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java - 通过 udp 从服务器向客户端传递双精度值时非法长度或偏移量

问题描述

我有以下情况：有一个客户端，它将一些值传递给服务器，服务器使用这些值进行一些计算，然后将它们传递回客户端。在将数据从服务器传回客户端时出现错误。这是我的做法：

在服务器中：

private void sendBack() {
        String str = String.valueOf(sum1 - sum2);
        System.out.println(str);
        byte[] send = str.getBytes();
        try {
            datagramPacket = new DatagramPacket(send, send.length, InetAddress.getByName("localhost"), 12346);
            socket.send(datagramPacket);
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

在客户端：

datagramPacket = new DatagramPacket(bytes, 18); //18, because it's the length of value which I pass from server
socket.receive(datagramPacket);
resultTf.setText(new String(datagramPacket.getData()));

但在客户端我收到以下错误：

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: illegal length or offset
    at java.base/java.net.DatagramPacket.setData(DatagramPacket.java:267)
    at java.base/java.net.DatagramPacket.<init>(DatagramPacket.java:84)
    at java.base/java.net.DatagramPacket.<init>(DatagramPacket.java:100)
    at com.mikhailovskii.lab2.ui.UdpClientWindow.onCalculateClick(UdpClientWindow.java:96)
    at com.mikhailovskii.lab2.ui.UdpClientWindow.lambda$new$0(UdpClientWindow.java:61)
    at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
    at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
    at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
    at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
    at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279)
    at java.desktop/java.awt.Component.processMouseEvent(Component.java:6632)
    at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
    at java.desktop/java.awt.Component.processEvent(Component.java:6397)
    at java.desktop/java.awt.Container.processEvent(Container.java:2263)
    at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5008)
    at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
    at java.desktop/java.awt.Component.dispatchEvent(Component.java:4840)
    at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918)
    at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547)
    at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488)
    at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
    at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2772)
    at java.desktop/java.awt.Component.dispatchEvent(Component.java:4840)
    at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
    at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
    at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
    at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
    at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
    at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
    at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
    at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

我认为，问题出在这一行：datagramPacket = new DatagramPacket(bytes, 18);，但我不明白这是怎么回事，我该如何解决这个问题。在此先感谢您的帮助！

标签： java

解决方案

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