web容器在启动的时候，它会为每个web程序都创建一个对应的ServletContext对象，他代表了当前的web应用；
* 共享数据
我在这个Sevlet中保存的数据数据 ，可以在另外一个servlet中拿到；
public class HelloServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // this.getInitParameter() 初始化参数 // this.getServletConfig() Servlet配置 // this.getServletContext() Servlet上下文 ServletContext context = this.getServletContext(); String username = "臧臧";//数据 context.setAttribute("username",username);//将一个数据保存在了ServlectContext中，名字为username，值 username } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
public class GetServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setCharacterEncoding("utf-8"); resp.setContentType("text/html"); ServletContext context = this.getServletContext(); Object username = (String)context.getAttribute("username"); resp.getWriter().print("名字"+username); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
<servlet> <servlet-name>hello</servlet-name> <servlet-class>com.zang.servlet.HelloServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>hello</servlet-name> <url-pattern>/hello</url-pattern> </servlet-mapping> <servlet> <servlet-name>getc</servlet-name> <servlet-class>com.zang.servlet.GetServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>getc</servlet-name> <url-pattern>/getc</url-pattern> </servlet-mapping>
测试访问结果
