Mybatis基于xml文件和注解的方式实现增删改查

整体目录结构：

基于XML文件实现

maven项目下添加mbatis和mysql的依赖包：
pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.lks</groupId>
    <artifactId>mybatis-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.12</version>
        </dependency>
        <dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>6.14.3</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

连接数据库，创建简单的users表：
sql语句

create database mybatis_demo;
use mybatis_demo;
CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(20), age INT, county VARCHAR(10))ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO users(name, age, county) VALUES('李寻欢', 30, '中国');
INSERT INTO users(name, age, county) VALUES('美国队长', 27, '美国');

创建User实体类实现序列化：
User.java

package com.lks.domain;

import java.io.Serializable;

/**
 * Created by likaisong on 2019/2/24.
 */
public class User implements Serializable {
    private int id;
    private String name;
    private int age;
    private String county;

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public String getCounty() {
        return county;
    }

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

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

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

    public void setCounty(String county) {
        this.county = county;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", age=" + age + ", county=" + county + "]";
    }
}

mybatis的配置文件：
mybatis-config.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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis_demo"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="userMapper.xml"/>
    </mappers>
</configuration>

数据库操作的配置文件：
mapper.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">
<!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的-->
<mapper namespace="userMapper">
    <!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，同一个namespace下id属性值必须是唯一的
    使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型-->
    <select id="getUser" parameterType="int"
            resultType="com.lks.domain.User">
        select * from users where id=#{id}
    </select>

    <!--useGeneratedKeys="true" keyProperty="id" 共同决定了sql执行后，会将主键封装到id属性上
　　自增主键封装到了对象的id属性上了，那么想要获取，直接调用对象的getId()方法-->
    <insert id="insertUser" parameterType="com.lks.domain.User"
            flushCache="true" useGeneratedKeys="true" keyProperty="id">
        insert into users (id,name,age,county)
        values (#{id},#{name},#{age},#{county})
    </insert>

    <update id="updateUser" parameterType="com.lks.domain.User" flushCache="true">
        update users set name = #{name} where id = #{id}
    </update>

    <delete id="deleteUser" parameterType="int" flushCache="true">
        delete from users where id = #{id}
    </delete>

</mapper>

pom.xml引入TestNg的依赖包，实现增删该查的测试：
TestMain.Java

package com.lks.test;

import com.lks.domain.User;
import com.lks.mapper.UserMapper;
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.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

import java.io.IOException;
import java.io.InputStream;

/**
 * Created by likaisong on 2019/2/24.
 */
public class TestMain {

    private static SqlSession getSqlSession(String resource){
        if (resource == null || "".equals(resource)){
            return null;
        }
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        return session;
    }
    @Test
    public static void testSelectByXml(){
        String resource = "mybatis-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            String statement = "userMapper.getUser";
            User user = session.selectOne(statement, 2);
            System.out.println(user);
        } finally {
            session.close();
        }
    }

    @Test
    public static void testInsertByXml(){
        String resource = "mybatis-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            String statement = "userMapper.insertUser";
            User user = new User();
            user.setName("阿飞");
            user.setAge(20);
            user.setCounty("中国");
            session.insert(statement, user);
            session.commit();
            System.out.println("插入数据后返回的自增ID：" + user.getId());
        } finally {
            session.close();
        }
    }

    @Test
    public static void testUpdateByXml(){
        String resource = "mybatis-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            String statement = "userMapper.updateUser";
            User user = new User();
            user.setId(1);
            user.setName("小李飞刀");
            session.update(statement, user);
            session.commit();
        } finally {
            session.close();
        }
    }

    @Test
    public static void testDeleteByXml(){
        String resource = "mybatis-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            //先增加一条数据
            String insertStatement = "userMapper.insertUser";
            User user = new User();
            user.setName("阿飞");
            user.setAge(20);
            user.setCounty("中国");
            session.insert(insertStatement, user);
            System.out.println("插入数据后返回的自增ID：" + user.getId());
            //再删掉刚刚加的数据
            String deleteStatement = "userMapper.deleteUser";
            session.delete(deleteStatement, user.getId());
            session.commit();
        } finally {
            session.close();
        }
    }
}

基于注解方式实现

mybatis配置文件：
mybatis-annotation-config.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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis_demo"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <package name="com.lks.mapper"/>
    </mappers>
</configuration>

映射Mapper接口：

package com.lks.mapper;

import com.lks.domain.User;
import org.apache.ibatis.annotations.*;

/**
 * Created by likaisong on 2019/2/24.
 */
public interface UserMapper {
    @Select("select * from users where id=#{id}")
    User getUser(int id);

    @Update("update users set name = #{name} where id = #{id}")
    void updateUser(User user);

    @Insert("insert into users (id,name,age,county) values (#{id},#{name},#{age},#{county})")
    @Options(useGeneratedKeys=true, keyProperty="id")
    void insertUser(User user);

    @Delete("delete from users where id = #{id}")
    void deleteUser(int id);
}

TestMain类中新增test方法：
TestMain.java

package com.lks.test;

import com.lks.domain.User;
import com.lks.mapper.UserMapper;
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.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

import java.io.IOException;
import java.io.InputStream;

/**
 * Created by likaisong on 2019/2/24.
 */
public class TestMain {
    private static SqlSession getSqlSession(String resource){
        if (resource == null || "".equals(resource)){
            return null;
        }
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        return session;
    }
    @Test
    public static void testSelectByAnnotation(){
        String resource = "mybatis-annotation-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            UserMapper mapper = session.getMapper(UserMapper.class);
            User user = mapper.getUser(1);
            System.out.println(user);
        } finally {
            session.close();
        }
    }

    @Test
    public static void testUpdateByAnnotation(){
        String resource = "mybatis-annotation-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            UserMapper mapper = session.getMapper(UserMapper.class);
            User user = new User();
            user.setId(2);
            user.setName("钢铁侠");
            mapper.updateUser(user);
            session.commit();
        } finally {
            session.close();
        }
    }

    @Test
    public static void testInsertByAnnotation(){
        String resource = "mybatis-annotation-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            UserMapper mapper = session.getMapper(UserMapper.class);
            User user = new User();
            user.setName("阿飞");
            user.setAge(20);
            user.setCounty("中国");
            mapper.insertUser(user);
            session.commit();
            System.out.println("插入数据后返回的自增ID：" + user.getId());
        } finally {
            session.close();
        }
    }

    @Test
    public static void testDeleteByAnnotation(){
        String resource = "mybatis-annotation-config.xml";
        SqlSession session = getSqlSession(resource);
        try {
            //先添加一条数据
            UserMapper mapper = session.getMapper(UserMapper.class);
            User user = new User();
            user.setName("阿飞");
            user.setAge(20);
            user.setCounty("中国");
            mapper.insertUser(user);
            System.out.println("插入数据后返回的自增ID：" + user.getId());
            //再删除刚加的数据
            mapper.deleteUser(user.getId());
            session.commit();
        } finally {
            session.close();
        }
    }
}

使用对于给定语句能够合理描述参数和返回值的接口（比如说UserMapper.class），你现在不但可以执行更清晰和类型安全的代码，而且还不用担心易错的字符串字面值以及强制类型转换。使用注解的方式还有很多优势，首先它不是基于字符串常量的，就会更安全；其次，如果你的 IDE 有代码补全功能，那么你可以在有了已映射 SQL 语句的基础之上利用这个功能。
项目地址：[email protected]:kaisongli/mybatis-demo.git