Java 异步任务完成后如何更改ActionBar的颜色？

在我的应用程序中，我正在连接到WebView的

onPageFinished

中执行

AsyncTask

。此方法如下所示：

@Override
public void onPageFinished(WebView myWebView, String url)
{
    new SendRequestAsyncTask().execute();

    // when a page has finished loading dismiss any progress dialog
    if (progressDialog != null && progressDialog.isShowing())
    {
        progressDialog.dismiss();
    }
}

public class SendRequestAsyncTask extends AsyncTask <Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        //runs in ui thread
    }

    @Override
    protected Void doInBackground(Void... params) {
        // TODO Auto-generated method stub

        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("myscript.php");

        try {
            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("request", "12345"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);

            // writing response to log
            HttpEntity resEntity = response.getEntity();

            if (resEntity != null) {

                String responseStr = EntityUtils.toString(resEntity).trim();
                Log.v(TAG, "Response: " +  responseStr);

                String[] parts = responseStr.split(":");
                parts[1] = parts[1].replace("\"", "");
                parts[1] = parts[1].replace("}", "");

                if (parts[1].equals("01")){
                    actionBar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#ffffff")));
                } else {
                    Log.v(TAG, "No success: " + parts[1]);
                }

            }

        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
        } catch (IOException e) {
            // TODO Auto-generated catch block
        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        //runs in ui thread you can update the layout here
    }
}

而

SendRequestAsyncTask

看起来是这样的：

@Override
public void onPageFinished(WebView myWebView, String url)
{
    new SendRequestAsyncTask().execute();

    // when a page has finished loading dismiss any progress dialog
    if (progressDialog != null && progressDialog.isShowing())
    {
        progressDialog.dismiss();
    }
}

public class SendRequestAsyncTask extends AsyncTask <Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        //runs in ui thread
    }

    @Override
    protected Void doInBackground(Void... params) {
        // TODO Auto-generated method stub

        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("myscript.php");

        try {
            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("request", "12345"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);

            // writing response to log
            HttpEntity resEntity = response.getEntity();

            if (resEntity != null) {

                String responseStr = EntityUtils.toString(resEntity).trim();
                Log.v(TAG, "Response: " +  responseStr);

                String[] parts = responseStr.split(":");
                parts[1] = parts[1].replace("\"", "");
                parts[1] = parts[1].replace("}", "");

                if (parts[1].equals("01")){
                    actionBar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#ffffff")));
                } else {
                    Log.v(TAG, "No success: " + parts[1]);
                }

            }

        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
        } catch (IOException e) {
            // TODO Auto-generated catch block
        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        //runs in ui thread you can update the layout here
    }
}

公共类SendRequestAsyncTask扩展了AsyncTask{
@凌驾
受保护的void onPreExecute（）{
//TODO自动生成的方法存根
super.onPreExecute（）；
//在ui线程中运行
}
@凌驾
受保护的Void doInBackground（Void…参数）{
//TODO自动生成的方法存根
HttpClient HttpClient=新的DefaultHttpClient（）；
HttpPost=newhttppost（“myscript.php”）；
试一试{
//添加您的数据
List nameValuePairs=新的ArrayList（2）；
添加（新的BasicNameValuePair（“请求”、“12345”）；
setEntity（新的UrlEncodedFormEntity（nameValuePairs））；
//执行HTTP Post请求
HttpResponse response=httpclient.execute（httppost）；
//将响应写入日志
HttpEntity当前性=response.getEntity（）；
if（最近性！=null）{
String responsest=EntityUtils.toString（resEntity.trim（）；
Log.v（标签，“响应：+responsest”）；
String[]parts=responsest.split（“：”）；
零件[1]=零件[1]。替换（“\”，“）；
零件[1]=零件[1]。替换（“}”和“）；
如果（第[1]部分等于（“01”））{
actionBar.setBackgroundDrawable（新的ColorDrawable（Color.parseColor（“#ffffffff”））；
}否则{
Log.v（标签“未成功：+部分[1]）；
}
}
}捕获（客户端协议例外e）{
//TODO自动生成的捕捉块
}捕获（IOE异常）{
//TODO自动生成的捕捉块
}
返回null；
}
@凌驾
受保护的void onPostExecute（void结果）{
//TODO自动生成的方法存根
super.onPostExecute（结果）；
//在ui线程中运行您可以在此处更新布局
}
}

---

但是，这会使我的应用程序崩溃。因此，我猜我需要在

onPageFinished

方法中更改Actionbar的颜色。但是，我真的不知道如何将变量从

AsyncTask

获取到

onPageFinished

。此外，我不知道如何将颜色从

@color/

xmlf更改为颜色ile…

不，您需要在onPostExecute中设置颜色。这在UI线程上，可以安全地触摸UI。只要将调用移动到那里，您就应该停止崩溃。当然，您可能需要将一些数据传递到onPostExecute才能正确执行（或者将其存储在AsyncTask的类变量中）。

尝试类似的方法

    public class SendRequestAsyncTask extends AsyncTask <Void, String, String> {

@Override
protected void onPreExecute() {
    // TODO Auto-generated method stub
    super.onPreExecute();
    //runs in ui thread
}

@Override
protected String doInBackground(Void... params) {
    // TODO Auto-generated method stub
    String strReturn = "";

    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost("myscript.php");

    try {
        // Add your data
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
        nameValuePairs.add(new BasicNameValuePair("request", "12345"));
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

        // Execute HTTP Post Request
        HttpResponse response = httpclient.execute(httppost);

        // writing response to log
        HttpEntity resEntity = response.getEntity();

        if (resEntity != null) {

            String responseStr = EntityUtils.toString(resEntity).trim();
            Log.v(TAG, "Response: " +  responseStr);

            String[] parts = responseStr.split(":");
            parts[1] = parts[1].replace("\"", "");
            parts[1] = parts[1].replace("}", "");

            strReturn = parts[1];
        }

    } catch (ClientProtocolException e) {
        // TODO Auto-generated catch block
    } catch (IOException e) {
        // TODO Auto-generated catch block
    }

    return strReturn;
}

@Override
protected void onPostExecute(String result) {
    // TODO Auto-generated method stub
    super.onPostExecute(result);
    //runs in ui thread you can update the layout here

    if (result.equals("01")){
        actionBar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#ffffff")));
    } else {
        Log.v(TAG, "No success: " + parts[1]);
    }
}
}

公共类SendRequestAsyncTask扩展了AsyncTask{
@凌驾
受保护的void onPreExecute（）{
//TODO自动生成的方法存根
super.onPreExecute（）；
//在ui线程中运行
}
@凌驾
受保护字符串doInBackground（无效…参数）{
//TODO自动生成的方法存根
字符串strReturn=“”；
HttpClient HttpClient=新的DefaultHttpClient（）；
HttpPost=newhttppost（“myscript.php”）；
试一试{
//添加您的数据
List nameValuePairs=新的ArrayList（2）；
添加（新的BasicNameValuePair（“请求”、“12345”）；
setEntity（新的UrlEncodedFormEntity（nameValuePairs））；
//执行HTTP Post请求
HttpResponse response=httpclient.execute（httppost）；
//将响应写入日志
HttpEntity当前性=response.getEntity（）；
if（最近性！=null）{
String responsest=EntityUtils.toString（resEntity.trim（）；
Log.v（标签，“响应：+responsest”）；
String[]parts=responsest.split（“：”）；
零件[1]=零件[1]。替换（“\”，“）；
零件[1]=零件[1]。替换（“}”和“）；
strReturn=零件[1]；
}
}捕获（客户端协议例外e）{
//TODO自动生成的捕捉块
}捕获（IOE异常）{
//TODO自动生成的捕捉块
}
返回strReturn；
}
@凌驾
受保护的void onPostExecute（字符串结果）{
//TODO自动生成的方法存根
super.onPostExecute（结果）；
//在ui线程中运行您可以在此处更新布局
如果（结果等于（“01”））{
actionBar.setBackgroundDrawable（新的ColorDrawable（Color.parseColor（“#ffffffff”））；
}否则{
Log.v（标签“未成功：+部分[1]）；
}
}
}

确实有道理，我如何将数据正确地传递给onPostExecute？从doInBackground返回的值被传递到onPostExecute。