JavaWeb将验证码转换为Base64格式字符串输出到前端

来源：互联网发布：matlab最优化算法例题编辑：程序博客网时间：2024/06/10 12:14

最近项目中有个需求,将验证码转换为base64格式字符串，输出到前端，以下作为笔记:

JavaWeb后端：

public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
response.setHeader("Pragma", "No-cache");

response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expire", 0);

HttpSession session = request.getSession();

BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();

g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));
g.setColor(getRandColor(110, 133));
//绘制干扰线
for(int i=0;i<=lineSize;i++){
drowLine(g);
}
//绘制随机字符
String randomString = "";
for(int i=1;i<=stringNum;i++){
randomString=drowString(g,randomString,i);
}
session.removeAttribute(RANDOMCODEKEY);
session.setAttribute(RANDOMCODEKEY, randomString);
g.dispose();
try {
Base64.Encoder base64 = Base64.getEncoder();
ByteArrayOutputStream output = new ByteArrayOutputStream();
//ImageIO.write(image, "JPEG", response.getOutputStream());//将图片直接输出到前端
ImageIO.write(image, "JPEG", output);
String imgsrc = base64.encodeToString(output.toByteArray());
// Base64Util.createImageByBase64(imgsrc,"F:\\temp\\randomIamge.png");//输出到本地
// PrintWriter pt = response.getWriter();
// pt.print(imgsrc);
// pt.close();

Map<String,Object> result = new HashMap<String, Object>();
result.put("image_base64", imgsrc);
response.getWriter().write(JSONObject.valueToString(result).toString());
response.getWriter().close();

} catch (Exception e) {
e.printStackTrace();
}
}

核心是使用ByteArrayOutputStream output = new ByteArrayOutputStream();流将图片对象转换为字节数组，再使用JDK自带的Base64.Encoder进行转换。

前端加载图片：

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