我一直在尝试使用文件传输功能创建一个Messenger，但最后我仍然有太多的空字符。任何时候我使用文件长度去除它们，由于某种原因，更多的文件被剥离，它只是变得一团糟。我没有使用任何Java 7或更高版本的元素，因为我希望它与Java 6和Windows 98（grandma的PC）兼容。
我也在文件中添加了很多随机空字符，我不知道如何避免这个
这是我的代码： 发送
package com.androdome.lunacoffee.management;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import com.androdome.lunacoffee.ErrorScreen;
import com.androdome.lunacoffee.SendScreen;
public class FileTransmitter implements Runnable{
String adds;
FileInputStream message;
int filecut = 4096;
byte[] fileName;
long fileSize;
SendScreen send;
public FileTransmitter(String address, FileInputStream msg, byte[] fnme, SendScreen snd, long l) {
adds = address;
send = snd;
message = msg;
fileName = fnme;
fileSize = l;
}
public void run()
{
try {
InetAddress add = InetAddress.getByName(adds);
Socket sock = new Socket(add, 11001);
DataOutputStream da = new DataOutputStream(sock.getOutputStream());
PrintWriter output = new PrintWriter(da);
da.write(fileName);
da.writeLong(message.getChannel().size());
byte[] filebuffer = new byte[filecut];
int g = 0;
int back = 0;
while((g = message.read(filebuffer)) != -1)
{
if(g != filecut && g > 0)
{
back = g;
}
da.write(filebuffer);
filebuffer = new byte[filecut];
}
da.writeInt(back);
System.out.print(back);
output.flush();
output.close();
send.incrementSent();
} catch (UnknownHostException e) {
send.incrementError();
// TODO Auto-generated catch block
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
new ErrorScreen("Unable to send file", "Your file was not able to send because the host \"" + adds + "\" was not availible!", sw.toString());
pw.close();
try {
sw.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
} catch (IOException e) {
send.incrementError();
// TODO Auto-generated catch block
new ErrorScreen("Unable to send file", "Your file was not able to send due to a bad output stream!", e.getMessage());
}
}
}
收到：
package com.androdome.lunacoffee.management;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Arrays;
import com.androdome.lunacoffee.ErrorScreen;
import com.androdome.lunacoffee.FileScreen;
import com.androdome.lunacoffee.Main;
public class FileReciever implements Runnable {
int bufferSize = 4096;
int headerSize = 32;
byte[] filebuffer = new byte[bufferSize];
byte[] fileheader = new byte[headerSize];
Main main;
File downloadfile = new File("tmp");
File transferFile = new File("dnl.ldf");
public FileReciever(Main mn)
{
main = mn;
}
static byte[] trim(byte[] bytes)
{
int i = bytes.length - 1;
while (i >= 0 && bytes[i] == 0)
{
--i;
}
return Arrays.copyOf(bytes, i + 1);
}
public void run() {
try {
ServerSocket recieveSocket = new ServerSocket(11001);
while (this != null) {
try{
downloadfile.createNewFile();
Socket connectionSocket = recieveSocket.accept();
DataInputStream reader = new DataInputStream(connectionSocket.getInputStream());
reader.read(fileheader);
long fileSize = reader.readLong();
System.out.println(bufferSize);
filebuffer = new byte[bufferSize];
String fileName = new String(fileheader);
fileheader = new byte[headerSize];
FileOutputStream fw = new FileOutputStream(downloadfile);
while(reader.read(filebuffer) != -1)
{
fw.write(filebuffer);
filebuffer = new byte[bufferSize];
}
//reader.readInt();
reader.close();
fw.close();
//RandomAccessFile file = new RandomAccessFile(downloadfile, "Rwd");
//file.setLength(fileSize); // Strip off the last _byte_, not the last character
//file.close();
connectionSocket.close();
FileScreen fs = new FileScreen(downloadfile, fileName, connectionSocket.getInetAddress().getHostName());
fs.setVisible(true);
fs.setLocationRelativeTo(null);
}
catch(Exception ex)
{}
}
} catch (IOException e) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
new ErrorScreen("Unable to start the File Recieve Thread", "Luna Messenger may already be running, or another program is using port 11001. Please close any program running on port 11001.", sw.toString());
pw.close();
try {
sw.close();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
}
}
答案 0 :(得分：0)
在上面的代码中，我认为它会导致以下错误。 首先，你应该添加一个数字来表示文件名的长度。就像这样：
da.writeInt(fileName.length); //the added code
da.write(fileName);
在FileReciever上，接收代码为：
int fileNameLength = reader.readInt();
fileheader=new byte[fileNameLength];
read(reader,fileheader,0,fileNameLength);
read方法可以读取从输入流到字节数组的长度字节，直到流结束。
public static int read(InputStream in, byte[] b, int off, int len) throws IOException {
if (len < 0) {
throw new IndexOutOfBoundsException("len is negative");
}
int total = 0;
while (total < len) {
int result = in.read(b, off + total, len - total);
if (result == -1) {
break;
}
total += result;
}
return total;
}
第二，FileTransmitter将文件日期转换为FileReciever并不正确，并且不应该在末尾添加数字。适当的方法是将文件数据写入套接字输出流FileTransmitter，并且不做任何其他事情。就像这样：
while((g = message.read(filebuffer)) != -1)
{
da.write(filebuffer,0,g);
}
在另一方面，当你从socket oupustream读取字节到filebuffer时，应该重新加入多少字节取决于你从套接字输入流中提取的字节长度。接收者代码：
int readLength;
int sumLength=0;
while((readLength=reader.read(filebuffer,0,(int)(fileSize-sumLength>filebuffer.length?filebuffer.length:fileSize-sumLength))) != -1){
sumLength+=readLength;
fw.write(filebuffer,0,readLength);
if(sumLength==fileSize){
break;
}
}