Io流Reader

Posted 2020-12-25 java-jiangtao-home

package reader;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class Demo1 {
    public static void main(String[] args) {
    
        readFile();
        
    }
    public static void readFile() {
        FileReader fr = null;
        
        try {
            fr = new FileReader("Text.txt");
            //返回的是字符的ascll码值
//            int num  =fr.read();
//            System.out.println((char)num);
//            num  =fr.read();
//            System.out.println(num);
            //
//            while(num!=-1) {
//                num  =fr.read();
//                System.out.print((char)num);
//            }
            /**
             * 用这种方式
             */
            int num = 0;
            while((num = fr.read()) != -1) {
                System.out.print((char)num);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }catch(IOException e) {
            e.printStackTrace();
        }finally {
            if(fr!=null) {
                try {
                    fr.close();
                } catch (IOException e) {
                    // TODO Auto-gene     rated catch block
                    e.printStackTrace();
                }
            }
        }
        
        
    }
}

package reader;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class Demo2 {
    public static void main(String[] args) {
    
        readFile();
        
    }
    public static void readFile() {
        FileReader fr = null;
        
        try {
            fr = new FileReader("Text.txt");
            //创建一个字符串的数组
            /*
            char[] chs = new char[5];
            //读取五个字符放入字符数组中
            int num = fr.read(chs);
            String str = new String(chs);
            System.out.println(num);
            System.out.println(chs);
            System.out.println("-----------------------");
            num = fr.read(chs);
            
                str = new String(chs,0,num);

            System.out.println(num);
            System.out.println(str);
            num = fr.read(chs);
            str = new String(chs,0,num);
            System.out.println(num);
            System.out.println(str);
            num = fr.read(chs);
            str = new String(chs,0,num);
            System.out.println(num);
            System.out.println(str);
            */
            
            char [] cha = new char[1024];
            int num1 = -1;
            while((num1 = fr.read(cha))!= -1)
            {
                System.out.println(new String(cha,0,num1));
            }
        
        
            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }catch(IOException e) {
            e.printStackTrace();
        }finally {
            if(fr!=null) {
                try {
                    fr.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
        
        
    }
}