idea上MyBatis第一个例子

接着上面创建的maven项目来。

1.java目录下创建cn.happy.entity包

2.idea下创建数据库连接

配置连接参数

3.把数据库表变成实体类

导入成功，改一下包名就可以用了

4.新建cn.happy.dao包，在下面新建IUserDAO接口，代码如下

 package cn.happy.dao;

 import cn.happy.entity.Smbms_user;

 import java.util.List;

 public interface IUserDAO {

     List<Smbms_user> findAll();

 }

5.在IUserDAO同包下新建IUserDAO.xml文件（俗称小配置），文件名一定要相同（这样做可以规避后面的一些问题）。

官方文档中找到

2.1.4 Exploring Mapped SQL Statements

把下面的文档直接粘贴到IUserDAO.xml里

 <?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="org.mybatis.example.BlogMapper">

  <select id="selectBlog" parameterType="int" resultType="Blog">

  select * from Blog where id = #{id}

  </select>

 </mapper>

修改包名和<mapper>节点，比如我的代码修改如下即可

 <?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">

 <!--关联接口的全限定名-->

 <mapper namespace="cn.happy.dao.IUserDAO">

     <!--大配置中settings autoMappingBehavior NONE,所以数据库只会装配以下column-->

     <resultMap id="UserMapper" type="cn.happy.entity.Smbms_user">

         <id property="id" column="id"/>

         <result property="username" column="username"/>

         <result property="userpassword" column="userpassword"/>

     </resultMap>

     <!--id要与接口中的方法名相同-->

     <select id="findAll" resultMap="UserMapper">

         select * from smbms_user

     </select>

 </mapper>

6.配置resources

这里需要配置三个文件

1.jdbc.properties

2.log4j.properties

3.mybatis-config.xml

jdbc.properties

 jdbc.driver=com.mysql.jdbc.Driver

 jdbc.url=jdbc:mysql:///t14_smbms?characterEncoding=utf8&useSSL=true

 jdbc.username=root

 jdbc.password=root

log4j.properties

 log4j.rootLogger=debug,stdout,file

 ### direct log messages to stdout ###

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

 log4j.appender.stdout.Target=System.out

 log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

 log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{}:%L - %m%n

 ### direct messages to file mylog.log ###

 log4j.appender.file=org.apache.log4j.FileAppender

 log4j.appender.file.File=c:\\logs\\log.log

 log4j.appender.file.layout=org.apache.log4j.PatternLayout

 log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{}:%L - %m%n

 ### set log levels - for more verbose logging change 'info' to 'debug' ###

 log4j.logger.cn.happy.dao=debug, stdout,file

mybatis-config.xml,俗称大配置

 <?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>

     <!--引入 jdbc.properties-->

     <properties resource="jdbc.properties"/>

     <settings>

         <setting name="logImpl" value="LOG4J"/>

         <setting name="autoMappingBehavior" value="NONE"/>

     </settings>

     <!--别名，这里不使用别名，一律使用全限定名-->

     <!--<typeAliases>

         <package name="cn.happy.entity"/>

     </typeAliases>-->

     <!--DB connection info,配置mybatis多套运行环境-->

     <environments default="development">

         <environment id="development">

             <!--采用jdbc事务管理-->

             <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>

     <!--大配置关联小配置-->

     <mappers>

         <!--关联单个小配置,不能重复关联-->

         <mapper resource="cn/happy/dao/IUserDAO.xml"/>

         <!--关联整个包,dao层接口名字和对应的xml名字要一样-->

         <!--<package name="cn.happy.dao"/>-->

     </mappers>

 </configuration>

7.编写MyBatisUtil类

 package cn.happy.util;

 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 java.io.IOException;

 import java.io.InputStream;

 public class MyBatisUtil {

     private static InputStream is;

     private static SqlSessionFactory sqlSessionFactory;

     static {

         try {

             is=Resources.getResourceAsStream("mybatis-config.xml");

         } catch (IOException e) {

             e.printStackTrace();

         }

         sqlSessionFactory= new SqlSessionFactoryBuilder().build(is);

     }

     private MyBatisUtil(){}

     public static SqlSession getSession(){

         return sqlSessionFactory.openSession();

     }

 }

8.创建测试类

代码：

 package cn.happy.test;

 import cn.happy.dao.IUserDAO;

 import cn.happy.entity.Smbms_user;

 import cn.happy.util.MyBatisUtil;

 import org.apache.ibatis.session.SqlSession;

 import org.junit.Test;

 import java.util.List;

 public class Test20170916 {

     @Test

     public void findAll(){

         SqlSession session = MyBatisUtil.getSession();

         IUserDAO mapper = session.getMapper(IUserDAO.class);

         List<Smbms_user> users = mapper.findAll();

         for (Smbms_user user:users

              ) {

             System.out.println(user.getId()+"\t"+user.getUsername()+"\t"+user.getUserpassword());

         }

     }

 }

运行结果：

巴特西

idea上MyBatis第一个例子

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