Spring RestTemplate的幾種請求調用


1、背景介紹

Spring RestTemplate 是 Spring 提供的用於訪問 Rest 服務的客戶端,RestTemplate 提供了多種便捷訪問遠程Http服務的方法,能夠大大提高客戶端的編寫效率,所以很多客戶端比如 Android或者第三方服務商都是使用 RestTemplate 請求 restful 服務。

調用 RestTemplate 的默認構造函數,RestTemplate 對象在底層通過使用 java.net 包下的實現創建 HTTP 請求,可以通過使用 ClientHttpRequestFactory 指定不同的HTTP請求方式。默認使用 SimpleClientHttpRequestFactory,是 ClientHttpRequestFactory 實現類.

2.方法使用

  1.用統一的方法模板進行四種請求:POST,PUT,DELETE,GET

restTemplate.exchange(
        String url, 
        HttpMethod method,
        HttpEntity requestEntity, 
        Class responseType, 
        Object uriVariables[]
    )
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

例如:

(1)POST請求

1 String reqJsonStr = "{\"code\":\"testCode\", \"group\":\"testGroup\",\"content\":\"testContent\", \"order\":1}";
2 HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON);
3 HttpEntity<String> entity = new HttpEntity<String>(reqJsonStr,headers);
4 ResponseEntity<Map> resp = restTemplate.exchange(DIC_DATA_URL, HttpMethod.POST, entity, Map.class);

(2)PUT請求

String reqJsonStr = "{\"id\":227,\"code\":\"updateCC\", \"group\":\"UPDATE\",\"content\":\"updateCT\", \"order\":9}";
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> entity = new HttpEntity<String>(reqJsonStr,headers);
ResponseEntity<Map> resp = restTemplate.exchange(DIC_DATA_URL, HttpMethod.PUT, entity, Map.class);

(3)DELETE請求

ResponseEntity<Map> resp = restTemplate.exchange(DIC_DATA_URL + "?id={id}", HttpMethod.DELETE, null, Map.class, 227);

(4)GET請求

ResponseEntity<String> results = restTemplate.exchange(url,HttpMethod.GET, null, String.class, params);

  2.用各種請求對應的專一接口

(1)POST請求

postForObject(String url, Object request, Class responseType, Object uriVariables[]):
返回數據對象Object,例如:
       DicData data = new DicData();
        data.setCode("cd123"); data.setGroup("TEST"); data.setContent("測試數據"); data.setOrder(5);    
        DicData obj = restTemplate.postForObject(DIC_DATA_URL, data, DicData.class);
> 或者
postForEntity:(String url, Object request, Class responseType, Object uriVariables[])
返回封裝了數據對象的ResponseEntity對象,例如:
DicData data = new DicData();
data.setCode("cd123"); data.setGroup("TEST"); data.setContent("測試數據"); data.setOrder(5);        
ResponseEntity<Map> respEntity = restTemplate.postForEntity(DIC_DATA_URL, data, Map.class);
(2)PUT請求

    put(String url, Object request, Object urlVariables[])
例如:
    DicData data = new DicData();
    data.setId(226L); data.setCode("updateCode"); data.setGroup("UPDATE"); 
    data.setContent("測試數據"); data.setOrder(9);      
    restTemplate.put(DIC_DATA_URL, data); 

 (3)DELETE請求

    delete(String url, Object urlVariables[])

例如:
    restTemplate.delete(DIC_DATA_URL + "?id={id}", 222);

(4)GET請求

    getForObject(String url, Class responseType, Object urlVariables[]):

返回請求的結果對象,例如
    Order o = restTemplate.getForObject(Constants.SERVER_URL+"/order?orderCode={orderCode}",
                        Order.class,order.getOrderCode());
getForEntity(String url, Class responseType, Object urlVariables[]):
返回封裝了數據對象的ResponseEntity對象,例如:
ResponseEntity<EBTUser> ebtuserResponse = restTemplate.getForEntity(url,EBTUser.class);
EBTUser user = ebtuserResponse.getBody();

  3.GET請求,要返回一些復合數據類型時的處理

(1)返回List類型數據

    DicData[] dicResult = restTemplate.getForObject( Constants.SERVER_URL + "/dicDatas/dicData?"
                + "group={group}", DicData[].class, group);
    List<DicData> list = Arrays.asList(dicResult);
或者
// pass generic information to resttemplate; ParameterizedTypeReference為spring3.2版本后引進的類
    ParameterizedTypeReference<List<DicData>> responseType = new ParameterizedTypeReference<List<DicData>>();
    ResponseEntity<List<DicData>> resp = restTemplate.exchange(Constants.SERVER_URL + "/dicDatas/dicData?group={group}", 
            HttpMethod.GET, null, responseType);
    List<DicData> list = resp.getBody();

(2)返回屬性中有范型數據的復合對象
    比如,分頁對象
    ResponseEntity<String> results = restTemplate.exchange(url,HttpMethod.GET, null, String.class, params);
    // 借助com.fasterxml.jackson.databind.ObjectMapper 對象來解析嵌套的json字符串    
    ObjectMapper mapper = new ObjectMapper(); mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    PageInfo<Product> page = mapper.readValue(results.getBody(), new TypeReference<PageInfo<Product>>() { });

 

 


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