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
我是使用网络服务的新手，我不太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 "";
}
我不必返回响应字符串，但我不知道我必须做什么。那么如何显示返回Web服务的pdf呢？
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。它是用同样的方式完成的吗？
非常感谢。我已经搜索了很长时间，但我没有找到任何东西。
编辑
我找到了那个网址：http ://www.androidsnippets.com/download-an-http-file-to-sdcard-with-progress-notification 我使用它所说的，但文件没有创建（我没有在 sdcard 根目录中看不到它）。
这是我修改后的代码：
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？我现在需要创建该文件并将其显示在手机中。