java - Java 中的数据包发送

Question

好吧，我正在尝试将数据包发送到本地游戏服务器，但数据包和连接让我有点困惑。这是我的代码:

public class Packet{
DataOutputStream os;
DataInputStream is;

public void test() throws IOException 
{
    try {
        Socket socket = new Socket("127.0.0.1", 25565);
    } catch (UnknownHostException e) {
    } catch (IOException e) {
    }
    os.writeByte(1);
    os.writeInt(23);
    writeString2("TEST", os);
    os.writeLong(0);
    os.writeShort(0);
    os.writeInt(0);
    os.writeByte(0);
    os.writeByte(0);
    os.writeByte(0);
    os.writeByte(0);        
    Menu.log1.addElement("Testing");
}

但是当我启动它时，我收到此错误:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at Packet.test(Packet.java:29)
    at Menu$2.actionPerformed(Menu.java:309)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6373)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6138)
    at java.awt.Container.processEvent(Container.java:2085)
    at java.awt.Component.dispatchEventImpl(Component.java:4735)
    at java.awt.Container.dispatchEventImpl(Container.java:2143)
    at java.awt.Component.dispatchEvent(Component.java:4565)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4621)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4282)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4212)
    at java.awt.Container.dispatchEventImpl(Container.java:2129)
    at java.awt.Window.dispatchEventImpl(Window.java:2478)
    at java.awt.Component.dispatchEvent(Component.java:4565)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:679)
    at java.awt.EventQueue.access$000(EventQueue.java:85)
    at java.awt.EventQueue$1.run(EventQueue.java:638)
    at java.awt.EventQueue$1.run(EventQueue.java:636)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
    at java.awt.EventQueue$2.run(EventQueue.java:652)
    at java.awt.EventQueue$2.run(EventQueue.java:650)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:649)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)`

有人可以帮我解决他的问题吗，我已经困扰了我一段时间了。

Answer 1

在使用它们之前，您需要实际使 os 和 is 引用指向某些对象:

Socket socket = new Socket("127.0.0.1", 25565);
is = new DataInputStream(socket.getInputStream());
os = new DataOutputStream(socket.getOutputStream());