MyBatis（9）- mybatis 的CRUD

• log4j 配置
  

# Set root category priority to INFO and its only appender to CONSOLE.
#log4j.rootCategory=INFO, CONSOLE            debug   info   warn error fatal
log4j.rootCategory=debug, CONSOLE, LOGFILE

# Set the enterprise logger category to FATAL and its only appender to CONSOLE.
log4j.logger.org.apache.axis.enterprise=FATAL, CONSOLE

# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n

# LOGFILE is set to be a File appender using a PatternLayout.
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d://axis.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n

1 保存

1.1 DAO

package com.tzb.dao;

import com.tzb.domain.User;


import java.util.List;

public interface IUserDao {
    List<User> findAll();

    void saveUser(User user);
}

---

• 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">

<mapper namespace="com.tzb.dao.IUserDao">
    <!--配置查詢所有-->
    <select id="findAll" resultType="com.tzb.domain.User">
        select * from user
    </select>

    <insert id="saveUser" parameterType="com.tzb.domain.User">
        insert into user(username,address,sex,birthday)
        values (#{username},#{address},#{sex},#{birthday})
    </insert>
</mapper>

1.2 SqlMapConfig.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">
<!-- mybatis 的主配置文件-->
<configuration>
    <!--配置環境-->
    <environments default="mysql">
        <environment id="mysql">
            <!--配置事務類型-->
            <transactionManager type="JDBC"></transactionManager>

            <!--配置數據源（連接池）-->
            <dataSource type="POOLED">
                <!--配置連接數據庫的基本信息-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis-test?useSSL=false&amp;characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <!--指定映射配置文件的位置，映射配置文件指的是每個 dao 獨立的配置文件-->
    <mappers>
        <!--<mapper resource="com/tzb/dao/IUserDao.xml"></mapper>-->
        <mapper class="com.tzb.dao.IUserDao"></mapper>
    </mappers>
</configuration>

1.3 單元測試

public class MyBatisTest {

    private InputStream in;
    private SqlSession sqlSession;
    private IUserDao userDao;

    @Before
    public void init() throws IOException {
        // 1.讀取配置文件
        in = Resources.getResourceAsStream("SqlMapConfig.xml");

        //2.創建 SqlSessionFactory 工廠
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);

        // 3.使用工廠生產 SqlSession 對象
        sqlSession = factory.openSession();

        // 4.使用 SqlSession 創建DAO接口的代理對象
        userDao =  sqlSession.getMapper(IUserDao.class);
    }

    @After
    public void destory() throws IOException {
    	// 提交事務
        sqlSession.commit();
        //6.釋放資源
        sqlSession.close();
        in.close();
    }


    @Test
    public void testFindAll() throws IOException {
        List<User> users = userDao.findAll();
        for (User user : users) {
            System.out.println(user);
        }
    }

    @Test
    public void testSave() throws IOException {
        User user = new User();
        user.setUsername("趙子龍");
        user.setAddress("河北石家莊");
        user.setSex("男");
        user.setBirthday(new Date());

        userDao.saveUser(user);
    }
}

---

2 更新和刪除

2.1 DAO

package com.tzb.dao;

import com.tzb.domain.User;


import java.util.List;

public interface IUserDao {
    List<User> findAll();

    void saveUser(User user);

    void updateUser(User user);

    void deleteUser(Integer userId);
}

---

• 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">

<mapper namespace="com.tzb.dao.IUserDao">
    <!--配置查詢所有-->
    <select id="findAll" resultType="com.tzb.domain.User">
        select * from user
    </select>

    <insert id="saveUser" parameterType="com.tzb.domain.User">
        insert into user(username,address,sex,birthday)
        values (#{username},#{address},#{sex},#{birthday})
    </insert>

    <update id="updateUser" parameterType="com.tzb.domain.User">
        update user
        set
        username=#{username},
        address=#{address},
        sex=#{sex},
        birthday=#{birthday}
        where id=#{id}
    </update>

    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id=#{userId}
    </delete>
</mapper>

3 查詢一個

3.1 DAO

 User findById(Integer userId);

---

• IUserDao.xml

   <select id="findById" parameterType="int" resultType="com.tzb.domain.User">
        select * from user where id=#{userId}
    </select>
</mapper>

4 模糊查詢

• IUserDao

 List<User> findbyName(String username);

---

• IUserDao.xml

<select id="findbyName" parameterType="String" resultType="com.tzb.domain.User">
        select * from user where username like #{username}
    </select>

---

• 單元測試

 @Test
    public void testFindByName(){

        List<User> users = userDao.findbyName("%趙%");
        System.out.println(users);

    }

4.1 模糊查詢的另一種寫法【瞭解】

將原來的#{}佔位符，改成了${value}。注意如果用模糊查詢的這種寫法，那麼${value}的寫法就是固定的，不能寫成其它名字。

  <select id="findbyName" parameterType="String" resultType="com.tzb.domain.User">
       <!-- select * from user where username like #{username}-->
       select * from user where username like '%${value}%'
    </select>

• 單元測試

 @Test
    public void testFindByName() {

        List<User> users = userDao.findbyName("趙");
        System.out.println(users);
    }

4.1.1 模糊查詢的${value}源碼分析

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5 查詢一行一列

  /**
     * 查詢總的用戶數
     * @return
     */
    int findTotal();

<select id="findTotal" resultType="int">
        select count(id) from user;
    </select>

---