HttpServlet


HttpServlet:

1).是一个Servlet，继承自GenericServlet.针对于HTTP协议所制定.

2).在service()方法中直接把ServletRequest和ServletResponse转为HttpServletRequest和HttpServletResponse 并调用 了重载的service(HttpServletRequest,HttpServletResponse)

在service(HttpServletRequest,HttpServletResponse)中获取了请求方式：request.getMethod().根据请求方式又创建了doXxx()方法(xxx为具体的请求方式，比如doGet,doPost

public class MyHttpServlet extends MyGenericServlet {

@Override

public void service(ServletRequest req, ServletResponse res)

throws ServletException, IOException {

if (req instanceof HttpServletRequest) {

HttpServletRequest request = (HttpServletRequest) req;

if (res instanceof HttpServletResponse) {

HttpServletResponse response = (HttpServletResponse) res;

service(request, response);

}

}

}

public void service(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// 1.获取请求方式

String method = request.getMethod();

// 2.根据请求方式在调用对应的处理方法

if ("GET".equalsIgnoreCase(method)) {

doGet(request, response);

} else if ("POST".equalsIgnoreCase(method)) {

doPost(request, response);

}

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// TODO Auto-generated method stub

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// TODO Auto-generated method stub

}

}

3)实际开发中，直接继承HttpServlet，并根据请求方式复写doXxx（）方法接口。

4)好处：直接有针对性的覆盖doXxx()方法；直接使用HttpServletRequest和HttpServletResponse，不再需要强转。