Java——字节流简单介绍

谁借莪１个温暖的怀抱￠ 2022-06-06 20:05 172阅读 0赞

/* 字节输出流 OutputStream: 字节输入流 InputStream: */
    import java.io.*;
    class test{
        public static void main(String[] args)throws IOException{
            //writeFile();
            //readFile1();
            //readFile2();
            readFile3();
        }
    
        public static void readFile3()throws IOException{
            FileInputStream fis = new FileInputStream("temp.txt");
            int num = fis.available();//返回文件的总大小，单位是字节，文件太大时不适合，数组要开辟内存，太大会溢出
            byte[] arr = new byte[num];
    
            int len = fis.read(arr);
            System.out.print(new String(arr,0,len));
    
            fis.close();
    
        }
    
        public static void readFile2()throws IOException{
            FileInputStream fis = new FileInputStream("temp.txt");
            byte[] arr = new byte[1024];
            int num;
            while((num = fis.read(arr))!=-1){
                System.out.print(new String(arr,0,num));
            }
            fis.close();
        }
    
        //使用字节输入流从文件中读取数据
        public static void readFile1()throws IOException{
            FileInputStream fis = new FileInputStream("temp.txt");
    
            //一次读一个字节
            int num;
            while((num = fis.read())!=-1){
                System.out.print((char)num);
            }
            fis.close();
        }
    
        //使用字节输出流向文件中写入数据
        public static void writeFile()throws IOException{
            //创建字节输出流对象和文件相关联
            FileOutputStream fos = new FileOutputStream("temp.txt");
    
            //直接写入文件，不需要flush
            fos.write("abcde".getBytes());//[97,98,99,100,101]
    
            fos.close();
        }
    }