java FileInputStream
(12.1)FileInputStream将文件读入作为流来处理,有两种实例化方式
// 方式1
FileInputStream fis = new FileInputStream("./learn.txt");
// 方式2
File f = new File("./learn.txt");
FileInputStream fis = new FileInputStream(f);(12.2) java FileInputStream.read方法
java FileInputStream.read默认读取的是文件的一个字节,并且返回的是二进制代表的字符编码,还需要转换下才能正常显示
File f = new File("./learn.txt");
FileInputStream fis = new FileInputStream(f);
while (true) {
int num = fis.read();
if (num != -1) {
System.out.println((char) num);
} else {
break;
}
}(12.3) java FileInputStream.read[byte b]方法
从文件中读取b.length个字节到b中，例如
File f = new File("./learn.txt");
FileInputStream fis = new FileInputStream(f);
byte[] b = new byte[10];
int number = fis.read(b);
System.out.println("读取到" + number + "字节");
System.out.println(Arrays.toString(b));
fis.close();文件内容如下:
1
2
总共读取到7个字节输出内容为:
[49, 13, 10, 50, 0, 0, 0, 0, 0, 0]
49 ASCII对应为1
13 ASCII对应为回车
10 ASCII对应为换行
50 ASCII对应为2
