mybatis之DAO层自动实现接口

* 使用mybatis举例，使用DAO接口方式实现
* 不需要针对接口去编写具体的实现类代码，编写映射XML文件，直接拿来使用即可。
* 1、导入jar包：mybatis和mysql-connector
* 2、mybatis配置文件：mybatis-config.xml，加载映射XML文件
* 3、编写JavaBean类，如UserBean
* 4、编写DAO接口和映射XML文件（namespace=DAO接口文件路径、id=接口方法名）

mybatis-config-dao.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>
    <!--从外部配置文件导入jdbc信息-->
    <properties resource="jdbc.properties"></properties>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

    <!--指定映射资源文件-->
    <mappers>
        <mapper resource="dao/DaoMapper.xml"/>

    </mappers>
</configuration>

DaoMapper.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">

<mapper namespace="dao.UserDao">
    <!--id：名称； parameterType传入参数类型； resultType：返回数据类型-->
    <select id="selectOneUser" parameterType="int" resultType="bean.User">
        select * from user where id = #{id}
    </select>

    <!--批量查询-->
    <select id="selectAllUser" resultMap="userList">
        select * from user
    </select>
    <resultMap type="bean.User" id="userList">
        <result property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
    </resultMap>

    <insert id="insertUser" useGeneratedKeys="true" keyProperty="id">
        insert into user (id, name, age) values (#{id} ,#{name}, #{age})
    </insert>

    <update id="updateUser">
      update user set name=#{name},age=#{age} where id=#{id}
   </update>

    <delete id="deleteUser">
        delete from user where id=#{id}
    </delete>

    <!-- 传入多个参数时，自动转换为map形式 -->
    <insert id="insertByColumns" useGeneratedKeys="true" keyProperty="id">
        insert into user (id, name, age) values (NULL ,#{param1}, #{param2})
    </insert>
    <insert id="insertByZhuJie" useGeneratedKeys="true" keyProperty="id">
        insert into user (id, name, age) values (NULL ,#{name}, #{age})
    </insert>
    <insert id="insertByMap" useGeneratedKeys="true" keyProperty="id">
        insert into user (id, name, age) values (NULL ,#{name}, #{age})
    </insert>

</mapper>

UserDao.java

package dao;

import bean.User;
import org.apache.ibatis.annotations.Param;


import java.util.List;
import java.util.Map;

/*
* 使用mybatis举例，使用DAO接口方式实现
* 不需要针对UserMapperI接口去编写具体的实现类代码，这个具体的实现类由MyBatis帮我们动态构建出来，我们只需要直接拿来使用即可。
* */
public interface UserDao {

    // 根据id查询单一数据
    public User selectOneUser(int id);

    // 查询所有用户
    public List<User> selectAllUser();

    // 插入数据
    public int insertUser(User user);

    // 修改用户
    public int updateUser(User user);

    // 删除用户
    public int deleteUser(User user);

    // 插入数据；多参数三种方式：默认Map、使用Map传参和使用注解别名
    public int insertByColumns(String name, int age);
    public int insertByZhuJie(@Param("name") String name, @Param("age") int age);
    public int insertByMap(Map map);

}

TestDao.java

package dao;

import bean.User;
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 org.junit.After;
import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;

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

/*
* 使用mybatis举例，使用DAO接口方式实现
* 不需要针对接口去编写具体的实现类代码，编写映射XML文件，直接拿来使用即可。
* 1、导入jar包：mybatis和mysql-connector
* 2、mybatis配置文件：mybatis-config.xml，加载映射XML文件
* 3、编写JavaBean类，如UserBean
* 4、编写DAO接口和映射XML文件（namespace=DAO接口文件路径、id=接口方法名）
* */
public class TestDao {
    String resource = "mybatis-config-dao.xml";
    SqlSessionFactory sqlSessionFactory = null;
    SqlSession session = null;

    @Before
    public void before() {
//        System.out.println("Before");
        try {
            InputStream inputStream = Resources.getResourceAsStream(resource);
//            创建工厂
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//            创建session对象
            session = sqlSessionFactory.openSession();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @After
    public void close() {
        session.close();
//        System.out.println("After");
    }

    @Test
    public void testSelectOneUser() {
//        接口自动实例化
        UserDao userDao = session.getMapper(UserDao.class);
//        执行sql
        User user = userDao.selectOneUser(1);
        System.out.println(user);
    }

    //    批量查询
    @Test
    public void testSelectAllUser() {
//        接口自动实例化
        UserDao userDao = session.getMapper(UserDao.class);
//        执行sql
        List<User> listUser = userDao.selectAllUser();
        System.out.println("记录个数：" + listUser.size());
        System.out.println(listUser);
    }

    //   插入数据
    @Ignore
    @Test
    public void testInsertUser() {
        UserDao userDao = session.getMapper(UserDao.class);
        User user = new User("AA", "29");
        int n = userDao.insertUser(user);
        session.commit();
        System.out.println("插入数据：" + user);
        System.out.println(n);
    }

    // 修改数据
    @Ignore
    @Test
    public void testUpdateUser() {
        UserDao userDao = session.getMapper(UserDao.class);
        User user = new User(2, "Tom5", "29");
        int n = userDao.updateUser(user);
        session.commit();
        System.out.println("修改数据：" + user);
        System.out.println(n);
    }

    // 修改数据
    @Ignore
    @Test
    public void testDeleteUser() {
        UserDao userDao = session.getMapper(UserDao.class);
        User user = new User(13, "XX", "XX");
        int n = userDao.deleteUser(user);
        session.commit();
        System.out.println("删除数据：" + user);
        System.out.println(n);
    }

    //   多参数插入数据的三种方式
    @Ignore
    @Test
    public void testInsertByColumns() {
        UserDao userDao = session.getMapper(UserDao.class);
        String name = "insertByColumns";
        int age = 33;
//        int n = userDao.insertByColumns(name, age);
//        int n = userDao.insertByZhuJie(name, age);

        Map map = new HashMap();
        map.put("name", name);
        map.put("age", age);
        int n = userDao.insertByMap(map);

        session.commit();
        System.out.println("插入数据name：" + name);
        System.out.println(n);
    }


}

User.java

package bean;

/**
 * 数据封装类
 * JavaBean
 */
public class User {
    private int id;
    private String name;
    private String age;

    public User() {

    }

    public User(String name, String age) {
        this.name = name;
        this.age = age;
    }
    public User(int id, String name, String age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "User{id：" + id + "; 姓名：" + name + "; 年龄：" + age + "}";
    }
}