输入输出

package shurushuchu;

import  java.io.*;

public class main {

    public static void main(String[] args)
    {
    File f =new File ("d:/test.txt");
    
    if (f.exists())
    {
        System.out.println("文件存在");
        System.out.println("getname="+f.getName());
        System.out.println("getpath="+f.getPath());             //目录和文件名
        System.out.println("getparent="+f.getParent());         //只获取父目录
        System.out.println("sss="+f.getAbsolutePath());         //绝对路径
        System.out.println("changdu="+f.length());                   //文件长度
        
        //f.delete();
        
        try {
            //写
            FileOutputStream fis = new FileOutputStream("d:/test.txt");
        //FileInputStream fis = new FileInputStream("f");
            
        String strIn = "大家好";
            byte[] by = strIn.getBytes();
            
            fis.write(by,  0,  by.length);
            
            fis.close();
            
            //读
            FileInputStream fin = new      FileInputStream ("d:/test.txt");
            
            byte [] inp = new byte [256];
            
            fin.read(inp);
            fin.close();
            
            String r = new String (inp, 0, inp.length);
            
            System.out.println("读取的是 "+r);
            
            FileWriter fw = new FileWriter(f);
            
            fw.write("我要写的字符");
            
            fw.close();
            
            FileReader fr = new FileReader(f);
            
            char [] cin = new char [123];
            
            fr.read(cin);
            fr.close();
            
            String strin = new String(cin);
            System.out.println("读出的内容 "+strin.trim());    //strin.trim()   去空格
            
            
            
            
            
            
        }
        
        
        catch (Exception e) {
        
            e.printStackTrace();
        }
        
        
        
        
        
    }
    else
    {
        
        try {                                                                              //处理异常
            
        if (f.createNewFile())
        {
            System.out.println("文件创建成功");
        }
        else
        {
            System.out.println("文件创建失败");
        }
        } 
        catch (IOException e) {                                  //捕获异常
            // 输出错误信息
            e.printStackTrace();
        }
        
        // System.out.println("文件不存在");
    }
    
    System.out.println();
    
    
    
    

    
    
    
    
    
    
    
    
    
}
}