showinfo.java

java网络编程 包含全书所有代码编程以及实例

package showinfo;

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.*;

/**
 * Title:        Applet显示滚动信息
 * Description:  在浏览器页面左上角滚动信息，鼠标移动上去即停止滚动，移开则继续滚动。
 * Copyright:    Copyright (c) 2002
 * Company:      北京师范大学计算机系
 * @author 孙一林
 * @version 1.0
 */

public class ShowInfo extends Applet implements Runnable, MouseListener{
  Thread thread;
  private int y;
  private Image offImg;							// 定义缓冲图象变量
  private Graphics offG;
  boolean pause = false;							// 暂停标志
  private int info_num;							// 定义输入参数个数
  public void init()  {
    setBackground(Color.orange);						// 设置Applet的背景
    addMouseListener(this);						// 增加鼠标监听
    offImg = createImage(getSize().width, getSize().height);	// 创建缓冲图象大小
    offG = offImg.getGraphics();
    y=getSize().height+14;							// 设置初始值为Applet的高度
    try {    									// 取HTML网页中的参数
      info_num = Integer.parseInt(getParameter("info_num"));
    }
    catch(Exception e) {
      showStatus("参数错误!");						// 在IE的状态栏目中显示错误信息
      System.exit(-1);
    }
  }
  public void paint(Graphics g) {
    offG.clearRect(0,0, getSize().width, getSize().height);		// 显示到缓冲区中
    for(int i=1; i<=info_num; i++)        				// 显示信息
      offG.drawString(getParameter("info_"+String.valueOf(i)),10,y+(i*14));
    if(offG!=null) g.drawImage(offImg,0,0,this);
  }
  public void update(Graphics g) {						// 防止画面闪烁
    paint(g);
  }
  public void run() {
    Thread current = Thread.currentThread();
    while (thread == current) {
      try {
        Thread.currentThread().sleep(100);				// 暂时1秒
      }
      catch (InterruptedException e) {}
      repaint();
      if(!pause) y--;
      if(y<0-info_num*14) y=getSize().height+14;
    }
  }
  public void start() {
    thread = new Thread(this);						// 启动线程
    thread.start();
  }
  public void stop() {
    thread = null;								// 停止线程序
    removeMouseListener(this);						// 删除鼠标监听
  }
  public void mouseEntered(MouseEvent e) {				// 鼠标监听
    pause = true;								// 设置暂停
  }
  public void mouseExited(MouseEvent e) {
    pause = false;								// 恢复滚动
  }
  public void mouseReleased(MouseEvent e) {}
  public void mousePressed(MouseEvent e) {}
  public void mouseClicked(MouseEvent e) {y=0;}
  public String getAppletInfo() {
    return "滚动显示信息";
  }
  public String[][] getParameterInfo() {
    String[][] pinfo = {
      {"info_num","int","信息数量"},
      {"info_X","String","信息,X代表1-->info_num"}
    };
    return pinfo;
  }
}