Android由于httppost而获取pdf文件

Question

我正在开发一个必须从Web服务下载一些文件的Android应用程序.

目标

我想从网络服务下载PDF文件并在手机上显示.

问题

我是新手使用webservices并且我已经非常清楚如何获取文件并打开它.

这是我迄今为止的代码:

public void downloadFile(String username, String password, String filename) {       
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
    nameValuePairs.add(new BasicNameValuePair("username", username));
    nameValuePairs.add(new BasicNameValuePair("password", password));
    nameValuePairs.add(new BasicNameValuePair("filename", filename));

    String output = httpPost(URL_DESCARGAS, nameValuePairs);
}

private String httpPost(String url, List<NameValuePair> nameValuePairs) {
    /* Create new HttpClient and Post Header */
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost(url);

    try {
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs, HTTP.UTF_8));

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

        /* Get output */            
        return inputStreamToString(response.getEntity().getContent()).toString();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return "";
}

我没有返回响应字符串,但我不知道我该做什么.那么如何显示返回Web服务的pdf？

在另一个活动中,我必须执行相同的操作,但Web服务返回一个.png,我想在imageview或类似的东西中显示它.这是以同样的方式完成的吗？

非常感谢你.我搜索了很长时间,但我没有找到任何东西.

编辑

我发现了url:http://www.androidsnippets.com/download-an-http-file-to-sdcard-with-progress-notification 我使用了它所说的内容,但文件没有创建(我不知道)在sdcard root中看到它.

这是我修改过的代码:

public void downloadFile(String username, String password, String filename) {       
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
    nameValuePairs.add(new BasicNameValuePair("username", username));
    nameValuePairs.add(new BasicNameValuePair("password", password));
    nameValuePairs.add(new BasicNameValuePair("filename", filename));

    HttpResponse response = httpPost(URL_DESCARGAS, nameValuePairs);
    HttpEntity entity = response.getEntity();
    if (entity != null) {
        try {
            InputStream inputStream = entity.getContent();
             //set the path where we want to save the file
            //in this case, going to save it on the root directory of the
            //sd card.
            File SDCardRoot = Environment.getExternalStorageDirectory();
            //create a new file, specifying the path, and the filename
            //which we want to save the file as.
            File file = new File(SDCardRoot, filename);

            //this will be used to write the downloaded data into the file we created
            FileOutputStream fileOutput = new FileOutputStream(file);

            //create a buffer...
            byte[] buffer = new byte[1024];
            int bufferLength = 0; //used to store a temporary size of the buffer

            //now, read through the input buffer and write the contents to the file
            while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
                //add the data in the buffer to the file in the file output stream (the file on the sd card
                fileOutput.write(buffer, 0, bufferLength);
            }
            //close the output stream when done
            fileOutput.close();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

你能帮助我吗？我需要创建该文件并在手机中显示它.

Answer 1

我已经解决了。我忘记在 AndroidManifest.xml 中添加权限。

这是我的代码，它获取 httppost 的输出，在 SD 卡中创建文件并在用户已安装在设备中的 pdf 查看器中打开它：

活动课

public void downloadInvoice(View view) {
    boolean ok = myApplication.downloadFile("pdf");
    if (!ok) {
        //If not ok, show error message
    } else {
        //Open file in pdf viewer that user has in the device
        File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() 
                +"/"+ myApplication.getActualUser().getActualInvoice().getPdf());
        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.fromFile(file));
        intent.setType("application/pdf");
        startActivity(intent);
    }
}

AndroidManifest.xml

...
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
...