可以对上一节中使用mybatis打开一次session的业务逻辑进行封装,封装的成工具类命名为: 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 { /** * 获取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; } /** * 获取SqlSession * * @return SqlSession */ public static SqlSession getSqlSession() { return getSqlSessionFactory().openSession(); } /** * 获取SqlSession * * @param isAutoCommit * true 表示创建的SqlSession对象在执行完SQL之后会自动提交事务 false * 表示创建的SqlSession对象在执行完SQL之后不会自动提交事务,这时就需要我们手动调用sqlSession. * commit()提交事务 * @return SqlSession */ public static SqlSession getSqlSession(boolean isAutoCommit) { return getSqlSessionFactory().openSession(isAutoCommit); } }
一 使用mybatis对表执行CRUD操作--基于XML的实现
1 定义sql映射xml文件
userMaper.xml文件的内容如下:
<?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"> <!-- 为这个mapper指定一个唯一的namespace,namespace的值习惯上设置成包名+sql映射文件名,这样就能够保证namespace的值是唯一的 例如namespace="com.mybatis.mapping.userMapper"就是com.mybatis.mapping(包名)+userMapper(userMapper.xml文件去除后缀) --> <mapper namespace="com.mybatis.mapping.userMapper"> <!-- 在select标签中编写查询的SQL语句, 设置select标签的id属性为getUser,id属性值必须是唯一的,不能够重复 使用parameterType属性指明查询时使用的参数类型,resultType属性指明查询返回的结果集类型 resultType="com.mybatis.domain.User"就表示将查询结果封装成一个User类的对象返回 User类就是users表所对应的实体类 --> <!-- 根据id查询得到一个user对象 --> <select id="getUser" parameterType="int" resultType="com.mybatis.pojo.User"> select * from users where id=#{id} </select> <!-- 创建用户(Create) --> <insert id="addUser" parameterType="com.mybatis.pojo.User"> insert into users(username ,age) values(#{username},#{age}) </insert> <!-- 删除用户(Remove) --> <delete id="deleteUser" parameterType="int"> delete from users where id=#{id} </delete> <!-- 修改用户(Update) --> <update id="updateUser" parameterType="com.mybatis.pojo.User"> update users set username=#{username},age=#{age} where id=#{id} </update> <!-- 查询全部用户--> <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" /> <!-- 配置数据库连接信息 --> <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> <!-- 注册userMapper.xml文件, userMapper.xml位于com.mybatis.mapping这个包下,所以resource写成com/mybatis/mapping/userMapper.xml --> <mapper resource="com/mybatis/mapping/userMapper.xml"/> </mappers> </configuration>
3 单元测试类代码如下:
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的标识字符串, * me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值, * addUser是insert标签的id属性值,通过insert标签的id属性值就可以找到要执行的SQL */ String statement = "com.mybatis.mapping.userMapper.addUser";//映射sql的标识字符串 User user = new User(); user.setUsername("李四"); user.setAge(20); //执行插入操作 int retResult = sqlSession.insert(statement,user); //手动提交事务 //sqlSession.commit(); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(retResult); } @Test public void testUpdate(){ SqlSession sqlSession = MyBatisUtil.getSqlSession(true); /** * 映射sql的标识字符串, * com.mybatis.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值, * updateUser是update标签的id属性值,通过update标签的id属性值就可以找到要执行的SQL */ String statement = "com.mybatis.mapping.userMapper.updateUser";//映射sql的标识字符串 User user = new User(); user.setId(2); user.setUsername("王五"); user.setAge(30); //执行修改操作 int retResult = sqlSession.update(statement,user); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(retResult); } @Test public void testDelete(){ SqlSession sqlSession = MyBatisUtil.getSqlSession(true); /** * 映射sql的标识字符串, * com.mybatis.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值, * deleteUser是delete标签的id属性值,通过delete标签的id属性值就可以找到要执行的SQL */ String statement = "com.mybatis.mapping.userMapper.deleteUser";//映射sql的标识字符串 //执行删除操作 int retResult = sqlSession.delete(statement,1); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(retResult); } @Test public void testGetAll(){ SqlSession sqlSession = MyBatisUtil.getSqlSession(); /** * 映射sql的标识字符串, * com.mybatis.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值, * getAllUsers是select标签的id属性值,通过select标签的id属性值就可以找到要执行的SQL */ String statement = "com.mybatis.mapping.userMapper.getAllUsers";//映射sql的标识字符串 //执行查询操作,将查询结果自动封装成List<User>返回 List<User> lstUsers = sqlSession.selectList(statement); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(lstUsers); } }
二 使用mybatis对表执行CRUD操作--基于注解实现
1 定义sql映射的接口
IUserMapper接口的代码如下:
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; /** * 定义sql映射的接口,使用注解指明方法要执行的SQL * */ public interface IUserMapper { //使用@Insert注解指明add方法要执行的SQL @Insert("insert into users(username, age) values(#{username}, #{age})") public int add(User user); //使用@Delete注解指明deleteById方法要执行的SQL @Delete("delete from users where id=#{id}") public int deleteById(int id); //使用@Update注解指明update方法要执行的SQL @Update("update users set username=#{username},age=#{age} where id=#{id}") public int update(User user); //使用@Select注解指明getById方法要执行的SQL @Select("select * from users where id=#{id}") public User getById(int id); //使用@Select注解指明getAll方法要执行的SQL @Select("select * from users") public List<User> getAll(); }
不需要针对IUserMapperI接口去编写具体的实现类代码,这个具体的实现类由MyBatis帮我们动态构建出来,我们只需要直接拿来使用即可。
2 在 mybatis.cfg.com注册这个映射接口。
<?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" /> <!-- 配置数据库连接信息 --> <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> <!-- 注册UserMapper映射接口--> <mapper class="com.mybatis.mapping.IUserMapper"/> </mappers> </configuration>
3 单元测试类
TestCRUDByAnnotationMapper的具体代码如下:
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接口的实现类对象,UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来 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执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(add); } @Test public void testUpdate(){ SqlSession sqlSession = MyBatisUtil.getSqlSession(true); //得到UserMapperI接口的实现类对象,UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来 IUserMapper mapper = sqlSession.getMapper(IUserMapper.class); User user = new User(); user.setId(2); user.setUsername("王五2"); user.setAge(30); //执行修改操作 int retResult = mapper.update(user); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(retResult); } @Test public void testDelete(){ SqlSession sqlSession = MyBatisUtil.getSqlSession(true); //得到UserMapperI接口的实现类对象,UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来 IUserMapper mapper = sqlSession.getMapper(IUserMapper.class); //执行删除操作 int retResult = mapper.deleteById(1); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(retResult); } @Test public void testGetUser(){ SqlSession sqlSession = MyBatisUtil.getSqlSession(); //得到UserMapperI接口的实现类对象,UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来 IUserMapper mapper = sqlSession.getMapper(IUserMapper.class); //执行查询操作,将查询结果自动封装成User返回 User user = mapper.getById(2); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(user); } @Test public void testGetAll(){ SqlSession sqlSession = MyBatisUtil.getSqlSession(); //得到UserMapperI接口的实现类对象,UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来 IUserMapper mapper = sqlSession.getMapper(IUserMapper.class); //执行查询操作,将查询结果自动封装成List<User>返回 List<User> lstUsers = mapper.getAll(); //使用SqlSession执行完SQL之后需要关闭SqlSession sqlSession.close(); System.out.println(lstUsers); } }
4 本节的测试代码下载地址: http://onl5wa4sd.bkt.clouddn.com/MyBatis02.rar
5 使用Maven建立的JAVA项目的源码下载地址: http://ovy7j2mnc.bkt.clouddn.com/MavenMyBatis02.rar
时间: 2024-08-06 04:31:24