在servlet中使用bean [英] Using beans in servlets

问题描述

我有一个jsp页面(index.jsp)，其表单带有两个文本字段用户名和密码，例如.

I has a jsp page (index.jsp) with a form with two text fileds username and password like.

 <form action="MyClass">
        <input type="text" name="username" id="username" />
        <input type="password" name="password" id="password" />
        <input type="submit" />
  </form>

在提交表单时，我正在调用servlet.我知道我们可以使用请求方法来获取输入的用户名和密码值，

On form submition i am invocking a servlet. I know that we can get the entered username and password values by using request methods,

  request.getParameter("username");
  request.getParameter("password");

但是我不想使用它们，相反，我想将这些值存储在一个名为BeanClass的bean中，并且希望从sevlet中的bean中检索值.我怎么得到它?

But i don't want to use them , instead i want to store these values in a bean called BeanClass and i want to retrieve values from the bean in the sevlet. How can i get it??

推荐答案

您必须使用<jsp:useBean/>操作在request或session范围的实例化BeanClass实例化docs.oracle.com/javaee/1.3/tutorial/doc/JSPIntro11.html"rel =" nofollow> JSP .

You have to use <jsp:useBean/> action to instantiate the BeanClass with request or session scope in JSP.

示例-EmpServlet.java

Sample - EmpServlet.java

package com.me;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class EmpServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
         PrintWriter pw=response.getWriter();
         Emp emp=(Emp)request.getAttribute("emp");
         pw.print(emp);
    }
}

Emp.java:Emp bean

Emp.java : Emp bean

package com.me;
public class Emp {
    private int age;
    private String name;
    public Emp() {
        name="";
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public boolean valid()
    {
        return age!=0 && name.length()!=0;
    }
    @Override
    public String toString() {
        return "Emp{" + "age=" + age + ", name=" + name + '}';
    }
}

emp.jsp(查看)

emp.jsp (view)

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib  prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<jsp:useBean id="emp" class="com.me.Emp" scope="request">
    <jsp:setProperty name="emp" property="*"/>
</jsp:useBean>

<c:if test="${emp.valid()}">
    <jsp:forward page="emp"/>
</c:if>
<form method="post" action="emp.jsp">
    <br/><input type="text" name="age"/>
    <br/><input type="text" name="name"/>
    <br/><input type="submit"/>
</form>

web.xml

<servlet>
    <servlet-name>EmpServlet</servlet-name>
    <servlet-class>com.me.EmpServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>EmpServlet</servlet-name>
    <url-pattern>/emp</url-pattern>
</servlet-mapping>

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