Java 显示进度条直到下载完成-Android

我使用以下代码从internet下载视频：

class DownloadFile1 extends AsyncTask<String, Integer, String> {

    public String videoToDownload;
    public String fileName;

    @Override
    protected String doInBackground(String... params) {
        int count;

        try {
            mp4load(videoToDownload);
        } catch (Exception e) {
            // TODO: handle exception
        }

        return null;
    }

    public void mp4load(String urling) {
        try {
            System.out.println("Downloading");
            URL url = new URL(urling);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            con.setRequestMethod("GET");
            //c.setDoOutput(true);
            con.connect();

            // String downloadsPath = Environment.getExternalStoragePublicDirectory();
            File SDCardRoot = Environment.getExternalStorageDirectory();

            File outputFile = new File(SDCardRoot, fileName);

            if (!outputFile.exists()) {
                outputFile.createNewFile();
            }

            FileOutputStream fos = new FileOutputStream(outputFile);

            int status = con.getResponseCode();

            InputStream is = con.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len1);
            }
            fos.close();
            is.close();
            System.out.println("Downloaded");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

---

更改代码，如下所示：

class DownloadFile1 extends AsyncTask<String, Integer, String> {
    ProgressDialog bar;
    public String videoToDownload;
    public String fileName;
    private Context mContext;

    public DownloadFile1(Context context)
     {
      mContext=context;  
     }
    @Override
    protected void onPreExecute()
    {
       super.onPreExecute();
       bar = new ProgressDialog(mContext);
       bar.setMessage("Processing...");
       bar.setIndeterminate(true);
    }

    @Override
    protected String doInBackground(String... params) {
        int count;

        try {
            mp4load(videoToDownload);
        } catch (Exception e) {
            // TODO: handle exception
        }

        return null;
    }

    @Override
    protected String onPostExecute()
    {
      super.onPostExecute(result);
      bar.dismiss();
    }

    public void mp4load(String urling) {
        try {
            System.out.println("Downloading");
            URL url = new URL(urling);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            con.setRequestMethod("GET");
            //c.setDoOutput(true);
            con.connect();

            // String downloadsPath = Environment.getExternalStoragePublicDirectory();
            File SDCardRoot = Environment.getExternalStorageDirectory();

            File outputFile = new File(SDCardRoot, fileName);

            if (!outputFile.exists()) {
                outputFile.createNewFile();
            }

            FileOutputStream fos = new FileOutputStream(outputFile);

            int status = con.getResponseCode();

            InputStream is = con.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len1);
            }
            fos.close();
            is.close();
            System.out.println("Downloaded");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

或

然后

---

“取得进展”对话框，如下面的代码所示。。 制作如下所示的显示和隐藏两种方法

    private ProgressDialog progressDialog; // it create local level of class.
        progressDialog=new ProgressDialog(MainActivity.this); // this line define into onCreateView method.
    private void showProgress(){
    progressDialog.setMessage("Loading");
    progressDialog.show();
}
private void closeProgress(){
    progressDialog.dismiss();
}

在调用showProgress方法之前启动dowload时，下载结束完成，然后显示closeProgress

 /**
     * Showing Dialog
     * */
    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
        case progress_bar_type: // we set this to 0
            pDialog = new ProgressDialog(this);
            pDialog.setMessage("Downloading file. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setMax(100);
            pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pDialog.setCancelable(true);
            pDialog.show();
            return pDialog;
        default:
            return null;
        }

下载类

class DownloadFile1 extends AsyncTask<String, Integer, String> {

    public String videoToDownload;
    public String fileName;

    @Override 
    protected String doInBackground(String... params) {
        int count;

        try { 
            mp4load(videoToDownload);
        } catch (Exception e) {
            // TODO: handle exception 
        } 

        return null; 
    } 

    public void mp4load(String urling) {
        try { 
            System.out.println("Downloading");
            URL url = new URL(urling);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            con.setRequestMethod("GET");
            //c.setDoOutput(true); 
            con.connect();

            // String downloadsPath = Environment.getExternalStoragePublicDirectory(); 
            File SDCardRoot = Environment.getExternalStorageDirectory();

            File outputFile = new File(SDCardRoot, fileName);

            if (!outputFile.exists()) {
                outputFile.createNewFile();
            } 

            FileOutputStream fos = new FileOutputStream(outputFile);

            int status = con.getResponseCode();

            InputStream is = con.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len1);
            } 
            fos.close();
            is.close();
            System.out.println("Downloaded");
        } catch (IOException e) {
            e.printStackTrace();
        } 
    }

---

这是你问题的最佳解决方案

AndroidNetworking.download(url,dirPath,fileName)
                 .setTag("downloadTest")
                 .setPriority(Priority.MEDIUM)
                 .build()
                 .setDownloadProgressListener(new DownloadProgressListener() {
                    @Override
                    public void onProgress(long bytesDownloaded, long totalBytes) {
                      // do anything with progress  
                    }
                 })
                 .startDownload(new DownloadListener() {
                    @Override
                    public void onDownloadComplete() {
                      // do anything after completion
                    }
                    @Override
                    public void onError(ANError error) {
                      // handle error    
                    }
                });

您可以从下面的链接找到这个FastNetworking库

---

你到底改变了什么，这些更改会产生什么影响？我更改以显示需要重写哪些方法来实现这一点，以及需要应用哪些代码/策略。@KoustuvGanguly这本可以在不复制粘贴50行未更改的代码的情况下完成…@KoustuvGanguly我必须对这段代码运行一个diff，才能意识到您所做的一切都是重写方法void onPreExecute和String onPostExecuty，其正文中有注释。@重写受保护的字符串onPostExecute{//此处使进度条不可见}我在这里遇到错误请参考此链接：是的，您的代码正确请检查我的回答如何在异步任务中执行此操作？异步任务有一个方法在POST上执行此方法在隐藏进度栏中并绑定其他数据，然后形成异步taks start，称为showprogress方法

    private ProgressDialog progressDialog; // it create local level of class.
        progressDialog=new ProgressDialog(MainActivity.this); // this line define into onCreateView method.
    private void showProgress(){
    progressDialog.setMessage("Loading");
    progressDialog.show();
}
private void closeProgress(){
    progressDialog.dismiss();
}

 /**
     * Showing Dialog
     * */
    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
        case progress_bar_type: // we set this to 0
            pDialog = new ProgressDialog(this);
            pDialog.setMessage("Downloading file. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setMax(100);
            pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pDialog.setCancelable(true);
            pDialog.show();
            return pDialog;
        default:
            return null;
        }

class DownloadFile1 extends AsyncTask<String, Integer, String> {

    public String videoToDownload;
    public String fileName;

    @Override 
    protected String doInBackground(String... params) {
        int count;

        try { 
            mp4load(videoToDownload);
        } catch (Exception e) {
            // TODO: handle exception 
        } 

        return null; 
    } 

    public void mp4load(String urling) {
        try { 
            System.out.println("Downloading");
            URL url = new URL(urling);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            con.setRequestMethod("GET");
            //c.setDoOutput(true); 
            con.connect();

            // String downloadsPath = Environment.getExternalStoragePublicDirectory(); 
            File SDCardRoot = Environment.getExternalStorageDirectory();

            File outputFile = new File(SDCardRoot, fileName);

            if (!outputFile.exists()) {
                outputFile.createNewFile();
            } 

            FileOutputStream fos = new FileOutputStream(outputFile);

            int status = con.getResponseCode();

            InputStream is = con.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len1);
            } 
            fos.close();
            is.close();
            System.out.println("Downloaded");
        } catch (IOException e) {
            e.printStackTrace();
        } 
    }

/**
         * Updating progress bar
         * */
        protected void onProgressUpdate(String... progress) {
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
       }



/**
         * After completing background task
         * Dismiss the progress dialog
         * **/
        @Override
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);


        }


}

AndroidNetworking.download(url,dirPath,fileName)
                 .setTag("downloadTest")
                 .setPriority(Priority.MEDIUM)
                 .build()
                 .setDownloadProgressListener(new DownloadProgressListener() {
                    @Override
                    public void onProgress(long bytesDownloaded, long totalBytes) {
                      // do anything with progress  
                    }
                 })
                 .startDownload(new DownloadListener() {
                    @Override
                    public void onDownloadComplete() {
                      // do anything after completion
                    }
                    @Override
                    public void onError(ANError error) {
                      // handle error    
                    }
                });