public class Test {
    public static void main(String[] args) throws IOException {
        final String path = "D:/1.txt";
	//1、得到数据文件
	File file = new File(path); 
	//2、建立数据通道
	FileInputStream fileInputStream = new FileInputStream(file);   
	byte[] buf = new byte[1024];  
	int length = 0;
	//循环读取文件内容，输入流中将最多buf.length个字节的数据读入一个buf数组中,返回类型是读取到的字节数。
	//当文件读取到结尾时返回 -1,循环结束。
	while((length = fileInputStream.read(buf)) != -1){   
	    System.out.print(new String(buf,0,length));
	}
	//最后记得，关闭流
	fileInputStream.close();
    }
}

 

详细请看FileInputStream 读取文件内容_有酒醉三生丶-CSDN博客_fileinputstream