDao.selectAllUser");
            for(User user : userList) {
                System.out.println(user);
            }
        } finally {
            openSession.close();
        }
    }
}