spring學習之restTemplate常用方法介紹

原創 xiyang.ycj 2020-05-31 15:39

restTemplate學習

什麼是RestTemplate

  • RestTemplate用於同步client端的核心類，簡化了與http服務的通信，並滿足RestFul原則，程序代碼可以給它提供URL，並提取結果
  • 默認情況下，RestTemplate默認使用jdk提供http鏈接的能力（HttpURLConnection）
  • 可以通過setRequestFactory屬性切換到不同的HTTP源，Apache HttpComponents,Netty和OkHttp。

常用方法

restTemplate其他的先不講，直接上來操作，熟個手

getForObject

getForObject函數實際上是對getForEntity函數的進一步封裝，如果你只關注返回的消息體的內容，對其他信息都不關注，此時可以使用getForObject

  1. public T getForObject(String url, Class responseType, Object… uriVariables)
    String oneGet = restTemplate.getForObject("http://localhost:6788/oneGet", String.class);
System.out.println(oneGet);
//可以用一個數字做佔位符，最後是一個可變長度的參數，來一一替換前面的佔位符
String oneGet1 = restTemplate.getForObject("http://localhost:6788/oneGet/{1}", String.class,"1");
System.out.println(oneGet1);
  2. public T getForObject(String url, Class responseType, Map<String, ?> uriVariables)
    //也可以前面使用id={id}這種形式，最後一個參數是一個map，map的key即爲前邊佔位符的名字，map的value爲參數值
HashMap<String, Object> twoGetMap = new HashMap<>();
twoGetMap.put("id","1");
String twoGet = restTemplate.getForObject("http://localhost:6788/twoGet?id={id}", String.class,twoGetMap);
System.out.println(twoGet);
  3. public T getForObject(URI url, Class responseType)
    String threeGet = restTemplate.getForObject(new URI("http://localhost:6788/threeGet"), String.class);
System.out.println(threeGet);

    ====================getForObject=======================
{"code":1,"message":"","data":"oneGet"}
{"code":1,"message":"","data":"oneGet1--1"}
{"code":1,"message":"","data":"twoGet--1"}
{"code":1,"message":"","data":"threeGet"}

getForEntity

getForEntity方法的返回值是一個ResponseEntity，ResponseEntity是Spring對HTTP請求響應的封裝，包括了幾個重要的元素，如響應碼、contentType、contentLength、響應消息體等

  1. public ResponseEntity getForEntity(String url, Class responseType, Object… uriVariables)
    ResponseEntity<String> oneGetEntity = restTemplate.getForEntity("http://localhost:6788/oneGet", String.class);
System.out.println(oneGetEntity);
ResponseEntity<String> oneGetEntity1 = restTemplate.getForEntity("http://localhost:6788/oneGet/{1}", String.class, "1");
System.out.println(oneGetEntity1);
  2. public ResponseEntity getForEntity(String url, Class responseType, Map<String, ?> uriVariables)
    //也可以前面使用id={id}這種形式，最後一個參數是一個map，map的key即爲前邊佔位符的名字，map的value爲參數值
HashMap<String, Object> twoGetMapEntity = new HashMap<>();
twoGetMapEntity.put("id","1");
ResponseEntity<String> twoGetEntity = restTemplate.getForEntity("http://localhost:6788/twoGet?id={id}", String.class,twoGetMapEntity);
System.out.println(twoGetEntity);
  3. public ResponseEntity getForEntity(URI url, Class responseType)
    ResponseEntity<String> threeGetEntity = restTemplate.getForEntity(new URI("http://localhost:6788/threeGet"), String.class);
System.out.println(threeGetEntity);

    ====================getForEntity=======================
<200,{"code":1,"message":"","data":"oneGet"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Fri, 24 May 2019 01:09:43 GMT"]>
<200,{"code":1,"message":"","data":"oneGet1--1"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Fri, 24 May 2019 01:09:43 GMT"]>
<200,{"code":1,"message":"","data":"twoGet--1"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Fri, 24 May 2019 01:09:43 GMT"]>
<200,{"code":1,"message":"","data":"threeGet"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Fri, 24 May 2019 01:09:43 GMT"]>

headForHeaders

獲取請求頭，用於檢查對象是否存在，不返回body信息

  1. public HttpHeaders headForHeaders(String url, Object… uriVariables)
    HttpHeaders oneHeaders = restTemplate.headForHeaders("http://localhost:6788/oneGet");
System.out.println(oneHeaders);
  2. public HttpHeaders headForHeaders(String url, Map<String, ?> uriVariables)
    HashMap<String, Object> headMap = new HashMap<>();
headMap.put("id","1");
HttpHeaders twoHeaders = restTemplate.headForHeaders("http://localhost:6788/twoGet?id={id}", headMap);
System.out.println(twoHeaders);
  3. public HttpHeaders headForHeaders(URI url)
    HttpHeaders threeHeaders = restTemplate.headForHeaders(new URI("http://localhost:6788/oneGet"));
System.out.println(threeHeaders);

    ====================headForHeaders=======================
[Content-Type:"application/json;charset=UTF-8", Content-Length:"39", Date:"Fri, 24 May 2019 02:05:03 GMT"]
[Content-Type:"application/json;charset=UTF-8", Content-Length:"42", Date:"Fri, 24 May 2019 02:05:03 GMT"]
[Content-Type:"application/json;charset=UTF-8", Content-Length:"39", Date:"Fri, 24 May 2019 02:05:03 GMT"]

postForLocation

post提交，獲取重定向的url,該Uri表示新資源的位置

  1. public URI postForLocation(String url, @Nullable Object request, Object… uriVariables)
    HttpEntity<Object> entity = new HttpEntity<>(null,null);//第一個參數爲body參數，第二個參數爲headers（請求頭）
URI oneUri = restTemplate.postForLocation("http://localhost:6788/onePost",entity);
System.out.println(oneUri);
URI oneUri1 = restTemplate.postForLocation("http://localhost:6788/onePost?id={id}",entity,"---1");
System.out.println(oneUri1);
  2. public URI postForLocation(String url, @Nullable Object request, Map<String, ?> uriVariables)
    HttpEntity<Object> entity = new HttpEntity<>(null,null);
HashMap<String, Object> uriMap = new HashMap<>();
uriMap.put("id","---1");
URI twoUri = restTemplate.postForLocation("http://localhost:6788/onePost?id={id}", entity, uriMap);
System.out.println(twoUri);
  3. public URI postForLocation(URI url, @Nullable Object request)
    URI threeUri = restTemplate.postForLocation(new URI("http://localhost:6788/onePost"), entity);
System.out.println(threeUri);

    ====================postForLocation=======================
https://blog.csdn.net/YCJ_xiyang/column/info/38209
https://blog.csdn.net/YCJ_xiyang/column/info/38209---1
https://blog.csdn.net/YCJ_xiyang/column/info/38209---1
https://blog.csdn.net/YCJ_xiyang/column/info/38209

postForObject

  1. public T postForObject(String url, @Nullable Object request, Class responseType,
    Object… uriVariables)
    HttpHeaders headers = new HttpHeaders();
headers.add("Content-Type", MediaType.APPLICATION_JSON_VALUE);
Gson gson = new Gson();
Map<String,String> postMaps = new HashMap<>();
postMaps.put("name","cat");
HttpEntity<Object> postEntity = new HttpEntity<>(gson.toJson(postMaps),headers);
String onePost = restTemplate.postForObject("http://localhost:6788/onePost",postEntity,String.class);
System.out.println(onePost);
String onePost1 = restTemplate.postForObject("http://localhost:6788/onePost?id={id}",postEntity,String.class,"---1");
System.out.println(onePost1);
  2. public T postForObject(String url, @Nullable Object request, Class responseType,
    Map<String, ?> uriVariables)
    HttpHeaders headers = new HttpHeaders();
headers.add("Content-Type", MediaType.APPLICATION_JSON_VALUE);
Gson gson = new Gson();
Map<String,String> postMaps = new HashMap<>();
postMaps.put("name","cat");
HttpEntity<Object> postEntity = new HttpEntity<>(gson.toJson(postMaps),headers);
HashMap<String, Object> postMap = new HashMap<>();
postMap.put("id","---1");
String twoPost = restTemplate.postForObject("http://localhost:6788/onePost?id={id}", postEntity,String.class, postMap);
System.out.println(twoPost);
  3. public T postForObject(URI url, @Nullable Object request, Class responseType)
    HttpHeaders headers = new HttpHeaders();
headers.add("Content-Type", MediaType.APPLICATION_JSON_VALUE);
Gson gson = new Gson();
Map<String,String> postMaps = new HashMap<>();
postMaps.put("name","cat");
HttpEntity<Object> postEntity = new HttpEntity<>(gson.toJson(postMaps),headers);
String threePost = restTemplate.postForObject(new URI("http://localhost:6788/onePost"), postEntity,String.class);
System.out.println(threePost);

    ====================postForObject=======================
{"code":1,"message":"","data":"onePostnull----{\"name\":\"cat\"}"}
{"code":1,"message":"","data":"onePost---1----{\"name\":\"cat\"}"}
{"code":1,"message":"","data":"onePost---1----{\"name\":\"cat\"}"}
{"code":1,"message":"","data":"onePostnull----{\"name\":\"cat\"}"}

postForEntity

  1. public ResponseEntity postForEntity(String url, @Nullable Object request,
    Class responseType, Object… uriVariables)
    HttpHeaders postHeadersEntity = new HttpHeaders();
postHeadersEntity.add("Content-Type", MediaType.APPLICATION_FORM_URLENCODED_VALUE);
MultiValueMap<String,String> body = new LinkedMultiValueMap<>();
body.add("name","tom");
HttpEntity<Object> postEntitys = new HttpEntity<>(body,postHeadersEntity);
ResponseEntity<String> onePostEntity = restTemplate.postForEntity("http://localhost:6788/onePostEntity", postEntitys, String.class);
System.out.println(onePostEntity);
ResponseEntity<String> onePostEntity1 = restTemplate.postForEntity("http://localhost:6788/onePostEntity?id={id}",postEntitys,String.class,"---1");
System.out.println(onePostEntity1);
  2. public ResponseEntity postForEntity(String url, @Nullable Object request,
    Class responseType, Map<String, ?> uriVariables)
    HttpHeaders postHeadersEntity = new HttpHeaders();
postHeadersEntity.add("Content-Type", MediaType.APPLICATION_FORM_URLENCODED_VALUE);
MultiValueMap<String,String> body = new LinkedMultiValueMap<>();
body.add("name","tom");
HttpEntity<Object> postEntitys = new HttpEntity<>(body,postHeadersEntity);
HashMap<String, Object> postMapEntity = new HashMap<>();
postMapEntity.put("id","---1");
ResponseEntity<String> twoPostEntity = restTemplate.postForEntity("http://localhost:6788/onePostEntity?id={id}", postEntitys,String.class, postMapEntity);
System.out.println(twoPostEntity);
  3. public ResponseEntity postForEntity(URI url, @Nullable Object request, Class responseType)
    HttpHeaders postHeadersEntity = new HttpHeaders();
postHeadersEntity.add("Content-Type", MediaType.APPLICATION_FORM_URLENCODED_VALUE);
MultiValueMap<String,String> body = new LinkedMultiValueMap<>();
body.add("name","tom");
HttpEntity<Object> postEntitys = new HttpEntity<>(body,postHeadersEntity);
HashMap<String, Object> postMapEntity = new HashMap<>();
postMapEntity.put("id","---1");
ResponseEntity<String> threePostEntity = restTemplate.postForEntity(new URI("http://localhost:6788/onePostEntity"), postEntitys,String.class);
System.out.println(threePostEntity);

    擴展content-type:form-data

     HttpHeaders postHeadersEntitys = new HttpHeaders();
 postHeadersEntity.add("Content-Type", MediaType.MULTIPART_FORM_DATA_VALUE);
 MultiValueMap<String,String> bodys = new LinkedMultiValueMap<>();
 bodys.add("name","sam");
 HttpEntity<Object> postEntityss = new HttpEntity<>(bodys,postHeadersEntitys);
 ResponseEntity<String> onePostEntitys = restTemplate.postForEntity("http://localhost:6788/onePostEntity", postEntityss, String.class);
 System.out.println(onePostEntitys);

    ====================postForEntity=======================
<200,{"code":1,"message":"","data":"onePostEntitynull----tom"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Tue, 28 May 2019 01:20:58 GMT"]>
<200,{"code":1,"message":"","data":"onePostEntity---1----tom"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Tue, 28 May 2019 01:20:58 GMT"]>
<200,{"code":1,"message":"","data":"onePostEntity---1----tom"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Tue, 28 May 2019 01:20:58 GMT"]>
<200,{"code":1,"message":"","data":"onePostEntitynull----tom"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Tue, 28 May 2019 01:20:58 GMT"]>
====================postForEntity擴展=======================
<200,{"code":1,"message":"","data":"onePostEntitynull----sam"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Tue, 28 May 2019 01:20:58 GMT"]>

put

put 在restful中 表示更新或創建，清楚參數和post差不多，只不過沒有返回值，這裏只演示一種

  1. public void put(String url, @Nullable Object request, Object… uriVariables)
    HttpHeaders putHeaders = new HttpHeaders();
putHeaders.add("Content-Type", MediaType.APPLICATION_JSON_VALUE);
HttpEntity<Object> putEntity = new HttpEntity<>(null,putHeaders);
restTemplate.put("http://localhost:6788/put?id={id}",putEntity,"--1");
  2. public void put(String url, @Nullable Object request, Map<String, ?> uriVariables)
  3. public void put(URI url, @Nullable Object request)

patchForObject

patch接口表示修改,參數和上面的類似，不一一演示了
注意：restTemplate默認使用的jdk的HttpURLConnection，不支持patch，需要替換爲Apache HttpComponents
引入依賴compile group: 'org.apache.httpcomponents', name: 'httpclient', version: '4.5.2'

restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());
  1. public T patchForObject(String url, @Nullable Object request, Class responseType,
    Object… uriVariables)
    HttpHeaders patchHeaders = new HttpHeaders();
patchHeaders.add("Content-Type", MediaType.APPLICATION_JSON_VALUE);
HttpEntity<Object> patchEntity = new HttpEntity<>(null,patchHeaders);
String patch = restTemplate.patchForObject("http://localhost:6788/patch?id={id}", patchEntity, String.class, "--1");
System.out.println(patch);
  2. public T patchForObject(String url, @Nullable Object request, Class responseType,
    Map<String, ?> uriVariables)
  3. public T patchForObject(URI url, @Nullable Object request, Class responseType)
    ====================patchForObject=======================
{"code":1,"message":"","data":"patch----1"}

delete

顧名思義：表示刪除的接口,無返回值

  1. public void delete(String url, Object… uriVariables)
    restTemplate.delete("http://localhost:6788/delete?id={id}",  "--1");
  2. public void delete(String url, Map<String, ?> uriVariables)
  3. public void delete(URI url)
    ====================delete=======================
[GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS]

optionsForAllow

詢問可以執行哪些方法，參數跟上面類似，演示一種

  1. public Set optionsForAllow(String url, Object… uriVariables)
     Set<HttpMethod> httpMethods = restTemplate.optionsForAllow("http://localhost:6788/optionsForAllow?id={id}", "--1");
 System.out.println(httpMethods);
  2. public Set optionsForAllow(String url, Map<String, ?> uriVariables)
  3. public Set optionsForAllow(URI url)
    ====================optionsForAllow=======================
[GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS]

exchange

exchange方法提供統一的方法模板進行四種請求：POST,PUT,DELETE,GET
說明：
1）url: 請求地址；
2）method: 請求類型(如：POST,PUT,DELETE,GET)；
3）requestEntity: 請求實體，封裝請求頭，請求內容
4）responseType: 響應類型，根據服務接口的返回類型決定
5）uriVariables: url中參數變量值

  1. public ResponseEntity exchange(String url, HttpMethod method,@Nullable HttpEntity<?> requestEntity,
    Class responseType, Object… uriVariables)
  2. public ResponseEntity exchange(String url, HttpMethod method,@Nullable HttpEntity<?> requestEntity,
    Class responseType ,Map<String, ?> uriVariables )
  3. public ResponseEntity exchange(URI url, HttpMethod method, @Nullable HttpEntity<?> requestEntity,
    Class responseType)

前面3種，參數類似，和上面的操作相同

  1. public ResponseEntity exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity,
    ParameterizedTypeReference responseType, Object… uriVariables)
  2. public ResponseEntity exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity,
    ParameterizedTypeReference responseType, Map<String, ?> uriVariables)
  3. public ResponseEntity exchange(URI url, HttpMethod method, @Nullable HttpEntity<?> requestEntity,
    ParameterizedTypeReference responseType)
  4. public ResponseEntity exchange(RequestEntity<?> requestEntity, ParameterizedTypeReference responseType)

上面4種，ParameterizedTypeReference 支持即泛型類作爲返回類型
例子：ParameterizedTypeReference 例子

  1. public ResponseEntity exchange(RequestEntity<?> requestEntity, Class responseType)

    最後一種RequestEntity<?>裏面加請求頭，請求方法，請求地址

    //get添加請求頭
HttpHeaders exchangeHeaders = new HttpHeaders();
exchangeHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
URI url = new URI("http://localhost:6788/exchange?id=--1");
RequestEntity<Object> orderEntity = new RequestEntity<>(exchangeHeaders,HttpMethod.GET,url);
ResponseEntity<String> result = restTemplate.exchange(orderEntity, String.class);
System.out.println(result);
====================exchange=======================
<200,{"code":1,"message":"","data":"exchange--1"},[Content-Type:"application/json;charset=UTF-8", Transfer-Encoding:"chunked", Date:"Tue, 28 May 2019 02:45:26 GMT"]>

例子源碼地址

例子源碼地址

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