mainui.java

基于手机蓝牙的即时通讯平台

import java.util.Date;
import java.util.Vector;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.CustomItem;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;

public class MainUI extends Form implements CommandListener,DeviceConnection.EventHandler {
	//通过继承列表类构造文本域用作公共聊天板
	class MessageArea extends CustomItem {
		private int inHeight;

		protected MessageArea(String label, int inHeight) {
			super(label);
			if (inHeight > MainUI.this.getHeight())
				this.inHeight = MainUI.this.getHeight() / 4;
			else
				this.inHeight = inHeight;
		}

		protected int getMinContentWidth() {
			return MainUI.this.getWidth();
		}

		protected int getMinContentHeight() {
			return MainUI.this.getHeight() - inHeight;
		}

		protected int getPrefContentWidth(int arg0) {
			return getMinContentWidth();
		}

		protected int getPrefContentHeight(int arg0) {
			return getMinContentHeight();
		}

		protected void paint(Graphics g, int w, int h) {

			g.setColor(0xFFFFA0); // 背景颜色
			g.fillRect(0, 0, w, h);

			Font f = Font.getDefaultFont();
			g.setColor(0); // 字体颜色
			g.setFont(f);

			synchronized (messages) {
				int rowsLeft = getMinimumHeight() / f.getHeight();
				if ((getMinimumHeight() % f.getHeight()) > 0)
					rowsLeft--;
				for (int msgIdx = messages.size() - 1; rowsLeft >= 0&& msgIdx >= 0; msgIdx--) 
				{
					rowsLeft -= drawMessage(g, f, messages.elementAt(msgIdx).toString(), rowsLeft);
				}
			}

		}
		
		//画聊天区
		private int drawMessage(Graphics g, Font f, String msg, int rowsLeft) {
			int maxWidth = MainUI.this.getWidth();
			int begin = 0, end = 0;
			int rows = getApproximationOfRowCount(f, msg);
			for (int rowIdx = 0; rowIdx < rows; rowIdx++) {
				for (; end <= msg.length()&& f.substringWidth(msg, begin, end - begin) < maxWidth; end++)
				{
				}
				end--;
				g.drawSubstring(msg, begin, end - begin, 0,
						(rowsLeft - rows + rowIdx) * f.getHeight(),
						Graphics.TOP | Graphics.LEFT);
				begin = end;
			}
			return rows;
		}
		
		private int getApproximationOfRowCount(Font f, String msg) {
			int maxWidth = MainUI.this.getWidth();
			int strWidth = f.stringWidth(msg);
			int rows = strWidth / maxWidth;
			if ((strWidth % maxWidth) > 0)
				rows++;
			return rows;
		}

		public void refresh() {
			repaint();
		}
	}

	class Message {
		Date date;
		String userName;
		String msg;

		Message(String userName, String msg) {
			this.date = new Date();
			this.userName = userName;
			this.msg = msg;
		}

		public String toString() {
			if (userName == null)
				return msg;

			StringBuffer buf = new StringBuffer();
			buf.append(userName);
			buf.append(": ");
			buf.append(msg);
			return buf.toString();
		}
	}

	private MIDlet midlet;
	private Vector messages = new Vector();
	private DeviceConnection protocol;
	private TextField field;
	private MessageArea messageArea;
	private Command send = new Command("发送消息", Command.SCREEN, 1);
	//private Command log = new Command("日志", Command.SCREEN, 2);

	public MainUI(MIDlet m) {
		super("聊天室");
		this.midlet = m;

		field = new TextField("信息发送栏:", "", 128, TextField.ANY);
		messageArea = new MessageArea("信息接收区:", field.getMinimumHeight());

		append(messageArea);
		append(field);

		addCommand(send);
		//addCommand(log);

		setCommandListener(this);
	}

	public void chatMessage(String userName, String msg) {
		messages.addElement(new Message(userName, msg));
		messageArea.refresh();
	}

	public void chatLeave(String userName) {
		messages.addElement(new Message(null, userName + " 已经离开"));
		messageArea.refresh();
	}

	public void chatEnter(String userName) {
		messages.addElement(new Message(null, userName + " 已经加入"));
		messageArea.refresh();
	}

	public void setCurrent() {
		Display.getDisplay(midlet).setCurrent(this);
		messageArea.refresh();
	}

	public void setProtocol(DeviceConnection protocol) {
		this.protocol = protocol;
	}

	public void commandAction(Command cmd, Displayable d) {
		if (cmd == send) {
			protocol.broadcastMessage(field.getString());
			field.setString("");
		} /*else if (cmd == log) {
			Log.setCurrent(midlet);
		}*/

	}

}