3.2. @RestController

3.2.1. 返回实体

@RequestMapping("/get/{id}")public Member getStatistics(@PathVariable long id) {Member statistics = memberRepostitory.findOne(id);if (statistics == null) {statistics = new Member();}return statistics;}

3.2.2. JSON

MediaType.APPLICATION_JSON_VALUE 执行结果反馈json数据

@RestController @RequestMapping("/api/persons") public class MainController {@RequestMapping(value = "/detail/{id}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)public ResponseEntity<Persons> getUserDetail(@PathVariable Long id) {Persons user = personsRepository.findById(id);return new ResponseEntity<>(user, HttpStatus.OK);}}

3.2.3. 返回 JSON 对象 NULL 专为 "" 字符串

package api.config;import java.io.IOException;import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Primary; import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.JsonSerializer; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.SerializerProvider;@Configuration public class JacksonConfig {@Bean@Primary@ConditionalOnMissingBean(ObjectMapper.class)public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {ObjectMapper objectMapper = builder.createXmlMapper(false).build();objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {@Overridepublic void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {jsonGenerator.writeString("");}});return objectMapper;} }

3.2.4. XML

restful 将同时支持 json 和 xml 数据传递

package com.example.api.restful;import java.util.List;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.domain.PageRequest; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; 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 com.example.api.domain.RecentRead; import com.example.api.repository.RecentReadRepostitory;@RestController @RequestMapping("/restful/article") public class ArticleRestController {@Autowiredprivate RecentReadRepostitory recentReadRepostitory;@RequestMapping(value = "/recent/read/add/{memberId}/{articleId}", method = RequestMethod.GET, produces = { "application/xml", "application/json" })public ResponseEntity<RecentRead> recentAdd(@PathVariable long memberId, @PathVariable long articleId) {RecentRead recentRead = new RecentRead();recentRead.setMemberId(memberId);recentRead.setArticleId(articleId);recentReadRepostitory.save(recentRead);return new ResponseEntity<RecentRead>(recentRead, HttpStatus.OK);}@RequestMapping(value="/recent/read/list/{id}", produces = { "application/xml", "application/json" })public List<RecentRead> recentList(@PathVariable long id) {int page = 0;int limit = 20;List<RecentRead> recentRead = recentReadRepostitory.findByMemberId(id, new PageRequest(page, limit));return recentRead;} }

3.2.5. 兼容传统 json 接口

开发中发现很多人不适应新的接口方式，有时候只能妥协，这些顽固不化的人需要这样的数据库格式

{ "status":true,"reason":"登录成功","code":1,"data":{"id":2,"name":null,"sex":null,"age":0,"wechat":null,"mobile":"13113668890","picture":null,"ipAddress":"0:0:0:0:0:0:0:1"} }

返回数据必须放在 data 字典中, 而我通常是采用 http status code 来返回状态，返回结果是对象。实现上面的需求我们需要加入一个data成员变量，因为我们不清楚最终要返回什么对象。所以声明为 java.lang.Object

package com.example.api.pojo;import java.io.Serializable;public class RestfulResponse implements Serializable {/*** */private static final long serialVersionUID = -4045645995352698349L;private boolean status;private String reason;private int code;private Object data;public RestfulResponse(boolean status, int code, String reason, Object data) {this.status = status;this.code = code;this.reason = reason;this.data = data;}public boolean isStatus() {return status;}public void setStatus(boolean status) {this.status = status;}public String getReason() {return reason;}public void setReason(String reason) {this.reason = reason;}public int getCode() {return code;}public void setCode(int code) {this.code = code;}public Object getData() {return data;}public void setData(Object data) {this.data = data;}@Overridepublic String toString() {return "RestfulResponse [status=" + status + ", reason=" + reason + ", code=" + code + ", data=" + data + "]";}}

Service

public RestfulResponse bindWechat(String mobile, String wechat) {Member member = memberRepository.findByMobile(mobile);member.setWechat(wechat);memberRepository.save(member);return new RestfulResponse(true, 1, "微信绑定成功", member);}

Controller

@RequestMapping("/login/sms/{mobile}/{code}")public RestfulResponse sms(@PathVariable String mobile, @PathVariable String wechat) {return memberService.bindWechat(mobile, wechat);}

3.2.6. @PageableDefault 分页

@RequestMapping(value = "/list", method=RequestMethod.GET) public Page<Blog> getEntryByPageable1(@PageableDefault( sort = { "id" }, direction = Sort.Direction.DESC) Pageable pageable) {return blogRepository.findAll(pageable); }@RequestMapping(value = "/blog", method=RequestMethod.GET) public Page<Blog> getEntryByPageable(@PageableDefault(value = 15, sort = { "id" }, direction = Sort.Direction.DESC) Pageable pageable) {return blogRepository.findAll(pageable); }@RequestMapping(value = "/list", method=RequestMethod.GET) public Page<Blog> getEntryByPageable2(@PageableDefault Pageable pageable) {return blogRepository.findAll(pageable); }@ModelAttribute("users") public Page<User> users(@PageableDefault(size = 5) Pageable pageable) {return userManagement.findAll(pageable); } 我们只需要在方法的参数中直接定义一个pageable类型的参数，当Spring发现这个参数时，Spring会自动的根据request的参数来组装该pageable对象，Spring支持的request参数如下：page，第几页，从0开始，默认为第0页 size，每一页的大小，默认为20 sort，排序相关的信息，以property,property(,ASC|DESC)的方式组织，例如sort=firstname&sort=lastname,desc表示在按firstname正序排列基础上按lastname倒序排列 这样，我们就可以通过url的参数来进行多样化、个性化的查询，而不需要为每一种情况来写不同的方法了。通过url来定制pageable很方便，但唯一的缺点是不太美观，因此我们需要为pageable设置一个默认配置，这样很多情况下我们都能够通过一个简洁的url来获取信息了。Spring提供了@PageableDefault帮助我们个性化的设置pageable的默认配置。例如@PageableDefault(value = 15, sort = { "id" }, direction = Sort.Direction.DESC)表示默认情况下我们按照id倒序排列，每一页的大小为15。

原文出处：Netkiller 系列 手札
本文作者：陈景峯
转载请与作者联系，同时请务必标明文章原始出处和作者信息及本声明。

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