经过第一次的学习mybatis之后，我们对于这个有了简单的了解和认识之后呢，就可以简单的使用啦，昨天呢，我们仅仅是使用了简单的一个查询的功能，对于一些常用的findAll，findBy..,deleteByIds,deleteByid,add等等功能，基本的了解还是十分的有必要的。就在昨天的基础之上进行复制，重新处理了一个projetc进行说明。
mybaitsFactory的简单的封装
package com.common.utils;
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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
/**
* descrption: 获取Sqlsession
* authohr: wangji
* date: 2017-07-20 8:34
*/
public class MybatisSessionFactory{
private static final Logger log = LoggerFactory.getLogger(MybatisSessionFactory.class);
private static volatile SqlSessionFactory sqlSessionFactory;
public static SqlSessionFactory getInstatnce(){
if(sqlSessionFactory == null){
synchronized (MybatisSessionFactory.class){
if(sqlSessionFactory ==null){
try {
sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader("mybatis-config.xml"));
} catch (IOException e) {
log.error("mybatits 启动异常");
}
}
}
}
return sqlSessionFactory;
};
public static SqlSession getSQLSesssion(){
if( getInstatnce() !=null){
return sqlSessionFactory.openSession();
}
return null;
}
public static void closeSession(SqlSession sqlSession){
if(sqlSession !=null){
sqlSession.close();
}
}
}
重点在于我们的Dao层也就是Dao接口，同时在Mybatis中我们也可以认为是Mapping层的操作，我们看看接口需要实现一些什么样的功能。
package com.jet.module.UserManage.dao;
import com.jet.module.UserManage.entity.User;
import java.util.List;
import java.util.Map;
/**
* Created by JetWang on 2017/7/19.
*/
public interface UserDao {
User findById(Integer id);
List<User> findAll();
//这里只是插入一个数据
void addUser(User user);
//这里插入多个数据
void addUsers(List<User> userList);
void deleteById(Integer id);
void deleteByIds(List<Integer> ids);
void deleteByArrayIds(Integer []ids);
void deleteByMapIds(Map<String,Object> map);
}
下面一个个的进行讲解
- findAll我们查找出来的时候是个List，必须使用ResultMap进行处理，ResultMap很强大，可以想象成为一个简单的Bean或者是一个List< Bean>的集合，我们SQL查找后的字段对于column,Bean中的属性也就是对应property.
<resultMap id="listUser" type="User"><!--type对应我们list中的实体，或者就是一个JavaBean--> <id column="id" property="id" /><!--column不是我们数据库中的字段名称，而是查找出来之后对应的字段的信息--> <result column="name" property="name" /> <result column="age" property="age" /> <result column="address" property="address" /> </resultMap> <!--resultMap 很强大，这里只是返回了一个List的数据而已--> <select id="findAll" resultMap="listUser" > select id,userName as name,userAge as age,userAddress as address from user </select> - addUser 插入一个数据，由于一般来说自增的主键，我们这里也是需要配置使用,useGeneratedKeys使用key，然后对于的属性为id.除此之外我们传入的使用User的Bean我们可以想象为Map，其实这里想象为Map或者Bean都是差不多的的，对于#{}中的对象就是属性或者键值。
<insert id="addUser" parameterType="User" useGeneratedKeys="true" keyProperty="id" > INSERT INTO USER(userName,userAge,userAddress) VALUES (#{name},#{age},#{address} ) </insert> - addUsers这中批量增加的需要动态的SQL支持,这里使用了重构SQL标签减少重复的使用相同的文字。foreach 很好理解吧，集合就是list或者array或者map中的键，item就是当前的一个项，index是第几项，分割符意思就是每一项分割使用的分隔符。
<!--这里的inser into后面的 user(userName,userAge,userAddress)重复的使用,mybatis中提供了重构的--><sql id="insertUserColumn"> USER(userName,userAge,userAddress) </sql> <!--所有的属性都必须在一行中书写完成哦--> <insert id="addUsers" parameterType="java.util.List" useGeneratedKeys="true" keyProperty="id"> INSERT INTO <include refid="insertUserColumn"></include> VALUES <foreach collection="list" item="item" index="index" separator=",">/*这里的分割符是插入之后的分割符*/ (#{item.name},#{item.age},#{item.address}) </foreach> /*(wangji,1,'zunyi'),(wangji,1,'zunyi') 动态SQl的强大之处*/ </insert> - delete一样的就不用多说了
<delete id="deleteById" parameterType="int" >
DELETE FROM USER WHERE id = #{id}
</delete>
<delete id="deleteByIds" parameterType="java.util.List" >
DELETE FROM USER WHERE id in
/*open 和close就是构建的时候需要括号包起来这个sql语句*/
<foreach collection="list" separator="," index="index" open="(" close=")" item="item">
#{item}/*这里的list中就是一个包装Integer，所以就是这个自己本身*/
</foreach>
</delete>
<!--http://blog.net/u013083576/article/details/51577954 这种写法-->
<delete id="deleteByArrayIds" parameterType="int[]" >
DELETE FROM USER WHERE id in
<foreach collection="array" separator="," index="index" open="(" close=")" item="item">
#{item}
</foreach>
</delete>
<delete id="deleteByMapIds" parameterType="java.util.Map">
DELETE FROM USER WHERE id in
/*这里的ids是放置在Map中的键，值可能是数组或者List*/
<foreach collection="ids" separator="," index="index" open="(" close=")" item="item">
#{item}
</foreach>
</delete>
测试一下(包含了昨天的内容)
import com.common.utils.MybatisSessionFactory;
import com.jet.module.UserManage.dao.UserDao;
import com.jet.module.UserManage.entity.User;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Assert;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Created by JetWang on 2017/7/19.
*/
public class UserDaoTest {
//添加了日志
private static final Logger log = LoggerFactory.getLogger(UserDaoTest.class);
@Test
public void testDeleteByMapIds(){
SqlSession sqlSession = MybatisSessionFactory.getSQLSesssion();
try {
UserDao userDao = sqlSession.getMapper(UserDao.class);
Integer[] ids = {8,9};
Map<String,Object> map = new HashMap<String,Object>();
map.put("ids",ids);
userDao.deleteByMapIds(map);
//这里需要提交事务才能写入数据库
sqlSession.commit();
} catch (Exception e) {
log.error(e.getMessage(),e);
} finally {
MybatisSessionFactory.closeSession(sqlSession);
}
}
@Test
public void testDeleteByIdsArray(){
SqlSession sqlSession = MybatisSessionFactory.getSQLSesssion();
try {
UserDao userDao = sqlSession.getMapper(UserDao.class);
Integer[] ids = {8,9};
userDao.deleteByArrayIds(ids);
//这里需要提交事务才能写入数据库
sqlSession.commit();
} catch (Exception e) {
log.error(e.getMessage(),e);
} finally {
MybatisSessionFactory.closeSession(sqlSession);
}
}
@Test
public void testDeleteByIdsList(){
SqlSession sqlSession = MybatisSessionFactory.getSQLSesssion();
try {
UserDao userDao = sqlSession.getMapper(UserDao.class);
List<Integer> ids = new ArrayList<Integer>();
ids.add(10);
ids.add(11);
userDao.deleteByIds(ids);
//这里需要提交事务才能写入数据库
sqlSession.commit();
} catch (Exception e) {
log.error(e.getMessage(),e);
} finally {
MybatisSessionFactory.closeSession(sqlSession);
}
}
@Test
public void testDeleteById(){
SqlSession sqlSession = MybatisSessionFactory.getSQLSesssion();
try {
UserDao userDao = sqlSession.getMapper(UserDao.class);
userDao.deleteById(6);
//这里需要提交事务才能写入数据库
sqlSession.commit();
} catch (Exception e) {
log.error(e.getMessage(),e);
} finally {
MybatisSessionFactory.closeSession(sqlSession);
}
}
@Test
public void testAddUsers(){
List<User> userList = new ArrayList<User>(5);
for(int i=0;i<5;i++){
User user = new User();
user.setAge(i);
user.setAddress("zunyi"+i);
user.setName("wangji"+i);
userList.add(user);
}
SqlSession sqlSession = MybatisSessionFactory.getSQLSesssion();
try {
UserDao userDao = sqlSession.getMapper(UserDao.class);
userDao.addUsers(userList);
//这里需要提交事务才能写入数据库
sqlSession.commit();
} catch (Exception e) {
log.error(e.getMessage(),e);
} finally {
MybatisSessionFactory.closeSession(sqlSession);
}
log.info(userList.toString());
}
@Test
public void testAddUser(){
User user = new User();
user.setName("wangwang");
user.setAddress("zunyi");
user.setAge(5);
SqlSession sqlSession = MybatisSessionFactory.getSQLSesssion();
try {
UserDao userDao = sqlSession.getMapper(UserDao.class);
userDao.addUser(user);
//这里需要提交事务才能写入数据库
sqlSession.commit();
} catch (Exception e) {
log.error(e.getMessage(),e);
} finally {
MybatisSessionFactory.closeSession(sqlSession);
}
log.info(user.toString());
}
@Test
public void testFindAll(){
SqlSession sqlSession = MybatisSessionFactory.getSQLSesssion();
try {
UserDao userDao = sqlSession.getMapper(UserDao.class);
log.info(userDao.findAll().toString());
} catch (Exception e) {
log.error(e.getMessage(),e);
} finally {
MybatisSessionFactory.closeSession(sqlSession);
}
}
@Test
public void testSessionFactory(){
Assert.assertNotNull(MybatisSessionFactory.getInstatnce());
}
@Test
public void findByIdTest() {
InputStream inputStream = null;
SqlSessionFactory sqlSessionFactory = null;
SqlSession sqlSession = null;
try {
inputStream = org.apache.ibatis.io.Resources.getResourceAsStream("mybatis-config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
sqlSession = sqlSessionFactory.openSession();
//这里面向接口的，mybatis使用动态代理给你生成实现类，不需要DaoImpl
UserDao userDao = sqlSession.getMapper(UserDao.class);
User user = userDao.findById(1);
/*
通过命名空间进行查询
User user = sqlSession.selectOne("com.jet.module.UserManage.dao.UserDao.findById",1);
*/
Assert.assertNotNull(user);
System.out.println(user.toString());
} catch (IOException e) {
e.printStackTrace();
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (sqlSession != null) {
sqlSession.close();
}
}
}
}
资源地址：https://github.com/WangJi92/mybatits-study/blob/master/mybatis-study/study-2
