Salesforce Invoking Http Callouts and Testing Http Callouts

本文参考官方文档和zero zhang的博客：

　　https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_integration_intro.htm

Salesforce调用外部接口的方法或者数据，常用的访问方式有两种：

1. Soap方式：Web Service 通过XML方式调用Soap Web服务器；
2. Rest方式：Http通过JSON使用REST方式调用服务器。

下面了解一下REST方式获取外部Service数据。

• Salesforce 通过REST方式获取外部Service数据
  　　REST方式原理图如下：

  

• Salesforce 通过REST方式访问外界站点步骤如下
  1. 将Webservice的授权端点地址添加到Remote Site中：set -> Administer->Security Site Settings->Remote Site Settings。
     Salesforce提供了两个测试URL。将两个测试的URL添加到Remote Site中。两个URL分别为：
     Http:https://ap2.salesforce.com/0rp28000000TSqv
     Soap:https://ap2.salesforce.com/0rp28000000TSr0
     

  2. 代码进行访问，通过Http方式可以使用以下方法进行相关操作的访问：
     

• 下面是我自己封装的一个简单的Salesforce调用外部接口的帮助类和测试类：
  1. Helper类：

     global class HttpHelper {
     
         private Http Http{get;set;}
     
         private HttpRequest Request{get;set;}
     
         private HttpResponse Response{get;set;}
     
         public HttpResponse service(String method,String url,String body,String contentType,String authoriziton,String certificateName){
             Http = new Http();
             Request = new HttpRequest();
             try{
                 Request.setMethod(method);
                 Request.setEndpoint(url);
                 Request.setTimeout(120000);
                 if(string.isEmpty(contentType) || string.isBlank(contentType)){
                     Request.setHeader('Content-Type','application/json;charset=utf-8');
                 }else{
                    Request.setHeader('Content-Type',contentType);
                 }
                 if(string.isNotEmpty(authoriziton)&&string.isNotBlank(authoriziton)){
                    Request.setHeader('Authorization', authoriziton);
                 }
                 if(string.isNotEmpty(certificateName)&&string.isNotBlank(certificateName)){
                     Request.setClientCertificateName(certificateName);
                 }
                 if(string.isNotEmpty(body)&&string.isNotBlank(body)){
                     Request.setBody(body);
                 }
                 Response = Http.send(Request);
                 System.debug('Response：'+Response);
             }catch(Exception e){
                 system.debug('RequstException：'+e);
             }
             return Response;
         }
     
         /**
         Execute the Get Method
         */
         public HttpResponse doGet(String url,String body,String authoriziton,String certificateName){
             return service('GET', url, body, null, authoriziton,certificateName);
         }
     
         /**
          * Execute the Post Method
         */
         public HttpResponse doPost(String url,String body,String authoriziton,String certificateName){
             return service('POST', url, body, null, authoriziton,certificateName);
         }
     
     }

  2. 需要注意的是在测试帮助类的时候，我们必须实现HttpCalloutMock的这个类并实现其方法respond(),如：

     @isTest global class HttpCallOutMockImpl implements HttpCalloutMock{
         global HttpResponse respond(HttpRequest request){
             //Optionally,only send a mock response for a specific endpoint.
             System.assertEquals('http://example.com/example/test',request.getEndpoint());
             System.assertEquals('GET',request.getMethod());
     
             //Create a fake response
             HttpResponse response = new HttpResponse();
             response.setHeader('Content-Type', 'application/json');
             response.setBody('{"example":"test"}');
             response.setStatusCode(200);
             return response;
         }
     }

  3. 编写测试类，如：

     @isTest
     private class HttpHelperTest {
         @isTest static void testCallOut(){
             Test.setMock(HttpCalloutMock.class,new HttpCallOutMockImpl());
             HttpHelper httpHelper = new HttpHelper();
             HttpResponse resp=  httpHelper.doGet('http://example.com/example/test', null, null, null);
             string contentType = resp.getHeader('Content-Type');
             System.assert(contentType == 'application/json');
             String actualValue = resp.getBody();
             System.debug('Body:'+actualValue);
             String expectedValue = '{"example":"test"}';
             System.assertEquals(actualValue, expectedValue);
             System.assertEquals(200, resp.getStatusCode());
         }
     
     }

     注：测试类必须加上标记@IsTest