Java 示例 - 使用 Applet 写入文件

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  问题描述

  如何使用 Applet 写入文件？
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  解决方案

  以下示例演示了如何通过使用 TextArea() 制作标签在浏览器中写入 textarea 然后使用 File() 构造函数创建文件来写入文件。

  
  import java.io.*;
  import java.awt.*;
  import java.awt.event.*;
  import javax.swing.*;
  import java.applet.Applet;
  import java.net.*;
  public class WriteFile extends Applet {
     Button write = new Button("WriteToFile");
     Label label1 = new Label("Enter the file name:");
     TextField text = new TextField(20);
     Label label2 = new Label("Write your text:");
     TextArea area = new TextArea(10,20);
     
     public void init() {
        add(label1);
        label1.setBackground(Color.lightGray);
        add(text);
        add(label2);
        
        label2.setBackground(Color.lightGray);
        add(area);
        add(write,BorderLayout.CENTER);
        
        write.addActionListener(new ActionListener () {
           public void actionPerformed(ActionEvent e) { 
              new WriteText();
           }
        });
     } 
     public class WriteText {
        WriteText() { 
           try {
              String str = text.getText();
              
              if(str.equals("")) { 
                 JOptionPane.showMessageDialog(null, "Please enter the file name!");
                 text.requestFocus();
              } else { 
                 File f = new File(str);
                 if(f.exists()) {
                    BufferedWriter out = new BufferedWriter(new FileWriter(f,true));
                    if(area.getText().equals("")) {
                       JOptionPane.showMessageDialog (null,"Please enter your text!");
                       area.requestFocus();
                    } else {
                       out.write(area.getText());
                       if(f.canWrite()) {
                          JOptionPane.showMessageDialog(null, "Text is written in "+str);
                          text.setText("");
                          area.setText("");
                          text.requestFocus();
                       } else {
                          JOptionPane.showMessageDialog(null, "Text isn't written in "+str);
                       }
                       out.close();
                    }
                 } else {
                    JOptionPane.showMessageDialog (null,"File not found!");
                    text.setText("");
                    text.requestFocus();
                 }
              }
           } catch(Exception x) {
              x.printStackTrace();
           }
        }
     }
  }
  

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  结果

  上面的代码示例将在启用 java 的 Web 浏览器中产生以下结果。

  
  View in Browser. 
  

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