摘要:
下文使用Java代码常见的属性简介说明,如下所示:
Servlet属性应用范围:
Servlet属性用于在以下几个范围中获取和删除对象:
请求,会话,应用
在日常开发中,我们可以将一个Servlet传递到另一个Servlet中,
ServletRequest,HttpSession和ServletContext接口常见的四种属性方法
keyId | 方法 | 备注 |
---|---|---|
1 | public void setAttribute(String nameObject object) |
在应用程序范围内设置给定的对象。 |
2 | public Object getAttribute(String name) |
返回指定名称的属性。 |
3 | public Enumeration getInitParameterNames() |
以字符串对象的枚举形式返回上下文的初始化参数的名称。 |
4 | public void removeAttribute(String name) |
从Servlet上下文中删除给定名称的属性。 |
例:
Java ServletAttribute的示例
创建一个Servlet类
TestServlet1.java
package com.maomao365.servlet; import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class TestServlet1 extends HttpServlet { public void doGet(HttpServletRequest req HttpServletResponse res) { try { res.setContentType("text/html;charset=utf-8"); res.setCharacterEncoding("utf-8"); PrintWriter out = res.getWriter(); ServletContext context = getServletContext(); context.setAttribute("maomao365" "Test"); out.println("欢迎使用 servlet"); out.println("<a href='/servlet2'>预览</a>"); out.close(); } catch (Exception e) { e.printStackTrace(); } } }
创建第二个Servlet类
TestServlet2.java
package com.maomao365.servlet; import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class TestServlet2 extends HttpServlet { public void doGet(HttpServletRequest req HttpServletResponse res) { try { res.setContentType("text/html;charset=utf-8"); res.setCharacterEncoding("utf-8"); PrintWriter out = res.getWriter(); ServletContext context = getServletContext(); String n = (String) context.getAttribute("maomao365"); out.println("欢迎 " + n); out.close(); } catch (Exception e) { e.printStackTrace(); } } }
文件test.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>ServletAttribute</display-name> <servlet> <servlet-name>s1</servlet-name> <servlet-class>com.maomao365.servlet.TestServlet1</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>com.maomao365.servlet.TestServlet2</servlet-class> </servlet> <servlet-mapping> <servlet-name>s2</servlet-name> <url-pattern>/servlet2</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.html</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> </web-app>
启动Tomcat服务器,打开浏览器访问
http://localhost:8899/servletcontext/servlet1