JSP中传递参数方式之参数列表

偏执的太偏执、 2022-12-28 00:40 132阅读 0赞

### 参数列表 ###

*  一、form表单
 *  二、a标签
 *  三、jsp:forward
 *  四、取参数
 *  五、取web.xml定义的参数Filter
 *   *  5.1在web.xml中定义参数
     *  5.2在servlet中取参数

# 一、form表单 #

# 二、a标签 #

//单个参数：<a href="地址？参数名=值"></a>，
    
    //多个参数用&隔开：<a href="地址?参数1=值&参数2=值"></a>
    <a href="demo02.jsp?name=zhangsan&age=5">demo02</a>

# 三、jsp:forward #

把请求转到一个新的页面

<jsp:forward page=“new URL”>

forward动作用于将控制权从JSP页面传递给本地服务器的另一个位置。丢弃当前页面生成的任何内容，并在替换位置上重新处理请求。forward标签只有一个page属性。page属性包含的是一个相对URL ，可以是HTML页面、JSP页面或者是Servlet的url-pattern。page的值既可以直接给出，也可以在请求的时候动态计算，通过表达式来实现，如：

<jsp:forward page=’<%=“new”+newNo+".html"%>’ >

此标签在传递页面的控制权到另外的页面的时候，可以把相应的参数值传递到目的页面。如果需要传递参数，使用<jsp:param >标签，注意这时必须要使用对标签。把<jsp:param >标签包含在里面。

<jsp:forward page="demo02.jsp">
        <jsp:param name="" value=""/>
    </jsp:forward>

# 四、取参数 #

JSP

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
    ${
        param.name}<br>
    ${
        param.pwd}<br>
    ${
        paramValues.hobby}<br>
    </body>
    </html>

servlet

import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/HelloServlet")
    public class HelloServlet extends HttpServlet {
        
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            String [] hobbies = req.getParameterValues("hobby");//可以使用req.getParameter（“参数名”）的方式获得。
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            doGet(req, resp);
        }
    }

# 五、取web.xml定义的参数Filter #

## 5.1在web.xml中定义参数 ##

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
             version="4.0">
        <filter>
            <filter-name>FilterServlet</filter-name>
            <filter-class>FilterServlet</filter-class>
            <init-param>
                <param-name>name</param-name>
                <param-value>seven</param-value>
            </init-param>
        </filter>
        <filter-mapping>
            <filter-name>FilterServlet</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>
    
    
          <context-param>
            <param-name>startTime</param-name>
            <param-value>9</param-value>
        </context-param>
    
        <context-param>
            <param-name>endTime</param-name>
            <param-value>22</param-value>
        </context-param>
    </web-app>

## 5.2在servlet中取参数 ##

import javax.servlet.ServletContext;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/HelloServlet")
    public class HelloServlet extends HttpServlet {
        
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
          
         	ServletContext application = request.getServletContext();
            String startTime = application.getInitParameter("startTime");
            String endTime = application.getInitParameter("endTime");
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            doGet(req, resp);
        }
    }