添加Axios请求

src/com/landaiqing/filter/UserSessionFilter.java

@@ -19,7 +19,7 @@ import java.io.IOException;
  */
 @WebFilter("/*")// 过滤器所有的请求
 public class UserSessionFilter implements Filter {
-    private String[] excludeUrls = new String[]{"/login", "/register", "/VerifycodeServlet"};
+    private String[] excludeUrls = new String[]{"/login", "/register", "/VerifycodeServlet","/ExUserNameServlet"};
 
     @Override
     public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

src/com/landaiqing/servlet/ExUserNameServlet.java

@@ -0,0 +1,42 @@
+package com.landaiqing.servlet;
+
+
+import com.landaiqing.entity.UserEntity;
+import com.landaiqing.service.UserService;
+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;
+import java.io.PrintWriter;
+
+/**
+ * http://localhost:8080/mayikt_session_war_exploded/exUserNameServlet?name=1
+ * @author 余胜军
+ * @ClassName ExUserNameServlet
+ * @qq 644064779
+ * @addres www.mayikt.com
+ * 微信:yushengjun644
+ */
+@WebServlet("/exUserNameServlet")
+public class ExUserNameServlet extends HttpServlet {
+
+    private UserService UserService = new UserService();
+
+    @Override
+    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        resp.setContentType("text/html;charset=utf-8");
+        //1.获取到用户输入的userName参数值
+        String userName = req.getParameter("userName");
+        //2.调用数据库根据userName查询用户名称是否存在
+        UserEntity mayiktUserEntity = UserService.findByUserName(userName);
+        PrintWriter writer = resp.getWriter();
+        if (mayiktUserEntity != null) {
+            writer.print("该用户" + userName + "已经存在的 无法注册!");
+        }
+        writer.close();
+    }
+}
+