【加精】Spring全家桶–SpringBoot Rest API

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原文链接:blog.ouyangsihai.cn >> 【加精】Spring全家桶–SpringBoot Rest API

//本文作者:cuifuan

//本文将收录到菜单栏:《Spring全家桶》专栏中

Spring Boot通过提供开箱即用的默认依赖或者转换来补充Spring REST支持。在Spring Boot中编写RESTful服务与SpringMVC没有什么不同。总而言之,基于Spring Boot的REST服务与基于Spring的REST服务完全相同,只是在我们引导底层应用程序的方式上有所不同。

1.REST简短介绍

REST代表Representational State Transfer. 是一种架构风格,设计风格而不是标准,可用于设计Web服务,可以从各种客户端使用.

基于REST的基本设计,其是根据一组动词来控制的操作

  • 创建操作:应使用HTTP POST
  • 查询操作:应使用HTTP GET
  • 更新操作:应使用HTTP PUT
  • 删除操作:应使用HTTP DELETE

作为REST服务开发人员或客户端,您应该遵守上述标准。

2.准备工作

项目的环境工具

  • SpringBoot 2.0.1.RELEASE
  • Gradle 4.7
  • IDEA 2018.2
  • MySQL5.7

项目结构图

Spring全家桶--SpringBoot Rest API

3.开始

下面基于一种方式讲解Restful

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package com.example.controller; import com.example.beans.PageResultBean;import com.example.beans.ResultBean;import com.example.entity.User;import com.example.service.UserService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RestController; import java.util.List; @RestController@RequestMapping("/user")public class UserControllerAPI {    private final UserService userService;    @Autowired   public UserControllerAPI(UserService userService) {       this.userService = userService;   }    @RequestMapping(value = "/api", method = RequestMethod.GET)   public PageResultBeanListUser getUserAll(PageResultBean page) {       return new PageResultBean(userService.getUserAll(page.getPageNo(), page.getPageSize()));   }    @RequestMapping(value = "/api/{id}", method = RequestMethod.GET)   public ResultBeanUser getUserByPrimaryKey(@PathVariable("id") Integer id) {       return new ResultBean(userService.selectByPrimaryKey(id));   }    @RequestMapping(value = "/api/{id}", method = RequestMethod.PUT)   public ResultBeanInteger updateUserByPrimaryKey(@PathVariable("id") Integer id,User user) {       user.setId(id);       return new ResultBean(userService.updateByPrimaryKeySelective(user));   }    @RequestMapping(value = "/api/{id}", method = RequestMethod.DELETE)   public ResultBeanString deletePrimaryKey(@PathVariable("id") Integer id) {       return new ResultBean(userService.deleteByPrimaryKey(id));   }    @RequestMapping(value = "/api", method = RequestMethod.POST)   public ResultBeanInteger deletePrimaryKey(User user) {       return new ResultBean(userService.insertSelective(user));   } }

package com.example.controller;

import com.example.beans.PageResultBean;
import com.example.beans.ResultBean;
import com.example.entity.User;
import com.example.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping(“/user”)
public class UserControllerAPI {

private final UserService userService;

@Autowired
public UserControllerAPI(UserService userService) {
this.userService = userService;
}

@RequestMapping(value = “/api”, method = RequestMethod.GET)
public PageResultBeanListUser getUserAll(PageResultBean page) {
return new PageResultBean(userService.getUserAll(page.getPageNo(), page.getPageSize()));
}

@RequestMapping(value = “/api/{id}”, method = RequestMethod.GET)
public ResultBeanUser getUserByPrimaryKey(@PathVariable(“id”) Integer id) {
return new ResultBean(userService.selectByPrimaryKey(id));
}

@RequestMapping(value = “/api/{id}”, method = RequestMethod.PUT)
public ResultBeanInteger updateUserByPrimaryKey(@PathVariable(“id”) Integer id,User user) {
user.setId(id);
return new ResultBean(userService.updateByPrimaryKeySelective(user));
}

@RequestMapping(value = “/api/{id}”, method = RequestMethod.DELETE)
public ResultBeanString deletePrimaryKey(@PathVariable(“id”) Integer id) {
return new ResultBean(userService.deleteByPrimaryKey(id));
}

@RequestMapping(value = “/api”, method = RequestMethod.POST)
public ResultBeanInteger deletePrimaryKey(User user) {
return new ResultBean(userService.insertSelective(user));
}

}

 

  • 对于/user/api HTTP GET来请求获取全部用户
  • 对于/user/api HTTP POST来创建用户
  • 对于/user/api/1 HTTP GET请求来获取id为1的用户
  • 对于/user/api/1 HTTP PUT请求来更新
  • 对于/user/api/1 HTTP DELETE请求来删除id为1的用户
HTTP GET请求/user/api 查询全部

URL:http://localhost:8080/user/api

Spring全家桶--SpringBoot Rest API
HTTP GET请求/user/api/65 跟据id查询

URL:http://localhost:8080/user/api/65

Spring全家桶--SpringBoot Rest API
HTTP POST请求/user/api 创建用户

URL:http://localhost:8080/user/api

Spring全家桶--SpringBoot Rest API
HTTP PUT请求/user/api/65 来更新用户信息

URL:http://localhost:8080/user/api/65

Spring全家桶--SpringBoot Rest API
HTTP DELETE请求/user/api/85 来删除id为85的用户

URL:http://localhost:8080/user/api/85

Spring全家桶--SpringBoot Rest API

4.业务层及dao层代码

UserService.java 接口

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package com.example.service; import com.example.entity.User; import java.util.List; public interface UserService {    /**    * 删除    * @param id    * @return    */   String deleteByPrimaryKey(Integer id);    /**    * 创建    * @param record    * @return    */   int insertSelective(User record);    /**    * 单个查询    * @param id    * @return    */   User selectByPrimaryKey(Integer id);    /**    * 更新    * @param record    * @return    */   int updateByPrimaryKeySelective(User record);    /**    * 查询全部    * @return    */   ListUser getUserAll(Integer pageNum, Integer pageSize);}

package com.example.service;

import com.example.entity.User;

import java.util.List;

public interface UserService {

/**
* 删除
* @param id
* @return
*/
String deleteByPrimaryKey(Integer id);

/**
* 创建
* @param record
* @return
*/
int insertSelective(User record);

/**
* 单个查询
* @param id
* @return
*/
User selectByPrimaryKey(Integer id);

/**
* 更新
* @param record
* @return
*/
int updateByPrimaryKeySelective(User record);

/**
* 查询全部
* @return
*/
ListUser getUserAll(Integer pageNum, Integer pageSize);
}

UserServiceImpl.java

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package com.example.service.impl; import com.example.dao.UserMapper;import com.example.entity.User;import com.example.service.UserService;import com.github.pagehelper.PageHelper;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.transaction.annotation.Transactional; import java.util.List; @Servicepublic class UserServiceImpl implements UserService {    private final static Logger logger = LoggerFactory.getLogger(UserServiceImpl.class);    private final UserMapper userMapper;    @Autowired(required = false)   public UserServiceImpl(UserMapper userMapper) {       this.userMapper = userMapper;   }    /**    * 删除    *    * @param id    * @return    */   @Transactional   @Override   public String deleteByPrimaryKey(Integer id) {       logger.info("UserServiceImpl deleteByPrimaryKey id = " + id);       User user = userMapper.selectByPrimaryKey(id);       String result;       if (user == null) {           result = "用户ID[" + id + "]找不到!";       } else {           result = String.valueOf(userMapper.deleteByPrimaryKey(id));       }       return result;   }    /**    * 创建    *    * @param record    * @return    */   @Transactional   @Override   public int insertSelective(User record) {       logger.info("UserServiceImpl insertSelective record="+record.toString());       return userMapper.insertSelective(record);   }    /**    * 单个查询    *    * @param id    * @return    */   @Override   public User selectByPrimaryKey(Integer id) {       logger.info("UserServiceImpl selectByPrimaryKey id="+id);       return userMapper.selectByPrimaryKey(id);   }    /**    * 更新    *    * @param record    * @return    */   @Override   public int updateByPrimaryKeySelective(User record) {       logger.info("UserServiceImpl updateByPrimaryKeySelective record="+record.toString());       return userMapper.updateByPrimaryKeySelective(record);   }    /**    * 查询全部    *    * @param pageNum    * @param pageSize    * @return    */   @Override   public ListUser getUserAll(Integer pageNum, Integer pageSize) {       logger.info("UserServiceImpl getUserAll pageNum="+pageNum+"=pageSize="+pageSize);       PageHelper.startPage(pageNum,pageSize);       ListUser userList = userMapper.getUserAll();       logger.info("UserServiceImpl getUserAll userList"+userList.size());       return userList;   }}

package com.example.service.impl;

import com.example.dao.UserMapper;
import com.example.entity.User;
import com.example.service.UserService;
import com.github.pagehelper.PageHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {

private final static Logger logger = LoggerFactory.getLogger(UserServiceImpl.class);

private final UserMapper userMapper;

@Autowired(required = false)
public UserServiceImpl(UserMapper userMapper) {
this.userMapper = userMapper;
}

/**
* 删除
*
* @param id
* @return
*/
@Transactional
@Override
public String deleteByPrimaryKey(Integer id) {
logger.info(“UserServiceImpl deleteByPrimaryKey id = “ + id);
User user = userMapper.selectByPrimaryKey(id);
String result;
if (user == null) {
result = “用户ID[“ + id + “]找不到!”;
} else {
result = String.valueOf(userMapper.deleteByPrimaryKey(id));
}
return result;
}

/**
* 创建
*
* @param record
* @return
*/
@Transactional
@Override
public int insertSelective(User record) {
logger.info(“UserServiceImpl insertSelective record=”+record.toString());
return userMapper.insertSelective(record);
}

/**
* 单个查询
*
* @param id
* @return
*/
@Override
public User selectByPrimaryKey(Integer id) {
logger.info(“UserServiceImpl selectByPrimaryKey id=”+id);
return userMapper.selectByPrimaryKey(id);
}

/**
* 更新
*
* @param record
* @return
*/
@Override
public int updateByPrimaryKeySelective(User record) {
logger.info(“UserServiceImpl updateByPrimaryKeySelective record=”+record.toString());
return userMapper.updateByPrimaryKeySelective(record);
}

/**
* 查询全部
*
* @param pageNum
* @param pageSize
* @return
*/
@Override
public ListUser getUserAll(Integer pageNum, Integer pageSize) {
logger.info(“UserServiceImpl getUserAll pageNum=”+pageNum+”=pageSize=”+pageSize);
PageHelper.startPage(pageNum,pageSize);
ListUser userList = userMapper.getUserAll();
logger.info(“UserServiceImpl getUserAll userList”+userList.size());
return userList;
}
}

UserMapper.java

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package com.example.dao; import com.example.entity.User; import java.util.List; public interface UserMapper {   int deleteByPrimaryKey(Integer id);    int insert(User record);    int insertSelective(User record);    User selectByPrimaryKey(Integer id);    int updateByPrimaryKeySelective(User record);    int updateByPrimaryKey(User record);    ListUser getUserAll();}

package com.example.dao;

import com.example.entity.User;

import java.util.List;

public interface UserMapper {
int deleteByPrimaryKey(Integer id);

int insert(User record);

int insertSelective(User record);

User selectByPrimaryKey(Integer id);

int updateByPrimaryKeySelective(User record);

int updateByPrimaryKey(User record);

ListUser getUserAll();
}

PageResultBean和ResultBean的代码在GitHub

https://github.com/cuifuan/springboot-demo

实体层和mapper.xml代码都是可以自动生成的,教程导航:

4.理解RESTful

通过上面的编码,如果你已经走通了上面的代码,相信你已经对REST有了大致的掌握,时今当下的前端Client层出不穷,后端接口或许来自不同平台,这时候需要请求一批接口,而RESTful风格的api,使人从请求方式和地址一看就知道是要做什么操作,根据返回code状态就知道结果如何

使用RESTful直接带来的便利:

之前的接口

  • 删除 /user/delete
  • 添加 /user/create
  • 单个查询 /user/queryById
  • 查询全部 /user/queryAll
  • 更新 /user/update

采用RESTful设计API之后 /user/api一个URL地址解决,再也不用跟前端废舌头了,同时GET请求是幂等的,什么是幂等?简单通俗的说就是多次请求返回的效果都是相同的,例如GET去请求一个资源,无论请求多少次,都不会对数据造成创建修改等操作,PUT用来更新数据也是,无论执行多次的都是最终一样的效果

问题:使用PUT改变学生年龄并且这样做10次和做了一次,学生的年龄是相同的,是幂等的,那么如果POST做相同操作,那么它是如何不是幂等的?

答:因为POST请求会在服务端创建与请求次数相同的服务,假如服务端每次请求服务会存在一个密钥,那么这个POST请求就可能不是幂等的,也或许是幂等的,所以POST不是幂等的。

因为PUT请求URL到客户端定义的URL处完整地创建或替换资源,所以PUT是幂等的。 DELETE请求也是幂等的,用来删除操作,其实REST就是相当于一个风格规范。

注意了,GET请求请不要用在delete操作上,你要问我为啥不行,你偏要那么做,其实,整个CRUD操作你也都可以用GET来完成,哈哈,这个只是一个开发的设计风格。

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Spring全家桶--SpringBoot Rest API
本人花费半年的时间总结的《Java面试指南》已拿腾讯等大厂offer,已开源在github ,欢迎star!

本文GitHub https://github.com/OUYANGSIHAI/JavaInterview 已收录,这是我花了6个月总结的一线大厂Java面试总结,本人已拿大厂offer,欢迎star

原文链接:blog.ouyangsihai.cn >> 【加精】Spring全家桶–SpringBoot Rest API


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