Java读取图片并修改像素，创建图片

public void replaceImageColor(String file, Color srcColor, Color targetColor) throws IOException{
        URL http;
        if(file.trim().startsWith("https")){
            http = new URL(file);
            HttpsURLConnection conn = (HttpsURLConnection) http.openConnection();
            conn.setRequestMethod("GET");
        }else if(file.trim().startsWith("http")){
            http = new URL(file);
            HttpURLConnection conn = (HttpURLConnection) http.openConnection();
            conn.setRequestMethod("GET");
        }else{
            http = new File(file).toURI().toURL();
        }
        BufferedImage bi = ImageIO.read(http.openStream());

        for (int i = 0; i < bi.getWidth(); i++) {
            for (int j = 0; j < bi.getHeight(); j++) {
                  System.out.println(bi.getRGB(i, j));
                  if(srcColor.getRGB()==bi.getRGB(i, j)){
                      System.out.println(i+","+j+"  from:"+srcColor.getRGB()+"to"+targetColor.getRGB());
                      bi.setRGB(i, j, targetColor.getRGB());
                  }
            }
        }
        Iterator<ImageWriter> it = ImageIO.getImageWritersByFormatName("png");
        ImageWriter writer = it.next();
        File f = new File("c://test02.png");
        ImageOutputStream ios = ImageIO.createImageOutputStream(f);
        writer.setOutput(ios);
        writer.write(bi);
        bi.flush();
        ios.flush();
        ios.close();
    }

    public void createImage(int width, int height) throws IOException{
        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_4BYTE_ABGR);
        Graphics2D graphic = bi.createGraphics();
        graphic.setColor(new Color(0.2f,0.3f,0.4f,0.4f));
        graphic.fillRect(0, 0, width, height);

        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                  //result[i][j] = bi.getRGB(i, j) & 0xFFFFFF;
                  System.out.println(bi.getRGB(i, j));
                 // bi.setRGB(i, j, 0xFFFFFF);
            }
       }

        Iterator<ImageWriter> it = ImageIO.getImageWritersByFormatName("png");
        ImageWriter writer = it.next();
        File f = new File("c://test02.png");
        ImageOutputStream ios = ImageIO.createImageOutputStream(f);
        writer.setOutput(ios);

        writer.write(bi);
    }