验证码图片转字符串

为什么？

因为之前一个项目，安卓那边说只能处理JSON，别的都不行。。。（后来问过他人，明明可以处理其他的~~）

当时因为赶进度，所以直接缓存了图片（囧），然后将图片地址发出去。

过后想了下完全可以转成字符串发送过去。

方法如下：

验证码图片

public BufferedImage getImage() throws IOException{
    int width = 60;
    int height = 32;
    //create the image
    BufferedImage image =  new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    Graphics g = image.getGraphics();

    // set the background color
    g.setColor(new Color(0xDCDCDC));
    g.fillRect(0, 0, width, height);
    // draw the border
    g.setColor(Color.black);
    g.drawRect(0, 0, width - 1, height - 1);
    // create a random instance to generate the codes
    Random rdm = new Random();
    String hash1 = Integer.toHexString(rdm.nextInt());
    // make some confusion
    for(int i = 0; i < 50; i++){
        int x = rdm.nextInt(width);
        int y = rdm.nextInt(height);
        g.drawOval(x, y, 0, 0);
    }
    // generate a random code
    String capstr = hash1.substring(0, 4);

    g.setColor(new Color(0, 100, 0));
    g.setFont(new Font("Candara", Font.BOLD, 24));
    g.drawString(capstr, 8, 24);
    g.dispose();

    return image;
}

JSP中直接输出

ImageIO.write(image, "JPEG", response.getOutputStream()); 

转成字符串的工具方法

public static byte[] object2byteArray(Object object){
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    ObjectOutputStream objectOutputStream = null;
    byte[] bytes = null;

    try{
        objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
        objectOutputStream.writeObject(object);
        bytes = byteArrayOutputStream.toByteArray();

        byteArrayOutputStream.close();
        objectOutputStream.close();
        return bytes;
    } catch(IOException e){
        e.printStackTrace();
    }
    return null;
}

测试方法

@Test
public void run() throws IOException{
    byte[] bytes = object2byteArray(getImage());
    String str = Base64.getEncoder().encodeToString(bytes);
    System.out.println(str);
}

但是，行不通！！！因为BufferedImage没有实现序列化接口，囧囧有神~

解决办法

/**
 * 这个类，纯粹为了实现序列化接口！
 */
public class MyBufferedImage extends BufferedImage implements Serializable {
    public MyBufferedImage(int width, int height, int imageType){
        super(width, height, imageType);
    }

    public MyBufferedImage(int width, int height, int imageType, IndexColorModel cm){
        super(width, height, imageType, cm);
    }

    public MyBufferedImage(ColorModel cm, WritableRaster raster, boolean isRasterPremultiplied, Hashtable<?, ?> properties){
        super(cm, raster, isRasterPremultiplied, properties);
    }
}

然后

public MyBufferedImage getImage() throws IOException{
    int width = 60;
    int height = 32;
    //create the image
    MyBufferedImage image =  new MyBufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    Graphics g = image.getGraphics();

    // set the background color
    g.setColor(new Color(0xDCDCDC));
    g.fillRect(0, 0, width, height);
    // draw the border
    g.setColor(Color.black);
    g.drawRect(0, 0, width - 1, height - 1);
    // create a random instance to generate the codes
    Random rdm = new Random();
    String hash1 = Integer.toHexString(rdm.nextInt());
    // make some confusion
    for(int i = 0; i < 50; i++){
        int x = rdm.nextInt(width);
        int y = rdm.nextInt(height);
        g.drawOval(x, y, 0, 0);
    }
    // generate a random code
    String capstr = hash1.substring(0, 4);

    g.setColor(new Color(0, 100, 0));
    g.setFont(new Font("Candara", Font.BOLD, 24));
    g.drawString(capstr, 8, 24);
    g.dispose();

    return image;
}

现在再执行测试就OK啦。