mybatis映射文件mapper.xml的具体写法 mybatis映射文件mapper.xml的具体写

Mapper映射文件是一个xml格式文件，必须遵循相应的dtd文件规范
在学习mybatis的时候我们通常会在映射文件这样写：

select *from student where id=#{id}select *from student where gid=#{gid}

然后再写dao的实现在写一个类，来实现dao的接口。但是这样在实现中需要这样写：

package com.qbd.service; import org.apache.ibatis.session.SqlSession; import org.apache.log4j.Logger; import com.qbd.mapper.StudentMappers; import com.qbd.model.Student; import com.qbd.util.SqlSessionFactoryUtil; public class StudentService {private static Logger logge=Logger.getLogger(StudentService.class); public static void main(String[] args) {SqlSession sqlSession=SqlSessionFactoryUtil.getSqlSession(); StudentMappers studentMappers=(StudentMappers)sqlSession.getMapper(StudentMappers.class); Student student=new Student(); student.setName("22"); student.setAge(2); int s=studentMappers.add(student); sqlSession.commit(); if(s>0){logge.info("success"); System.out.println("success"); }}}

来读取配置文件

另一种方法就是：
直接在mapper.xml中的这一部分写成dao如下

select * from userand uname like #{uname}limit #{start},#{size}select count(*) from userand uname like #{uname}select *from user where uname=#{uname} and upassword=#{upassword}delete from user where uid=#{uid}update useruname=#{uname},upassword=#{upassword},upower=#{upower},where uid=#{uid}insert into user values(null,#{uname},#{upassword},#{upower})

那么就不用写dao的实现在service中就能掉用mybatis默认会把mapper.xml映射为dao的实现
【mybatis映射文件mapper.xml的具体写法】那么下面dao就能这样写：

package com.qbd.ssm.dao; import java.util.List; import java.util.Map; import org.apache.ibatis.annotations.Delete; import com.qbd.ssm.model.User; public interface UserDao { public List getAll(); public User getUser(User user); public int delete(User user); public int update(User user); public int add(User user); public List find(Map map); public Long getTotal(Map map); }

service这样写

package com.qbd.ssm.service; import java.util.List; import java.util.Map; import com.qbd.ssm.model.User; public interface UserService { public List getAll(); public User getUser(User user); public int delete(User user); public int update(User user); public int add(User user); public List find(Map map); public Long getTotal(Map map); }

service的实现：

package com.qbd.ssm.serviceimpl; import java.util.List; import java.util.Map; import javax.annotation.Resource; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.qbd.ssm.dao.UserDao; import com.qbd.ssm.model.User; import com.qbd.ssm.service.UserService; @Service("userService")public class UserServiceImpl implements UserService { private UserDao userDao; public UserDao getUserDao() {return userDao; } @Resourcepublic void setUserDao(UserDao userDao) {this.userDao = userDao; } public List getAll() {// TODO Auto-generated method stubreturn userDao.getAll(); } public User getUser(User user) {// TODO Auto-generated method stubreturn userDao.getUser(user); } public int delete(User user) {// TODO Auto-generated method stubreturn userDao.delete(user); } public int update(User user) {// TODO Auto-generated method stubreturn userDao.update(user); } public int add(User user) {// TODO Auto-generated method stubreturn userDao.add(user); } public List find(Map map) {// TODO Auto-generated method stubreturn userDao.find(map); } public Long getTotal(Map map) {// TODO Auto-generated method stubreturn userDao.getTotal(map); }}

在这里面userDao不能写错，spring会按照name进行注入

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