写了一段服务器端和客户端通信代码，实现以下功能：客户端将文件发送到服务器端，服务器端接收完文件后给客户端发送一个消息。
运行代码后出现以下问题不知如何神马原因：
客户端文件可以正确地传到服务器端，但是服务器端接收完文件后发送给客户端地确认消息，客户端收不到，报java.net.SocketException: Socket is closed的异常，请各位帮忙看看
客户端代码
package client;
import java.io.*;
import java.net.*;
public class ClientThread extends Thread{
private int hostPort=3000;
protected BufferedReader socketReader;
protected PrintWriter socketWriter;
private BufferedReader streamReader;
public ClientThread(){
setUpConnection();
}
public void setUpConnection()
{
try
{
Socket client = new Socket("127.0.0.1", hostPort);
//socketWriter = new PrintWriter(client.getOutputStream());
InputStream inputFromSocket = client.getInputStream();
streamReader = new BufferedReader(
new InputStreamReader(inputFromSocket));
handleConnection(client);
} catch (UnknownHostException e) {
System.out.println("Error setting up socket connection: unknown host");
} catch (IOException e) {
System.out.println("Error setting up socket connection: " + e);
}
}
public void handleConnection(Socket client) {
try {
File file=new File("a.txt");
FileReader fileReader = new FileReader(new File("a.txt"));
BufferedReader bufferedFileReader = new BufferedReader(fileReader);
PrintWriter streamWriter = new PrintWriter(
client.getOutputStream());
String line = null;
while ((line = bufferedFileReader.readLine()) != null) {
streamWriter.println(line);
}
fileReader.close();
streamWriter.close();
//////读取服务器收到文件后的返回内容
String str=streamReader.readLine();
while(str!=null){
System.out.println(str);
}
} catch (Exception e) {
System.out.println("Error handling a client: " + e);
}
}
}
服务器端代码
import java.net.*;
import java.io.*;
public class ServerThread extends Thread{
private int listenPort = 3000;
public ServerThread(){
acceptConnections();
}
public void acceptConnections() {
try {
ServerSocket server = new ServerSocket(listenPort);
Socket incomingConnection = null;
while (true) {
incomingConnection = server.accept();
handleConnection(incomingConnection);
}
} catch (BindException e) {
System.out.println("Unable to bind to port " + listenPort);
} catch (IOException e) {
System.out.println("Unable to instantiate a ServerSocket on port: "
+ listenPort);
}
}
public void handleConnection(Socket incomingConnection) {
try {
BufferedReader socketReader = new BufferedReader(
new InputStreamReader(incomingConnection.getInputStream()));
String line = null;
while ((line = socketReader.readLine()) != null) {
//streamWriter.println(line);
System.out.println(line);
}
socketReader.close();
/////////接受完服务器发送的文件后给客户端
OutputStream os=incomingConnection.getOutputStream();
os.write("".getBytes());
} catch (Exception e) {
System.out.println("Error handling a client: " + e);
}
}
}
给你修改了一下，可以正常运行：
[code="java"]
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.BindException;
import java.net.ServerSocket;
import java.net.Socket;
public class ServerThread extends Thread {
private int listenPort = 30000;
public ServerThread() {
acceptConnections();
}
public void acceptConnections() {
try {
ServerSocket server = new ServerSocket(listenPort);
Socket incomingConnection = null;
int i=1;
while (true) {
System.out.println("i= " + (i++));
incomingConnection = server.accept();
handleConnection(incomingConnection);
}
} catch (BindException e) {
System.out.println("Unable to bind to port " + listenPort);
e.printStackTrace();
} catch (IOException e) {
System.out.println("Unable to instantiate a ServerSocket on port: "
+ listenPort);
}
}
public void handleConnection(Socket incomingConnection) {
try {
BufferedReader socketReader = new BufferedReader(
new InputStreamReader(incomingConnection.getInputStream()));
String line = null;
while (!(line = socketReader.readLine()).equals("xxx")) {
// streamWriter.println(line);
System.out.println(line);
}
// socketReader.close();
// ///////接受完服务器发送的文件后给客户端
OutputStream os = incomingConnection.getOutputStream();
os.write("message arrivered\n".getBytes());
os.write("\n".getBytes());
os.flush();
System.out.println("handleConnection() is over");
} catch (Exception e) {
System.out.println("Error handling a client: " + e);
}
}
public static void main(String[] args) {
new ServerThread().start();
}
}
[/code]
[code="java"]
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
public class ClientThread extends Thread{
private int hostPort = 30000;
protected BufferedReader socketReader;
protected PrintWriter socketWriter;
private BufferedReader streamReader;
public ClientThread() {
setUpConnection();
}
public void setUpConnection() {
try {
Socket client = new Socket("127.0.0.1", hostPort);
// socketWriter = new PrintWriter(client.getOutputStream());
InputStream inputFromSocket = client.getInputStream();
streamReader = new BufferedReader(new InputStreamReader(
inputFromSocket));
handleConnection(client);
} catch (UnknownHostException e) {
System.out
.println("Error setting up socket connection: unknown host");
} catch (IOException e) {
System.out.println("Error setting up socket connection: " + e);
}
}
public void handleConnection(Socket client) {
try {
File file = new File("src/test.txt");
FileReader fileReader = new FileReader(file);
BufferedReader bufferedFileReader = new BufferedReader(fileReader);
PrintWriter streamWriter = new PrintWriter(client.getOutputStream());
String line = null;
while ((line = bufferedFileReader.readLine()) != null) {
streamWriter.println(line);
}
streamWriter.println("xxx");
streamWriter.flush();
fileReader.close();
// 此处不能断，否则就断开了与服务器的 socket 连接
// streamWriter.close();
// ////读取服务器收到文件后的返回内容
String str;
while ((str = streamReader.readLine()) != null && !str.equals("")) {
System.out.println(str);
}
System.out.println("client thread is over");
} catch (Exception e) {
System.out.println("Error handling a client: " + e);
e.printStackTrace();
}
}
public static void main(String[] args) {
new ClientThread().start();
}
}
[/code]
[quote]java.net.SocketException: Socket is closed[/quote]
是哪一行报的错啊？
初步推测：
[quote]
//////读取服务器收到文件后的返回内容
String str=streamReader.readLine();
while(str!=null){
System.out.println(str);
}
[/quote]
这个操作在服务器返回有效结果前已经被执行过，导致客户端的 Thread 的线程执行完毕，从而断开发与服务器的连接（从而可能导致服务器还没有把文件接收结束就已经报了这个异常）。你可以在上面的操作之前加个
[code="java"]
Thread.sleep(2000);
[/code]
来模拟一下服务器返回结果的延迟效果，看看还能不能收到结果
那把
Thread.sleep(2000);
的时间设置成更大一点。
另外，你的 客户端 与 服务端 是分开启动的吧？
[quote]streamWriter.close();[/quote]
关键是你上面这句代码的问题，通过源码可以看出
[code="java"]
public void close() {
try {
synchronized (lock) {
if (out == null)
return;
out.close();
out = null;
}
}
catch (IOException x) {
trouble = true;
}
}
[/code]
会把 out 关闭且置为 null，那么 out 是什么呢？
[quote]PrintWriter streamWriter = new PrintWriter(client.getOutputStream());[/quote]
上面是你的代码。去看一下 PrintWriter 的源码便知：
[code="java"]
public PrintWriter(OutputStream out) {
this(out, false);
}
[/code]
[code="java"]
public PrintWriter(OutputStream out, boolean autoFlush) {
this(new BufferedWriter(new OutputStreamWriter(out)), autoFlush);
// save print stream for error propagation
if (out instanceof java.io.PrintStream) {
psOut = (PrintStream) out;
}
}
[/code]
[code="java"]
public PrintWriter(Writer out,
boolean autoFlush) {
super(out);
this.out = out;
this.autoFlush = autoFlush;
lineSeparator = (String) java.security.AccessController.doPrivileged(
new sun.security.action.GetPropertyAction("line.separator"));
}
[/code]
可见，这个 out 就是你通过 socket 得到的 getOutputStream，那么怎么才能将这个 getOutputStream 关闭呢，当然就是断开这个 socket 啦，所以，你会一直得到这个异常
另外判断一个文件是否读完，不能通过是否读取到了 null 来判断，而是应该使用特地的结束符来判断