clientform.java

J2ME程序设计实例教程的源码

import javax.microedition.lcdui.*;
import javax.microedition.io.*;
import java.io.*;

/**
 * 客户模式显示界面，为用户提供了连接到服务器的功能。
 */
public class ClientForm extends Form implements CommandListener, ItemStateListener {
    private QQMIDlet midlet;
    private TextField tfHost;
    private Command cmdBack = new Command("返回", Command.BACK, 1);
    private Command cmdConnect = new Command("连接", Command.SCREEN, 2);
    
    public ClientForm(String title, QQMIDlet midlet) {
        super(title);
        this.midlet = midlet;
        tfHost = new TextField("请输入服务器的地址：", "", 30, TextField.ANY);
        append(tfHost);
        addCommand(cmdBack);
        setCommandListener(this);
        setItemStateListener(this);
    }
    
    public void commandAction(Command cmd, Displayable d) {
        if(cmd == cmdBack) {    //返回到QQ启动模式列表
            midlet.backToModeList();
        }
        else if(cmd == cmdConnect) {    //连接到服务器
            //为了避免网络连接阻塞用户界面，连接服务器的过程在线程中完成。
            //创建并启动网络连接线程
            Thread t = new Thread(new Runnable() {
                public void run() {
                    try {
                        String hostAddr = "socket://" + tfHost.getString() + ":2000";
                        //创建客户端的套接字连接对象
                        SocketConnection sc = (SocketConnection)Connector.open(hostAddr);
                        
                        //创建并显示聊天交互界面
                        QQForm qqForm = new QQForm("客户端", sc, midlet);
                        Display.getDisplay(midlet).setCurrent(qqForm);
                    }
                    catch(IOException ioe) {
                        midlet.showError("连接服务器：\"" + tfHost.getString() + 
                                            "\"错误！\n" + ioe.toString());
                    }
                }
            });
            t.start();
        }
    }
    
    //
    public void itemStateChanged(Item item) {
        if(item == tfHost) {
            if(tfHost.getString().trim().equals("")) {
                removeCommand(cmdConnect);
            }
            else {
                addCommand(cmdConnect);
            }
        }
    }
}