java基础之I/O操作

字节流

直接上代码:

import java.io.*;

class Test{
    public static void main(String[] args){
        FileInputStream inputfile = null;
        FileOutputStream outputfile = null;
        try{
            inputfile = new FileInputStream("./input.txt");
            outputfile = new FileOutputStream("./output.txt");
            byte[] buffer = new byte[100];
            int temp = inputfile.read(buffer,0,buffer.length);
            String s = new String(buffer);
            s = s.trim();
            System.out.println(s);
            outputfile.write(buffer,0,temp);
            
        }
        catch(Exception e){
            System.out.println(e);
        }
        
    }
}

优化版：

通过循环1M 1M读取文件

import java.io.*;

class Test{
    public static void main(String[] args){
        FileInputStream inputfile = null;
        FileOutputStream outputfile = null;
        try{
            inputfile = new FileInputStream("./input.txt");
            outputfile = new FileOutputStream("./output.txt");
            byte[] buffer = new byte[1024];
            while(true){
                int temp = inputfile.read(buffer,0,buffer.length);
                if(temp == -1){
                    break;
                }
                outputfile.write(buffer,0,temp);
                
            }
            
            
        }
        catch(Exception e){
            System.out.println(e);
        }
        finally{
            try{
                inputfile.close();
                outputfile.close();
            }
            catch(Exception e){
                System.out.println(e);    
            }
            
        }
        
    }
}

字符流

import java.io.*;

class TestString{
    public static void main(String[] args){
        FileReader inputfile = null;
        FileWriter outputfile = null;
        try{
            inputfile = new FileReader("./input.txt");
            outputfile = new FileWriter("./output.txt");
            char[] buffer = new char[1024];
            while(true){
                int temp = inputfile.read(buffer,0,buffer.length);
                if(temp == -1){
                    break;
                }
                outputfile.write(buffer,0,temp);
                
            }
            
            
        }
        catch(Exception e){
            System.out.println(e);
        }
        finally{
            try{
                inputfile.close();
                outputfile.close();
            }
            catch(Exception e){
                System.out.println(e);    
            }
            
        }
        
    }
}

 BufferedReader.readLine

import java.io.*;

class TestBufferReader{
    public static void main(String[] args){
        FileReader fileReader = null;
        BufferedReader bufferReader = null;
        try{
            fileReader = new FileReader("./input.txt");
            bufferReader = new BufferedReader(fileReader);
            String line =null;
            while(true){
                line = bufferReader.readLine();
                if(line == null){
                    break;
                }
                System.out.println(line);
            }
        }
        catch(Exception e){
            System.out.println(e);
        }
        
    }
}