这是我在android上传文件的代码。
HttpURLConnection conn = null;
DataOutputStream dos = null;
DataInputStream inStream = null;
String existingFileName = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Bluetooth/my.txt";
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
int bytesRead, bytesAvailable, bufferSize;
byte[] buffer;
int maxBufferSize = 1 * 1024 * 1024;
String responseFromServer = "";
String urlString ="http://172.20.56.36:8084/AndroidTesting/UploadServlet.java";
try {
FileInputStream fileInputStream = new FileInputStream(new File(existingFileName));
URL url = new URL(urlString);
conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
dos = new DataOutputStream(conn.getOutputStream());
dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\"" + existingFileName + "\"" + lineEnd);
dos.writeBytes(lineEnd);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// read file and write it into form...
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
while (bytesRead > 0) {
dos.write(buffer, 0, bufferSize);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
}
// send multipart form data necesssary after file data...
dos.writeBytes(lineEnd);
dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
// close streams
Log.e("Debug", "File is written");
fileInputStream.close();
dos.flush();
dos.close();
} catch(Exception e){
Toast.makeText(getApplicationContext(),e.getMessage()+"error",Toast.LENGTH_SHORT).show();
}
//------------------ read the SERVER RESPONSE
try {
inStream = new DataInputStream(conn.getInputStream());
String str;
while ((str = inStream.readLine()) != null) {
Toast.makeText(getApplicationContext(),str,Toast.LENGTH_SHORT).show();
}
inStream.close();
} catch (Exception ioex) {
Toast.makeText(getApplicationContext(),ioex.getMessage()+"error",Toast.LENGTH_SHORT).show();
}
}
所以当我运行这个应用程序时它会崩溃然后我把try catch块，然后我得到一个null错误，我认为它在这一行
dos = new DataOutputStream(conn.getOutputStream());
logcat报告
06-23 12:02:50.159: D/AndroidRuntime(5832): Shutting down VM
06-23 12:02:50.169: W/dalvikvm(5832): threadid=1: thread exiting with uncaught exception (group=0x40c1aa68)
06-23 12:02:50.169: E/AndroidRuntime(5832): FATAL EXCEPTION: main
06-23 12:02:50.169: E/AndroidRuntime(5832): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.e.testing/com.e.testing.MainActivity}: android.os.NetworkOnMainThreadException
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1970)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.ActivityThread.access$600(ActivityThread.java:128)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.os.Handler.dispatchMessage(Handler.java:99)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.os.Looper.loop(Looper.java:137)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.ActivityThread.main(ActivityThread.java:4517)
06-23 12:02:50.169: E/AndroidRuntime(5832): at java.lang.reflect.Method.invokeNative(Native Method)
06-23 12:02:50.169: E/AndroidRuntime(5832): at java.lang.reflect.Method.invoke(Method.java:511)
06-23 12:02:50.169: E/AndroidRuntime(5832): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
06-23 12:02:50.169: E/AndroidRuntime(5832): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
06-23 12:02:50.169: E/AndroidRuntime(5832): at dalvik.system.NativeStart.main(Native Method)
06-23 12:02:50.169: E/AndroidRuntime(5832): Caused by: android.os.NetworkOnMainThreadException
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.io.IoBridge.connect(IoBridge.java:112)
06-23 12:02:50.169: E/AndroidRuntime(5832): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
06-23 12:02:50.169: E/AndroidRuntime(5832): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
06-23 12:02:50.169: E/AndroidRuntime(5832): at java.net.Socket.connect(Socket.java:848)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:77)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpConnection. <init>(HttpConnection.java:50)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:80)
06-23 12:02:50.169: E/AndroidRuntime(5832): at libcore.net.http.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:188)
06-23 12:02:50.169: E/AndroidRuntime(5832): at com.e.testing.MainActivity.onCreate(MainActivity.java:80)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.Activity.performCreate(Activity.java:4470)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1053)
06-23 12:02:50.169: E/AndroidRuntime(5832): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1934)
06-23 12:02:50.169: E/AndroidRuntime(5832): ... 11 more
出现此错误
06-23 12:02:50.169: E/AndroidRuntime(5832): at com.e.testing.MainActivity.onCreate(MainActivity.java:80)
和MainActivity的第80行是
dos = new DataOutputStream(conn.getOutputStream());
答案 0 :(得分：1)
Caused by: android.os.NetworkOnMainThreadException
您正尝试在主线程上执行网络任务，这是不允许的，请尝试使用AsyncTask
答案 1 :(得分：0)
您应该在AsyncTask或单独的线程中运行此函数。
答案 2 :(得分：0)
您的代码尝试在主线程上执行网络任务。网络任务需要一些时间来请求和响应。所以你必须使用AysncTask。
http://developer.android.com/reference/android/os/AsyncTask.html
更新您的代码： - （下方）
class MyTask extends AsyncTask<Void, Void, Void> {
protected RSSFeed doInBackground(String... urls) {
HttpURLConnection conn = null;
DataOutputStream dos = null;
DataInputStream inStream = null;
String existingFileName = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Bluetooth/my.txt";
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
int bytesRead, bytesAvailable, bufferSize;
byte[] buffer;
int maxBufferSize = 1 * 1024 * 1024;
String responseFromServer = "";
String urlString ="http://172.20.56.36:8084/AndroidTesting/UploadServlet.java";
try {
FileInputStream fileInputStream = new FileInputStream(new File(existingFileName));
URL url = new URL(urlString);
conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
dos = new DataOutputStream(conn.getOutputStream());
dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\"" + existingFileName + "\"" + lineEnd);
dos.writeBytes(lineEnd);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// read file and write it into form...
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
while (bytesRead > 0) {
dos.write(buffer, 0, bufferSize);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
}
// send multipart form data necesssary after file data...
dos.writeBytes(lineEnd);
dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
// close streams
Log.e("Debug", "File is written");
fileInputStream.close();
dos.flush();
dos.close();
} catch(Exception e){
Toast.makeText(getApplicationContext(),e.getMessage()+"error",Toast.LENGTH_SHORT).show();
}
//------------------ read the SERVER RESPONSE
try {
inStream = new DataInputStream(conn.getInputStream());
String str;
while ((str = inStream.readLine()) != null) {
Toast.makeText(getApplicationContext(),str,Toast.LENGTH_SHORT).show();
}
inStream.close();
} catch (Exception ioex) {
Toast.makeText(getApplicationContext(),ioex.getMessage()+"error",Toast.LENGTH_SHORT).show();
}
}
protected void onPostExecute(Void feed) {
}
}