使用MyBatis編寫Dao的兩種語法

原文連接：http://www.yiidian.com/mybatis/mybatis-dao.html

在MyBatis中，咱們有兩種Dao的寫法，一種叫傳統Dao寫法，一種叫Mapper代理接口。下面看看如何實現。

1 傳統Dao寫法

1.1 編寫CustomerDao接口

package com.yiidian.dao;
import com.yiidian.domain.Customer;
import java.util.List;
/**
 * Dao接口
 *一點教程網 - www.yiidian.com
 */
public interface CustomerDao {

    /**
     * 查詢全部用戶
     */
    public List<Customer> findAll();

    /**
     * 添加
     */
    public void save(Customer customer);

    /**
     * 修改
     */
    public void update(Customer customer);

    /**
     * 查詢一個
     */
    public Customer findById(Integer id);

    /**
     * 條件查詢
     */
    public List<Customer> findByName(String name);

    /**
     * 刪除
     */
    public void delete(Integer id);
}

1.2 編寫CustomerDao實現類

package com.yiidian.dao.impl;

import com.yiidian.dao.CustomerDao;
import com.yiidian.domain.Customer;
import com.yiidian.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

/**
 * Dao實現類
 */
public class CustomerDaoImpl implements CustomerDao{
    @Override
    public List<Customer> findAll() {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtils.getSession();
            return sqlSession.selectList("com.yiidian.dao.CustomerDao.findAll");
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            sqlSession.close();
        }
        return null;
    }

    @Override
    public void save(Customer customer) {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtils.getSession();
            sqlSession.insert("com.yiidian.dao.CustomerDao.save", customer);
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally{
            sqlSession.close();
        }
    }

    @Override
    public void update(Customer customer) {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtils.getSession();
            sqlSession.update("com.yiidian.dao.CustomerDao.update", customer);
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally{
            sqlSession.close();
        }
    }

    @Override
    public Customer findById(Integer id) {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtils.getSession();
            return sqlSession.selectOne("com.yiidian.dao.CustomerDao.findById",id);
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            sqlSession.close();
        }
        return null;
    }

    @Override
    public List<Customer> findByName(String name) {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtils.getSession();
            return sqlSession.selectList("com.yiidian.dao.CustomerDao.findByName",name);
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            sqlSession.close();
        }
        return null;
    }

    @Override
    public void delete(Integer id) {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtils.getSession();
            sqlSession.delete("com.yiidian.dao.CustomerDao.delete", id);
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally{
            sqlSession.close();
        }
    }
}

傳統方式的重點在於Dao實現類，在Dao實現類中，手動調用SqlSession提供的方法直接執行映射文件的SQL語句。

1.3 編寫CustomerDao.xml映射

<?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">
<!--
   namespace: 用於指定該映射文件須要映射的Dao接口
-->
<mapper namespace="com.yiidian.dao.CustomerDao">

    <!--查詢全部-->
    <select id="findAll" resultType="com.yiidian.domain.Customer">
        select * from t_customer
    </select>

    <!--1.添加方法-->
    <insert id="save" parameterType="com.yiidian.domain.Customer">
        INSERT INTO t_customer(NAME,gender,telephone) VALUES(#{name},#{gender},#{telephone})
    </insert>

    <!--2.修改方法-->
    <update id="update" parameterType="com.yiidian.domain.Customer">
        UPDATE t_customer SET
        NAME = #{name},
        gender = #{gender},
        telephone = #{telephone}
        WHERE id = #{id}
    </update>

    <!--查詢一個-->
    <select id="findById" parameterType="integer" resultType="com.yiidian.domain.Customer">
        select * from t_customer where id = #{id}
    </select>

    <!--條件查詢-->
    <select id="findByName" parameterType="string" resultType="com.yiidian.domain.Customer">
        select * from t_customer where name like #{name}
    </select>

    <!--刪除-->
    <delete id="delete" parameterType="integer">
        delete from t_customer where id = #{id}
    </delete>
</mapper>

1.4 編寫測試類

package com.yiidian.mybatis;

import com.yiidian.dao.CustomerDao;
import com.yiidian.dao.impl.CustomerDaoImpl;
import com.yiidian.domain.Customer;
import com.yiidian.utils.MyBatisUtils;
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.Test;

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

/**
 * MyBatis測試類 - 傳統Dao寫法
 * 一點教程網 - www.yiidian.com
 */
public class TestCustomerDao {

    /**
     * 添加
     */
    @Test
    public void testSave(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.建立傳統Dao實現類對象
        CustomerDao customerDao = new CustomerDaoImpl();

        //3.調用save方法
        Customer customer = new Customer();
        customer.setName("小蒼");
        customer.setGender("女");
        customer.setTelephone("15755556666");
        customerDao.save(customer);


        //4.關閉鏈接
        session.close();
    }

    /**
     * 修改
     */
    @Test
    public void testUpdate(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.建立傳統Dao實現類對象
        CustomerDao customerDao = new CustomerDaoImpl();

        //3.調用update方法
        Customer customer = new Customer();
        customer.setId(5);
        customer.setName("小澤");
        customer.setGender("女");
        customer.setTelephone("15755556666");
        customerDao.update(customer);

        session.commit();

        //4.關閉鏈接
        session.close();
    }

    /**
     * 查詢全部
     */
    @Test
    public void testFindAll(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.建立傳統Dao實現類對象
        CustomerDao customerDao = new CustomerDaoImpl();

        //3.調用findAll方法
        List<Customer> list = customerDao.findAll();

        for(Customer cust:list){
            System.out.println(cust);
        }

        //4.關閉鏈接
        session.close();
    }

    /**
     * 查詢一個
     */
    @Test
    public void testFindById(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.建立傳統Dao實現類對象
        CustomerDao customerDao = new CustomerDaoImpl();

        //3.調用findById方法
        Customer customer = customerDao.findById(3);

        System.out.println(customer);

        //4.關閉鏈接
        session.close();
    }

    /**
     * 條件查詢
     */
    @Test
    public void testFindByName(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.建立傳統Dao實現類對象
        CustomerDao customerDao = new CustomerDaoImpl();

        //3.調用findByName方法
        List<Customer> list = customerDao.findByName("%小%");

        for(Customer cust:list){
            System.out.println(cust);
        }

        //4.關閉鏈接
        session.close();
    }

    /**
     * 刪除
     */
    @Test
    public void testDelete(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.建立傳統Dao實現類對象
        CustomerDao customerDao = new CustomerDaoImpl();

        //3.調用findByName方法
        customerDao.delete(5);

        // 提交事務
        session.commit();

        //4.關閉鏈接
        session.close();
    }
}

2 Mapper代理接口

2.1 編寫CustomerDao接口

package com.yiidian.dao;
import com.yiidian.domain.Customer;
import java.util.List;
/**
 * Dao接口
 *一點教程網 - www.yiidian.com
 */
public interface CustomerDao {

    /**
     * 查詢全部用戶
     */
    public List<Customer> findAll();

    /**
     * 添加
     */
    public void save(Customer customer);

    /**
     * 修改
     */
    public void update(Customer customer);

    /**
     * 查詢一個
     */
    public Customer findById(Integer id);

    /**
     * 條件查詢
     */
    public List<Customer> findByName(String name);

    /**
     * 刪除
     */
    public void delete(Integer id);
}

2.2 編寫CustomerDao.xml映射

<?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">
<!--
   namespace: 用於指定該映射文件須要映射的Dao接口
-->
<mapper namespace="com.yiidian.dao.CustomerDao">

    <!--查詢全部-->
    <select id="findAll" resultType="com.yiidian.domain.Customer">
        select * from t_customer
    </select>

    <!--1.添加方法-->
    <insert id="save" parameterType="com.yiidian.domain.Customer">
        INSERT INTO t_customer(NAME,gender,telephone) VALUES(#{name},#{gender},#{telephone})
    </insert>

    <!--2.修改方法-->
    <update id="update" parameterType="com.yiidian.domain.Customer">
        UPDATE t_customer SET
        NAME = #{name},
        gender = #{gender},
        telephone = #{telephone}
        WHERE id = #{id}
    </update>

    <!--查詢一個-->
    <select id="findById" parameterType="integer" resultType="com.yiidian.domain.Customer">
        select * from t_customer where id = #{id}
    </select>

    <!--條件查詢-->
    <select id="findByName" parameterType="string" resultType="com.yiidian.domain.Customer">
        select * from t_customer where name like #{name}
    </select>

    <!--刪除-->
    <delete id="delete" parameterType="integer">
        delete from t_customer where id = #{id}
    </delete>
</mapper>

2.3 編寫測試類

package com.yiidian.mybatis;

import com.yiidian.dao.CustomerDao;
import com.yiidian.dao.impl.CustomerDaoImpl;
import com.yiidian.domain.Customer;
import com.yiidian.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

/**
 * MyBatis測試類 - Mapper代理接口
 * 一點教程網 - www.yiidian.com
 */
public class TestCustomerDao2 {

    /**
     * 添加
     */
    @Test
    public void testSave(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.生成Dao代理對象
        CustomerDao customerDao = session.getMapper(CustomerDao.class);

        //3.調用save方法
        Customer customer = new Customer();
        customer.setName("小蒼");
        customer.setGender("女");
        customer.setTelephone("15755556666");
        customerDao.save(customer);


        //4.關閉鏈接
        session.close();
    }

    /**
     * 修改
     */
    @Test
    public void testUpdate(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.生成Dao代理對象
        CustomerDao customerDao = session.getMapper(CustomerDao.class);

        //3.調用update方法
        Customer customer = new Customer();
        customer.setId(5);
        customer.setName("小澤");
        customer.setGender("女");
        customer.setTelephone("15755556666");
        customerDao.update(customer);

        session.commit();

        //4.關閉鏈接
        session.close();
    }

    /**
     * 查詢全部
     */
    @Test
    public void testFindAll(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.生成Dao代理對象
        CustomerDao customerDao = session.getMapper(CustomerDao.class);

        //3.調用findAll方法
        List<Customer> list = customerDao.findAll();

        for(Customer cust:list){
            System.out.println(cust);
        }

        //4.關閉鏈接
        session.close();
    }

    /**
     * 查詢一個
     */
    @Test
    public void testFindById(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.生成Dao代理對象
        CustomerDao customerDao = session.getMapper(CustomerDao.class);

        //3.調用findById方法
        Customer customer = customerDao.findById(5);

        System.out.println(customer);

        //4.關閉鏈接
        session.close();
    }

    /**
     * 條件查詢
     */
    @Test
    public void testFindByName(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.生成Dao代理對象
        CustomerDao customerDao = session.getMapper(CustomerDao.class);

        //3.調用findByName方法
        List<Customer> list = customerDao.findByName("%小%");

        for(Customer cust:list){
            System.out.println(cust);
        }

        //4.關閉鏈接
        session.close();
    }

    /**
     * 刪除
     */
    @Test
    public void testDelete(){
        //1.獲取SqlSession對象
        SqlSession session = MyBatisUtils.getSession();

        //2.生成Dao代理對象
        CustomerDao customerDao = session.getMapper(CustomerDao.class);

        //3.調用findByName方法
        customerDao.delete(5);

        // 提交事務
        session.commit();

        //4.關閉鏈接
        session.close();
    }
}

源碼下載：https://pan.baidu.com/s/1ZsM5CAu026zfF3wZEA-aFQ

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