Servlet中的属性介绍

1. Servlet中的属性
2. 属性特定的方法
3. 设置和获取属性的ServletContext示例
4. ServletConfig和ServletContext之间的区别

Servlet中的属性是可以从以下范围之一设置, 获取或删除的对象：

1. 请求范围
2. 会话范围
3. 适用范围

Servlet程序员可以使用属性将信息从一个Servlet传递到另一个。就像将对象从一个类传递到另一个类一样, 这样我们可以一次又一次地重用同一对象。

ServletRequest, HttpSession和ServletContext接口的特定于属性的方法

设置和获取属性的ServletContext示例

DemoServlet1.java

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class DemoServlet1 extends HttpServlet{
public void doGet(HttpServletRequest req, HttpServletResponse res)
{
try{

res.setContentType("text/html");
PrintWriter out=res.getWriter();

ServletContext context=getServletContext();
context.setAttribute("company", "IBM");

out.println("Welcome to first servlet");
out.println("<a href='servlet2'>visit</a>");
out.close();

}catch(Exception e){out.println(e);}

}}

DemoServlet2.java

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class DemoServlet2 extends HttpServlet{
public void doGet(HttpServletRequest req, HttpServletResponse res)
{
try{

res.setContentType("text/html");
PrintWriter out=res.getWriter();

ServletContext context=getServletContext();
String n=(String)context.getAttribute("company");

out.println("Welcome to "+n);
out.close();

}catch(Exception e){out.println(e);}
}}

web.xml

<web-app>

<servlet>
<servlet-name>s1</servlet-name>
<servlet-class>DemoServlet1</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>s1</servlet-name>
<url-pattern>/servlet1</url-pattern>
</servlet-mapping>

<servlet>
<servlet-name>s2</servlet-name>
<servlet-class>DemoServlet2</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>s2</servlet-name>
<url-pattern>/servlet2</url-pattern>
</servlet-mapping>

</web-app>

ServletConfig和ServletContext之间的区别