Obtain and configure the initialization parameters of the Servlet

There are two types of initialization parameters for configuring the Servlet:

1. Use the annotation method @WebServlet

To set the initialization parameters of the Servlet in the annotation, you need to configure the values ​​of name, urlPatterns, and inintParams

name is equivalent to <servlet-name> in the web.xml configuration file

urlPatterns is equivalent to <url-pattern>, used to specify the URL of the servlet

inintParams is equivalent to <init-pattern>, used to specify a set of servlet initialization parameters

@WebServlet(
name="/initParameterServlet", //name="/自定义"
urlPatterns={"/initParameterServlet"}, //urlPatterns={"/自定义"}
initParams={
@WebInitParam
(name="email",value = "123qq.com")  //name="设置的参数名"   value="设置的参数值"
})

If you need to configure multiple sets of parameters, you can do the following:

@WebServlet(
name="/InitParameterServlet",
urlPatterns={"/initParameterServlet"},
initParams={
@WebInitParam
(name="email",value = "[email protected]"),
@WebInitParam
(name="phone",value = "123456789"),
@WebInitParam
(name="参数名",value = "参数值")
})

The complete code of the servlet is as follows:

public class InitParameterServlet extends HttpServlet {

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		 ServletConfig config = this.getServletConfig();
		 String value = config.getInitParameter("email");
		 
		 String value1 = config.getInitParameter("phone");
		 PrintWriter writer = resp.getWriter();
		 writer.println("your email is:"+value);
		 writer.println("your phone munber is:"+value1);
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doGet(req, resp);
	}

}

Input in the address bar: http://hostname:port number/project name/value set by urlPatterns

The implementation is as follows:

2. Configure in the Web.xml file

<servlet-class>: The class address of the registered servlet, that is: package name.class name

Configuration initialization parameters are in

<context-param>

<param-name>Attribute name</param-name>
 <param-value>Attribute value</param-value> 

</context-param>

Write as many <context-param>s as you need to configure....</context-param>

Add the following code section to the Web.xml configuration file:

    <servlet>
		<servlet-name>InitParameterServlet1</servlet-name>
		<servlet-class>com.servlet.InitParameterServlet1</servlet-class>
    </servlet>
	<servlet-mapping>
		<servlet-name>InitParameterServlet1</servlet-name>
		<url-pattern>/initParameterServlet1</url-pattern>
	</servlet-mapping> 
	<!-- 配置InitParameterServlet1整个web应用的初始化参数 -->
	<context-param>
		<param-name>email</param-name>
		<param-value>123qq.com</param-value>
	</context-param>

The complete code of the servlet is as follows:

public class InitParameterServlet1 extends HttpServlet{

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		ServletContext servletContext = getServletContext();
		String initParameter = servletContext.getInitParameter("email");
        String initParameter1 = servletContext.getInitParameter("phone");
		
		//后台
		System.out.println("your email is:" + initParameter);
		System.out.println("your phone number is:" + initParameter1);

		//浏览器
		PrintWriter writer = resp.getWriter();
		writer.println("your email is" + initParameter);
        writer.println("your phone number  is" + initParameter1);
	}
}

Same effect as above

For reference only, please forgive me if there are any deficiencies.