MyBatis学习总结2

这一篇讲述MyBatis对数据库的CRUD操作，内容不做重复，只做添加：查看学习总结1

一、使用MyBatis对表执行CRUD操作——基于XML的实现

在SQL映射文件userMapper.xml中添加

<!-- 增加用户 -->
    <insert id="addUser" parameterType="com.tfj.domain.User">
        insert into users(name,age)
        values(#{name},#{age})
    </insert>
    <!-- 删除用户 -->
    <delete id="deleteUserById" parameterType="int">
        delete from users where
        id=#{id}
    </delete>
    <!-- 修改用户 -->
    <update id="updateUserById" parameterType="com.tfj.domain.User">
        update users set
        name=#{name},age=#{age} where id=#{id}
    </update>
    <!-- 获取全部用户 -->
    <select id="getAllUsers" resultType="com.tfj.domain.User">
        select * from users
    </select>

映射封装类->CRUDByXmlMapper.java

package com.tfj.test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import com.tfj.domain.User;
import com.tfj.util.MyBatisUtil;

public class CRUDByXmlMapper {

    public void insert() {
        // SqlSession sqlSession = MyBatisUtil.getSqlSession(false);
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        /**
         * 映射sql的标识字符串， com.tfj.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
         * addUser是insert标签的id属性值，通过insert标签的id属性值就可以找到要执行的SQL
         */
        String statement = "com.tfj.mapping.userMapper.addUser";// 映射sql的标识字符串
        User user = new User();
        user.setName("AfterInsert");
        user.setAge(20);
        // 执行插入操作
        int retResult = sqlSession.insert(statement, user);
        // 手动提交事务
        // sqlSession.commit();
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }

    public void update() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        /**
         * 映射sql的标识字符串， com.tfj.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
         * updateUser是update标签的id属性值，通过update标签的id属性值就可以找到要执行的SQL
         */
        String statement = "com.tfj.mapping.userMapper.updateUserById";// 映射sql的标识字符串
        User user = new User();
        user.setId(1);
        user.setName("AfterUpdate");
        user.setAge(25);
        // 执行修改操作
        int retResult = sqlSession.update(statement, user);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }

    public void delete() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        /**
         * 映射sql的标识字符串， com.tfj.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
         * deleteUser是delete标签的id属性值，通过delete标签的id属性值就可以找到要执行的SQL
         */
        String statement = "com.tfj.mapping.userMapper.deleteUserById";// 映射sql的标识字符串
        // 执行删除操作
        int retResult = sqlSession.delete(statement, 1);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }

    public void select() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        /**
         * 映射sql的标识字符串， com.tfj.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
         * getAllUsers是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
         */
        String statement = "com.tfj.mapping.userMapper.getUserById";// 映射sql的标识字符串
        // 执行查询返回一个唯一user对象的sql
        User user = sqlSession.selectOne(statement, 1);
        System.out.println(user);
    }

    public void selectAll() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        /**
         * 映射sql的标识字符串， com.tfj.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
         * getAllUsers是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
         */
        String statement = "com.tfj.mapping.userMapper.getAllUsers";// 映射sql的标识字符串
        // 执行查询操作，将查询结果自动封装成List<User>返回
        List<User> lstUsers = sqlSession.selectList(statement);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
　　　　 for(User lsts:lstUsers){
        System.out.println(lsts);
    }
 }
}

工具类（后续将一直使用）->MyBatisUtil.java

package com.tfj.util;

import java.io.InputStream;

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

public class MyBatisUtil {

    /**
     * 获取SqlSessionFactory
     *
     * @return SqlSessionFactory
     */
    public static SqlSessionFactory getSqlSessionFactory() {
        String resource = "conf.xml";
        InputStream is = MyBatisUtil.class.getClassLoader().getResourceAsStream(resource);
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        return factory;
    }

    /**
     * 获取SqlSession
     *
     * @return SqlSession
     */
    public static SqlSession getSqlSession() {
        return getSqlSessionFactory().openSession();
    }

    /**
     * 获取SqlSession
     *
     * @param isAutoCommit
     *            true 表示创建的SqlSession对象在执行完SQL之后会自动提交事务 false
     *            表示创建的SqlSession对象在执行完SQL之后不会自动提交事务，这时就需要我们手动调用sqlSession.commit()提交事务
     * @return SqlSession
     */
    public static SqlSession getSqlSession(boolean isAutoCommit) {
        return getSqlSessionFactory().openSession(isAutoCommit);
    }
}

测试类->CRUDTest.java

package com.tfj.test;

public class CRUDTest {
    public static void main(String[] args) {
        // 每次进行操作后都查询全部用户，从而观察变化
        CRUDByXmlMapper testCRUDByXmlMapper = new CRUDByXmlMapper();
        System.out.println("-------------------------");
        System.out.println("Look getAllUsers");
        testCRUDByXmlMapper.selectAll();
        System.out.println("-------------------------");
        System.out.println("Look after updateUser");
        testCRUDByXmlMapper.update();
        testCRUDByXmlMapper.selectAll();
        System.out.println("-------------------------");
        System.out.println("Look after delete");
        testCRUDByXmlMapper.delete();
        testCRUDByXmlMapper.selectAll();
        System.out.println("-------------------------");
        System.out.println("Look after insert");
        testCRUDByXmlMapper.insert();
        testCRUDByXmlMapper.selectAll();

    }
}

二、使用MyBatis对表执行CRUD操作——基于注解的实现

1、定义SQL映射的接口

UserMapperI接口的代码如下：

UserMapperI.java

package com.tfj.mapping;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.tfj.domain.User;

/**
 * @author gacl 定义sql映射的接口，使用注解指明方法要执行的SQL
 */
public interface UserMapperI {

    // 使用@Insert注解指明insert方法要执行的SQL
    @Insert("insert into users(name, age) values(#{name}, #{age})")
    public int insert(User user);

    // 使用@Delete注解指明delete方法要执行的SQL
    @Delete("delete from users where id=#{id}")
    public int delete(int id);

    // 使用@Update注解指明update方法要执行的SQL
    @Update("update users set name=#{name},age=#{age} where id=#{id}")
    public int update(User user);

    // 使用@Select注解指明select方法要执行的SQL
    @Select("select * from users where id=#{id}")
    public User select(int id);

    // 使用@Select注解指明selectAll方法要执行的SQL
    @Select("select * from users")
    public List<User> selectAll();
}

在配置文件conf.xml中添加这个注解接口

        <!-- 注册UserMapper映射接口 -->
        <mapper class="com.tfj.mapping.UserMapperI" />

映射封装类->CRUDByAnnotationMapper.java

package com.tfj.test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import com.tfj.domain.User;
import com.tfj.mapping.UserMapperI;
import com.tfj.util.MyBatisUtil;

public class CRUDByAnnotationMapper {

    public void insert() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        // 得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        User user = new User();
        user.setName("tufujie");
        user.setAge(20);
        int add = mapper.insert(user);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(add);
    }

    public void update() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        // 得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        User user = new User();
        user.setId(3);
        user.setName("Jacksile");
        user.setAge(26);
        // 执行修改操作
        int retResult = mapper.update(user);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }

    public void delete() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        // 得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        // 执行删除操作
        int retResult = mapper.delete(1);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }

    public void select() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        // 得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        // 执行查询操作，将查询结果自动封装成User返回
        User user = mapper.select(2);
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(user);
    }

    public void selectAll() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        // 得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        // 执行查询操作，将查询结果自动封装成List<User>返回
        List<User> lstUsers = mapper.selectAll();
        // 使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
　　　　 for(User lsts:lstUsers){
        System.out.println(lsts);
    }
}
}

测试类->CRUDTest2.java

package com.tfj.test;

public class CRUDTest2 {
    public static void main(String[] args) {
        // 每次进行操作后都查询全部用户，从而观察变化
        CRUDByAnnotationMapper testCRUDByXmlMapper = new CRUDByAnnotationMapper();
        System.out.println("-------------------------");
        System.out.println("Look after getUser id=2");
        testCRUDByXmlMapper.select();
        System.out.println("Look after getAllUsers");
        testCRUDByXmlMapper.selectAll();
        System.out.println("-------------------------");
        System.out.println("Look after updateUser");
        testCRUDByXmlMapper.update();
        testCRUDByXmlMapper.selectAll();
        System.out.println("-------------------------");
        System.out.println("Look after delete");
        testCRUDByXmlMapper.delete();
        testCRUDByXmlMapper.selectAll();
        System.out.println("-------------------------");
        System.out.println("Look after insert");
        testCRUDByXmlMapper.insert();
        testCRUDByXmlMapper.selectAll();

    }
}