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jsp - 如何在jsp中检索init参数

转载 作者:行者123 更新时间:2023-12-04 05:32:07 24 4
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我尝试使用jsp获取url数据,因为我使用jsp代码作为

  String Url = pageContext.getServletConfig().getInitParameter("url").toString();
out.println(Url);

web.xml
<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

最佳答案

我认为这可以解决您的问题。

更改web.xml文件后,请重新启动服务器。

web.xml

<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

如您在注释中询问的 to access parameters in all jsp files
要访问所有jsp文件中的参数,必须在 <context-param>中设置 web.xml
web.xml中添加以下行
<context-param>
<param-name>param1</param-name>
<param-value>hello</param-value>
</context-param>

您可以通过以下方式在 jsp文件中访问此参数:
<% 
String param1=application.getInitParameter("param1");
System.out.println(param1);
%>

更新2

web.xml
<?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>

关于jsp - 如何在jsp中检索init参数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/14973125/

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