FileOutputStream的三个write方法举例

第一个方法write(byte[] b)举例：

参数需要是字节数组的，字符串.getBytes()将字符串变为字节数组

public static void main(String[] args) {
        
        File file = new File("e:\12332.txt");
        try {
            FileOutputStream fos = new FileOutputStream(file,true);
            fos.write("www.sina.com.cn".getBytes());
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        
    }    

第二个方法write(int b) ，会把b对应的字符输出97：a

public static void main(String[] args) {
        
        File file = new File("e:\12332.txt");
        try {
            FileOutputStream fos = new FileOutputStream(file);
            int[] b = {49,50,97,98,99};
            for(int i = 0;i<b.length;i++){
            fos.write(b[i]);
            }
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        
    }    

第三个方法write(byte[] b,int off,int len)

 fis.read(b)是读取b字节数组总数的字节，当最后不够数组长度的时候就读出了剩下不够的字节总数

给了c

同样write方法写b字节数组，不够的话，就写剩下的总数，长度是c

public static void main(String[] args) {
        
        File file = new File("e:\12332.txt");
        try {
            FileOutputStream fos = new FileOutputStream(file);
            BufferedOutputStream bos = new BufferedOutputStream(fos);
            DataOutputStream dos = new DataOutputStream(bos);
            
            FileInputStream fis = new FileInputStream(new File("e:\12223.txt"));
            byte[] b = new byte[1024];
            int c = 0;
            while((c=fis.read(b))!=-1){
                dos.write(b, 0, c);;
            }
            fis.close();
            dos.close();
            bos.close();
            fos.close();
            System.out.println("运行到这");
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        
        
        
        
    }