对Mybatis的初步认识

1、认识Mybatis

MyBatis 是支持普通 SQL 查询，存储过程和高级映射的优秀持久层框架。 MyBatis 消除了几乎所有的 JDBC 代码和参数的手工设置以及对结果集的检索。 MyBatis 可以使用简单的XML 或注解用于配置和原始映射，将接口和 Java 的 POJO（ Plain Old Java Objects，普通的Java 对象）映射成数据库中的记录.

1）MyBATIS 目前提供了三种语言实现的版本，包括：Java、.NET以及Ruby。（我主要学习java，就讲java的使用）
2）它提供的持久层框架包括SQL Maps和Data Access Objects（DAO）。
3）mybatis与hibernate的对比？

mybatis提供一种“半自动化”的ORM实现。
这里的“半自动化”，是相对Hibernate等提供了全面的数据库封装机制的“全自动化”ORM实现而言，“全自动”ORM实现了POJO和数据库表之间的映射，以及 SQL 的自动生成和执行。

而mybatis的着力点，则在于POJO与SQL之间的映射关系。

2、基于配置文件的CRUD 使用的mybatis的版本是3.1.1

User.java

public class User {

   private Integer id;

   private String username;

   private String password;

   public Integer getId() {
       return id;
   }

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

   public String getUsername() {
       return username;
   }

   public void setUsername(String username) {
       this.username = username;
   }

   public String getPassword() {
       return password;
   }

   public void setPassword(String password) {
       this.password = password;
   }

   public User() {
       super();
       // TODO Auto-generated constructor stub
   }

   public User(Integer id, String username, String password) {
       super();
       this.id = id;
       this.username = username;
       this.password = password;
   }

   public User(String username, String password) {
       super();
       this.username = username;
       this.password = password;
   }
}

User.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.sram.pojo.User">
   
   <insert id="add" parameterType="com.sram.pojo.User">
       INSERT INTO t_user(USERNAME,PASSWORD) VALUES(#{username},#{password});
   </insert>
   
   <update id="update" parameterType="com.sram.pojo.User">
       UPDATE t_user SET USERNAME=#{username},PASSWORD=#{password} WHERE ID=#{id};
   </update>
   
   <delete id="delete" parameterType="int">
       DELETE FROM t_user WHERE ID=#{id};
   </delete>
   
   <select id="list" resultType="com.sram.pojo.User">
       SELECT ID,USERNAME,PASSWORD FROM t_user;
   </select>
   
   <select id="load" resultType="com.sram.pojo.User" parameterType="int">
       SELECT ID,USERNAME,PASSWORD FROM t_user where ID=#{id};
   </select>
</mapper>

Mybatis获取session的工具类MybatisUtil

public class MyBatiesUtil {

   private static SqlSessionFactory factory;

   //加载一次配置文件
   static{
       try {
           InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
           factory = new SqlSessionFactoryBuilder().build(in);
       } catch (IOException e) {
           e.printStackTrace();
       }

   }

   //得到sqlSession
   public static SqlSession getSqlSession(){
       return factory.openSession();
   }
}

数据库的配置文件jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url = jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8
jdbc.username = root
jdbc.password = rrb

日志配置文件log4j.properties

#--------------------------------
#
log4j.rootLogger=INFO, stdout
#log4j.logger.test=info
#log4j.logger.org.apache.jasper = DEBUG
#log4j.logger.org.apache.catalina.startup.TldConfig = DEBUG
#log4j.logger.org.apache.catalina.session.ManagerBase = DEBUG

#log4j.logger.com.fiscal = DEBUG
#log4j.logger.com.system = DEBUG

log4j.logger.com.ibatis = DEBUG
log4j.logger.com.ibatis.common.jdbc.SimpleDataSource = DEBUG
log4j.logger.com.ibatis.common.jdbc.ScriptRunner = DEBUG
log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate = DEBUG
log4j.logger.java.sql.Connection = DEBUG
log4j.logger.java.sql.Statement = DEBUG
log4j.logger.java.sql.PreparedStatement = DEBUG
log4j.logger.java.sql.ResultSet = INFO

log4j.appender.stdout=org.apache.log4j.ConsoleAppender

#log4j.appender.fileout=org.apache.log4j.RollingFileAppender
#log4j.appender.fileout.File=e:/log/ibatis.log
#log4j.appender.fileout.MaxFileSize=10000KB

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
#log4j.appender.stdout.layout.ConversionPattern=[%-5p] %d{yyyy-MM-dd HH:mm:ss} :%m%n
#log4j.appender.fileout.layout=org.apache.log4j.PatternLayout
#log4j.appender.fileout.layout.ConversionPattern=[%-5p]_%d{yyyy-MM-dd HH:mm:ss} :%m%n

#log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout

# log4j.logger.org=info

Mybatis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>
   
   <properties resource="jdbc.properties"></properties>
   <environments default="development">
       <environment id="development" >
           <transactionManager type="JDBC"/>
           <dataSource type="POOLED">
               <property name="driver" value="${jdbc.driver}"/>
               <property name="url" value="${jdbc.url}"/>
               <property name="username" value="${jdbc.username}"/>
               <property name="password" value="${jdbc.password}"/>
           </dataSource>
       </environment>
   </environments>
   
   <mappers>
       <mapper resource="com/sram/pojo/User.xml"/>
   </mappers>
</configuration>

测试CRUD的测试类

public class UserTest {

   //测试配置添加方法
   @Test
   public void add(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();

       try {
           User user = new User("张三","123");

           session.insert(User.class.getName()+".add",user);
           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试配置更新方法
   @Test
   public void update(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();

       try {
           User user = new User(9,"李四","567");

           session.update(User.class.getName()+".update",user);

           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试配置删除方法
   @Test
   public void delete(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();

       try {

           session.delete(User.class.getName()+".delete",10);

           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试配置查询集合方法
   @Test
   public void list(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();
       List<User> list = null;
       try {

           list = session.selectList(User.class.getName()+".list");

           System.out.println(list);
           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试配置查询单个方法
   @Test
   public void load(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();
       try {

           User user = session.selectOne(User.class.getName()+".load",9);

           System.out.println(user.getUsername());
           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
}

3、基于注解的CRUD 使用的mybatis的版本是3.1.1

User.java

UserMapper.java

public interface UserMapper {

   @Insert("INSERT INTO t_user(USERNAME,PASSWORD) VALUES(#{username},#{password})")
   public void addUser(User user);

   @Update("UPDATE t_user SET USERNAME=#{username},PASSWORD=#{password} WHERE ID=#{id}")
   public void update(User user);

   @Delete("DELETE FROM t_user WHERE ID=#{id}")
   public void delete(int id);

   @Select("SELECT ID,USERNAME,PASSWORD FROM t_user")
   public List<User> list();

   @Select("SELECT ID,USERNAME,PASSWORD FROM t_user where ID=#{id}")
   public User load(int id);
}

mybatis获取session的工具类 MybatisUtils.java

public class MyBatisUtil {

   private static SqlSessionFactory factory;

   //加载一次配置文件
   static{
       try {
           InputStream in = Resources.getResourceAsStream("mybaties-config.xml");
           factory = new SqlSessionFactoryBuilder().build(in);
       } catch (IOException e) {
           e.printStackTrace();
       }

   }

   //得到sqlSession
   public static SqlSession getSqlSession(){
       return factory.openSession();
   }

数据库的配置文件jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url = jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8
jdbc.username = root
jdbc.password = rrb

日志配置文件log4j.properties

mybatis配置文件mybatis-confg.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>
   
   <properties resource="jdbc.properties"></properties>
   <environments default="development">
       <environment id="development" >
           <transactionManager type="JDBC"/>
           <dataSource type="POOLED">
               <property name="driver" value="${jdbc.driver}"/>
               <property name="url" value="${jdbc.url}"/>
               <property name="username" value="${jdbc.username}"/>
               <property name="password" value="${jdbc.password}"/>
           </dataSource>
       </environment>
   </environments>
   
   <mappers>
       <mapper class="com.sram.mapper.UserMapper"/>
   </mappers>
</configuration>

测试类

public class UserTest {

   //测试注解添加方法
   @Test
   public void add(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();

       try {
           User user = new User("张三","123");

           session.getMapper(UserMapper.class).addUser(user);

           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试注解更新方法
   @Test
   public void update(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();

       try {
           User user = new User(13,"李四","567");

           session.getMapper(UserMapper.class).update(user);

           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试注解删除方法
   @Test
   public void delete(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();

       try {

           session.getMapper(UserMapper.class).delete(14);

           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试注解查询集合方法
   @Test
   public void list(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();
       List<User> list = null;
       try {

           list = session.getMapper(UserMapper.class).list();

           System.out.println(list);
           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
   //测试注解查询单个方法
   @Test
   public void load(){

       //得到sqlSession
       SqlSession session = MyBatiesUtil.getSqlSession();
       try {

           User user = session.getMapper(UserMapper.class).load(13);

           System.out.println(user);
           //事务提交
           session.commit();

           session.close();
       } catch (Exception e) {
           e.printStackTrace();
           session.rollback();
       }

   }
}