文件读写的简单例子（字节流）

小灰灰 2022-08-09 03:16 175阅读 0赞

package bytetest;
    
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    
    public class FileOutputStreamDemo { 
    
        public static void main(String[] args)  throws IOException{
            writeFile();
            readFile1();
            readFile2();
            readFile3();
        }
    
        public static void writeFile() throws IOException{
            FileOutputStream fos=new FileOutputStream("fos.txt");
    
            //没有缓冲区，不需要刷新
            fos.write("abcde阿飞".getBytes());
    
            fos.close();
        }
    
        public static void readFile1() throws IOException{      //一次读一个字节
            FileInputStream fis=new FileInputStream("fos.txt");
            int ch=0;
            while((ch=fis.read())!=-1){
                System.out.println((char)ch);
            }
            fis.close();
        }
    
        public static void readFile2() throws IOException{      //一次读一个数组
            FileInputStream fis=new FileInputStream("fos.txt");
    
            byte[]buf=new byte[1024];
            int len=0;
    
            while((len=fis.read(buf))!=-1){
                System.out.println(new String(buf,0,len));
            }
            fis.close();
        }
    
        public static void readFile3() throws IOException{      //利用available定义刚刚好大小的数组
    
            FileInputStream fis=new FileInputStream("fos.txt");
    
            byte[]buf=new byte[fis.available()];    //慎用，防止内存溢出
            fis.read(buf);
            System.out.println(new String(buf));
    
            fis.close();
        }
    }