Question

我正在开发一个从网络检索数据的应用程序，将它们存储到设备然后读取它们。问题是，我在异步任务中得到我的数据..而且我的应用程序在尝试向用户显示数据之前不会让任务完成。我已经尝试过task.get（）但没有结果（它只是停在那里）。

这是我的任务：

.warning @ vendor.bundle.js:11125ReactElementValidator.createElement @ vendor.bundle.js:27927render @ app.bundle.js:29792(anonymous function) @ app.bundle.js:407ReactCompositeComponentMixin._renderValidatedComponentWithoutOwnerOrContext @ vendor.bundle.js:14599ReactCompositeComponentMixin._renderValidatedComponent @ vendor.bundle.js:14619wrapper @ vendor.bundle.js:11394ReactCompositeComponentMixin.mountComponent @ vendor.bundle.js:14232wrapper @ vendor.bundle.js:11394ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactMultiChild.Mixin.mountChildren @ vendor.bundle.js:22652ReactDOMComponent.Mixin._createContentMarkup @ vendor.bundle.js:19830ReactDOMComponent.Mixin.mountComponent @ vendor.bundle.js:19718ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactCompositeComponentMixin.mountComponent @ vendor.bundle.js:14237wrapper @ vendor.bundle.js:11394ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactMultiChild.Mixin.mountChildren @ vendor.bundle.js:22652ReactDOMComponent.Mixin._createContentMarkup @ vendor.bundle.js:19830ReactDOMComponent.Mixin.mountComponent @ vendor.bundle.js:19718ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactMultiChild.Mixin.mountChildren @ vendor.bundle.js:22652ReactDOMComponent.Mixin._createContentMarkup @ vendor.bundle.js:19830ReactDOMComponent.Mixin.mountComponent @ vendor.bundle.js:19718ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactMultiChild.Mixin.mountChildren @ vendor.bundle.js:22652ReactDOMComponent.Mixin._createContentMarkup @ vendor.bundle.js:19830ReactDOMComponent.Mixin.mountComponent @ vendor.bundle.js:19718ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactCompositeComponentMixin.mountComponent @ vendor.bundle.js:14237wrapper @ vendor.bundle.js:11394ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactCompositeComponentMixin.mountComponent @ vendor.bundle.js:14237wrapper @ vendor.bundle.js:11394ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactCompositeComponentMixin.mountComponent @ vendor.bundle.js:14237wrapper @ vendor.bundle.js:11394ReactReconciler.mountComponent @ vendor.bundle.js:12542ReactCompositeComponentMixin.mountComponent @ vendor.bundle.js:14237wrapper @ vendor.bundle.js:11394ReactReconciler.mountComponent @ vendor.bundle.js:12542mountComponentIntoNode @ vendor.bundle.js:8912Mixin.perform @ vendor.bundle.js:13649batchedMountComponentIntoNode @ vendor.bundle.js:8928Mixin.perform @ vendor.bundle.js:13649ReactDefaultBatchingStrategy.batchedUpdates @ vendor.bundle.js:19229batchedUpdates @ vendor.bundle.js:13154ReactMount._renderNewRootComponent @ vendor.bundle.js:9122wrapper @ vendor.bundle.js:11394ReactMount._renderSubtreeIntoContainer @ vendor.bundle.js:9196ReactMount.render @ vendor.bundle.js:9216wrapper @ vendor.bundle.js:11394(anonymous function) @ app.bundle.js:280(anonymous function) @ app.bundle.js:285(anonymous function) @ app.bundle.js:286__webpack_require__ @ vendor.bundle.js:1051fn @ vendor.bundle.js:596(anonymous function) @ app.bundle.js:7__webpack_require__ @ vendor.bundle.js:1051webpackJsonpCallback @ vendor.bundle.js:22(anonymous function) @ app.bundle.js:1
vendor.bundle.js:9781 Uncaught Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. Check the render method of

此任务是我的自定义异步任务的一个实例：

我真的不知道该怎么做......执行变得快而且得不到任何事情，因为我没有回复任何我想的。

Answer 1

onPostExecute（Result），在后台计算完成后在UI线程上调用。后台计算的结果作为参数传递给此步骤。

@Override
protected void onPostExecute(String result) {

}

Answer 2

private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
     protected Long doInBackground(URL... urls) {
         int count = urls.length;
         long totalSize = 0;
         for (int i = 0; i < count; i++) {
             totalSize += Downloader.downloadFile(urls[i]);
             publishProgress((int) ((i / (float) count) * 100));
             // Escape early if cancel() is called
             if (isCancelled()) break;
         }
         return totalSize;
     }

     protected void onProgressUpdate(Integer... progress) {
         setProgressPercent(progress[0]);
     }

     protected void onPostExecute(Long result) {
         showDialog("Downloaded " + result + " bytes");
     }
 }

并将其称为：

new DownloadFilesTask().execute(url1, url2, url3);

Answer 3

我使用接口作为委托来执行此操作。这是一个例子：

在我的主要活动中，我有一个onClick监听器来触发我的异步调用，并在调用完成后处理一个监听器。

private void enableLocationButton(){
    locationButton = (Button) findViewById(R.id.locationButton);
    locationButton.setEnabled(true);
    locationButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(MainActivity.this, selectLocationActivity.class);
            intent.putExtra("serverURL",server.getWebServerAddressField());
            startActivityForResult(intent, 200);
        }
    });

}

 @Override
protected void onActivityResult(int requestCode,int resultCode, Intent data){
    if(resultCode == RESULT_OK) {
        switch (requestCode){
            case 100:
                processServerResponse((PmsWebServer) data.getBundleExtra("server").get("server"));
                break;
            case 200:
                processLocationResponse((PmsDataSource)data.getBundleExtra("location").get("location"));
            default:processError();
        }
    }else{
        processError();
    }
}

selectLocationActivity中的某处我调用了异步调用以及处理响应的内容，请注意此类实现了异步调用中使用的接口。

public class selectLocationActivity extends ListActivity implements SoapServiceInterface{

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_location_select);
    chosenServer = this.removeURLHeader(getIntent().getStringExtra("serverURL"));
    this.retrieveLocationOptionsByServer(chosenServer);
}

private void retrieveLocationOptionsByServer(String server) {
    Map<String,Object> parms = new HashMap<String,Object>();
    parms.put(WEB_SERVER_NAME,server);
    SoapServiceObject service = new SoapServiceObject(Services.SERVICE_DETAILS,parms);
    callTheService(service);
}

private void callTheService(SoapServiceObject service){
    SoapServiceHelper helper = new SoapServiceHelper();
    helper.delegate = thisActivity;
    helper.execute(service);
}

@Override
public void serviceCallComplete(SoapObject response){
    this.createClickableListOnScreen(response);
} 
//...more code...//
}

serviceCallComplete由asyncTask启动。以下是该任务的代码

public class SoapServiceHelper extends AsyncTask<SoapServiceObject, Void, SoapObject>{
public SoapServiceInterface delegate = null;
private Integer RETRY_COUNT = 0;
private final Integer MAX_RETRY_COUNT = 2;

protected SoapObject doInBackground(SoapServiceObject... args){
    SoapServiceObject service = args[0];
    try{
        service.callTheService();
    }catch(Exception e){
        System.out.println("An error occurred calling the service\n" + e.getMessage());
    }
    return service.getResponse();
    //return callDateTimeService();
}

protected void onPostExecute(SoapObject result){
    delegate.serviceCallComplete((SoapObject)(result.getProperty(0)));
} 
}

最后这是界面

public interface SoapServiceInterface {

    public void serviceCallComplete(SoapObject response);
}

我知道我正在直接从我的结果中向屏幕显示某些内容，只是将该部分保存并读取;）

Answer 4

这项任务的一件事是它将东西保存到单身人士中。我设法使用保存在onResume（）的单例中的网络信息调用方法。当线程结束时，它会转到onResume，一切正常！

如何让Async Task在Android中完成

4 个答案: