在安卓上保存文件

Question

我正在制作一个 xml 文件并将其保存在我的设备上，代码如下

HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://xx:xx:xx:xx:yy/LoginAndroid.asmx/login");
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        HttpResponse response = httpclient.execute(httppost);
        String responseBody = EntityUtils.toString(response.getEntity());
        //Toast.makeText( getApplicationContext(),"responseBody:   "+responseBody,Toast.LENGTH_SHORT).show();

        //saving the file as a xml
        FileOutputStream fOut = openFileOutput("loginData.xml",MODE_WORLD_READABLE);
        OutputStreamWriter osw = new OutputStreamWriter(fOut);
        osw.write(responseBody);
        osw.flush();
        osw.close();

        //reading the file as xml
        FileInputStream fIn = openFileInput("loginData.xml");
        InputStreamReader isr = new InputStreamReader(fIn);
        char[] inputBuffer = new char[responseBody.length()];
        isr.read(inputBuffer);
        String readString = new String(inputBuffer);

文件正在保存，我也可以读取文件，一切正常，但看看这一行

char[] inputBuffer = new char[responseBody.length()];

它正在计算保存文件时保存的字符串长度。我将文件保存在一个活动中并从另一个活动中读取它，我的应用程序将在本地保存文件一次，因此我无法获取每次返回字符串的长度那么有没有办法动态分配char[] inputBuffer的大小？

Answer 1

您可以在另一个活动中使用以下代码来读取文件。看看BufferedReader 类。

InputStream instream = new FileInputStream("loginData.xml");

// if file the available for reading
if (instream != null) {
  // prepare the file for reading

  InputStreamReader inputreader = new InputStreamReader(instream);
  BufferedReader buffreader = new BufferedReader(inputreader);

  String line;

  // read every line of the file into the line-variable, on line at the time
  while (buffreader.hasNext()) {
     line = buffreader.readLine();
    // do something with the line 

  }

}

编辑：

上面的代码可以正常读取文件，但是如果你只想分配char[] inputBufferdynamicall的大小，那么你可以使用下面的代码。

InputStream is = mContext.openFileInput("loginData.xml");
ByteArrayOutputStream bos = new ByteArrayOutputStream();
byte[] b = new byte[1024];
while ((int bytesRead = is.read(b)) != -1) {
   bos.write(b, 0, bytesRead);
}
byte[] inputBuffer = bos.toByteArray();

现在，根据需要使用 inputBuffer。