Question

请教一个JAVA Socket问题。我想实现服务器向客户端发送一张图片。但是我这个程序不能实现。什么原因呢？

服务器端：
package TCP;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Transfer2 {
int port = 8080;

void start() {
Socket s = null;
try {
ServerSocket ss = new ServerSocket(port);
while (true) {
// 选择进行传输的文件
String filePath = "F:\\我的军训照片\\sg.jpg";
File fi = new File(filePath);

System.out.println("文件长度:" + (int) fi.length());

// public Socket accept() throws
// IOException侦听并接受到此套接字的连接。此方法在进行连接之前一直阻塞。

s = ss.accept();
System.out.println("建立socket链接");

ObjectOutputStream ps = new ObjectOutputStream(s.getOutputStream());

ps.writeObject(fi);
ps.flush();
// 注意关闭socket链接哦，不然客户端会等待server的数据过来，
// 直到socket超时，导致数据不完整。
ps.close();
s.close();
System.out.println("文件传输完成");
}

} catch (Exception e) {
e.printStackTrace();
}
}

public static void main(String arg[]) {
new Transfer2().start();
}
}
客户端：
package TCP;
import java.net.*;

import java.io.*;

public class Transfer2 implements Runnable {

Socket clientsocket = null;

public static void main(String args[]) {
Thread thread = new Thread(new Transfer3());
thread.start();
}

public void run() {

try {
clientsocket = new Socket("localhost",8080);

System.out.println("连接已建立完毕!");
while(true)
{
InputStream is = clientsocket.getInputStream();
ObjectInputStream inObject = new ObjectInputStream(is);
File file = (File) inObject.readObject();
FileInputStream fis = new FileInputStream(file);

FileOutputStream fos = new FileOutputStream("D:\\sg.jpg");
byte[] buffer = new byte[1];
while (fis.read() != -1)
{
fos.write(buffer);
}
fos.flush();//可有可无
fis.close();
fos.close();
}

} catch (Exception e) {
System.out.println(e);
}

}

}

Answer 1

呵呵，这是第二次给你回答问题了。帮你把代码重构了，你自己体会下吧。你对线程，流的概念理解有点乱。
服务端：
package tcp;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Transfer_Server extends Thread {
int port = 8080;

public void run() {
Socket s = null;
try {
ServerSocket ss = new ServerSocket(port);
while (true) {
s = ss.accept();

String filePath = "D:\\1.JPG";
File fi = new File(filePath);

System.out.println("文件长度:" + (int) fi.length());

System.out.println("建立socket链接");

ObjectOutputStream ps = new ObjectOutputStream(s
.getOutputStream());

ps.writeObject(fi);
ps.flush();

ps.close();
s.close();
System.out.println("文件传输完成");
}

} catch (Exception e) {
e.printStackTrace();
}
}

public static void main(String arg[]) {
new Transfer_Server().start();
}
}
客户端：
package tcp;

import java.net.*;
import java.io.*;

public class Transfer_Client implements Runnable {

Socket clientsocket = null;

public static void main(String args[]) {
Thread thread = new Thread(new Transfer_Client());
thread.start();
}

public void run() {

try {
clientsocket = new Socket("localhost", 8080);

System.out.println("连接已建立完毕!");
//while (true) {此处代码不能这么写。你对Socket客户端的理解不太妥。
InputStream is = clientsocket.getInputStream();
ObjectInputStream inObject = new ObjectInputStream(is);
File file = (File) inObject.readObject();
FileInputStream fis = new FileInputStream(file);

FileOutputStream fos = new FileOutputStream("D:\\sg.jpg");
byte[] buffer = new byte[1];
while (fis.read(buffer) != -1) {
fos.write(buffer);
}
fos.flush();// 可有可无
fis.close();
fos.close();
//}

} catch (Exception e) {
System.out.println(e);
}

}

}

追问

非常感谢你帮了我两次忙!不胜感激啊！

Answer 2

服务器不能发送给客户端。但你可以会送给客户端，就是用输出流来使用

Answer 3

先运行客户端，再运行服务器，这样行吗？