Android AsyncHttpClient 调用等待完成

Question

在我的 Android 应用程序中，我有时会进行同步 HTTP 调用。由于这在主 UI 线程中是不可能的，因此我试图通过使用 com.loopj.android.http.AsyncHttpClient 和处理程序来规避问题。在我的代码中，我尝试等待调用完成：

public class someclass {
...
//asynchronous HTTP handler for Android
private static AsyncHttpClient httpClient = new AsyncHttpClient(); 
...
public void somemethod() {
...
httpClient.get(request, handler);
    ...
    //waiting for call to be finished
    do {
        Thread.sleep(100); //for testing only
        log.info("sleeping...");
    } while (!handler.isFinished());


    response = handler.getBody();
    log.info("Async resp = " + response);
 ...

我编写了自己的处理程序类：

    public class MyAsyncHTTPResponseHandler extends AsyncHttpResponseHandler {



    private String header = null;
    private String body = null;
    private int status = 0;
    boolean finish = false;

    public MyAsyncHTTPResponseHandler() {
        super();
        log.info("init Http handler ");
        finish = false;
    }

    @Override
    public void onStart() {
        // called before request is started
        log.info("starting Async Get");
        finish = false;
    }

    @Override
    public void onSuccess(int statusCode, cz.msebera.android.httpclient.Header[] headers, byte[] responseBody) {


        body = new String(responseBody);
        status = statusCode;
        finish = true;

        log.info("Async Get worked fine " + responseBody);
    }



    @Override
    public void onFailure(int statusCode, cz.msebera.android.httpclient.Header[] headers, byte[] responseBody, java.lang.Throwable error) {
        // called when response HTTP status is "4XX" (eg. 401, 403, 404)
        log.info("Error in executing URL get " + statusCode + " " + responseBody);
        finish = true;
    }

    @Override
    public void onRetry(int retryNo) {
        // called when request is retried
    }

    public String getBody() {
        return body;
    }

    public int getStatusCode() {
        return status;
    }

    public boolean isFinished() {
        return finish;
    }

}

不幸的是，这不起作用。 onStart() 方法将被执行，但循环将永远运行。不会调用onSuccess() 方法。

如果我注释掉循环，正文响应将为空。正如我在这种情况下的日志中看到的那样，onSuccess() 方法将被调用，但在我在somemethod() 中的日志语句之后。

我在这里做错了什么？

Answer 1

最简单的解决方案是将volatile关键字添加到变量finish。 或者使用同步：

public synchronized void setFinish()
   {
       finish = True;
   }

   public synchronized boolean isFinished()
   {
       return finish;
   }