JAVA中的文件输入,输出简单几例

(1)正常写入内容到一个文本文件中,然后输出.
import java.io.*;
public class File12
{
 public static void main(String[] args) throws Exception
 {
  FileOutputStream fos=new FileOutputStream("d:\\abc.txt");
  OutputStreamWriter osw=new OutputStreamWriter(fos);
  BufferedWriter bw=new BufferedWriter(osw);
  bw.write("这只是一个练习");
  bw.newLine();
  bw.write("只是试验一下:)");
  bw.newLine();
  bw.close();
  FileInputStream fis=new FileInputStream("d:\\abc.txt");
  InputStreamReader isr=new InputStreamReader(fis);
  BufferedReader br=new BufferedReader(isr);
  System.out.println(br.readLine());
  System.out.println(br.readLine());
  br.close();
 }
}

先将字符串写入文件d:\abc.txt,然后输出.

 

(2)输出d:\abc.txt另一例
import java.io.*;
public class File14
{
 public static void main(String[] args) throws Exception
 {
  FileReader fr=new FileReader("d:\\abc.txt");
  BufferedReader br=new BufferedReader(fr);
  String s;
  while((s=br.readLine())!=null)
   System.out.println(s);
  br.close();
 }
}

(3)选择一文件,然后输出内容
import java.awt.*;
import java.io.*;
public class FileDialog1 extends Frame
{
 FileDialog fopen;
 TextArea ta;
 public FileDialog1(String title)
 {
  super(title);
  ta=new TextArea();
  add(ta);
  setSize(300,300);
 }
 public String showLoad()
 {
  fopen=new FileDialog(this,"what",FileDialog.LOAD);
  fopen.setVisible(true);
  String fileName=fopen.getFile();
  String fileDir=fopen.getDirectory();
  if(fileName==null)
  {
   return null;
  }
  return fileDir+"\\"+fileName;
 }
 public void loadFile(String fileName) throws IOException
 {
  BufferedReader br=new BufferedReader(new FileReader(fileName));
  String aline;
  while((aline=br.readLine())!=null)
   ta.append(aline+'\n');
  br.close();
 }
 public void saveFile(){}
 public static void main(String[] args)
 {
  FileDialog1 fdlg=new FileDialog1("只是一个例子");
  String fileName;
  if((fileName=fdlg.showLoad())==null)
   System.out.println("加载不成功");
  else
  {
   try
   {
    fdlg.loadFile(fileName);
   }
   catch(IOException ie)
   {
    System.out.println(ie);
   }
  }
  fdlg.setVisible(true);
 }
}