为什么字节数组在另存为图像时返回 null

Question

>我编写了代码将消息隐藏为图像，起初我将图像转换为字节数组并将消息隐藏为图像，但是当我想将新字节数组转换为图像时，我得到null？我知道关于这个话题有很多问题，我尝试了答案但没有工作。请问谁能帮我？

import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageReader;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.stream.ImageOutputStream;
//import javax.swing.text.html.HTMLDocument.Iterator;
import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;
import java.util.Iterator;
public class test {
    public static void main(String[] args) throws IOException{

        if(args.length==0)
        {
            String dirName="C:\";
            ByteArrayOutputStream baos=new ByteArrayOutputStream(1000);
            BufferedImage img=ImageIO.read(new File("inacup_donut.jpg"));
            ImageIO.write(img, "jpg", baos);
            baos.flush();
            String base64String=Base64.encode(baos.toByteArray());
            baos.close();
            byte[] bytearray = Base64.decode(base64String);
            int [] int_array=new int [bytearray.length];
            for(int i=0;i<bytearray.length;i++)
            {
            int_array [i]=(int)bytearray[i];
            }//end for loop

            int x []= encodeMessage(int_array,img.getHeight(),img.getWidth(),
                    "message") ;
            System.out.println("read " + x[0]+ " bytes,");
            byte [] new_bytearray = new byte [x.length] ;
            for(int i=0;i<x.length;i++)
            {
                new_bytearray[i]=(byte)x[i];
            }//end for loop


            BufferedImage imag=ImageIO.read(new ByteArrayInputStream(new_bytearray));
            ImageIO.write(imag, "jpg", new File(dirName,"snap.jpg")); 
        }

        }//end main function


}//end  class

Answer 1

我用以下编码解决了这个问题：

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class EncodeImage  {
    public static void main(String[] args)  throws IOException{

        if(args.length!=0)
        {
        BufferedImage sourceImage = null;
        try {
            sourceImage = ImageIO.read(new File("inacup_donut.jpg"));
        } catch (IOException e) {
        }
        int type = sourceImage.getType();
        int w = sourceImage.getWidth();
        int h = sourceImage.getHeight();
        byte[] pixels = null;
        if (type == BufferedImage.TYPE_3BYTE_BGR)
        {
            System.out.println("type.3byte.bgr");
            pixels = (byte[]) sourceImage.getData().getDataElements(0, 0, w, h, null);
            //for(int i=0;i<pixels.length;i++)
                //pixels[i]=(byte) (pixels[i]|2);
            System.out.println(pixels[1]);
            int [] int_array=new int [pixels.length];
            for(int i=0;i< pixels.length;i++)
            {
            int_array [i]= pixels[i];
            }//end for loop

            int x []= encodeMessage(int_array,h,w,
                    "message") ;
            System.out.println("read " + x[0]+ " bytes,");
            byte [] new_bytearray = new byte [x.length] ;
            for(int i=0;i<x.length;i++)
            {
                new_bytearray[i]=(byte)x[i];
            }
            try {
                BufferedImage edgesImage = new BufferedImage(w, h, BufferedImage.TYPE_3BYTE_BGR);
                edgesImage.getWritableTile(0, 0).setDataElements(0, 0, w, h, new_bytearray);
                ImageIO.write(edgesImage, "png", new File("snap.png"));
            } catch (IOException e) {
            }



        }
        } 
  }