【java】io流之字节输入流：java.io.InputStream类及子类java.io.FileInputStream

 package 文件操作;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;

 public class TestInputStream {
     public static void main(String[] args) throws IOException {
         File file=new File("D:"+File.separator+"test.txt");

         /*一次性读取文件内容
         if(file.exists()){
             InputStream inputStream=new FileInputStream(file);
             byte[] bytes=new byte[1024];
             int length=inputStream.read(bytes);
             inputStream.close();
             System.out.println("【"+new String(bytes,0,length)+"】");
         }
         */

         if(file.exists()){//单个读取
             InputStream inputStream=new FileInputStream(file);
             byte[] bytes=new byte[1024];
             int foot=0;
             byte tmp=0;
             while((tmp=(byte)inputStream.read())!=-1)
                 bytes[foot++]=tmp;
             inputStream.close();
             System.out.println("【"+new String(bytes,0,foot)+"】");
         }
     }
 }