Spring全家桶–SpringBoot Rest API

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

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
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 PageResultBean<List<User>> getUserAll(PageResultBean page) {
       return new PageResultBean<>(userService.getUserAll(page.getPageNo(), page.getPageSize()));
   }
 
   @RequestMapping(value = "/api/{id}", method = RequestMethod.GET)
   public ResultBean<User> getUserByPrimaryKey(@PathVariable("id") Integer id) {
       return new ResultBean<>(userService.selectByPrimaryKey(id));
   }
 
   @RequestMapping(value = "/api/{id}", method = RequestMethod.PUT)
   public ResultBean<Integer> updateUserByPrimaryKey(@PathVariable("id") Integer id,User user) {
       user.setId(id);
       return new ResultBean<>(userService.updateByPrimaryKeySelective(user));
   }
 
   @RequestMapping(value = "/api/{id}", method = RequestMethod.DELETE)
   public ResultBean<String> deletePrimaryKey(@PathVariable("id") Integer id) {
       return new ResultBean<>(userService.deleteByPrimaryKey(id));
   }
 
   @RequestMapping(value = "/api", method = RequestMethod.POST)
   public ResultBean<Integer> deletePrimaryKey(User user) {
       return new ResultBean<>(userService.insertSelective(user));
   }
 
}

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 PageResultBean<List<User>> getUserAll(PageResultBean page) {
return new PageResultBean<>(userService.getUserAll(page.getPageNo(), page.getPageSize()));
}

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

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

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

@RequestMapping(value = “/api”, method = RequestMethod.POST)
public ResultBean<Integer> 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

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
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
    */
   List<User> getUserAll(Integer pageNum, Integer pageSize);
}

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
*/
List<User> getUserAll(Integer pageNum, Integer pageSize);
}

UserServiceImpl.java

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
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 List<User> getUserAll(Integer pageNum, Integer pageSize) {
       logger.info("UserServiceImpl getUserAll pageNum=>"+pageNum+"=>pageSize=>"+pageSize);
       PageHelper.startPage(pageNum,pageSize);
       List<User> userList = userMapper.getUserAll();
       logger.info("UserServiceImpl getUserAll userList"+userList.size());
       return userList;
   }
}

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 List<User> getUserAll(Integer pageNum, Integer pageSize) {
logger.info(“UserServiceImpl getUserAll pageNum=>”+pageNum+”=>pageSize=>”+pageSize);
PageHelper.startPage(pageNum,pageSize);
List<User> userList = userMapper.getUserAll();
logger.info(“UserServiceImpl getUserAll userList”+userList.size());
return userList;
}
}

UserMapper.java

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
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);
 
   List<User> getUserAll();
}

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);

List<User> 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:

Spring全家桶系列–SpringBoot与Mybatis结合

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。

发表评论

您的电子邮箱地址不会被公开。 必填项已用*标注

关注我们