servlet3.0注解@WebInitParam和@WebServlet

Posted 2020-10-04 stAr_1

转自：http://blog.csdn.net/qq924862077/article/details/52883973?locationNum=2&fps=1

在以前的servlet中我们初始化一些参数都是配置在web.xml中的，自从servlet3.0之后给我们提供了注解@WebServlet和@WebInitParam，@WebServlet是用来配置servlet的属性的，@WebInitParam是用来配置一些初始化属性的。

@WebServlet和@WebInitParam使用如下：

package roseindia.net;  
import java.io.IOException;  
import java.io.PrintWriter;  
import javax.servlet.ServletConfig;  
import javax.servlet.ServletException;  
import javax.servlet.annotation.WebServlet;  
import javax.servlet.annotation.WebInitParam;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
  
@WebServlet(  
    name = "WebInitParamExample", urlPatterns = {"/hello"}  
    ,initParams = {  
    @WebInitParam(name= "Site :", value="http://roseindia.net"),  
    @WebInitParam(name= "Rose", value= "India"),  
    }  
)  
public class WebInitParamExample extends HttpServlet{  
    public void doGet(HttpServletRequest request, HttpServletResponse response)  
    throws ServletException, IOException  
    {  
        response.setContentType("text/html");  
        PrintWriter out = response.getWriter();  
        out.println("<h2>Init Param Servlet Example</h2>");  
        ServletConfig config= getServletConfig();  
        String pValue= config.getInitParameter("Site :");  
        out.println("Param Value : "+pValue);  
        String pValue1= config.getInitParameter("Rose");  
        out.println("<br>Param Value : "+pValue1);  
        out.close();  
    }  
}  

如果在web.xml中配置则如下：

<?xml version="1.0" encoding="UTF-8"?>  
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">  
    <display-name>servletAnnotationExample</display-name>  
    <servlet>  
        <servlet-name>WebInitParamExample</servlet-name>  
        <servlet-class>roseindia.net.WebInitParamExample</servlet-class>  
        <init-param>  
            <param-name>Site :</param-name>  
            <param-value>http://roseindia.net</param-value>  
        </init-param>  
    </servlet>  
    <servlet-mapping>  
        <servlet-name>WebInitParamExample</servlet-name>  
        <url-pattern>/hello</url-pattern>  
    </servlet-mapping>  
</web-app>