我是java的新手，我做了一个聊天应用程序，客户端和服务器可以通过它发送和接收消息，现在我试图从客户端发送文件到服务器，但是服务器，客户端和服务器接收到文件之后无法发送消息，以下是代码：
客户端：
import java.io.*;
import java.net.*;
import javax.swing.JFileChooser;
public class ClientFrame extends javax.swing.JFrame {
static Socket s;
static DataOutputStream dos1;
static DataInputStream dis;
static javax.swing.JTextArea jT;
static JFileChooser fc = new JFileChooser();
File file;
public ClientFrame() {
initComponents();
jT = jTextArea1;
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
//send message
try {
String str1 = jTextField1.getText();
String o = jT.getText() + "\n" + " Client ->" + str1;
jT.setText(o);
dos1.writeUTF(str1);
} catch (Exception ex) {
}
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
//open file chooser
fc.showOpenDialog(this);
file = fc.getSelectedFile();
jTextField3.setText(file.getAbsolutePath());
}
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
//send file
try {
String st = jT.getText() + "\n" + " Client -> " + "Sending a file";
jT.setText(st);
String str1 = "Client Sending a file,Press 'REC File' ";
String st1 = "\n" + " Client ->" + str1;
dos1.writeUTF(st1);
} catch (Exception e) {
}
long length = file.length();
byte[] bytes = new byte[65536];//65536 is max, i think
InputStream in;
try {
in = new FileInputStream(file);
OutputStream out = s.getOutputStream();
int count;
while ((count = in.read(bytes)) > 0) {
out.write(bytes, 0, count);
}
out.close();
in.close();
s_r_m();
} catch (Exception ex) {
}
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new ClientFrame().setVisible(true);
}
});
try {
s = new Socket("localhost", 3000);
} catch (Exception e) {
}
s_r_m();
}
public static void s_r_m() {
System.out.println("call srm");
try {
dis = new DataInputStream(s.getInputStream());
dos1 = new DataOutputStream(s.getOutputStream());
while (true) {
String str = (String) dis.readUTF();
String out = jT.getText() + "\n" + " Server ->" + str;
jT.setText(out);
}
} catch (Exception ex) {
}
}
}
服务器端：
import java.io.*;
import java.net.*;
import javax.swing.JFileChooser;
public class ServerFrame extends javax.swing.JFrame {
static ServerSocket ss;
static Socket s;
static DataInputStream dis;
static DataOutputStream dos1;
static javax.swing.JTextArea jT;
static JFileChooser fc = new JFileChooser();
File file;
public ServerFrame() {
initComponents();
jT = jTextArea1;
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
//send message
try {
String str1 = jTextField1.getText();
String out = jT.getText() + "\n" + " Server ->" + str1;
jT.setText(out);
dos1.writeUTF(str1);
} catch (Exception ex) {
}
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
//open file chooser
fc.showOpenDialog(this);
file = fc.getSelectedFile();
jTextField3.setText(file.getAbsolutePath());
}
private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
//rec file
InputStream in = null;
OutputStream out = null;
try {
in = s.getInputStream();
out = new FileOutputStream("F:\\yoMama.exe");
int count;
byte[] buffer = new byte[65536];
while ((count = in.read(buffer)) > 0) {
out.write(buffer, 0, count);
}
String o = jT.getText() + "\n" + " Client ->" + " File received";
jT.setText(o);
out.close();
in.close();
s_r_m();
} catch (Exception ex) {
}
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new ServerFrame().setVisible(true);
}
});
try {
ss = new ServerSocket(3000);
s = ss.accept();//will accept connection from client,waiting state untill client connects
s_r_m();
} catch (Exception e) {
}
}
public static void s_r_m() {
System.out.println("call srm");
try {
dis = new DataInputStream(s.getInputStream());
dos1 = new DataOutputStream(s.getOutputStream());
while (true) {
String str = dis.readUTF();
String out = jT.getText() + "\n" + " Client ->" + str;
jT.setText(out);
}
} catch (Exception ex) {
}
}
}
答案 0 :(得分：1)
问题出在s_r_m()函数中。在while循环中，第一个语句是String str = dis.readUTF();所以此处Client和Server都将等待来自另一方的回复，这将最终以Deadlock结尾。所以他们中的任何一方都无法发送任何数据，直到从另一方收到。
因此您需要相应地更改代码。我已经实现了一个代码来解决这个问题，它从Key-Board(STDIN)输入。
DataInputStream dis=new DataInputStream(sckt.getInputStream());
DataInputStream dis1=new DataInputStream(System.in);
DataOutputStream dos=new DataOutputStream(sckt.getOutputStream());
String str="";
while(true)
{
while(dis.available()>0) //If input is available from the other side.
{
String out = jT.getText() + "\n" + " Client ->" + dis.readUTF();
jT.setText(out);
}
while(dis1.available()>0) //If input is available from STDIN to send it to the other side.
{
str=sc.nextLine();
dos.writeUTF(str);
dos.flush();
}
}
您可以在此处更改从应用程序中的STDIN到Text-Field的输入代码。因此，每当用户按下Send按钮时，它会将消息发送到另一方。