我尝试使用jsp获取url数据,因为我使用了jsp代码 String Url = pageContext.getServletConfig().getInitParameter("url").toString(); out.println(Url); web.xml中 servletservlet-nameIploginJSP/servlet-namejsp-file/Iplogin.jsp/jsp-fi
String Url = pageContext.getServletConfig().getInitParameter("url").toString();
out.println(Url);
web.xml中
<servlet>
<servlet-name>IploginJSP</servlet-name>
<jsp-file>/Iplogin.jsp</jsp-file>
<init-param>
<param-name>url</param-name>
<param-value>http://xxx.xxx.xxx.xxx:9000</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>IploginJSP</servlet-name>
<url-pattern>/Iplogin</url-pattern>
</servlet-mapping>
但是我显示了NullPointerException
我认为这将解决您的问题.更改web.xml文件后,请重新启动服务器.
web.xml中
<servlet>
<servlet-name>GetInitParam</servlet-name>
<jsp-file>/GetInitParam.jsp</jsp-file>
<init-param>
<param-name>url</param-name>
<param-value>hello</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>GetInitParam</servlet-name>
<url-pattern>/GetInitParam.jsp</url-pattern>
</servlet-mapping>
GetInitParam.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Example of getting init param</title>
</head>
<body>
<%!
String url= null;
public void jspInit() {
ServletConfig config = getServletConfig();
url= config.getInitParameter("url");
}
%>
<%
System.out.println(url);
%>
</body>
</html>
更新1
正如您在评论中要求访问所有jsp文件中的参数.
要访问您必须设置的所有jsp文件中的参数< context-param>在你的web.xml中
在web.xml中放入以下行
<context-param> <param-name>param1</param-name> <param-value>hello</param-value> </context-param>
您可以在jsp文件中以下列方式访问此参数：
<%
String param1=application.getInitParameter("param1");
System.out.println(param1);
%>
UPDATE2
web.xml中
<?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"> <context-param> <param-name>param1</param-name> <param-value>hello</param-value> </context-param> </web-app>
JSP文件
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Example of getting init param</title>
</head>
<body>
<%
String param1=application.getInitParameter("param1");
System.out.println(param1);
%>
</body>
</html>