检测Java中的HTTP中断

Question

我正在用Java从外部系统调用REST.如果有任何连接中断,如外部系统脱机,我需要一个侦听器来检测并执行相应的操作.如果我能用Java实现这一点,请告诉我.优选地在Java 8中.

如果我遇到任何这种情况,目前我没有任何例外.我目前有以下代码

    Client client = ClientBuilder.newClient();
    WebTarget target = client.target(HOSTNAME);
    Invocation.Builder requestBuilder;

    requestBuilder = target.path(URL).request(MediaType.APPLICATION_JSON)
                                                .header(HEADER_AUTHORIZATION, AUTH_TOKEN);      
    Response response = null;
    if (HTTP_POST.equalsIgnoreCase(method)) {
        try{
        response = requestBuilder.post(Entity.entity(message, MediaType.APPLICATION_JSON_TYPE));
        }catch(Exception ex ){
            ex.printStackTrace();
        }
    } else if (HTTP_GET.equalsIgnoreCase(method)) {
        response = requestBuilder.get();
    } 

    String executeMessage = null;
    if(response != null){
        if (response.getStatus() == 200) {
            executeMessage = response.readEntity(String.class);         
            return new JSONObject(executeMessage);
        } else {
            executeMessage = response.readEntity(String.class);
            final JSONObject status = new JSONObject();
            status.put(STATUS_CODE, response.getStatus());
            status.put(STATUS_INFO, response.getStatusInfo());
            status.put("response", executeMessage);
            final JSONObject error = new JSONObject();
            error.put(ERROR, status);
            return error;
        }
    }

Answer 1

您可以创建自己的侦听器，并使您的 Http 调用与 HTTP 响应/错误准备好后传回调用类的结果异步。例如（有错别字）：

创建一个您的主类将实现并且您的 Http 客户端将使用的接口...

public interface MyHttpListener {
  public httpComplete(MyHttpResults results);
}

在你的主类中实现。

public MyClass implements MyHttpListener {

  public void processHttpRequests(){
      for(int i=0; i<10; i++){
        // instantiate your Http Client class 
        HttpClient client = new HttpClient();

        // register the listener
        client.addHttpListener(this);

        // execute whatever URL you want and you are notified later when complete
        client.executeRequest("http://whatever");
     }
  }

  public httpRequestComplete(MyHttpResults results) {
    // do something with the results   
    results.getResponseCode();
    results.getRawResponse();
    results.whatever();
  }  

}

向 HttpClient 添加方法以接受侦听器

public class MyHttpClient {
    List<MyHttpListener> httpListenerList = new ArrayList();   

   // register listeners
   public void addHttpListener(MyHttpListener listener){
     httpListenerList.add(listener);
   }   

   // this is the method that processes the request
   public void executeRequest(String url) {

     // do whatever you were doing previously here   

     // optional POJO to wrap the results and/or exceptions
     MyHttpResults results = new MyHttpResults();
     results.withResponseCode(response.getResponseCode());
     results.withResponse(responseAsString);
     results.withException(ex);
     results.withWhatever(whatever);

     // notify listeners
     notify(results);

   }

  public void notify(MyHttpResults results){
      // notify listeners
      for(MyHttpListener listener : httpListenerList){
         listener.httpComplete(results);
      }
  }


 }