MyBatis 學習總結 02 對表執行增刪改查(CRUD)操作 OLD
阿新 • • 發佈:2017-09-15
去除 dev ins tlist 只需要 獲取 exception ref ssi
可以對上一節中使用mybatis打開一次session的業務邏輯進行封裝,封裝的成工具類命名為: MyBatisUtil
package com.mybatis.util;
import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MyBatisUtil
{
/**
* 獲取SqlSessionFactory
*
* @return SqlSessionFactory
*/
public static SqlSessionFactory getSqlSessionFactory()
{
String resource = "mybatis.cfg.xml";
InputStream is = MyBatisUtil.class.getClassLoader().getResourceAsStream(resource);
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
return factory;
}
/**
* 獲取SqlSession
*
* @return SqlSession
*/
public static SqlSession getSqlSession()
{
return getSqlSessionFactory().openSession();
}
/**
* 獲取SqlSession
*
* @param isAutoCommit
* true 表示創建的SqlSession對象在執行完SQL之後會自動提交事務 false
* 表示創建的SqlSession對象在執行完SQL之後不會自動提交事務,這時就需要我們手動調用sqlSession.
* commit()提交事務
* @return SqlSession
*/
public static SqlSession getSqlSession(boolean isAutoCommit)
{
return getSqlSessionFactory().openSession(isAutoCommit);
}
}
一 使用mybatis對表執行CRUD操作--基於XML的實現
1 定義sql映射xml文件
userMaper.xml文件的內容如下:
<?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">
<!-- 為這個mapper指定一個唯一的namespace,namespace的值習慣上設置成包名+sql映射文件名,這樣就能夠保證namespace的值是唯一的
例如namespace="com.mybatis.mapping.userMapper"就是com.mybatis.mapping(包名)+userMapper(userMapper.xml文件去除後綴)
-->
<mapper namespace="com.mybatis.mapping.userMapper">
<!-- 在select標簽中編寫查詢的SQL語句, 設置select標簽的id屬性為getUser,id屬性值必須是唯一的,不能夠重復
使用parameterType屬性指明查詢時使用的參數類型,resultType屬性指明查詢返回的結果集類型
resultType="com.mybatis.domain.User"就表示將查詢結果封裝成一個User類的對象返回
User類就是users表所對應的實體類
-->
<!--
根據id查詢得到一個user對象
-->
<select id="getUser" parameterType="int"
resultType="com.mybatis.pojo.User">
select * from users where id=#{id}
</select>
<!-- 創建用戶(Create) -->
<insert id="addUser" parameterType="com.mybatis.pojo.User">
insert into users(username ,age) values(#{username},#{age})
</insert>
<!-- 刪除用戶(Remove) -->
<delete id="deleteUser" parameterType="int">
delete from users where id=#{id}
</delete>
<!-- 修改用戶(Update) -->
<update id="updateUser" parameterType="com.mybatis.pojo.User">
update users set username=#{username},age=#{age} where id=#{id}
</update>
<!-- 查詢全部用戶-->
<select id="getAllUsers" resultType="com.mybatis.pojo.User">
select * from users
</select>
</mapper>
2 mybatis.cfg.xml配置文件如下:
<?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> <environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <!-- 配置數據庫連接信息 --> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/myDb?useUnicode=true&characterEncoding=utf8" /> <property name="username" value="root" /> <property name="password" value="123456" /> </dataSource> </environment> </environments> <mappers> <!-- 註冊userMapper.xml文件, userMapper.xml位於com.mybatis.mapping這個包下,所以resource寫成com/mybatis/mapping/userMapper.xml --> <mapper resource="com/mybatis/mapping/userMapper.xml"/> </mappers> </configuration>
3 單元測試類代碼如下:
package com.mybatis.test;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.mybatis.pojo.User;
import com.mybatis.util.MyBatisUtil;
public class TestMybatisXmlMapper
{
@Before
public void setUp() throws Exception
{
}
@After
public void tearDown() throws Exception
{
}
@Test
public void testAdd(){
//SqlSession sqlSession = MyBatisUtil.getSqlSession(false);
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
/**
* 映射sql的標識字符串,
* me.gacl.mapping.userMapper是userMapper.xml文件中mapper標簽的namespace屬性的值,
* addUser是insert標簽的id屬性值,通過insert標簽的id屬性值就可以找到要執行的SQL
*/
String statement = "com.mybatis.mapping.userMapper.addUser";//映射sql的標識字符串
User user = new User();
user.setUsername("李四");
user.setAge(20);
//執行插入操作
int retResult = sqlSession.insert(statement,user);
//手動提交事務
//sqlSession.commit();
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(retResult);
}
@Test
public void testUpdate(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
/**
* 映射sql的標識字符串,
* com.mybatis.mapping.userMapper是userMapper.xml文件中mapper標簽的namespace屬性的值,
* updateUser是update標簽的id屬性值,通過update標簽的id屬性值就可以找到要執行的SQL
*/
String statement = "com.mybatis.mapping.userMapper.updateUser";//映射sql的標識字符串
User user = new User();
user.setId(2);
user.setUsername("王五");
user.setAge(30);
//執行修改操作
int retResult = sqlSession.update(statement,user);
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(retResult);
}
@Test
public void testDelete(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
/**
* 映射sql的標識字符串,
* com.mybatis.mapping.userMapper是userMapper.xml文件中mapper標簽的namespace屬性的值,
* deleteUser是delete標簽的id屬性值,通過delete標簽的id屬性值就可以找到要執行的SQL
*/
String statement = "com.mybatis.mapping.userMapper.deleteUser";//映射sql的標識字符串
//執行刪除操作
int retResult = sqlSession.delete(statement,1);
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(retResult);
}
@Test
public void testGetAll(){
SqlSession sqlSession = MyBatisUtil.getSqlSession();
/**
* 映射sql的標識字符串,
* com.mybatis.mapping.userMapper是userMapper.xml文件中mapper標簽的namespace屬性的值,
* getAllUsers是select標簽的id屬性值,通過select標簽的id屬性值就可以找到要執行的SQL
*/
String statement = "com.mybatis.mapping.userMapper.getAllUsers";//映射sql的標識字符串
//執行查詢操作,將查詢結果自動封裝成List<User>返回
List<User> lstUsers = sqlSession.selectList(statement);
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(lstUsers);
}
}
二 使用mybatis對表執行CRUD操作--基於註解實現
1 定義sql映射的接口
IUserMapper接口的代碼如下:
package com.mybatis.mapping;
import java.util.List;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import com.mybatis.pojo.User;
/**
* 定義sql映射的接口,使用註解指明方法要執行的SQL
*
*/
public interface IUserMapper
{
//使用@Insert註解指明add方法要執行的SQL
@Insert("insert into users(username, age) values(#{username}, #{age})")
public int add(User user);
//使用@Delete註解指明deleteById方法要執行的SQL
@Delete("delete from users where id=#{id}")
public int deleteById(int id);
//使用@Update註解指明update方法要執行的SQL
@Update("update users set username=#{username},age=#{age} where id=#{id}")
public int update(User user);
//使用@Select註解指明getById方法要執行的SQL
@Select("select * from users where id=#{id}")
public User getById(int id);
//使用@Select註解指明getAll方法要執行的SQL
@Select("select * from users")
public List<User> getAll();
}
不需要針對IUserMapperI接口去編寫具體的實現類代碼,這個具體的實現類由MyBatis幫我們動態構建出來,我們只需要直接拿來使用即可。
2 在 mybatis.cfg.com註冊這個映射接口。
<?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> <environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <!-- 配置數據庫連接信息 --> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/myDb?useUnicode=true&characterEncoding=utf8" /> <property name="username" value="root" /> <property name="password" value="123456" /> </dataSource> </environment> </environments> <mappers> <!-- 註冊UserMapper映射接口--> <mapper class="com.mybatis.mapping.IUserMapper"/> </mappers> </configuration>
3 單元測試類
TestCRUDByAnnotationMapper的具體代碼如下:
package com.mybatis.test;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.mybatis.mapping.IUserMapper;
import com.mybatis.pojo.User;
import com.mybatis.util.MyBatisUtil;
public class TestCRUDByAnnotationMapper
{
@Before
public void setUp() throws Exception
{
}
@After
public void tearDown() throws Exception
{
}
@Test
public void testAdd(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
//得到UserMapperI接口的實現類對象,UserMapperI接口的實現類對象由sqlSession.getMapper(UserMapperI.class)動態構建出來
IUserMapper mapper = sqlSession.getMapper(IUserMapper.class);
User user = new User();
user.setUsername("王五");
user.setAge(20);
int add = mapper.add(user);
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(add);
}
@Test
public void testUpdate(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
//得到UserMapperI接口的實現類對象,UserMapperI接口的實現類對象由sqlSession.getMapper(UserMapperI.class)動態構建出來
IUserMapper mapper = sqlSession.getMapper(IUserMapper.class);
User user = new User();
user.setId(2);
user.setUsername("王五2");
user.setAge(30);
//執行修改操作
int retResult = mapper.update(user);
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(retResult);
}
@Test
public void testDelete(){
SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
//得到UserMapperI接口的實現類對象,UserMapperI接口的實現類對象由sqlSession.getMapper(UserMapperI.class)動態構建出來
IUserMapper mapper = sqlSession.getMapper(IUserMapper.class);
//執行刪除操作
int retResult = mapper.deleteById(1);
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(retResult);
}
@Test
public void testGetUser(){
SqlSession sqlSession = MyBatisUtil.getSqlSession();
//得到UserMapperI接口的實現類對象,UserMapperI接口的實現類對象由sqlSession.getMapper(UserMapperI.class)動態構建出來
IUserMapper mapper = sqlSession.getMapper(IUserMapper.class);
//執行查詢操作,將查詢結果自動封裝成User返回
User user = mapper.getById(2);
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(user);
}
@Test
public void testGetAll(){
SqlSession sqlSession = MyBatisUtil.getSqlSession();
//得到UserMapperI接口的實現類對象,UserMapperI接口的實現類對象由sqlSession.getMapper(UserMapperI.class)動態構建出來
IUserMapper mapper = sqlSession.getMapper(IUserMapper.class);
//執行查詢操作,將查詢結果自動封裝成List<User>返回
List<User> lstUsers = mapper.getAll();
//使用SqlSession執行完SQL之後需要關閉SqlSession
sqlSession.close();
System.out.println(lstUsers);
}
}
4 本節的測試代碼下載地址: http://onl5wa4sd.bkt.clouddn.com/MyBatis02.rar
5 使用Maven建立的JAVA項目的源碼下載地址: http://ovy7j2mnc.bkt.clouddn.com/MavenMyBatis02.rar
MyBatis 學習總結 02 對表執行增刪改查(CRUD)操作 OLD