如何使用 apache tomcat servlet 导航到另一个 html 文件并发送 jinja 变量？

Question

使用 flask python 来渲染另一个模板并在获取请求时发送 jinja 变量，您可以简单地执行以下操作：

@app.route("/login", methods=["GET", "POST"])
def login():
    # User reached route via POST (as by submitting a form via POST)
    if request.method == "POST":
        # Ensure username was submitted
        username = request.form.get("username"):
        password = request.form.get("password"):
        # Redirect user to home page
        return render_template("home.html", username=username)

    # User reached route via GET
    else:
        return render_template("login.html")

在 Java 上使用 tomcat Servlets 的等价物是什么？

Answer 1

使用 Servlet 需要两部分：配置文件 (web.xml) 和 Servlet 代码。

1. 在web.xml中设置配置：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>Servlet Example</display-name>
  <welcome-file-list>
    <!-- you will want to take a look at jsp as well --> 
    <welcome-file>login.jsp</welcome-file>
  </welcome-file-list>

  <servlet>
    <servlet-name>Login Servlet</servlet-name>
    <!-- dont forget to put the canonical name, including the package name -->
    <servlet-class>com.example.LoginServlet</servlet-class>
  </servlet>
</web-app>

1. 然后你编写 servlet：

   package com.example;
   public class LoginServlet extends HttpServlet {
   
   // GET
   protected void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
       response.sendRedirect("index.jsp");
   }
   
   // POST
   protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
       String username = request.getParameter("username");
       String password = request.getParameter("password");
   
       // method credentialsOk validate the user/password
       if(credentialsOk(username, password)){
           response.sendRedirect("home.jsp");
       }else{
           response.sendRedirect("login.jsp");
       }
    } 
   

   }

看这里的 Servlet 介绍：https://www.baeldung.com/intro-to-servlets