MyBatis使用注解实现简单的增删改查

【=。=】个人觉得MyBatis的注解实现其实并没有xml好用和方便，首先它违背了MyBatis的代码和数据库分离的设计原则，另外复杂的sql查询通过注解的方式实现并不如在xml里面配置看起来直观明了，方便修改。如果项目比较简单，涉及到的sql语句也比较简单，通过注解实现MyBatis或许是不错的选择呢。

项目前准备

1.搭载了WindowsOs的pc一台

2.确保jdk1.7可正常运行

3.确保mysql可正常运行

4.确保eclipse可正常运行

5.jar包准备（可前往阿里云资源库下载相关jar包点击打开链接）

   

创建项目

1.新建项目（file ==》new ==》Dynamic web project）

 

2.把下载好的jar包放入，复制粘贴即可

3.全选==》右键==》build path ==》all

4.添加单元测试所需的jar包

项目名==》右键==》build path ==》config...

5.项目目录预览

新建数据库新建表

#创建用户表
create table user(
	id int primary key auto_increment,
	username varchar(20),
	password varchar(20),
	sex varchar(10),
	address varchar(20)
);

配置文件

1.mybatis.cfg.xml（src包下直接创建）

java代码编写

1.User.java(创建与数据库相对应的实体类)

package com.jiuwea.model;

public class User {
	/**id*/
	private Integer id;
	/**用户名*/
	private String username;
	/**密码*/
	private String password;
	/**性别*/
	private String sex;
	/**地址*/
	private String address;
	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 getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", username=" + username + ", password=" + password + ", sex=" + sex + ", address="
				+ address + "]";
	}
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((address == null) ? 0 : address.hashCode());
		result = prime * result + ((id == null) ? 0 : id.hashCode());
		result = prime * result + ((password == null) ? 0 : password.hashCode());
		result = prime * result + ((sex == null) ? 0 : sex.hashCode());
		result = prime * result + ((username == null) ? 0 : username.hashCode());
		return result;
	}
	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		User other = (User) obj;
		if (address == null) {
			if (other.address != null)
				return false;
		} else if (!address.equals(other.address))
			return false;
		if (id == null) {
			if (other.id != null)
				return false;
		} else if (!id.equals(other.id))
			return false;
		if (password == null) {
			if (other.password != null)
				return false;
		} else if (!password.equals(other.password))
			return false;
		if (sex == null) {
			if (other.sex != null)
				return false;
		} else if (!sex.equals(other.sex))
			return false;
		if (username == null) {
			if (other.username != null)
				return false;
		} else if (!username.equals(other.username))
			return false;
		return true;
	}
	
}

2.UserMapper.java(创建映射接口)

package com.jiuwea.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.jiuwea.model.User;

public interface UserMapper {
	/**
	 * 新增用户
	 * @param user
	 * @return
	 * @throws Exception
	 */
	@Insert("insert into user(username,password,sex,address) values (#{username},#{password},#{sex},#{address})")
	@Options(useGeneratedKeys = true,keyProperty = "id")
	public int insertUser(User user) throws Exception;
	/**
	 * 修改用户
	 * @param user
	 * @return
	 * @throws Exception
	 */
	@Update("update user set password=#{password} where id=#{id}")
	public int updateUser(User user) throws Exception;

	/**
	 * 删除用户
	 * @param id
	 * @return
	 * @throws Exception
	 */
	@Delete("delete from user where id = #{id}")
	public int deleteUser(Integer id) throws Exception;
	
	/**
	 * 根据用户id查询用户信息
	 * @return
	 * @throws Exception
	 */
	@Select("select * from user where id = #{id}")
	@Results({
		@Result(id = true,property = "id",column = "id"),
		@Result(property = "username",column = "username"),
		@Result(property = "password",column = "password"),
		@Result(property = "sex",column = "sex"),
		@Result(property = "address",column = "address")	
	})
	public User selectUserById(Integer id) throws Exception;
	
	/**
	 * 查询出全部用户的信息
	 * @return
	 * @throws Exception
	 */
	@Select("select * from user")
	public List selectAllUser() throws Exception;
	
}

3.编写测试类

package com.jiuwea.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import javax.annotation.Resource;
import javax.jws.soap.SOAPBinding.Use;
import javax.websocket.Session;

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 com.jiuwea.mapper.UserMapper;
import com.jiuwea.model.User;

public class Test {
	private static SqlSessionFactory sqlSessionFactory;
	static {
		//获取mybatis 的配置文件
		String resource = "mybatis.cfg.xml";
		//创建配置文件流
		InputStream inputStream = null;
		try {
				inputStream = Resources.getResourceAsStream(resource);
		} catch (IOException e) {
			e.printStackTrace();
		}
				
		//创建会话工厂
		sqlSessionFactory  = new SqlSessionFactoryBuilder().build(inputStream);
	}
	/**
	 * 新增用户
	 */
	public static void insertUser(){
		SqlSession sqlSession = sqlSessionFactory.openSession(); //会话工厂打开会话
		UserMapper mapper = sqlSession.getMapper(UserMapper.class); //结果集
		User user = new User();
		user.setUsername("jiuwea");
		user.setSex("女");
		user.setPassword("jiuwea");
		user.setAddress("上海市浦东新区北蔡镇北艾路");
		try {
			mapper.insertUser(user); //执行插入操作
			sqlSession.commit(); //提交
		} catch (Exception e) {
			e.printStackTrace();
			sqlSession.rollback(); //若有异常事务回滚
		} finally {
			sqlSession.close(); //最后关闭session
		}
		
	}
	
	/**
	 * 更新用户
	 */
	public static void updateUser(Integer id) {
		//打开会话
		SqlSession session = sqlSessionFactory.openSession();
		UserMapper mapper = session.getMapper(UserMapper.class);
		User user = null;
		try {
			user = mapper.selectUserById(id);
		} catch (Exception e) {
			e.printStackTrace();
		} 
		
		user.setPassword("123456");
		try {
			int result = mapper.updateUser(user);
			if(result == 1) {
				System.out.println("更新成功！");
			}else {
				System.out.println("更新失败！");
			}
			session.commit();
		} catch (Exception e) {
			e.printStackTrace();
			session.rollback();
		}finally {
			session.close();
		}
		
	}
	
	/**
	 * 根据id删除用户
	 */
	public static void deleteUser(Integer id) {
		SqlSession session = sqlSessionFactory.openSession();
		UserMapper mapper = session.getMapper(UserMapper.class);
		try {
			int result = mapper.deleteUser(id);
			if(result == 1) {
				System.out.println("删除成功！");
			}else {
				System.out.println("删除失败！");
			}
			session.commit();//事务提交
		} catch (Exception e) {
			e.printStackTrace();
			session.rollback();//异常回滚
		} finally {
			session.close();
		}
	}
	
	/**
	 * 查找出来所有的用户
	 */
	public static void selectAllUser() {
		//创建会话
		SqlSession session = sqlSessionFactory.openSession();
		UserMapper mapper = session.getMapper(UserMapper.class);
		try {
			List users = mapper.selectAllUser();
			System.out.println("查找出来的用户为：");
			for (User user : users) {
				System.out.println(user.toString());
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			session.close();
		}
	
	}
	
	/**
	 * 根据id查找用户
	 */
	public static void selectUserById( Integer id) {
		SqlSession session = sqlSessionFactory.openSession();
		UserMapper mapper = session.getMapper(UserMapper.class);
		
		User user = null;
		try {
			user = mapper.selectUserById(id);
			if(user != null) {
				System.out.println("查找成功："+user.toString());
			}else {
				System.out.println("查找失败："+user);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	

	/**
	 * 测试创建用户
	 */
	@org.junit.Test
	public  void insertUserTest() {
		for(int i = 0;i<7;i++) {
			insertUser();
		}
	}
	
	/**
	 * 测试删除用户
	 */
	@org.junit.Test
	public void deleteUserTest() {
		//删除id为10的用户
		deleteUser(10);
		
	}
	/**
	 * 根据id查找用户
	 */
	@org.junit.Test
	public void selectUserByIdTest() {
		selectUserById(7);
	}
	/**
	 * 查找出来所有的用户
	 */
	@org.junit.Test
	public void selectAllUserTest() {
		selectAllUser();
	}
	
	/**
	 * 更新用户信息测试
	 */
	@org.junit.Test
	public void updateUserTest() {
		updateUser(11);
	}
}

进行单元测试

1.全选带有 @org.junit.Test 注解的方法名 ==》右键==》run as ==》junit test

2.结果

总结

SqlSessionFactoryBuildder 创建出 SqlSessionFactory

SqlSessionFactory 打开SqlSession

SqlSession来和数据库进行数据交互

commit();方法是开启事务

rollback();事务回滚

close();关闭会话避免造成不必要的空间浪费

                                                                                                                                                                           【ಥ﹏ಥ】