Question

我有一个带有按钮和标签的活动。在按钮上单击我的应用程序必须下载几个文件（约9000）。如果用户再次单击按钮，则必须停止下载，而在另一次单击时，必须从头开始。

所以我这样做：

活动：

    file.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Button b = (Button)v;
            if(canFile){
                b.setText("Stop download");
                changeLabelInfo("Getting file list...");
                labelFile.setVisibility(View.VISIBLE);
                fileTask.start();
            }else{
                b.setText("Download files");
                if(fileTask.isAlive()){  
                   fileTask.interrupt();
                   fileTask = null;
                   fileTask = new UpdateFilesThread(this);
                }
                labelFile.setVisibility(View.INVISIBLE);
                Kernel.setManualUpdate("file",false);
            }
            canFile = !canFile;
        }
    });

必须下载文件的帖子是UpdateFilesThread：

public class UpdateFilesThread extends Thread{
    private MainActivity activity;
    private final String rootPath = "/mnt/local/";
    public UpdateFilesThread(MainActivity activity){
        this.activity = activity;
    }


    public void run(){
        String json = getFilesURL();
        JSONObject a = (JSONObject)JSONValue.parse(json);
        boolean isZip = false,canDownload = true;
        String[] keys = new String[]{"key1","key2","key3","key4"};

        for(String key:keys){
            Object folder = (Object)a.get(key);
            if(folder instanceof JSONObject){
                JSONObject fold = (JSONObject)folder;
                for(Object path_o:fold.keySet()){
                    path = path_o.toString().replace(" ", "%20");
                    if(local.endsWith(".php")){
                        isZip = true;
                        try {
                            Jsoup.connect(mywebserviceURL).data("path",path).timeout(0).post(); // If php generate zip containing php file
                        } catch (IOException e) {
                            canDownload = false;
                        }
                    }
                    if(canDownload){
                        try{
                            if(downloadFromUrl(path,isZip))
                                //SAVE URL DOWNLOADED
                        }catch(Exception e){
                            e.printStackTrace();
                        }
                    }
                    canDownload = true;
                    isZip = false;
                }
            }
        }
        a.remove(key);
    }

    private String getFilesURL(){
        try {

            MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
            entity.addPart("type", new StringBody("all"));
            HttpPost post = new HttpPost("mywebserviceURL");
            post.setEntity(entity);
            HttpClient client = new DefaultHttpClient();
            HttpResponse response = client.execute(post);

            return EntityUtils.toString(response.getEntity());
        } catch (UnsupportedEncodingException e) {
            Support.writeError(e, null);
            e.printStackTrace();
            return "";
        } catch (ClientProtocolException e) {
            Support.writeError(e, null);
            e.printStackTrace();
            return "";
        } catch (ParseException e) {
            Support.writeError(e, null);
            e.printStackTrace();
            return "";
        } catch (IOException e) {
            Support.writeError(e, null);
            e.printStackTrace();
            return "";
        }
    }
    public boolean downloadFromUrl(String path,boolean isZip){
        InputStream is = null;
        FileOutputStream fos = null;
        String localFilename = rootPath+path;
        String local = isZip?rootPath+"tmp.zip":localFilename;


        boolean return_ = false;
        try {
            URL url = new URL(isZip?mywebserviceURLZip:mywebserviceURLZip+path);
            URLConnection urlConn = url.openConnection();
            urlConn.setReadTimeout(0);
            is = urlConn.getInputStream();
            fos = new FileOutputStream(local);

            byte[] buffer = new byte[51200];
            int len;

            while ((len = is.read(buffer)) > 0) {
                fos.write(buffer, 0, len);
            }
            fos.close();
            is.close();
            if(isZip){
                ZipFile zip = new ZipFile(local);
                zip.extractAll(rootPath);
                new File(local).delete();
            }

            return_= true;
        }catch(Exception e){
            e.printStackTrace();
            return false;
        }
        return return_;
    }
}

当用户点击两次按钮（停止下载并重新开始）时，我的问题就出现了。提示错误说该线程已经是startend并且正在运行..我该如何解决？我知道asyncTask应该更好但是我的问题导致在我的应用程序中有很多线程在运行并且设备很糟糕。有可能停止definitelly一个线程？还有其他更好的解决方案吗？

Answer 1

尝试实施AsyncTask。当用户首次点击按钮时，请调用任务execute (Params... params)。在第二次点击时，调用任务cancel (boolean mayInterruptIfRunning)。将下载功能放在任务的doInBackground (Params... params)

中

Answer 2

您的运行线程需要偶尔检查isInterrupted（）并在它返回true时退出。否则线程永远不会被取消。

我认为你的整个架构都是错误的。将9000个文件下载到手机上？即使每个文件只有1KB，这也是移动应用程序的大量内存。为了你自己的理智，至少你应该压缩这些数据并下载一个拉链。

如何在android中启动和停止下载多个文件

2 个答案: