随笔-28  评论-51  文章-10  trackbacks-0
以前虽然看了很多书,但是只重理论不重实践,bebeyond说的没错,如果你不把知识内化,那么即使你读的书再多,你的老师水平再高也于事无补,现代社会看能力啊。所以清明也懒得去玩了,静下心,重头再来!!这是第一篇
[java重头再来系列之一]java界面布局,文件操作,线程,事件响应
源码有200多行,若要显示动画(线程)需要5张gif图片,但程序中有一个疑问,用红色高亮显示的update为何不会调用?如果把Animation类独立出来(不继承JPanel,而继承JFrame),那是会首先调用update的啊。。。向高人求助


FocusCrawler.java
  1 package kyle;
  2 
  3 import java.awt.BorderLayout;
  4 import java.awt.Color;
  5 import java.awt.Container;
  6 import java.awt.Dimension;
  7 import java.awt.Graphics;
  8 import java.awt.GridLayout;
  9 import java.awt.Image;
 10 import java.awt.MediaTracker;
 11 import java.awt.Toolkit;
 12 import java.awt.event.ActionEvent;
 13 import java.awt.event.ActionListener;
 14 import java.awt.event.WindowAdapter;
 15 import java.awt.event.WindowEvent;
 16 import java.io.BufferedReader;
 17 import java.io.BufferedWriter;
 18 import java.io.File;
 19 import java.io.FileReader;
 20 import java.io.FileWriter;
 21 import java.io.IOException;
 22 
 23 import javax.swing.JButton;
 24 import javax.swing.JFileChooser;
 25 import javax.swing.JFrame;
 26 import javax.swing.JLabel;
 27 import javax.swing.JPanel;
 28 import javax.swing.JScrollPane;
 29 import javax.swing.JTextArea;
 30 import javax.swing.filechooser.FileFilter;
 31 /*
 32  * 2008.3 fullfocus
 33  * 一个图像界面的文件读取,保存和动画显示
 34  * 主要涉及 界面设计,文件流读取,线程应用,事件响应
 35  */
 36 public class FocusCrawler extends JFrame {
 37 
 38     private static JTextArea jarea;//文本内容显示区
 39     private static JLabel jlbl;//文件名显示区
 40     
 41     public FocusCrawler()
 42     {
 43 
 44         JPanel panelC = new JPanel(); //中心
 45         JPanel panelS = new JPanel();//
 46 
 47 
 48 
 49         
 50         setTitle("文件阅览器");
 51         
 52 
 53         jarea = new JTextArea();
 54         JScrollPane scrollPane = new JScrollPane(jarea);//使文本可以滚动的方法
 55         
 56         jlbl = new JLabel("文件名");
 57         JButton openfile = new JButton("打开");
 58         JButton savefile = new JButton("保存");
 59         
 60         Container cp = getContentPane();
 61         
 62         /*添加顶部图像区*/
 63         Animation ani = new Animation();
 64         ani.setVisible(true);
 65         ani.setPreferredSize(new Dimension(ani.getImageWidth(),ani.getImageHight())); //组件自身的大小优先级弱与layout的优先级,需指定setPreferredSize方可
 66         cp.add(ani,"North");
 67         /*添加中间文本显示区*/
 68         panelC.setLayout(new BorderLayout());
 69         panelC.add(jlbl,"North");   
 70         panelC.add(scrollPane,"Center");
 71         cp.add(panelC,"Center");
 72         /*添加底下按钮*/
 73 
 74          
 75          openfile.addActionListener(new ActionListener()
 76          {
 77 
 78             @Override
 79             public void actionPerformed(ActionEvent arg0) {
 80                 // TODO Auto-generated method stub
 81                 JFileChooser chooser = new JFileChooser();
 82                 TextFilter filter = new TextFilter();
 83                  chooser.setFileFilter(filter);
 84                 int returnVal = chooser.showOpenDialog(null);
 85                  if(returnVal == JFileChooser.APPROVE_OPTION) {
 86                     System.out.println("You chose to open this file: " +
 87                          chooser.getSelectedFile().getName());
 88                     File inputfile = chooser.getSelectedFile();
 89                     //文件名显示在LABEL
 90                     FocusCrawler.jlbl.setText(inputfile.getAbsolutePath());
 91                     
 92                     try {
 93                         String line = null;
 94                         BufferedReader in = 
 95                             new BufferedReader(new FileReader(inputfile));
 96                         while( (line=in.readLine())!= null)
 97                         {
 98                             FocusCrawler.jarea.append(line + "\n");
 99                         }
100                         in.close();
101                     } catch (Exception e) {
102                         // TODO Auto-generated catch block
103                         e.printStackTrace();
104                     }
105                  }
106             }
107              
108          });         
109          savefile.addActionListener(new ActionListener()
110          {
111 
112             @Override
113             public void actionPerformed(ActionEvent arg0) {
114                 // TODO Auto-generated method stub
115                 File f = new File(FocusCrawler.jlbl.getText());
116                 if(f.exists())
117                 {
118                     try {
119                         BufferedWriter bw = new BufferedWriter(new FileWriter(f));
120                         bw.write(FocusCrawler.jarea.getText());
121                         FocusCrawler.jlbl.setText("works is done!!");
122                         bw.close();
123                     } catch (IOException e) {
124                         // TODO Auto-generated catch block
125                         e.printStackTrace();
126                     }
127                     
128                 }
129             }
130              
131          });    
132         
133         
134         
135         panelS.setLayout(new GridLayout(1,2));
136         panelS.add(openfile); 
137         panelS.add(savefile);
138         cp.add(panelS,"South");
139         
140     }
141 
142     /**
143      * @param args
144      */
145     public static void main(String[] args) {
146         // TODO Auto-generated method stub
147         System.out.println("hello world!");
148         JFrame frame = new FocusCrawler();
149         frame.setSize(500,500);
150         frame.addWindowListener(new WindowAdapter(){
151             
152         public void windowClosing(WindowEvent e)
153         {
154             System.exit(0);
155         }
156         });
157         frame.setVisible(true);
158     }
159 
160 }
161 
162 class Animation extends JPanel implements Runnable
163 {
164 
165     int totalNum = 5;
166     int currentNum = 0;
167     int x,x1;
168     int delay = 100;
169     Image images[];
170     Thread animator;
171     
172     public Animation()
173     {
174         images = new Image[totalNum];
175         Toolkit defaultTk = Toolkit.getDefaultToolkit();
176         MediaTracker tracker = new MediaTracker(this);
177         for(int i = 0; i < totalNum; i++)
178         {
179             images[i] = defaultTk.getImage("rene"+i+".gif");
180             tracker.addImage(images[i], i);
181             try {
182                 tracker.waitForID(i);
183             } catch (InterruptedException e) {
184                 // TODO Auto-generated catch block
185                 e.printStackTrace();
186             }
187         }
188         x = 0;
189         x1 = 0;
190         animator = new Thread(this);
191         animator.start();
192     }
193     @Override
194     public void run() {
195         // TODO Auto-generated method stub
196         while(Thread.currentThread() == animator)
197         {
198             repaint();
199             try {
200                 Thread.sleep(delay);
201             } catch (InterruptedException e) {
202                 // TODO Auto-generated catch block
203                 e.printStackTrace();
204             }
205         }
206     }
207 /*为什么这个方法得不到调用????   继承JPanel 的原因?*/
208 //    public void update(Graphics g)
209 //    {
210 //    System.out.println("update");//<<
211 //        g.setColor(Color.yellow);
212 //        g.fillRect(x1, 0, images[0].getWidth(this), images[0].getHeight(this));
213 //        paint(g);
214 //    }
215     public void paint(Graphics g)
216     {
217 System.out.println("paint");//<<
218         g.setColor(Color.yellow);
219         g.fillRect(x1, 0, images[0].getWidth(this), images[0].getHeight(this));
220         
221         g.drawImage(images[currentNum], 10+x, 0this);
222         x1 = x;
223         x = (x+5)%400;
224         currentNum = ++currentNum%totalNum;
225     }
226     
227     public int getImageWidth()
228     {
229         return images[0].getWidth(this);
230     }
231     public int getImageHight()
232     {
233         return images[0].getHeight(this);
234     }
235 }
236 
237 
238 /*文件选择框只选择TXT文件*/
239 class TextFilter extends FileFilter
240 {
241 
242     @Override
243     public boolean accept(File f) {
244         // TODO Auto-generated method stub
245           String filename = f.getName();
246             return filename.endsWith(".txt");
247     }
248 
249     @Override
250     public String getDescription() {
251         // TODO Auto-generated method stub
252         return  "*.txt";
253     }
254     
255 }









posted on 2008-04-06 14:23 fullfocus 阅读(1894) 评论(1)  编辑  收藏 所属分类: JAVA/J2EE

评论:
# re: [java重头再来系列之一]java界面布局,文件操作,线程,事件响应 2008-04-06 15:47 | BeanSoft
自定义JComponent组件时,应该覆盖 paintComponent(Graphics g) 方法,而不是update()和paint(),因为JComponent绘制时要做很多工作。
参考:http://www.java3z.com/cwbwebhome/article/pr/sw4.jsp  回复  更多评论
  

只有注册用户登录后才能发表评论。


网站导航: