第三次作业GUI文本编辑器

import javax.swing.*;import java.awt.*;import java.io.*;import java.awt.event.*;public class TxtEditor extends JFrame implements ActionListener{String file_name;String file_dir;String tempString;//上次保存后的文件名和地址String fileName = ""; JPanel x=new JPanel();     JTextArea wen=new JTextArea(20,50);        JMenuItem ziti=new  JMenuItem("字体");   JMenuItem a=new JMenuItem("普通");         //定义菜单项   JMenuItem xin=new  JMenuItem("新建");   JMenuItem open=new JMenuItem("打开");   JMenuItem save=new JMenuItem("保存 ");   JMenuItem lsave=new  JMenuItem("另存为");   JMenuItem tui=new  JMenuItem("退出");      JMenuItem cut=new JMenuItem("剪切 ");   JMenuItem copy=new JMenuItem("复制");   JMenuItem cast=new  JMenuItem("粘贴");   JMenuItem delete=new  JMenuItem("删除 ");     JMenuItem b=new JMenuItem("粗体");   JMenuItem c=new JMenuItem("斜体");TxtEditor(){ super ("文本编辑器       By  强凯 V1.0");//小小对话框   setBounds(250,100,700,450);   setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);   addWindowListener(new WindowAdapter(){       public void windowClosing(WindowEvent e) {       int   option=   JOptionPane.showConfirmDialog(        TxtEditor.this, "你真的想退出吗... ", "系统和你对话 ",JOptionPane.YES_NO_OPTION);       if(option==JOptionPane.YES_OPTION)    if(e.getWindow()   ==   TxtEditor.this)    {           System.exit(0);           }           else           {           return;                     }    }       });      //热键设置  xin.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N,ActionEvent.CTRL_MASK));  open.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O,ActionEvent.CTRL_MASK));  save.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,ActionEvent.CTRL_MASK));  cut.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X,ActionEvent.CTRL_MASK));  copy.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C,ActionEvent.CTRL_MASK));  cast.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V,ActionEvent.CTRL_MASK));  //定义面板       // x.add(        add(new  JScrollPane (wen));//);//滚动条         wen.setFont(new Font("楷体" , Font.PLAIN ,20));        // wen.setBackground(Color.blue);         // add(x);           //菜单栏的创建   JMenuBar cai=new JMenuBar();   this.setJMenuBar(cai);   cai.setOpaque(true);   JMenu jian=new JMenu("文件");   jian.add(xin);   jian.add(open);   jian.add(save);   jian.add(lsave);   jian.addSeparator( );   jian.add(tui);  cai.add(jian);    JMenu bian= new JMenu("编辑  ");  bian.add(cut);  bian.add(copy);  bian.add(cast);  bian.add(delete);   cai.add(bian);       JMenu geshi = new JMenu ("格式");      JMenu optionsMenu=new JMenu("字体");      geshi.add(optionsMenu);      optionsMenu.add(a);      optionsMenu.add(b);      optionsMenu.add(c);  cai.add(geshi);       //增加监听器 xin.addActionListener(this); open.addActionListener(this); save.addActionListener(this); lsave.addActionListener(this); tui.addActionListener(this); cut.addActionListener(this); copy.addActionListener(this); cast.addActionListener(this); delete.addActionListener(this); ziti.addActionListener(this); a.addActionListener(this); b.addActionListener(this); c.addActionListener(this);// 文本框锁定         //this.setResizable(false);} //重写方法public void actionPerformed(ActionEvent e){String actionCommand=e.getActionCommand();if(e.getSource()instanceof JMenu);{  if(e.getSource()==xin){newfile();    }         else if(e.getSource()==open){        openfile();    } else if(e.getSource()==save){  savefile();   }  else if(e.getSource()==lsave){    lsavefile();   }  else if(e.getSource()==cut){    cutfile();    }  else if(e.getSource()==copy){     copyfile();    }  else if(e.getSource()==cast){  castfile();  }  else if(e.getSource()==delete){  deletefile();  }  else if(e.getSource()==a){  afile(); }  else if(e.getSource()==b){  bfile();  }  else if(e.getSource()==c){  cfile();  }  else if("退出".equals(actionCommand)) System.exit(0);}}    // 方法定义    public void newfile(){         savefile();    wen.setText(null);        fileName = "";             }    //打开         public void openfile(){         String fileName = null;          FileDialog df = new FileDialog(this,"打开文件",FileDialog.LOAD);          df.setVisible(true);         //建立新文件          File f = new File( df.getDirectory()+df.getFile() );          //得到文件名          fileName = df.getDirectory()+df.getFile();         //用此文件的长度建立一个字符数组  （特别标注）           char ch[] = new char [(int)f.length()];           //异常处理             try             {              //读出数据，并存入字符数组ch中              BufferedReader bw = new BufferedReader( new FileReader(f) );                   bw.read(ch);                         bw.close();             }             catch( FileNotFoundException fe ){              System.out.println("file not found");              System.exit(0);             }             catch( IOException ie){              System.out.println("IO error");              System.exit(0);             }                         String s =new String (ch);             wen.setText(s);                     }                   //保存        public void savefile(){        if( fileName.equals("") ){     FileDialog df = new FileDialog(this,"保存文件",FileDialog.SAVE);          df.addWindowListener( new WindowAdapter(){      public void windowClosing(WindowEvent ee){       System.exit(0);      }     });     df.setVisible(true);     String s = wen.getText();         try     {      File f = new File( df.getDirectory()+df.getFile());      fileName = df.getDirectory()+df.getFile();      BufferedWriter bw = new BufferedWriter( new FileWriter (f));      bw.write(s , 0 , s.length());      bw.close();     }     catch(FileNotFoundException fe_){      System.out.println("file not found");      System.exit(0);     }     catch( IOException ie_)     {      System.out.println(" IO error");      System.exit(0);     }        }      //如果文件已经保存过     else      {      String s = wen.getText();          try     {      File f = new File( fileName );           BufferedWriter bw = new BufferedWriter( new FileWriter (f));      bw.write(s , 0 , s.length());      bw.close();          }     catch(FileNotFoundException fe_){      System.out.println("file not found");      System.exit(0);     }     catch( IOException ie_)     {      System.out.println(" IO error");      System.exit(0);     }          }                }     //另存为        public void lsavefile(){        FileDialog df = new FileDialog(this,"另存为",FileDialog.SAVE);        df.addWindowListener( new WindowAdapter(){              public void windowClosing(WindowEvent ee){               System.exit(0);              }             });             df.setVisible(true);             String s = wen.getText();             try             {              File f = new File( df.getDirectory()+df.getFile());              BufferedWriter bw = new BufferedWriter( new FileWriter (f));              bw.write(s , 0 , s.length());              bw.close();             }             catch(FileNotFoundException fe_){              System.out.println("file not found");              System.exit(0);             }             catch( IOException ie_)             {              System.out.println(" IO error");              System.exit(0);             }                 }                  //剪切           public void cutfile(){                     tempString = wen.getSelectedText();              StringBuffer tmp = new StringBuffer ( wen.getText());             int start = wen.getSelectionStart();             int len = wen.getSelectedText().length();              tmp.delete( start , start+len);              wen.setText(tmp.toString());                }   //复制       public void copyfile(){       tempString = wen.getSelectedText();        }         //粘贴       public void castfile(){       StringBuffer tmp = new StringBuffer ( wen.getText());         //得到要粘贴的位置         int start = wen.getSelectionStart();          tmp.insert(start , tempString);        //用新文本设置原文本          wen.setText(tmp.toString());        }              //删除       public void deletefile(){       StringBuffer tmp = new StringBuffer ( wen.getText());       int start = wen.getSelectionStart();        int len = wen.getSelectedText().length();         tmp.delete( start , start+len);         wen.setText(tmp.toString());       }//字体       public void afile(){        wen.setFont(new Font("楷体", Font.PLAIN ,wen.getFont().getSize()) );//普通文字       }              public void bfile(){        wen.setFont(new Font("楷体" , Font.BOLD ,wen.getFont().getSize()) );//粗体文字                     }       public void cfile(){       wen.setFont(new Font("楷体" , Font.ITALIC ,wen.getFont().getSize()) );//斜体文字       }public static void main(String[] args) {TxtEditor w=new TxtEditor();w.pack();w.setVisible(true);}}