Servlets servelinit参数返回null
我试图通过web.xml文件将一些init param值加载到serevlet中,但它们始终显示为null。我有两个上下文参数,很好用。有人知道我做错了什么吗 这是我在应用程序中使用的web.xml文件Servlets servelinit参数返回null,servlets,jakarta-ee,Servlets,Jakarta Ee,我试图通过web.xml文件将一些init param值加载到serevlet中,但它们始终显示为null。我有两个上下文参数,很好用。有人知道我做错了什么吗 这是我在应用程序中使用的web.xml文件 <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLS
<?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_3_1.xsd"
version="3.1"
>
<display-name>Hello World Application</display-name>
<servlet>
<servlet-name>contextxParameterServlet</servlet-name>
<servlet-class>com.wrox.HelloServlet</servlet-class>
<init-param>
<param-name>database</param-name>
<param-value>CustomerSupport</param-value>
</init-param>
<init-param>
<param-name>server</param-name>
<param-value>10.0.12.5</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>contextxParameterServlet</servlet-name>
<url-pattern>/contextParameters</url-pattern>
</servlet-mapping>
<context-param>
<param-name>settingOne</param-name>
<param-value>foo</param-value>
</context-param>
<context-param>
<param-name>settingTwo</param-name>
<param-value>bar</param-value>
</context-param>
<servlet>
<servlet-name>servletParameterServlet</servlet-name>
<servlet-class>com.wrox.initParams</servlet-class>
<init-param>
<param-name>database</param-name>
<param-value>CustomerSupport</param-value>
</init-param>
<init-param>
<param-name>server</param-name>
<param-value>10.0.12.5</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>servletParameterServlet</servlet-name>
<url-pattern>/servletParameter</url-pattern>
</servlet-mapping>
</web-app>
Hello World应用程序
contextxParameterServlet
com.wrox.HelloServlet
数据库
客户支持
服务器
10.0.12.5
1.
contextxParameterServlet
/上下文参数
设置一
福
第二组
酒吧
servletParameterServlet
com.wrox.initParams
数据库
客户支持
服务器
10.0.12.5
servletParameterServlet
/servletParameter
这是映射到servletParameterServlet的页面
package com.wrox;
import javax.servlet.http.HttpServlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.List;
public class initParams extends HttpServlet{
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
ServletContext c = this.getServletContext();
PrintWriter writer = response.getWriter();
Enumeration<String> temp = c.getInitParameterNames();
while(temp.hasMoreElements()) {
writer.append(temp.nextElement());
}
writer.append("database: ").append(c.getInitParameter("database"))
.append(", server: ").append(c.getInitParameter("server"));
}
@Override
public void init(ServletConfig config) throws ServletException
{
super.init(config);
System.out.println("Servlet " + this.getServletName() + " has started.");
}
@Override
public void destroy() {
System.out.println("Servlet " + this.getServletName() + " has stopped.");
}
}
package com.wrox;
导入javax.servlet.http.HttpServlet;
导入javax.servlet.ServletConfig;
导入javax.servlet.ServletContext;
导入javax.servlet.ServletException;
导入javax.servlet.annotation.WebInitParam;
导入javax.servlet.annotation.WebServlet;
导入javax.servlet.http.HttpServletRequest;
导入javax.servlet.http.HttpServletResponse;
导入java.io.IOException;
导入java.io.PrintWriter;
导入java.util.Enumeration;
导入java.util.List;
公共类initParams扩展了HttpServlet{
@凌驾
受保护的void doGet(HttpServletRequest请求、HttpServletResponse响应)
抛出ServletException、IOException
{
ServletContext c=this.getServletContext();
PrintWriter=response.getWriter();
枚举温度=c.getInitParameterNames();
while(temp.hasMoreElements()){
writer.append(temp.nextElement());
}
writer.append(“数据库”).append(c.getInitParameter(“数据库”))
.append(,server:).append(c.getInitParameter(“server”);
}
@凌驾
public void init(ServletConfig config)抛出ServletException
{
super.init(config);
System.out.println(“Servlet”+this.getServletName()+“已启动”);
}
@凌驾
公共空间销毁(){
System.out.println(“Servlet”+this.getServletName()+“已停止”);
}
}
按照您初始化事物的方式,我认为您所寻找的应该在
this.getServletConfig().getInitParameter("foo");
一般来说,servlet上下文由JVM中的servlet共享,但该对象存在于特定servlet的servlet配置中,而
则存在于servlet配置中。
有关更多详细信息,我强烈建议您阅读这些文档。按照您初始化内容的方式,我认为您正在寻找的内容应该可以在
this.getServletConfig().getInitParameter("foo");
一般来说,servlet上下文由JVM中的servlet共享,但该对象存在于特定servlet的servlet配置中,而
则存在于servlet配置中。
关于更多的细节,我强烈建议阅读这些文档