【JavaWeb】 ServletConfig

最新推荐文章于 2023-07-21 14:18:41 发布

dzp443366

最新推荐文章于 2023-07-21 14:18:41 发布

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本文链接：https://blog.youkuaiyun.com/dzp443366/article/details/50352171

本文详细介绍了如何在Web.xml文件中配置Servlet，并通过代码示例展示了如何使用ServletConfig来获取初始化参数，最终实现输出参数值的功能。

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在Web.xml上的代码，作用配置Servlet

<servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>ServletDemo4</servlet-name>
    <servlet-class>cn.itcast.domain.ServletDemo4</servlet-class>
    <init-param>
    	<param-name>data1</param-name>
    	<param-value>1111</param-value>
    </init-param>
    <init-param>
    	<param-name>data2</param-name>
    	<param-value>2222</param-value>
    </init-param>
    <init-param>
    	<param-name>data3</param-name>
    	<param-value>3333</param-value>
    </init-param>
    <init-param>
    	<param-name>data4</param-name>
    	<param-value>4444</param-value>
    </init-param>
  </servlet>

ServletDemo4的代码如下

package cn.itcast.domain;


import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;


import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class ServletDemo4 extends HttpServlet {


<span style="white-space:pre">	</span>/**
<span style="white-space:pre">	</span> * Constructor of the object.
<span style="white-space:pre">	</span> */
<span style="white-space:pre">	</span>public ServletDemo4() {
<span style="white-space:pre">		</span>super();
<span style="white-space:pre">	</span>}
<span style="white-space:pre">	</span>public void doGet(HttpServletRequest request, HttpServletResponse response)
<span style="white-space:pre">			</span>throws ServletException, IOException {


<span style="white-space:pre">		</span>response.setContentType("text/html");
<span style="white-space:pre">		</span>PrintWriter out = response.getWriter();
<span style="white-space:pre">		</span>String value =this.getServletConfig().getInitParameter("data");
<span style="white-space:pre">		</span>out.println(value);
<span style="white-space:pre">		</span>Enumeration e = this.getServletConfig().getInitParameterNames();
<span style="white-space:pre">		</span>while(e.hasMoreElements()){
<span style="white-space:pre">			</span>String name = (String) e.nextElement();
<span style="white-space:pre">			</span>String value1= this.getServletConfig().getInitParameter(name);
<span style="white-space:pre">			</span>out.println(name+"="+value1);
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>out.flush();
<span style="white-space:pre">		</span>out.close();
<span style="white-space:pre">	</span>}

打印结果为:data1=1111 data2=2222 data3=3333 data4=4444

问:this.getServletConfig().getInitParameter();是什么东西，怎么构成

就是MyEclipse在创建Servlet写了函数，有把ServletConfig封装进去.

如下图的封装