一、改造UserMapperTest类的代码
（将公共代码创建factory和sqlSession，关闭sqlSession写在MyBatisUtil里面）
在src下面新建一个包cn.smbms.utils，在新建的包cn.smbms.utils里面新建类MyBatisUtil，将UserMapperTest类里面的创建factory，sqlSession和关闭sqlSession写在MyBatisUtil里面
改造后MyBatisUtil里面代码如下：
package cn.smbms.utils;
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;
public class MyBatisUtil {
private static SqlSessionFactory factory;
static{
try {
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
factory = new SqlSessionFactoryBuilder().build(is);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession createSqlSession(){
return factory.openSession(false);
}
public static void closeSqlSession(SqlSession sqlSession){
if(null!=sqlSession){
sqlSession.close();
}
}
}
改造后UserMapperTest代码如下：
package cn.smbms.dao.user;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.Test;
import cn.smbms.utils.MyBatisUtil;
public class UserMapperTest {
private Logger logger = Logger.getLogger(UserMapperTest.class);
@Test
public void test() {
int count = 0;
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil.createSqlSession();
count = sqlSession.selectOne("cn.smbms.dao.user.UserMapper.count");
logger.debug("UserMapperTest count---> " + count);
} catch (Exception e) {
e.printStackTrace();
}finally{
MyBatisUtil.closeSqlSession(sqlSession);
}
}
}
二、如何查看源码：比如查看SqlSession源码
按住ctrl健鼠标移动到SqlSession上点击Open declared Type可打开SqlSession类，执行window—show view—outline可以查看 SqlSession的相关方法
三、改造UserMapperTest类的代码实现用户列表的查询
（使用sqlSession.selectList()方法）
在UserMapper.xml文件中增加查询用户列表配置：增加后的完整代码为：
"1.0" encoding="UTF-8" ?>
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
select count(1) as count from smbms_user
select * from smbms_user
在UserMapperTest类中增加testGetUserList()方法增加后代码：
package cn.smbms.dao.user;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.Test;
import cn.smbms.pojo.User;
import cn.smbms.utils.MyBatisUtil;
public class UserMapperTest {
private Logger logger = Logger.getLogger(UserMapperTest.class);
@Test
public void test() {
int count = 0;
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil.createSqlSession();
count = sqlSession.selectOne("cn.smbms.dao.user.UserMapper.count");
logger.debug("UserMapperTest count---> " + count);
} catch (Exception e) {
e.printStackTrace();
}finally{
MyBatisUtil.closeSqlSession(sqlSession);
}
}
@Test
public void testGetUserList() {
List
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil.createSqlSession();
userList = sqlSession.selectList("cn.smbms.dao.user.UserMapper.getUserList");
} catch (Exception e) {
e.printStackTrace();
}finally{
MyBatisUtil.closeSqlSession(sqlSession);
}
for(User user:userList){
logger.debug("UserMapperTest userCode---> " + user.getUserCode()
+"and userName:"+user.getUserName());
}
}
}
四、使用sqlSession.getMapper(Mapper.class)方法改造UserMapperTest
由于userList = sqlSession.selectList("cn.smbms.dao.user.UserMapper.getUserList");中cn.smbms.dao.user.UserMapper.getUserList字符串书写容易出错
在cn.smbms.dao.user下创建UserMapper接口
接口中代码如下：
package cn.smbms.dao.user;
import java.util.List;
import cn.smbms.pojo.User;
public interface UserMapper {
public List
}
UserMapperTest修改后的代码如下：
package cn.smbms.dao.user;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.Test;
import cn.smbms.pojo.User;
import cn.smbms.utils.MyBatisUtil;
public class UserMapperTest {
private Logger logger = Logger.getLogger(UserMapperTest.class);
@Test
public void test() {
int count = 0;
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil.createSqlSession();
count = sqlSession.selectOne("cn.smbms.dao.user.UserMapper.count");
logger.debug("UserMapperTest count---> " + count);
} catch (Exception e) {
e.printStackTrace();
}finally{
MyBatisUtil.closeSqlSession(sqlSession);
}
}
@Test
public void testGetUserList() {
List
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil.createSqlSession();
userList = sqlSession.getMapper(UserMapper.class).getUserList();
} catch (Exception e) {
e.printStackTrace();
}finally{
MyBatisUtil.closeSqlSession(sqlSession);
}
for(User user:userList){
logger.debug("UserMapperTest userCode---> " + user.getUserCode()
+"and userName:"+user.getUserName());
}
}
}
五、修改mybatis-config.xml的properties配置
将
六、将UserMapper.xml中的resultType="cn.smbms.pojo.User"简写成resultType="User"的配置
在mybatis-config.xml里面配置
在configuration处右键-Add Child-typeAliases,系统会自动的将
（这里注意typeAlias标签最好自动生成，不然容易报错）
然后将UserMapper.xml中的
resultType="cn.smbms.pojo.User"改成resultType="User"
如果太多了，配置起来很麻烦，与是进一步做如下改进
将mybatis-config.xml里面的
七、使用URL的方式配置mybatis-config.xml中的mappers标签
在工作空间中找到UserMapper.xml，将其复制到D:\javastudy\练习素材，进入mybatis-config.xml中将
/练习素材/UserMapper.xml"/>