OKHttp 使用注意

1.若想在 Callback 中修改畫面(包含產生 Dialog, Toast 等等)，必須使用 runonUiThread 包含要更改的畫面的行為，如下為使用 OKHttp 包裝器的方法宣告，

  public static void sendPostWithJSONFormat(String URL, Map<String, String> requestParameter, Callback callback) {  
      MediaType JSON = MediaType.parse("application/json; charset=utf-8");  
      RequestBody requestBody = RequestBody.create(JSON, new JSONObject(requestParameter).toString());  
      Request request = new Request.Builder().url(URL).post(requestBody).build();  
      Call call = sOKHttpClient.newCall(request);  
      call.enqueue(callback);  
    }

以下是使用該包裝器方法的範例

    OKHttpWrapper.sendPostWithJSONFormat(URL, httpParameter, new Callback() {  
                  @Override  
                  public void onResponse(Call call, Response response) throws IOException {  
                   //更改畫面行為  
                  }  
    
                  @Override  
                  public void onFailure(Call call, IOException e) {  
                   //更改畫面行為  
                  }  
              });

重點在於第 4 行和第 9 行若有更改畫面的行為必須使用 runOnUiThread 去包含。否則會出現以下 Exception:

E/AndroidRuntime: FATAL EXCEPTION: OkHttp Dispatcher  
      java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()  
          at android.os.Handler.<init>(Handler.java:200)  
          at android.os.Handler.<init>(Handler.java:114)  
          at android.app.Dialog.<init>(Dialog.java:119)  
          at android.app.AlertDialog.<init>(AlertDialog.java:200)  
          at android.app.AlertDialog$Builder.create(AlertDialog.java:1086)  
          at okhttp3.RealCall$AsyncCall.execute(RealCall.java:153)  
          at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)  
          at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)  
          at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)  
          at java.lang.Thread.run(Thread.java:818)

 

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