public void writeTo(DataOutput out) throws IOException{
        out.writeChars("sexgirl.jpg");
        out.writeLong(181818);//181818 是图片数据的长度
        //write the image data into out
        out.writeChars("sexboy.jpg");
        out.writeLong(181817);//181817 是另一图片数据的长度
        //write the other image data into out
    }
    
    public void readFrom(DataInput in) throws IOException{
        String name1 = in.readLine();
        long size1 = in.readLong();//这是第一张图片的大小
        byte[] data1 = new byte[(int) size1];
        for(int i=0;i<size1;i++){//读取图片数据
            data1[i] = in.readByte();
        }
        
        String name2 = in.readLine();
        long size2 = in.readLong();//这是第二张图片的大小
        byte[] data2 = new byte[(int) size2];
        for(int i=0;i<size2;i++){//读取图片数据
            data2[i] = in.readByte();
        }
        
    }