J2EE技术规范(三)——Servlet的生命周期与接口
2012-12-03 20:16 218人阅读 评论(6) 收藏 举报
一、Servlet概览
什么是Servlet
(1) Servlet是提供基于协议的请求/响应服务的java类
(2) HTTP servlets是能被HTTP命令调用的servlet
二、理解servlet生命周期
Servlet生命周期通过Web容器控制
简单的概括这就分为四步:servlet类加载--->实例化--->服务--->销毁。
三、HTTP Servlet示例
(1)HTTP servlet继承自Httpservlet
(2)每一次请求都通过servlet容器调用服务方法
servlet示例:
- import javax.servlet.*;
- import javax.servlet.http.*;
- import java.io.*;
- public class MyServlet extends HttpServlet{
- public void service(HttpServletRequest req,HttpServletResponse res)throws
- ServletException,IOException{
- //process request,generate response
- }
- }
四、HttpServletRequest接口
HttpServletRequest接口代表了从客户来的请求处理HTTP请求的servlet示例:
- import javax.servlet.*;import javax.servlet.http.*;
- import java.io.*;
- public class MyServlet extends HttpServlet{
- public void service(HttpServletRequest req,HttpServletResponse res)throws
- ServletException,IOException{
- String server=req.getServerName();
- int port=req.getServerPort();
- Enumeration headers=req.getHeaders();
- String method=req.getMethod(0);
- String query=req.getQueryString();
- String param1=req.getParameter("p1");
- }
- }
五、HttpServletResponse接口
HttpServletResponse接口代表Servlet的响应
处理HTTP请求的servlet示例:
- import javax.servlet.*;import javax.servlet.http.*;
- import java.io.*;
- public class MyServlet extends HttpServlet{
- public void service(HttpServletRequest req,HttpServletResponse res)throws
- ServletException,IOException{
- res.setContentType("text/html");
- printWriter out=res.getWriter();
- res.setBufferSize(1024);
- res.addHeader("headerName","value");
- res.sendError(404,"error message");
- }
我们接下来看一个简单的servlet示例:
- import javax.servlet.*;
- import