我需要你的帮助来解决我遇到的两个错误
- 创建一个线程，我正在创建一个文件
- 在文件内容之后，执行 AsyncTask 以将文件发送到服务器（multipart/form-data）
这就是第一部分的样子：
public void startResultTransfer(final int timestamp, final int duration, final String correction, final float textSize, final int age, final int switch_count, final Activity activity){
synchronized(DataTransmission.class){
new Thread() {
public void run() {
FileWriter fw = null;
//1.Check if file exists
File file = new File(FILE_PATH);
if(!file.exists()){
//File does not exists, when we have to generate the head-line
try {
fw = new FileWriter(FILE_PATH);
fw.append("timestamp\tduration\tcorrection\ttext_size\tage\tswitch_count"); //Headline
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//2. Write Result
try {
if(fw == null)
fw = new FileWriter(FILE_PATH);
fw.append("\n"+String.valueOf(timestamp)+"\t");
fw.append(""+String.valueOf(duration)+"\t");
fw.append(""+correction+"\t");
fw.append(""+String.valueOf(textSize)+"\t");
fw.append(""+String.valueOf(age)+"\t");
fw.append(""+String.valueOf(switch_count)+"\t");
fw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//3. File Transfer
if(isOnline(activity))
transferFileToServer(activity);
}
}.start();
}
}
函数“transferFileToServer”如下所示：
public synchronized void transferFileToServer(Activity activity){
String id = id(activity);
File file = new File(FILE_PATH);
if(id != null && file.exists()){
final String url = URL+id;
activity.runOnUiThread(new Runnable() {
@Override
public void run() {
TransmissionTask task = new TransmissionTask();
task.execute(url);
}
});
}
}
现在，我收到带有解释性消息的“ExceptionInInitializerError”
由 java.lang.RuntimeException 导致无法在未调用 Looper.prepare() 的线程内创建处理程序”
在“activity.runOnUiThread”行。
在第一个函数中，我需要在一些预先设置后调用“transferFileToServer”。但是该函数也应该从第一个函数中单独调用。
我是否应该在线程结束时实现一个 MessageHandler 来执行 AsyncTask？ http://developer.android.com/reference/android/os/Looper.html
或者我应该将“transferFileToServer”函数中的“AsyncTask”更改为线程，因为我不做任何 UI 操作？
编辑：从异步任务开始的方法
class TransmissionTask extends AsyncTask<String, Void, String> {
public TransmissionTask() {
}
@Override
protected String doInBackground(String... params) {
synchronized(DataTransmission.class){
try {
HttpURLConnection urlConn;
java.net.URL mUrl = new java.net.URL(params[0]);
urlConn = (HttpURLConnection) mUrl.openConnection();
urlConn.setDoOutput(true);
urlConn.setRequestMethod("POST");
String boundary = "---------------------------14737809831466499882746641449";
String contentType = "multipart/form-data; boundary="+boundary;
urlConn.addRequestProperty("Content-Type", contentType);
DataOutputStream request = new DataOutputStream(urlConn.getOutputStream());
request.writeBytes("\r\n--"+boundary+"\r\n");
request.writeBytes("Content-Disposition: form-data; name=\"userfile\"; filename=\""+FILE_NAME+"\"\r\n");
request.writeBytes("Content-Type: application/octet-stream\r\n\r\n");
File myFile = new File(FILE_PATH);
int size = (int) myFile.length();
byte[] bytes = new byte[size];
try {
BufferedInputStream buf = new BufferedInputStream(new FileInputStream(myFile));
buf.read(bytes, 0, bytes.length);
buf.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
request.write(bytes);
request.writeBytes("\r\n--"+boundary+"--\r\n");
request.flush();
request.close();
InputStream responseStream = new BufferedInputStream(urlConn.getInputStream());
BufferedReader responseStreamReader = new BufferedReader(new InputStreamReader(responseStream));
String line = "";
StringBuilder stringBuilder = new StringBuilder();
while ((line = responseStreamReader.readLine()) != null)
{
stringBuilder.append(line).append("\n");
}
responseStreamReader.close();
String response = stringBuilder.toString();
responseStream.close();
urlConn.disconnect();
return response;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if(result != null){
if(result.toLowerCase().contains("erfolgreich")){
//If successfull delete File
File file = new File(FILE_PATH);
file.delete();
}
}
}
}