mybatis映射文件mapper.xml的写法。

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mybatis映射文件mapper.xml的写法。

2024-07-16 22:08| 来源: 网络整理| 查看: 265

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 user and uname like #{uname} limit #{start},#{size} select count(*) from user and uname like #{uname} select *from user where uname=#{uname} and upassword=#{upassword} delete from user where uid=#{uid} update user uname=#{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

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; } @Resource public void setUserDao(UserDao userDao) { this.userDao = userDao; } public List getAll() { // TODO Auto-generated method stub return userDao.getAll(); } public User getUser(User user) { // TODO Auto-generated method stub return userDao.getUser(user); } public int delete(User user) { // TODO Auto-generated method stub return userDao.delete(user); } public int update(User user) { // TODO Auto-generated method stub return userDao.update(user); } public int add(User user) { // TODO Auto-generated method stub return userDao.add(user); } public List find(Map map) { // TODO Auto-generated method stub return userDao.find(map); } public Long getTotal(Map map) { // TODO Auto-generated method stub return 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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mybatis映射文件mapper.xml的写法。

mybatis映射文件mapper.xml的写法。

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