import java.io.IOException;
import java.io.InputStream;import junit.framework.TestCase;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 com.guowuxin.mybatis.mapper.UserMapper;
import com.guowuxin.mybatis.model.User;/*用户表
drop table if exists user;
create table user(id int primary key auto_increment,username varchar(50) unique,password varchar(100),useraddress varchar(50)
);
insert into user values(1,"guowuxin","guowuxin","beijing");
insert into user values(1,"guoxiaoming","guowuxin","beijing");
*///如果两次查询都是查询1 将只会发送一条sql语句到数据库，否则将是2条sql语句public class TestClass extends TestCase{public static SqlSessionFactory sqlSessionFactoy;static{String resource = "mybatis-config.xml";try {InputStream inputStream = Resources.getResourceAsStream(resource);sqlSessionFactoy = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}@Test public void testgetUserById() { SqlSession sqlSession = sqlSessionFactoy.openSession(); try { UserMapper mapper = sqlSession.getMapper(UserMapper.class); User u1=mapper.getUserById(1);System.out.println(u1);User u2=mapper.getUserById(1);System.out.println(u2);sqlSession.commit();} finally { sqlSession.close(); } }
}

package com.guowuxin.mybatis.mapper;import com.guowuxin.mybatis.model.User;//通过面向接口的mybatis编程方式，需要保证方法名和配置文件中的id名称一致
public interface UserMapper {public User getUserById(int id);
}

package com.guowuxin.mybatis.model;public class User {private int id;private int age;private String userName;private String userAddress;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}public String getUserAddress() {return userAddress;}public void setUserAddress(String userAddress) {this.userAddress = userAddress;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString(){final StringBuilder builder = new StringBuilder();builder.append("id=").append(id).append(",");builder.append("age=").append(age).append(",");builder.append("userName=").append(userName).append(",");builder.append("userAddress=").append(userAddress).append(".");return builder.toString();}
}

log4j.rootLogger=DEBUG,Console
ˆ†
#Console
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d %t %-5p (%c) - %m%nlog4j.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

<?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><typeAliases><typeAlias alias="User" type="com.guowuxin.mybatis.model.User" /></typeAliases><environments default="development"><environment id="development"><transactionManager type="JDBC" /><dataSource type="POOLED">  <property name="driver" value="com.mysql.jdbc.Driver" /><property name="url" value="jdbc:mysql://127.0.0.1:3306/guowuxin" /><property name="username" value="root" /><property name="password" value="admin" /></dataSource></environment></environments><mappers><mapper resource="UserMapper.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">
<!-- 这里namespace必须是PostsMapper接口的路径，不然要运行的时候要报错 “is not known to the MapperRegistry”-->
<mapper namespace="com.guowuxin.mybatis.mapper.UserMapper"> <!-- 这儿的resultType是配置在mybatis-config.xml中得别名 --><select id="getUserById" parameterType="int" resultType="User">select * from user where id=#{id}</select>
</mapper>

....................
2016-02-24 20:12:37,568 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@3b1d04]
2016-02-24 20:12:37,568 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==>  Preparing: select * from user where id=?
2016-02-24 20:12:37,586 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==> Parameters: 1(Integer)
id=1,age=0,userName=guowuxin,userAddress=beijing.
id=1,age=0,userName=guowuxin,userAddress=beijing.
2016-02-24 20:12:37,593 main DEBUG (org.apache.ibatis.transaction.jdbc.JdbcTransaction) - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3b1d04]
2016-02-24 20:12:37,593 main DEBUG (org.apache.ibatis.transaction.jdbc.JdbcTransaction) - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3b1d04]
2016-02-24 20:12:37,593 main DEBUG (org.apache.ibatis.datasource.pooled.PooledDataSource) - Returned connection 3874052 to pool.

.......................
2016-02-24 20:12:57,655 main DEBUG (org.apache.ibatis.datasource.pooled.PooledDataSource) - Created connection 3874052.
2016-02-24 20:12:57,656 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@3b1d04]
2016-02-24 20:12:57,656 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==>  Preparing: select * from user where id=?
2016-02-24 20:12:57,664 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==> Parameters: 1(Integer)
id=1,age=0,userName=guowuxin,userAddress=beijing.
2016-02-24 20:12:57,679 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@3b1d04]
2016-02-24 20:12:57,679 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==>  Preparing: select * from user where id=?
2016-02-24 20:12:57,679 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==> Parameters: 2(Integer)
id=2,age=0,userName=guoxiaoming,userAddress=beijing.
2016-02-24 20:12:57,679 main DEBUG (org.apache.ibatis.transaction.jdbc.JdbcTransaction) - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3b1d04]
2016-02-24 20:12:57,679 main DEBUG (org.apache.ibatis.transaction.jdbc.JdbcTransaction) - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3b1d04]
2016-02-24 20:12:57,679 main DEBUG (org.apache.ibatis.datasource.pooled.PooledDataSource) - Returned connection 3874052 to pool.

import java.io.IOException;
import java.io.InputStream;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 com.guowuxin.mybatis.mapper.UserMapper;
import com.guowuxin.mybatis.model.User;import junit.framework.TestCase;public class TestTwoCache extends TestCase{public static SqlSessionFactory sqlSessionFactory;static{String resource = "mybatis-config.xml";try {InputStream inputStream = Resources.getResourceAsStream(resource);sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}@Test public void testCache() { SqlSession sqlSession1 = sqlSessionFactory.openSession();SqlSession sqlSession2 = sqlSessionFactory.openSession();try { UserMapper mapper1 = sqlSession1.getMapper(UserMapper.class); User u1=mapper1.getUserById(1);System.out.println(u1);sqlSession1.commit();UserMapper mapper2 = sqlSession2.getMapper(UserMapper.class);User u2=mapper2.getUserById(1);System.out.println(u2);sqlSession2.commit();} finally { sqlSession1.close(); sqlSession2.close();} }
}

<?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">
<!-- 这里namespace必须是PostsMapper接口的路径，不然要运行的时候要报错 “is not known to the MapperRegistry”-->
<mapper namespace="com.guowuxin.mybatis.mapper.UserMapper"> <!-- 这儿的resultType是配置在mybatis-config.xml中得别名 --><cache /><select id="getUserById" parameterType="int" resultType="User">select * from user where id=#{id}</select>
</mapper>

2016-02-25 10:15:11,162 main DEBUG (org.apache.ibatis.datasource.pooled.PooledDataSource) - Created connection 22522451.
2016-02-25 10:15:11,164 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@157aa53]
2016-02-25 10:15:11,164 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==>  Preparing: select * from user where id=?
2016-02-25 10:15:11,182 main DEBUG (com.guowuxin.mybatis.mapper.UserMapper.getUserById) - ==> Parameters: 1(Integer)
id=1,age=0,userName=guowuxin,userAddress=beijing.
2016-02-25 10:15:11,196 main DEBUG (org.apache.ibatis.cache.decorators.LoggingCache) - Cache Hit Ratio [com.guowuxin.mybatis.mapper.UserMapper]: 0.5
id=1,age=0,userName=guowuxin,userAddress=beijing.
2016-02-25 10:15:11,196 main DEBUG (org.apache.ibatis.transaction.jdbc.JdbcTransaction) - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@157aa53]
2016-02-25 10:15:11,196 main DEBUG (org.apache.ibatis.transaction.jdbc.JdbcTransaction) - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@157aa53]
2016-02-25 10:15:11,197 main DEBUG (org.apache.ibatis.datasource.pooled.PooledDataSource) - Returned connection 22522451 to pool.