文件读取

package FileStream;import java.io.File;import java.io.FileInputStream;import java.io.InputStream;import java.util.Arrays;public class FileInputStreamDemo {public static void main(String[] args) throws Exception {//第一步，创建源（挖井）File f = new File("file/stream.txt");//第二步，创建文件字节输入流对象，并接在源上InputStream in =  new FileInputStream(f);//第三步，具体读取操作,读到没有的时候返回-1//int data = in.read(); 表示获取文件中第一个字节byte[] buffer = new byte[3];//此时一个小桶装5滴水，buffer装5字节System.out.println(Arrays.toString(buffer));//int ret = in.read(buffer, 1, 3);//返回读取了几个字节//System.out.println(Arrays.toString(buffer));//String str = new String(buffer,0,ret);//将数组转为String//System.out.println(str);int len = -1;while((len = in.read(buffer)) != -1){//读取整个文件String str = new String(buffer, 0, len);System.out.println(str);}//第四步，关闭资源in.close();}}