文件处理

package demo13;
import java.io.*;
import java.util.*;
public class text1 {
    String dir="d:\\mytext.txt";
    int max=-1;
    public void seta() {
        Random rd=new Random();
        try{
            PrintWriter out=new PrintWriter(dir);
            for(int i=0;i<=4;i++) {
                 out.println(rd.nextInt(9));
            }  
                out.close();}catch(Exception e) {
                    System.out.println(e);
                }
    }
    public void js() {
        File myf=new File(dir);
        String  x;
        int xint;
        try {
         if (myf.exists()){
             Scanner in=new Scanner(myf);
              while(in.hasNextLine()){
                x=in.nextLine();
                System.out.println(x);
                xint=Integer.parseInt(x);
                if(max<xint) {    max=xint; }
                }     
                in.close();}
                }catch(Exception e){
             System.out.println(e);     }
    }
    public static void main(String[] args) {
        text1 my=new text1();
        my.seta();
        my.js();
        System.out.println("................");
        System.out.println(my.max);
    }
}

package demo13;
//实例：输入一个文件名并显示该文件的相关属性
import java.io.*;
public class l3 {
    public static void main(String[] args) {
        try{
              File f=new File("d:\\myfile1.txt");
        if(f.exists()){
                System.out.println("文件是否可读"+f.canRead());
                System.out.println("文件名："+f.getName());
                System.out.println("文件路径"+f.getPath());
                System.out.println("文件绝对路径"+f.getAbsolutePath());
                System.out.println("文件长度"+f.length());
          }else{
              System.out.println("文件没有找到");
          }
        }catch(Exception e){
               System.out.print(e);
              }
    }
}

package demo13;
import java.io.*;
public class l4 {
     public void filewrite(String filename) {
        try {
         FileInputStream fin=new FileInputStream(FileDescriptor.in);
         FileOutputStream fout=new FileOutputStream(filename);
             System.out.println("以#字号结束");
             char ch;
         while((ch=(char)fin.read())!='#'){
             fout.write(ch);
             }
             fin.close();
             fout.close(); }catch(Exception e){
                   System.out.print(e);
                  }
     }
     public void fileread(String filename) {
        try {
            FileInputStream fin=new FileInputStream(filename);
            FileOutputStream fout=new FileOutputStream(FileDescriptor.out);
                while(fin.available()>0){
                    int data=fin.read();
                    fout.write(data);
                      }
                    fin.close();
                    fout.close();     }catch(Exception e) {
                        System.out.print(e);
                    }   
     }
    public static void main(String[] args) {
        l4 my=new l4();
        my.filewrite("d:\\myfile.txt");
        my.fileread("d:\\myfile.txt");
    }
}

package demo13;
import java.io.*;
import java.util.*;
public class l6 {
    public static void main(String[] args) {
          String name="有趣而简单的写操作";
          String name1="即文本的输出";
                double x=3445.4;
               String dir="d:\\myfile1.txt";   
            String list;
    //--------------------------------------------------------------------------------------------------------
            try{
                PrintWriter out=new PrintWriter(dir);
                  out.print(name+'\n');
                  out.println(name1);
                  out.println(" ***************  ");
                  out.println(x);
                  out.close();
            File my1=new File(dir);
             if (my1.exists()){
                 Scanner in=new Scanner(my1);
                  while(in.hasNextLine()){
                    System.out.println(in.nextLine());
                    }
                          in.close(); }        
                                       }
            catch(Exception e){
                 System.out.println(e);     }
    }
}

package demo13;
import java.io.*;
public class l5 {
    public void fileread(String s) {
        String thisline;
        int count=0;
        try{
          FileReader fr=new FileReader(s);    
          BufferedReader bfr=new BufferedReader(fr);
          while((thisline=bfr.readLine())!=null){
              count++;
              System.out.println(thisline);
          }
            System.out.println("共读取了"+count+"行");
           bfr.close();
        }catch(IOException e){
            System.out.println(e);
        }
    }
    public void filewrite(String sn){
        String str=new String();
    try{
         String s="hello \n java!";
               BufferedWriter out=new BufferedWriter(new FileWriter(sn));
            out.write(s);
            out.close();
    }catch(IOException e){
        System.out.println(e);
    }
    }
    public static void main(String[] args) {
        l5 my=new l5();
        my.fileread("d:\\myfile.txt");
        my.filewrite("d:\\myfile1.txt");
        my.fileread("d:\\myfile1.txt");
    }   }