<?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="test">
  <!-- 根據(jù)用戶編號(hào)，查詢單個(gè)用戶實(shí)體 -->
  <select id="findUserById" parameterType="int" resultType="com.pjb.mybatis.po.User">
    SELECT * FROM tb_user WHERE id = #{id}
  </select>
 
  <!-- 新增用戶 -->
  <insert id="insertUser" parameterType="com.pjb.mybatis.po.User">
    INSERT INTO tb_user(user_name,blog_url,remark)
    VALUES(#{userName},#{blogUrl},#{remark});
  </insert>
</mapper>

<?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="test">
  <!-- 根據(jù)用戶名稱，模糊查詢用戶列表 -->
  <select id="findUserByUserName" parameterType="java.lang.String" resultType="com.pjb.mybatis.po.User">
    SELECT * FROM tb_user WHERE user_name LIKE '%${value}%'
  </select>
</mapper>

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/db_admin?useSSL=false&amp
#jdbc.username=root
#jdbc.password=123456

<!-- 加載用于數(shù)據(jù)庫(kù)配置的屬性文件 -->
<properties resource="db.properties">
  <!-- 啟用默認(rèn)值特性，這樣${}拼接符才可以設(shè)置默認(rèn)值 -->
  <property name="org.apache.ibatis.parsing.PropertyParser.enable-default-value" value="true"/>
</properties>

package com.lanou3g.mybaties.bean;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class Teacher {
  private Integer id;
  private String tname;
  private Integer age;
  private Integer salary;
public Teacher(){}
  @Override
  public String toString() {
    return "Teacher{" +
        "id=" + id +
        ", tname='" + tname + '\'' +
        ", salary=" + salary +
        ", remark='" + remark + '\'' +
        ", age=" + age +
        '}';
  }
  private String remark;
  public Teacher(Integer id, String tname, Integer age, Integer salary, String remark) {
    this.id = id;
    this.tname = tname;
    this.age = age;
    this.salary = salary;
    this.remark = remark;
  }
  public Teacher(Integer id) {
    this.id = id;
  }  
}

package com.lanou3g.mybaties.dao;
import com.lanou3g.mybaties.bean.Teacher;
import org.apache.ibatis.annotations.Param;
import java.util.List;
public interface TeacherDao {
  List<Teacher> queryAll();
  Teacher queryById(int id);
  Teacher queryByIdAndAge(@Param("id") int id, @Param("age") int age);
  int insertTeacher(Teacher teacher);
  int insertTeacherByParam(@Param("tname") String tname, @Param("age") int age);
  int updateTeacherById(Teacher teacher);
  int deleteTeacherById(int id);
}

<?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>
  <properties resource="jdbc.properties" />
  <settings>
  <setting name="mapUnderscoreToCamelCase" value="false"/>
  </settings>
  <typeAliases>
    <!--這樣我們就可以在mybatis的的上下文中使用Teacher來代替全路徑名了，減少配置的復(fù)雜度。 -->
    <typeAlias type="com.lanou3g.mybaties.bean.Teacher" alias="Teacher" />
  <!--default屬性，這個(gè)屬性作用就是指定當(dāng)前情況下使用哪個(gè)數(shù)據(jù)庫(kù)配置，
  也就是使用哪個(gè)<environment>節(jié)點(diǎn)的配置，
  default的值就是配置的<environment>標(biāo)簽元素的id值。-->
  <environments default="test">
    <environment id="test">
      <!-- 事務(wù)管理器：
     MANAGED: 這個(gè)配置就是告訴mybatis不要干預(yù)事務(wù)，具體行為依賴于容器本身的事務(wù)處理邏輯。
     JDBC: 這個(gè)配置就是直接使用了 JDBC 的提交和回滾設(shè)置，它依賴于從數(shù)據(jù)源得到的連接來管理事務(wù)作用域。
    -->
      <!-- 使用jdbc事務(wù)管理 -->
      <transactionManager type="JDBC"/>
      <!-- 數(shù)據(jù)庫(kù)連接池 -->
      <dataSource type="POOLED">
        <property name="driver" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.user}"/>
        <property name="password" value="${jdbc.password}"/>
      </dataSource>
    </environment>
  </environments>
  <!--<mappers>用來在mybatis初始化的時(shí)候，告訴mybatis需要引入哪些Mapper映射文件。-->
  <mappers>
    <!--通過class屬性指定mapper接口名稱，此時(shí)對(duì)應(yīng)的映射文件必須與接口位于同一路徑下，
    并且名稱相同-->
    
    <!--通過resource屬性引入classpath路徑的相對(duì)資源-->
    <mapper resource="mapper/TeacherMapper.xml" />
   
  </mappers>
</configuration>

<?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對(duì)應(yīng)空Dao接口的全名 -->
<!--namespace屬性
在MyBatis中，Mapper中的namespace用于綁定Dao接口的，即面向接口編程。
它的好處在于當(dāng)使用了namespace之后就可以不用寫接口實(shí)現(xiàn)類，
業(yè)務(wù)邏輯會(huì)直接通過這個(gè)綁定尋找到相對(duì)應(yīng)的SQL語(yǔ)句進(jìn)行對(duì)應(yīng)的數(shù)據(jù)處理-->
<mapper namespace="com.lanou3g.mybaties.dao.TeacherDao">
  <!-- 此處的id是查詢語(yǔ)句的名稱，對(duì)應(yīng)接口中的方法名 -->
  <!--指定 resultType 返回值類型時(shí) Teacher 類型的，
    Teacher 在這里是一個(gè)別名，代表的是 com.lanou3g.mybaties.bean.Teacher
    對(duì)于引用數(shù)據(jù)類型，都是將大寫字母轉(zhuǎn)小寫，比如 HashMap 對(duì)應(yīng)的別名是 'hashmap'
    基本數(shù)據(jù)類型考慮到重復(fù)的問題，會(huì)在其前面加上 '_'，比如 byte 對(duì)應(yīng)的別名是 '_byte'
-->
  <select id="queryAll" resultType="Teacher">
    <!--
     通過 resultType 指定查詢的結(jié)果是 Teacher 類型的數(shù)據(jù)
     只需要指定 resultType 的類型，MyBatis 會(huì)自動(dòng)將查詢的結(jié)果映射成 JavaBean 中的屬性
      -->
  select * from teacher;
 </select>
  <!-- 帶一個(gè)簡(jiǎn)單類型的參數(shù)， 這種情況下parameterType屬性可以省略，
  mybatis可以自動(dòng)推斷出類型 -->
  <select id="queryById" resultType="Teacher">
        select * from teacher where id = #{id};
  </select>
  <!-- 帶兩個(gè)參數(shù)，需要在接口中通過@Param注解指定名稱（因?yàn)榫幾g時(shí)參數(shù)名不會(huì)保留） -->
  <select id="queryByIdAndAge" resultType="Teacher">
    select * from teacher where id = #{id} and age &lt;= #{age};
  </select>
  <!-- insert、update、delete的返回值都是int（影響行數(shù)） -->
  <!-- 自定義類型參數(shù)，通過#{屬性名}可以直接獲取引入類型參數(shù)的屬性值 -->
  <insert id="insertTeacher" parameterType="Teacher">
    insert into teacher(tname) values (#{tname});
  </insert>
  <insert id="insertTeacherByParam">
    insert into teacher(tname, age) values (#{tname}, #{age});
  </insert>
  <update id="updateTeacherById" parameterType="Teacher">
    update teacher set tname = #{tname}, age = #{age} where id = #{id}
  </update>
  <delete id="deleteTeacherById">
    delete from teacher where id = #{id};
  </delete>
</mapper>

package com.lanou3g.mybaties;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.InputStream;
import java.util.concurrent.ConcurrentHashMap;
/**
 * 封裝Mybatis初始化操作
 * 支持創(chuàng)建多env sqlSessionFactory
 * 整個(gè)應(yīng)用生命周期內(nèi)相同env的sqlSessionFactory對(duì)象只有一個(gè)
 */
@Slf4j
public class MyBatisTools {
  private static ConcurrentHashMap<String, SqlSessionFactory> factoryMap = new MyConcurrentHashMap();
  private static MyBatisTools myBatisTools;
  private MyBatisTools() {}
  public static MyBatisTools getInstance() {
    if(myBatisTools == null) {
      synchronized (MyBatisTools.class) {
        if(myBatisTools == null) {
          myBatisTools = new MyBatisTools();
        }
      }
    }
    log.debug("當(dāng)前一共有: " + factoryMap.size() +"個(gè)SqlSessionFactory實(shí)例");
    log.debug("他們分別是: " + factoryMap);
    return myBatisTools;
  }
  public SqlSessionFactory getSessionFactory(String env) {
    try {
      // 1. 讀入配置文件
      InputStream in = Resources.getResourceAsStream("mybatis_conf.xml");
      // 2. 構(gòu)建SqlSessionFactory(用于獲取sqlSession)
      SqlSessionFactory sessionFactory = null;
      synchronized (factoryMap) {
        if(factoryMap.containsKey(env)) {
          return factoryMap.get(env);
        } else {
          sessionFactory = new SqlSessionFactoryBuilder().build(in, env);
          factoryMap.put(env, sessionFactory);
        }
      }
      return sessionFactory;
    } catch (Exception e) {
      log.error("初始化SqlSessionFactory失敗", e);
      return null;
    }
  }
  public SqlSession openSession() {
    return getSessionFactory(null).openSession();
  }
  public SqlSession openSession(boolean autoCommit) {
    return getSessionFactory(null).openSession(autoCommit);
  }
  public SqlSession openSession(ExecutorType executorType, boolean autoCommit) {
    return getSessionFactory(null).openSession(executorType, autoCommit);
  }
}
/**
 * 繼承原生ConcurrentHashMap，處理null key問題
 */
class MyConcurrentHashMap extends ConcurrentHashMap {
  @Override
  public Object put(Object key, Object value) {
    if(key == null) {
      key = "null";
    }
    return super.put(key, value);
  }
  @Override
  public boolean containsKey(Object key) {
    if(key == null) {
      key = "null";
    }
    return super.containsKey(key);
  }
  @Override
  public Object get(Object key) {
    if(key == null) {
      key = "null";
    }
    return super.get(key);
  }
}

@Slf4j
public class AppTest 
{
  /**
   * Rigorous Test :-)
   */
  TeacherDao teacherDao = null;
  @Before
  public void setUp() {  
    teacherDao = MyBatisTools.getInstance().openSession(true).getMapper(TeacherDao.class);
  }
  /**
   * 練習(xí)查詢多個(gè)庫(kù)(用到了多環(huán)境配置)
   */ 
  @Test
  public void textqueryById(){
    Teacher teacher=teacherDao.queryById(1);
    System.out.println(teacher);
  }
  @Test
  public void text(){
    List<Teacher> teachers=teacherDao.queryAll();
    System.out.println(teachers);
  }
  /**
   * 多個(gè)參數(shù)查詢語(yǔ)句
   */
  @Test
  public void testQueryByIdAndAge() {
    Teacher teacherList = teacherDao.queryByIdAndAge(1, 65);
    log.info("查詢結(jié)果：" + teacherList);
  }
  @Test
  public void testInsert() {
    // 新增Teacher表
    System.out.println("--------------插入前：");
    List<Teacher> teacherList = teacherDao.queryAll();
    System.out.println(teacherList);
    int ret = teacherDao.insertTeacher(new Teacher("好人"));
    log.info("影響的行數(shù): " + ret);
    // 比較low的寫法（不推薦）
    //int ret = teacherDao.insertTeacherByParam("哈哈哥", 99);
    //log.info("影響的行數(shù): " + ret);
    System.out.println("--------------插入后：");
    teacherList = teacherDao.queryAll();
    System.out.println(teacherList);
  }
  @Test
  public void testUpdate() {
    Teacher teacher = new Teacher();
    teacher.setId(6);
    teacher.setAge(99);
    teacher.setTname("喬巴老師");
    int rows = teacherDao.updateTeacherById(teacher);
    log.info("更新行數(shù)：" + rows);
  }
  @Test
  public void testDelete() {
    int rows = teacherDao.deleteTeacherById(13);
    log.info("刪除行數(shù)：" + rows);
  }
  @Test
  public void testinsertTeacherByParam(){
int row=teacherDao.insertTeacherByParam("hh",22);
    System.out.println(row);
  }
}