添加图形验证码功能

src/com/hellogithub/filter/SessionFilter.java

@@ -14,7 +14,7 @@ import java.io.IOException;
  */
 @WebFilter("/system/*")// 过滤器所有的请求
 public class SessionFilter implements Filter {
-    private String[] excludeUrls = new String[]{""}; //过滤器排除的请求url 格式:”/login“
+    private String[] excludeUrls = new String[]{"/VerifycodeServlet"}; //过滤器排除的请求url 格式:”/login“
 
     /**
      * 过滤器

src/com/hellogithub/servlet/VerifycodeServlet.java

@@ -0,0 +1,39 @@
+package com.hellogithub.servlet;
+
+import com.hellogithub.utils.RandomValidateCode;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.annotation.WebServlet;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+
+import java.io.IOException;
+
+/**
+ * 前台验证码处点击刷新,发送到该servlet的请求,
+ * 该servlet调用生成验证码的工具类返回一个图像验证码
+ */
+@WebServlet(name = "VerifycodeServlet", urlPatterns = "/VerifycodeServlet")
+public class VerifycodeServlet extends HttpServlet {
+    private static final long serialVersionUID = 1L;
+
+    public void doGet(HttpServletRequest request, HttpServletResponse response)
+            throws ServletException, IOException {
+        response.setContentType("image/jpeg");//设置相应类型,告诉浏览器输出的内容为图片
+        response.setHeader("Pragma", "No-cache");//设置响应头信息，告诉浏览器不要缓存此内容
+        //做浏览器兼容
+        response.setHeader("Cache-Control", "no-cache");
+        response.setDateHeader("Expire", 0);
+        RandomValidateCode randomValidateCode = new RandomValidateCode();
+        try {
+            randomValidateCode.getRandcode(request, response);//输出图片方法
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    public void doPost(HttpServletRequest request, HttpServletResponse response)
+            throws ServletException, IOException {
+        doGet(request, response);
+    }
+}