public abstract int read()throws IOException

依次读取单个字节数据，如果没有内容则返回-1

public int read(byte[] b) throws IOException

读出输入流的数据，写入字节数组，返回实际读取到的长度，如果没有内容则返回-1

public int read(byte[] b, int off, int len) throws IOException

读出输入流指定长度的数据，写入字节数组的指定位置，返回实际读取到的长度，如果没有内容则返回-1。但是当指定长度为0时返回0；

public void close()throws IOException

关闭数据流

public FileInputStream(File file) throws FileNotFoundException

从文件创建输入流（File类）

public FileInputStream(String name) throws FileNotFoundException

从文件创建输入流（String类）

test1.txt的内容

0123456789abcdefghijklmn

Test2.txt的内容

01234

package wiki.jjcc.test.ips;

?

import java.io.File;

import java.io.FileInputStream;

import java.io.InputStream;

?

public class Test1 {

????public static void main(String[] args) throws Exception {

????????String s = File.separator;

????????File file1 = new File("d:"+s+"temp"+s+"test1.txt");

????????File file2 = new File("d:"+s+"temp"+s+"test2.txt");

????????InputStream input = new FileInputStream(file1);

????????byte[] b1 = new byte[10];

????????byte[] b2 = new byte[10];

????????int num1 = input.read(b1,3,6);

????????int num2 = input.read(b2,3,6);

????????System.out.println(num1);

????????System.out.println("["+new String(b1)+"]");

????????System.out.println(num2);

????????System.out.println("["+new String(b2)+"]");

????????input.close();

????}

}

package wiki.jjcc.test.ips;

?

import java.io.File;

import java.io.FileInputStream;

import java.io.InputStream;

?

public class Test1 {

????public static void main(String[] args) throws Exception {

????????String s = File.separator;

????????File file1 = new File("d:"+s+"temp"+s+"test1.txt");

????????File file2 = new File("d:"+s+"temp"+s+"test2.txt");

????????InputStream input = new FileInputStream(file2);

????????byte[] b1 = new byte[10];

????????byte[] b2 = new byte[10];

????????int num1 = input.read(b1,3,6);

????????int num2 = input.read(b2,3,6);

????????System.out.println(num1);

????????System.out.println("["+new String(b1)+"]");

????????System.out.println(num2);

????????System.out.println("["+new String(b2)+"]");

????????input.close();

????}

}

package wiki.jjcc.test.ips;

?

import java.io.File;

import java.io.FileInputStream;

import java.io.InputStream;

?

public class Test1 {

????public static void main(String[] args) throws Exception {

????????String s = File.separator;

????????File file = new File("d:"+s+"temp"+s+"test1.txt");

????????InputStream input = new FileInputStream(file);

????????byte[] b = new byte[30];

????????int foot = 0;

????????int temp = 0;

????????while((temp=input.read())!=-1){

????????????b[foot++]=(byte)temp;

????????}

????????System.out.println(temp);

????????System.out.println("["+new String(b)+"]");

????????input.close();

????}

}