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我正在尝试Socket用 Java 发送图像，但是我得到了NullPointerException. 这是服务器的代码： 

package sendImage;


import java.net.*;
import javax.imageio.*;
import javax.swing.*;
import java.awt.image.BufferedImage;
import java.io.*;

public class Server {
    ServerSocket server;
    Socket client;
//------------------------------------------------------------------------------
    public static void main(String[] args) {
        new Server();
    }
//------------------------------------------------------------------------------
    public Server(){
        connect();
    }
//------------------------------------------------------------------------------
    public void connect(){
        try{
            server = new ServerSocket(9999);
            client = server.accept();

            sendImage();
        }catch(Exception e){
            e.printStackTrace();
        }
    }
//------------------------------------------------------------------------------
    public void sendImage(){
        String image = "C:/Users/JavaChild/Downloads/jo-d-101027-mentalist.jpg";
        try{
            InputStream in = Server.class.getResourceAsStream(image);
            BufferedImage img = ImageIO.read(in);
            JLabel l = new JLabel(new ImageIcon(img));
            JFrame frame = new JFrame("Server");
            frame.add(l);
            frame.setVisible(true);
            ImageIO.write(img, "JPG", client.getOutputStream());
        }catch(Exception e){
            e.printStackTrace();
        }
    }
//------------------------------------------------------------------------------
}

和客户： 

package sendImage;

import java.net.*;
import javax.imageio.*;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

import java.awt.image.BufferedImage;
import java.io.*;


public class Client {
    Socket server;

//------------------------------------------------------------------------------
    public static void main(String[] args) {
        new Client();
    }
//------------------------------------------------------------------------------
    public Client(){
        connect();
    }
//------------------------------------------------------------------------------
    public void connect(){
        try{
            server = new Socket("JavaChild-PC",9999);
            readImage();
        }catch(Exception e){
            e.printStackTrace();
        }
    }
//------------------------------------------------------------------------------
    public void readImage(){
        try{
            BufferedImage img = ImageIO.read(server.getInputStream());
            JLabel label = new JLabel(new ImageIcon(img));
            JFrame frame = new JFrame("Client");
            frame.add(label);
            frame.setVisible(true);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}

请告诉我如何通过套接字正确发送图像
以及导致异常的原因是什么？

堆栈跟踪

java.lang.NullPointerException
    at javax.swing.ImageIcon.<init>(Unknown Source)
    at sendImage.Client.readImage(Client.java:37)
    at sendImage.Client.connect(Client.java:28)
    at sendImage.Client.<init>(Client.java:22)
    at sendImage.Client.main(Client.java:18)
4

0 回答 0