public class ByteStreamMax { FileOutputStream fileOutputStream = null; FileInputStream fileInputStream = null; //打印文件内容 public void inPut() throws IOException { File file = new File("D:\\IdeaProjects\\javase\\src\\IOStream1"); fileInputStream = new FileInputStream(file); byte[] bytes = new byte[1024]; int len = 0; String str=""; while((len=fileInputStream.read(bytes))!=-1){ str = new String(bytes,"utf-8"); System.out.print(str); } System.out.println("\n"); fileInputStream.close(); } //修改文件内容 public void outPut() throws IOException { File file1 = new File("D:\\IdeaProjects\\javase\\src\\IOStream1"); File file2 = new File("D:\\IdeaProjects\\javase\\src\\IOStream2"); //读取file2的内容 fileInputStream = new FileInputStream(file2); //将file2的内容写入到file1中 fileOutputStream = new FileOutputStream(file1); byte[] bytes = new byte[1024]; int len = 0; while((len=fileInputStream.read(bytes))!=-1){ fileOutputStream.write(bytes,0,len); } fileInputStream.close(); fileOutputStream.flush(); fileOutputStream.close(); } public static void main(String[] args) throws IOException { ByteStreamMax byteStreamMax = new ByteStreamMax(); //打印文件内容 byteStreamMax.inPut(); //修改文件内容 byteStreamMax.outPut(); //再次打印文件内容,检测是否已修改 byteStreamMax.inPut(); }}