java io读写文件

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public class DemoIO {    public static byte[] readForInputStream(File file) throws IOException{        InputStream in = new FileInputStream(file);          byte b[]=new byte[(int)file.length()];     //创建合适文件大小的数组           int len = 0;          int temp=0; //所有读取的内容都使用temp接收          while((temp=in.read())!=-1){
   //当没有读取完时，继续读取                b[len]=(byte)temp;               len++;           }         in.close();           return b;      }        public static void writeForOutputStream(File file) throws IOException {        String content = "这是一段感人肺腑的文字";        FileOutputStream fop = new FileOutputStream(file,true);//第二个参数ture：表示在内容中追加        // 判断文件是否存在        if (!file.exists()) {            file.createNewFile();        }        byte[] contentInBytes = content.getBytes();        fop.write(contentInBytes);        fop.flush();        fop.close();        System.out.println("--------write success-------------");    }        /**     * @param args     * @throws IOException      */    public static void main(String[] args) throws IOException {                 writeForOutputStream(new File("e:/testio.txt"));                byte[] b = readForInputStream(new File("e:/testio.txt"));        System.out.println(new String(b, 0, b.length));    }}