NotePaid.java

 

package notepaid;

import java.awt.FileDialog;

importjava.awt.Frame;

importjava.awt.Menu;

importjava.awt.MenuBar;

importjava.awt.MenuItem;

importjava.awt.TextArea;

importjava.awt.event.ActionEvent;

importjava.awt.event.ActionListener;

importjava.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

public class NotePaid extends Frameimplements ActionListener{

       MenuBarmb ;

       Menufile,help;

       MenuItemmiOpen,miSave,miSaveAs,miExist;

       FileDialogfd_Open,fd_Save,fd_SaveAs;

   TextArea ta;

   String path = "";

       publicNotePaid(){

           Frame f = new Frame("记事本");

           mb = new MenuBar();

           file = new Menu("文件");

           help = new Menu("帮助");

           miOpen = new MenuItem("打开");

           miSave = new MenuItem("保存");

           miSaveAs = new MenuItem("另存为");

           miExist = new MenuItem("退出");

           ta = new TextArea();

           file.add(miOpen);

           file.add(miSave);

           file.add(miSaveAs);

           file.add(miExist);

          

           mb.add(file);

           mb.add(help);

           miOpen.addActionListener(this);

           miSave.addActionListener(this);

           miSaveAs.addActionListener(this);

           miExist.addActionListener(this);

              fd_Open= new FileDialog(this,"打开",FileDialog.LOAD);

           fd_Save = new FileDialog(this, "保存", FileDialog.SAVE);

           fd_SaveAs = new FileDialog(this, "另存为", FileDialog.SAVE);

           this.addWindowListener(newWindowAdapter(){

 

                     @Override

                     publicvoid windowClosing(WindowEvent e) {

                            System.exit(0);

                     }

                 

           });

           this.setMenuBar(mb);

           this.add(ta);

           this.setBounds(400,0,600,750);

           this.setVisible(true);

          

          

    }

      

       publicstatic void main(String[] args) {

              newNotePaid();

 

       }

 

       @Override

       publicvoid actionPerformed(ActionEvent e) {

              Stringname = e.getActionCommand();

              if(name.equals("打开")){

            fd_Open.setVisible(true);

            getReadPath(fd_Open);

              }elseif(name.equals("保存")){

                       /*

                        String d = fd_Save.getDirectory();

                        String f = fd_Save.getFile();

                        path = d+f;*/

                    

                     if((path== null) ||(path.equals(""))){

                            fd_Save.setVisible(true);

                            getWriteSaveAsPath(fd_Save);

                           

                     }else{

                           

                            getWriteSavePath(fd_Save);

                     }

                    

              }elseif(name.equals("另存为")){

                     fd_SaveAs.setVisible(true);

                     getWriteSaveAsPath(fd_SaveAs);

              }

          else if (name.equals("退出")){

              System.exit(0);

       }

       }

  public void openFile(String path){

          //再打开文件之前将记事本的内容清空。

          ta.setText("");

          FileReader fr = null;

              BufferedReaderbr = null;

          try {

              fr= new FileReader(path);

           br = new BufferedReader(fr);

              Stringcontent = null;

              while((content = br.readLine())!=null) {           

                     ta.append(content);

                     //每读出一行就向该行的末尾处追加一个换行符。

                     ta.append("\r\n");

              }

       }catch (IOException e) {

              e.printStackTrace();

       }finally{

              if(br!= null){

                     try{

                            br.close();

                     }catch (IOException e) {

                            e.printStackTrace();

                     }

              }

       }

   }

  public void saveFile(String path){

          FileWriter fw = null;

          BufferedWriter bw = null;

          try {

              fw= new FileWriter(path);

              bw= new BufferedWriter(fw);

              Stringcontent = ta.getText();

              bw.write(content);

              bw.flush();

       }catch (IOException e) {

      

              e.printStackTrace();

       }finally{

              if(bw!=null){

                     try{

                            bw.close();

                     }catch (IOException e) {

                            e.printStackTrace();

                     }

              }

       }

   }

  public void saveFileAs(String path){

          FileWriter fw = null;

          BufferedWriter bw = null;

          try {

                 fw = new FileWriter(path);

                 bw = new BufferedWriter(fw);

                 String content = ta.getText();

                 bw.write(content);

                 bw.flush();

          } catch (IOException e) {

                

                 e.printStackTrace();

          }finally{

                 if(bw!=null){

                        try {

                               bw.close();

                        } catch (IOException e) {

                               e.printStackTrace();

                        }

                 }

          }

   }

  public void getReadPath(FileDialog fd){

          String d = fd.getDirectory();

          String f = fd.getFile();

          if((d!=null &&!d.equals(""))&&(f!=null &&!f.equals(""))){

                 path = d+f;

                 openFile(path);

          }

 

   }

  public void getWriteSaveAsPath(FileDialog fd){

          String d = fd.getDirectory();

          String f = fd.getFile();

          if((d!=null && !d.equals(""))&&(f!=null&& !f.equals(""))){

                 path = d+f;

                 saveFileAs(path);

          }

   }

  public void getWriteSavePath(FileDialog fd){

        saveFile(path);

      

   }

}

好了，到这里，关于流的处理中的字符流部分已经介绍完了，之后会为您介绍关于字节流的操作。