在java中,在客户端获取负字节数组长度或大量字节数组长度

在java中,在客户端获取负字节数组长度或大量字节数组长度,java,sockets,Java,Sockets,我正在将图像从服务器传输到客户端。服务器捕获屏幕并将其转换为字节数组,客户端接收字节数组并将其转换回图像。但传输只发生了很少的帧,然后就发生了错误 接收端: while(true) { DataInputStream dis = new DataInputStream(csocket.getInputStream()); int len = dis.readInt(); System.out.println(len); byte data[] = null;

我正在将图像从服务器传输到客户端。服务器捕获屏幕并将其转换为字节数组,客户端接收字节数组并将其转换回图像。但传输只发生了很少的帧,然后就发生了错误

接收端:

while(true) {
    DataInputStream dis = new DataInputStream(csocket.getInputStream());
    int len = dis.readInt();
    System.out.println(len);
    byte data[] = null;
    data = new byte[len];
    dis.read(data);
    ByteArrayInputStream in = new ByteArrayInputStream(data);
    BufferedImage image1=ImageIO.read(in);
    ImageIcon imageIcon= new ImageIcon(image1);
    Image image = imageIcon.getImage();
    image = image.getScaledInstance(cPanel.getWidth(),cPanel.getHeight(),Image.SCALE_FAST);
    //Draw the recieved screenshot
    Graphics graphics = cPanel.getGraphics();
    graphics.drawImage(image, 0, 0, cPanel.getWidth(),cPanel.getHeight(),cPanel);
}
发送方:

while(continueLoop) {
    try {
        BufferedImage image = robot.createScreenCapture(rectangle);
        byte[] imageInByte;
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ImageIO.write(image,"jpg", baos);
        baos.flush();
        imageInByte = baos.toByteArray();
        baos.close();
        DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
        //PrintWriter out = new PrintWriter(socket.getOutputStream());

        //out.flush();
        dos.writeInt(imageInByte.length);
        System.out.println(imageInByte.length);
        dos.write(imageInByte);
        Thread.sleep(1000);
        dos.flush();
    }
    catch(Exception e) {
    }
}
接收机输出:

 1177222283
 -297418067
 1228900861
 -412483840
 189486847
 10536391
 -33405441
 12898815
 740182
 -16736067
 -805436987 
 -16726825
 258150991
 2137853087
 1917408603
 512024791 
 -1227886373
 -1034512766
 1772271848
 157387
 Exception in thread "Thread-3" java.lang.NullPointerException
 at javax.swing.ImageIcon.<init>(ImageIcon.java:228)
 at remoteclient.ClientScreenReciever.run(ClientScreenReciever.java:65)                                                                                                                                            
117722283
-297418067
1228900861
-412483840
189486847
10536391
-33405441
12898815
740182
-16736067
-805436987 
-16726825
258150991
2137853087
1917408603
512024791
-1227886373
-1034512766
1772271848
157387
线程“thread-3”java.lang.NullPointerException中的异常
位于javax.swing.ImageIcon.(ImageIcon.java:228)
在remoteclient.clientScreenReceiver.run(clientScreenReceiver.java:65)
请帮助我..如何在java中以更快的方式通过套接字将图像从服务器连续传输到客户端。

您正在使用

DataInputStream#read(byte[])
这(检查它的Javadoc)并不能保证读取完整数组的数据。此方法用于缓冲读取,而不是完全读取请求的字节量

相反,你必须打电话

DataInputStream#readFully(byte[])
它有一个适合您目的的合同(再次检查Javadoc)