mybatis的简单使用调用mapper接口
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mybatis 是apache下的一个面向sql编程的半自动化的ORM持久层的框架。特点：面向sql编程，达到高性能的使用目的。
下面是简单使用
现导入jar包,只有mybatis和数据库驱动包(这里用的是mysql的驱动包)是必须的,其余是日志需要的包
db.properties配置连接池的配置文件
1 jdbc.driverClassName=com.mysql.jdbc.Driver 2 jdbc.url=jdbc:mysql://localhost:3306/mybatis 3 jdbc.username=root 4 jdbc.password=12
创建一个mybatis数据库,执行下面的生sql语句插入数据
DROP TABLE IF EXISTS `user`; CREATE TABLE `user` ( `id` int(11) NOT NULL AUTO_INCREMENT, `username` varchar(32) NOT NULL COMMENT \'用户名称\', `birthday` date DEFAULT NULL COMMENT \'生日\', `sex` char(1) DEFAULT NULL COMMENT \'性别\', `address` varchar(256) DEFAULT NULL COMMENT \'地址\', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=27 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of user -- ---------------------------- INSERT INTO `user` VALUES (\'1\', \'王五\', null, \'2\', null); INSERT INTO `user` VALUES (\'10\', \'张三\', \'2014-07-10\', \'1\', \'北京市\'); INSERT INTO `user` VALUES (\'16\', \'张小明\', null, \'1\', \'河南郑州\'); INSERT INTO `user` VALUES (\'22\', \'陈小明\', null, \'1\', \'河南郑州\'); INSERT INTO `user` VALUES (\'24\', \'张三丰\', null, \'1\', \'河南郑州\'); INSERT INTO `user` VALUES (\'25\', \'陈小明\', null, \'1\', \'河南郑州\'); INSERT INTO `user` VALUES (\'26\', \'王五\', null, null, null);
log4j.properties 日志的配置文件
1 ### direct log messages to stdout ### 2 log4j.appender.stdout=org.apache.log4j.ConsoleAppender 3 log4j.appender.stdout.Target=System.err 4 log4j.appender.stdout.layout=org.apache.log4j.PatternLayout 5 log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n 6 7 ### direct messages to file mylog.log ### 8 log4j.appender.file=org.apache.log4j.FileAppender 9 log4j.appender.file.File=d:/mylog.log 10 log4j.appender.file.layout=org.apache.log4j.PatternLayout 11 log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n 12 13 ### set log levels - for more verbose logging change \'info\' to \'debug\' ### 14 15 log4j.rootLogger=info, stdout
SqlMapConfig.xml 是mybatis全局的配置文件
<?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> <properties resource="db.properties"> </properties> <typeAliases> <!-- 单个别名定义 ,后面就可用直接写user,不用写全路径名--> <!-- <typeAlias type="com.baoyuan.domain.User" alias="user"/> --> <!-- 批量别名定义，扫描整个包下的类，别名为类名（大小写不敏感） --> <package name="com.baoyuan.domain"/> </typeAliases> <!--名称随意 --> <environments default="development"> <!--id必须和上面的一致 --> <environment id="development"> <!--固定格式JDBC --> <transactionManager type="JDBC"></transactionManager> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driverClassName}"/> <property name="url" value="${jdbc.url}"/> <property name="username" value="${jdbc.username}"/> <property name="password" value="${jdbc.password}"/> </dataSource> </environment> </environments> <mappers> <!-- 使用mapper接口类路径 注意：此种方法要求mapper接口名称和mapper映射文件名称相同，且放在同一个目录中--> <!-- <mapper class="com.baoyuan.mapper.dao.UserMapper"/> --> <!-- 注意：此种方法要求mapper接口名称和mapper映射文件名称相同，且放在同一个目录中。 --> <package name="com.baoyuan.mapper.dao"/> </mappers> </configuration>
创建一个pojo类User类
package com.baoyuan.domain; import java.util.Date; public class User { private Integer id; private String username;// 用户姓名 private String sex;// 性别 private Date birthday;// 生日 private String address;// 地址 public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } @Override public String toString() { return "User [id=" + id + ", username=" + username + ", sex=" + sex + ", birthday=" + birthday + ", address=" + address + "]"; } }
在src目录下建立一个com.baoyuan.mapper.dao的包
在com.baoyuan.mapper.dao创建一个UserMapper.xml的映射文件
Mapper接口开发需要遵循以下规范：
1、 Mapper.xml文件中的namespace与mapper接口的类路径相同。
2、 Mapper接口方法名和Mapper.xml中定义的每个statement的id相同
3、 Mapper接口方法的输入参数类型和mapper.xml中定义的每个sql 的parameterType的类型相同
4、 Mapper接口方法的输出参数类型和mapper.xml中定义的每个sql的resultType的类型相同
<?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"> <mapper namespace="com.baoyuan.mapper.dao.UserMapper">
<!-- Id表示statement的id唯一标识符,resultType表示结果集的类型,parameterType表示形式参数类型 ,如果SqlMapConfig.xml中配置了别名,就可以直接谢别名user,不用再写全路径com.baoyuan.domain.User --> <select id="findUserById" resultType="com.baoyuan.domain.User" parameterType="int" >
<!--#{}大括号类随意写只是表示一个占位符,相当于statment中的"?" --> select * from user where id =#{id} </select>
<!--这里返回的类型虽然是list,resultType表示list泛型的类型 --> <select id="findUserByUsername" resultType="com.baoyuan.domain.User" parameterType="java.lang.String" >
<!--这里必须写value,${value}表示拼接字符串,如果用其他会报错,用#{}只是表示占位符,可以在调用时传"%条件%的参数" --> select * from user where username like \'%${value}%\' </select> <insert id="saveUser" parameterType="com.baoyuan.domain.User" >
<!--配置在插入一条数据后返回主键,会自动保存到pojo对象的主键属性中 -->
<selectKey keyProperty="id" resultType="java.lang.Integer" order="AFTER">
select LAST_INSERT_ID()
<!--必须是主键自增长 是mysql的函数，返回auto_increment自增列新记录id值 -->
</selectKey>
<!-- <selectKey resultType="java.lang.String" order="BEFORE" keyProperty="id">
select uuid()
需要增加通过select uuid()得到uuid值（前提是用户表中的id必须是字符串类型）
</selectKey> -->
<!--这里由于 parameterType形式参数的类型是user,所以这里#{}大括号中不能随便写,写的是user的属性 --> insert INTO user(username,birthday,sex,address) VALUES(#{username},#{birthday},#{sex},#{address}) </insert> <delete id="deleteUserById" parameterType="int"> delete from user where id =#{id} </delete> <update id="updateUserById" parameterType="com.baoyuan.domain.User"> update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id} </update> </mapper>
创建UserMapper的接口
package com.baoyuan.mapper.dao; import java.util.List; import com.baoyuan.domain.User; //类名必须和 public interface UserMapper { public User findUserById(Integer id); public List<User> findUserByUsername(String username); public void saveUser(User user); public void deleteUserById(Integer id); public void updateUserById(User user); }
测试代码
package com.baoyuan.test; import java.io.IOException; import java.io.InputStream; import java.util.Date; import java.util.List; 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.Before; import org.junit.Test; import com.baoyuan.domain.User; import com.baoyuan.mapper.dao.UserMapper; public class TestUserMapper { private SqlSessionFactory sqlSessionFactory ;
//表示运行测试代码前执行,给sqlSessionFactory赋值 @Before public void InitialContext() throws IOException{ SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); InputStream inputStream=Resources.getResourceAsStream("SqlMapConfig.xml"); SqlSessionFactory sqlSessionFactory = builder.build(inputStream); this.sqlSessionFactory=sqlSessionFactory; }
//通过id查询用户 @Test public void findUserById(){ //获取sqlsession SqlSession sqlSession=null; try { sqlSession = sqlSessionFactory.openSession(); //获取mapper接口代理对象 UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user = userMapper.findUserById(1); System.out.println(user); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ if(sqlSession!=null){ sqlSession.close(); } } }
//通过用户名模糊查询用户 @Test public void findUserByUsername(){ //获取sqlsession SqlSession sqlSession=null; try { sqlSession = sqlSessionFactory.openSession(); //获取mapper接口代理对象 UserMapper userMapper = sqlSession.getMapper(UserMapper.class); List<User> list = userMapper.findUserByUsername("张"); System.out.println(list); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ if(sqlSession!=null){ sqlSession.close(); } } }
//保存用户 @Test public void saveUser(){ //获取sqlsession SqlSession sqlSession=null; try { sqlSession = sqlSessionFactory.openSession(); //获取mapper接口代理对象 UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user=new User(); user.setUsername("李四"); user.setBirthday(new Date()); user.setSex("1"); user.setAddress("深圳");
System.out.println(user.getId()); userMapper.saveUser(user); sqlSession.commit();
System.out.println(user.getId()); } catch (Exception e) { e.printStackTrace(); }finally{ if(sqlSession!=null){ sqlSession.close(); } } }
//更新用户 @Test public void updateUserById(){ //获取sqlsession SqlSession sqlSession=null; try { sqlSession = sqlSessionFactory.openSession(); //获取mapper接口代理对象 UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user=new User(); user.setId(30); user.setUsername("李四"); user.setBirthday(new Date()); user.setSex("1"); user.setAddress("深圳"); userMapper.updateUserById(user);; sqlSession.commit(); } catch (Exception e) { e.printStackTrace(); }finally{ if(sqlSession!=null){ sqlSession.close(); } } }
//删除用户 @Test public void deleteUserById(){ //获取sqlsession SqlSession sqlSession=null; try { sqlSession = sqlSessionFactory.openSession(); //获取mapper接口代理对象 UserMapper userMapper = sqlSession.getMapper(UserMapper.class); userMapper.deleteUserById(30);; sqlSession.commit(); } catch (Exception e) { e.printStackTrace(); }finally{ if(sqlSession!=null){ sqlSession.close(); } } } }
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