Java EE基础request对象中方法含义

web.xml配置：

<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>TestServlet</servlet-name>
<servlet-class>com.nubb.servlet.TestServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>TestServlet</servlet-name>
<url-pattern>/servlet/TestServlet.do</url-pattern>
</servlet-mapping>

浏览器首次发送请求后经过Http协议在服务器端Servlet执行顺序：构造方法->init方法->service方法->doGet方法(若是Post请求则先经过doPost方法,这是传下来的习惯)->destory方法(此方法是在服务器关闭时才会调用)

在此请求时只是经过service、doGet方法。

访问url：localhost:8080/qq/servlet/TestServlet.do?flag=true&tag=qq

TestServlet源码：

package com.nubb.servlet;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class TestServlet extends HttpServlet {

private static final Logger log = LoggerFactory.getLogger(TestServlet.class);
/**
* 
*/
private static final long serialVersionUID = 3995193730201556140L;

/**
* Constructor of the object.
*/
public TestServlet() {
super();
log.info("TestServlet");
System.out.println("TestServlet");
}

/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
log.info("destory");
System.out.println("destroy");
}

/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
* 
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
log.info("doGet");
System.out.println("doGet");
request.setCharacterEncoding("UTF-8");
System.out.println("getContextPath: "+request.getContextPath());     //应用名称     /qq
System.out.println("getAuthType: "+request.getAuthType());     //认证类型     null
System.out.println("getCharacterEncoding: "+request.getCharacterEncoding());    //得到HTTP请求字符编码,若没指定返回null    UTF-8
System.out.println("getContentType: "+request.getContentType());     //HTTP请求类型     application/x-www-form-urlencoded
Enumeration enume = request.getHeaderNames();
//遍历
System.out.println("HeaderNames");
while(enume.hasMoreElements()){
System.out.print(enume.nextElement().toString()+":");     //host:connection:content-length:cache-control:accept:origin:user-agent:content-type:referer:accept-encoding:accept-language:accept-charset:cookie
}
System.out.println("getHeaders(Referer): "+request.getHeader("Referer"));     //getHeaders(Referer): http://localhost:8080/qq/
System.out.println("getPathInfo: "+request.getPathInfo());     //servlet映射之后的路径     null
System.out.println("getLocalPort: "+request.getLocalPort());     //访问端口     8080
System.out.println("getMethod: "+request.getMethod());     //获取请求方式。doPost     POST
System.out.println("getPathTranslated: "+request.getPathTranslated());     //暂不明了。。。     null
System.out.println("getQueryString: "+request.getQueryString());     //url所带参数     flag=login&tag=qq
System.out.println("getRemoteUser: "+request.getRemoteUser());     //单点登录验证用户是否登录 null
System.out.println("getRequestedSessionId: "+request.getRequestedSessionId());    //请求被记录在Session     A267E0ACCC3A85F76AF6ECEC0A8EAE4D
System.out.println("getRequestURI: "+request.getRequestURI());     //应用请求路径     /qq/servlet/TestServlet.do(注意斜杠“/”)
System.out.println("getRequestURL: "+request.getRequestURL().toString());     //完整路径 http://localhost:8080/qq/servlet/TestServlet.do
System.out.println("getServletPath: "+request.getServletPath());     //servlet请求路径     /servlet/TestServlet.do
System.out.println("getSession: "+request.getSession());     //获取Session如果没有则创建一个新的Session org.apache.catalina.session.StandardSessionFacade@6b3fc7
System.out.println("getSession(boolean): "+request.getSession(true));     //获取Session如果没有若参数为true则创建新的Sesion org.apache.catalina.session.StandardSessionFacade@6b3fc7
System.out.println("getSession(boolean): "+request.getSession(false));     //获取Session如果没有若参数为true则创建新的Sesion org.apache.catalina.session.StandardSessionFacade@6b3fc7
System.out.println("getUserPrincipal: "+request.getUserPrincipal());     //得到认证用户     null    
System.out.println("isUserInRole: "+request.isUserInRole("maomao"));     //判断role用户是否存在     false



}

/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
* 
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
log.info("doPost");
System.out.println("doPost");
this.doGet(request, response);
}

@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
System.out.println("service");
super.service(req, resp);
}

/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
log.info("init");
System.out.println("init");
}

}