JavaWeb_通過xml配置文件配置servlet訪問路徑

本文轉載自查看原文 2019-01-21 21:19 5722 JavaWeb

Servlet兩種訪問路徑

　　一、在Servlet類中通過設置@WebServlet標注訪問

　　二、在web.xml中編寫配置文件

　　第一種能比較直觀看到Servlet路徑，但當項目發布后不好再對Servlet路徑進行修改

　　第二種把Servlet路徑在web.xml中配置，能更好對Servlet路徑進行配置的修改

　　利用Servlet處理注冊登錄請求　　傳送門

　　項目結構

package com.Gary.servlet;

import java.io.IOException;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.Gary.model.User;
import com.Gary.util.DBUtil;


@WebServlet("/login_do")
public class LoginServlet extends HttpServlet {
   
    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        User user = DBUtil.verifyAccount(username,password);
        if(user==null){
//            out.println("登錄失敗，用戶名或密碼錯誤");
            request.setAttribute("message","登錄失敗，用戶名或密碼錯誤");
            request.getRequestDispatcher("login.jsp").forward(request,response);
        }else{
//            out.println("登錄成功");
            int number = 0;
            //獲取到application對象
            ServletContext application = this.getServletContext();
            //第一次登錄用戶時if不瞞住,number=0
            if(application.getAttribute("userNumber")!=null){
                number = (Integer)application.getAttribute("userNumber");
            }
            
            //登錄過一個用戶后在原基礎number上進行++
            number++;

            application.setAttribute("userNumber",number);
            
            //通過seesion的setAttribute傳遞數據
            request.getSession().setAttribute("user", user);
            //登錄請求的轉發,將數據傳遞給personCenter.jsp頁面
            request.getRequestDispatcher("personCenter.jsp").forward(request,response);
        }
    }

}

LoginServlet.java

package com.Gary.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.Gary.util.DBUtil;


//@WebServlet("/register_do")
public class RegisterServlet extends HttpServlet {

    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        int age = Integer.parseInt(request.getParameter("age"));
        String sex = request.getParameter("sex");

        boolean isSuccess = DBUtil.addUser(username,password,age,sex);

        //使用請求轉發
        if(isSuccess){
            request.setAttribute("message", "注冊成功，請登錄");
            //通過getRequestDispatcher傳遞路徑將請求轉發給login.jsp
            request.getRequestDispatcher("login.jsp").forward(request,response);
        }else{
            request.setAttribute("message", "注冊失敗，用戶名重復");
            //通過getRequestDispatcher傳遞路徑將請求轉發給login.jsp
            request.getRequestDispatcher("register.jsp").forward(request,response);
        }
        
    }

}

RegisterServlet.java

<%@page import="com.Gary.model.User"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Insert title here</title>
</head>
<body>
<%
Object o = session.getAttribute("user");
if(o!=null){
    User user = (User)o;
    out.println("當前登錄用戶："+user.getUsername()+"<br/>");
}
%>

<%
Object msg = request.getAttribute("message");
if(msg!=null)
    out.println(msg);
%>

登錄<hr>
<form action="login_do" method="post">
用戶名：<input type="text" name="username" /><br/>
密碼：<input type="password" name="password" /><br/>
<input type="submit" value="登錄" />
</form>
</body>
</html>

<%@page import="com.Gary.model.User"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Insert title here</title>
</head>
<body>
<%
Object o = session.getAttribute("user");
if(o!=null){
    User user = (User)o;
    out.println("當前登錄用戶："+user.getUsername()+"<br/>");
}
%>

<%
Object msg = request.getAttribute("message");
if(msg!=null)
    out.println(msg);
%>

<form action="register_do" method="post">
用戶名：<input type="text" name="username" /><br/>
密碼：<input type="password" name="password" /><br/>
年齡：<input type="text" name="age" /><br/>
性別： 男<input type="radio" name="sex" value="男" />女<input type="radio" name="sex" value="女" /><br/>
<input type="submit" value="注冊" />
</form>

</body>
</html>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
  version="3.1"
  metadata-complete="true">
  <!-- 配置servlet -->
    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.Gary.servlet.LoginServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>RegisterServlet</servlet-name>
        <servlet-class>com.Gary.servlet.RegisterServlet</servlet-class>
    </servlet>
    
    <!-- servlet路徑映射 -->
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/login_do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>RegisterServlet</servlet-name>
        <url-pattern>/register_do</url-pattern>
    </servlet-mapping>
</web-app>

web.xml

　　LoginServlet.java處理login.jsp登錄表單的請求

　　RegisterServlet.java處理register.jsp注冊表單的請求　　

第一種

　　通過在Servlet上設置@WebServlet標注，容器就會自動讀取當中的信息，@WebServlet告訴容器，如果請求的URL是"/xxxxxx"

　　LoginServlet.java中配置的路徑是login_do，在register.jsp的from表單中設置action也為login_do

　　由LoginServlet.java處理register.jsp的from表單提交的信息

@WebServlet("/login_do")
public class LoginServlet extends HttpServlet {
   
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        User user = DBUtil.verifyAccount(username,password);
        if(user==null){
//            out.println("登錄失敗，用戶名或密碼錯誤");
            request.setAttribute("message","登錄失敗，用戶名或密碼錯誤");
            request.getRequestDispatcher("login.jsp").forward(request,response);
        }else{
//            out.println("登錄成功");
            int number = 0;
            //獲取到application對象
            ServletContext application = this.getServletContext();
            //第一次登錄用戶時if不瞞住,number=0
            if(application.getAttribute("userNumber")!=null){
                number = (Integer)application.getAttribute("userNumber");
            }
            
            //登錄過一個用戶后在原基礎number上進行++
            number++;

            application.setAttribute("userNumber",number);
            
            //通過seesion的setAttribute傳遞數據
            request.getSession().setAttribute("user", user);
            //登錄請求的轉發,將數據傳遞給personCenter.jsp頁面
            request.getRequestDispatcher("personCenter.jsp").forward(request,response);
        }
    }

}

<form action="login_do" method="post">
用戶名：<input type="text" name="username" /><br/>
密碼：<input type="password" name="password" /><br/>
<input type="submit" value="登錄" />
</form>

第二種

　　通過web.xml配置文件進行配置

　　<servlet-name>中填寫項目中Servlet名字　　【可隨便填寫，用作后邊<servlet-mapping>映射url】

　　<servlet-class>中填寫項目中該Servlet路徑

　　<servlet-mapping>配置servlet-name和<url-pattern>地址映射

  <!-- 配置servlet -->
    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.Gary.servlet.LoginServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>RegisterServlet</servlet-name>
        <servlet-class>com.Gary.servlet.RegisterServlet</servlet-class>
    </servlet>
    
    <!-- servlet路徑映射 -->
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/login_do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>RegisterServlet</servlet-name>
        <url-pattern>/register_do</url-pattern>
    </servlet-mapping>

　　將com.Gary.servlet.LoginServlet路徑上的Servlet命名為LoginServlet，與后邊<servlet-mapping>中的<servlet-name>LoginServlet相匹配

　　【按住Ctrl+鼠標左鍵點擊<servlet-class>下的路徑可直接訪問對應Servlet下的路徑】

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