【发布时间】：2014-01-07 07:06:20
【问题描述】：
我正在将 pdf 文件从 android 平板电脑客户端发送到在 Windows 7 上运行的 Java 应用程序。该文件始终以零字节大小到达。这里有什么问题？
在客户端向服务器发送pdf文件之前，客户端向服务器发送的文件大小为long值，这个大小是正确的并且总是到达服务器。对于 pdf 文件，我用于此测试的大小为 566718 字节。
如何让 pdf 文件以正确的大小到达？
服务器代码
public class Server {
ServerSocket serverSocket;
Socket socket;
boolean runner = true;
Server() throws IOException{
serverRunner();
System.out.println("server constructor started");
} // Server() constructor
public void serverRunner() throws IOException {
System.out.println("serverrunner started");
try {
serverSocket = new ServerSocket(6789, 100);
runner = true;
while (runner) {
socket = serverSocket.accept();
MultiThreader multi = new MultiThreader(socket);
Thread t = new Thread(multi);
t.start();
} // while runner
} catch (IOException ex) {
}
} // serverRunner()
} // class Server
public class MultiThreader implements Runnable {
Socket socket;
public int fileSizeFromClient;
FileOutputStream fos = null;
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
DataInputStream dis = null;
DataOutputStream dos = null;
public MultiThreader(Socket socket){
System.out.println("print out from multithreader class");
this.socket = socket;
} // multiThreader
@Override
public void run() {
System.out.println("multi threader started");
// action #1 read file from client =====================================
// transfer.pdf read this file sent from android device to this computer
int bufferSize = 0;
try {
bis = new BufferedInputStream(socket.getInputStream());
dis = new DataInputStream(bis);
fileSizeFromClient = dis.readInt();
System.out.println("file size from client is " + fileSizeFromClient);
File fileDirectory = new File("C:/DOWNLOAD/");
if (!fileDirectory.exists()) {
fileDirectory.mkdir();
}
File file = new File("C:/DOWNLOAD/transfer.pdf");
file.createNewFile();
fos = new FileOutputStream(file);
bos = new BufferedOutputStream(fos);
dos = new DataOutputStream(bos);
byte[] buffer = new byte[fileSizeFromClient];
int totalBytesRead = 0;
while(totalBytesRead < fileSizeFromClient){
int bytesRemaining = fileSizeFromClient = totalBytesRead;
int bytesRead = dis.read(buffer, 0, (int) Math.min(buffer.length, bytesRemaining));
if(bytesRead == -1) {
break;
} else {
dos.write(buffer, 0, bytesRead);
totalBytesRead += bytesRead;
}
} // while
} catch (IOException ex) {
Logger.getLogger(MultiThreader.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
// socket.close();
} catch (IOException ex) {
Logger.getLogger(MultiThreader.class.getName()).log(Level.SEVERE, null, ex);
}
}
} // run
} // MultiThreader
客户端代码
public class MainActivity extends Activity implements Runnable {
TextView textViewOne;
Button buttonOne;
Socket socket;
private String serverIP = "192.XXX.X.X";
FileInputStream fis;
FileOutputStream fos;
private File file;
DataInputStream dis;
DataOutputStream dos;
BufferedInputStream bis;
BufferedOutputStream bos;
long length;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textViewOne = (TextView) findViewById(R.id.textView1);
buttonOne = (Button) findViewById(R.id.button1);
buttonOne.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Thread myThread = new Thread(MainActivity.this);
myThread.start();
}
});
} // oncreate
@Override
public void run() {
MainActivity.this.runOnUiThread(new Runnable(){
@Override
public void run() {
textViewOne.setText("run method started");
}
});
try {
socket = new Socket(InetAddress.getByName(serverIP), 6789);
if (socket == null) {
return;
} else {
MainActivity.this.runOnUiThread(new Runnable(){
@Override
public void run() {
textViewOne.setText("connected");
}
});
}
file = new File(Environment.getExternalStorageDirectory().getPath() + File.separator + "transfer.pdf");
length = file.length();
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
dis = new DataInputStream(bis);
bos = new BufferedOutputStream(socket.getOutputStream());
dos = new DataOutputStream(bos);
dos.writeInt((int) length); // sends the length as number bytes is file size
int count = 0;
byte[] buffer = new byte[(int) length];
while ((count = bis.read(buffer)) > 0)
{
bos.write(buffer, 0, count);
}
bos.flush();
bis.close();
socket.close();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} // mainactivity
【问题讨论】：
-
是否记录了任何异常？为什么不关闭服务器上的输出流？您是否尝试过在复制循环中添加诊断信息？
-
你不需要调用 createNewFile()，但是你需要关闭你的输出流。