Android：处理图像时 AsyncTask 崩溃

Question

我想上传一张图片到我的网络服务器。 我有来自服务器的响应，所以这不是问题。 当我将以下行粘贴到代码中时，它大多会崩溃。

我在调试器中看到 AsyncTask 的 RuntimeException，仅此而已。

另一个问题：我可以将位图解压缩成一个字节数组，这样我就可以上传带有原始文件结尾的原始文件吗？

以下是问题所在：

        // create the image for the server
    Bitmap bm=BitmapFactory.decodeFile(Values.imageFilePath);
        ByteArrayOutputStream stream=new ByteArrayOutputStream();
        bm.compress(Bitmap.CompressFormat.JPEG, 100, stream);
        byte[] byte_array=stream.toByteArray();
        String byteString=Base64.encodeToString(byte_array, Base64.DEFAULT);

这是整个异步任务类，上面的代码被注释掉并运行。 有什么问题？ （ProgressDialog 将在主活动中创建） 你 谢谢。

    class UploadThread extends AsyncTask<String, Void, String> 
    {
        private Context _context;
        private ProgressDialog pd;

        public UploadThread(Context context)
        {
            super();
            _context=context;
        }

        protected String doInBackground(String... urls) 
        {
            String response="Android says \"Nothing happened.\"";       
            InputStream is = null;
            StringBuilder sb=null;

            //http post
            try{
                HttpClient httpclient = new DefaultHttpClient();
                HttpPost httppost = new HttpPost(Values.hostname);

                ArrayList<NameValuePair> nvp=new ArrayList<NameValuePair>();
                // This is the Post data.
                nvp.add(new BasicNameValuePair("plog_android_upload","plogupload"));
                nvp.add(new BasicNameValuePair("thecomment",Values.comment));

                // get the image and process it.
//            Values.progressDialog.setMessage("Processing image..");
        // create the image for the server
    //  Bitmap bm=BitmapFactory.decodeFile(Values.imageFilePath);
    //    ByteArrayOutputStream stream=new ByteArrayOutputStream();
    //    bm.compress(Bitmap.CompressFormat.JPEG, 100, stream);
    //    byte[] byte_array=stream.toByteArray();
    //    String byteString=Base64.encodeToString(byte_array, Base64.DEFAULT);

        //Values.progressDialog.setMessage("Uploading..");
        //nvp.add(new BasicNameValuePair("upload_file",byteString));

        httppost.setEntity(new UrlEncodedFormEntity(nvp));

        HttpResponse httpresponse = httpclient.execute(httppost);
        HttpEntity entity = httpresponse.getEntity();
        is = entity.getContent();
        response="Connection established.";
    }catch(UnknownHostException eu){    // gets thrown on unknown host.
        return "No connection!\n(or wrong hostname)";
    }catch(HttpHostConnectException ex){ // gets thrown on unknown connection.
         return "No connection!\n(or wrong hostname)";
    }catch(Exception e){
        return "Error in http connection:"+e.toString();
    }

    //convert response to string
    try{
        BufferedReader reader = new BufferedReader(new InputStreamReader(is,"utf-8"),8);
        sb = new StringBuilder();
        sb.append(reader.readLine() + "\n");
        String line="0";
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
        is.close();
        response="Server says: "+sb.toString();
    }catch(Exception e){
        response= "Error converting HTTP result: "+e.toString();
        return response;
    }

    return response;
}

@Override
protected void onPostExecute(String result) 
{
    super.onPostExecute(result);
    // dismiss the progress dialog.
    Values.progressDialog.dismiss();
    // Show the user some feedback.
    Toast.makeText(_context,result, Toast.LENGTH_LONG).show();      
}

}

Answer 1

我认为你使用的代码

            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(Values.hostname);

            ArrayList<NameValuePair> nvp=new ArrayList<NameValuePair>();
            // This is the Post data.
            nvp.add(new BasicNameValuePair("plog_android_upload","plogupload"));
            nvp.add(new BasicNameValuePair("thecomment",Values.comment));

不应该在doInBackground中执行，当我不得不在doInBackground中使用arrayList时我遇到了同样的问题，所以我将那部分代码更改为在UIThread中工作的onPreExecute()