Java EE基礎-request對象中方法含義

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>

 

瀏覽器首次發送請求后經過Http協議在服務器端Servlet執行順序：構造方法->init方法->service方法->doGet方法(若是Post請求則先經過doPost方法,這是傳下來的習慣)->destory方法(此方法是在服務器關閉時才會調用)

在此請求時只是經過service、doGet方法。

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

TestServlet源碼：

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());     //應用名稱     /qq
System.out.println("getAuthType: "+request.getAuthType());     //認證類型     null
System.out.println("getCharacterEncoding: "+request.getCharacterEncoding());    //得到HTTP請求字符編碼,若沒指定返回null    UTF-8
System.out.println("getContentType: "+request.getContentType());     //HTTP請求類型     application/x-www-form-urlencoded
Enumeration enume = request.getHeaderNames();
//遍歷
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映射之后的路徑     null
System.out.println("getLocalPort: "+request.getLocalPort());     //訪問端口     8080
System.out.println("getMethod: "+request.getMethod());     //獲取請求方式。doPost     POST
System.out.println("getPathTranslated: "+request.getPathTranslated());     //暫不明了。。。     null
System.out.println("getQueryString: "+request.getQueryString());     //url所帶參數     flag=login&tag=qq
System.out.println("getRemoteUser: "+request.getRemoteUser());     //單點登錄驗證用戶是否登錄 null
System.out.println("getRequestedSessionId: "+request.getRequestedSessionId());    //請求被記錄在Session     A267E0ACCC3A85F76AF6ECEC0A8EAE4D
System.out.println("getRequestURI: "+request.getRequestURI());     //應用請求路徑     /qq/servlet/TestServlet.do(注意斜杠“/”)
System.out.println("getRequestURL: "+request.getRequestURL().toString());     //完整路徑 http://localhost:8080/qq/servlet/TestServlet.do
System.out.println("getServletPath: "+request.getServletPath());     //servlet請求路徑     /servlet/TestServlet.do
System.out.println("getSession: "+request.getSession());     //獲取Session如果沒有則創建一個新的Session org.apache.catalina.session.StandardSessionFacade@6b3fc7
System.out.println("getSession(boolean): "+request.getSession(true));     //獲取Session如果沒有若參數為true則創建新的Sesion org.apache.catalina.session.StandardSessionFacade@6b3fc7
System.out.println("getSession(boolean): "+request.getSession(false));     //獲取Session如果沒有若參數為true則創建新的Sesion org.apache.catalina.session.StandardSessionFacade@6b3fc7
System.out.println("getUserPrincipal: "+request.getUserPrincipal());     //得到認證用戶     null    
System.out.println("isUserInRole: "+request.isUserInRole("maomao"));     //判斷role用戶是否存在     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");
}

}