servlet配置多个路径访问,包括注解和xml,javaweb之过滤器,

过滤器

1.处理中文乱码

• xml配置实现

• web.xml

• <?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_4_0.xsd"
           version="4.0">
  
  
      <!--注册过滤器-->
      <filter>
          <filter-name>CharacterEncodingFilte</filter-name>
          <filter-class>com.ding.filter.CharacterEncodingFilte</filter-class>
      </filter>
  
      <filter-mapping>
          <filter-name>CharacterEncodingFilte</filter-name>
          <!--只要是/servlet下的所有请求，都会走这个过滤器-->
          <url-pattern>/servlet/*</url-pattern>
      </filter-mapping>
  
  
      <servlet>
          <servlet-name>ShowServlet</servlet-name>
          <servlet-class>com.ding.servlet.ShowServlet</servlet-class>
      </servlet>
  
      <!--经过过滤器-->
      <servlet-mapping>
          <servlet-name>ShowServlet</servlet-name>
          <url-pattern>/servlet/show</url-pattern>
      </servlet-mapping>
  
      <!--不经过过滤器-->
      <servlet-mapping>
          <servlet-name>ShowServlet</servlet-name>
          <url-pattern>/show</url-pattern>
      </servlet-mapping>
      
      <welcome-file-list>
          <welcome-file>shouye.jsp</welcome-file>
      </welcome-file-list>
  
  
  
  
  </web-app>
  

• Filter

• package com.ding.filter;
  
  import javax.servlet.*;
  import java.io.IOException;
  
  /**
   * @Description 过滤器处理乱码
   * @Author 丁帅帅
   * @Date 21/08/10 10:02
   * @Version 1.0
   */
  public class CharacterEncodingFilter implements Filter {
      @Override
      public void init(FilterConfig filterConfig) throws ServletException {
  
      }
  
      @Override
      public void doFilter(ServletRequest Request, ServletResponse Response, FilterChain filterChain) throws IOException, ServletException {
                 //处理中文乱码
                  Request.setCharacterEncoding("UTF-8");
                  Response.setCharacterEncoding("UTF-8");
                  Response.setContentType("text/html;charset=utf-8");
  
                  filterChain.doFilter(Request,Response);
      }
  
      @Override
      public void destroy() {
  
      }
  }
  
  

• servlet

• package com.ding.servlet;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  
  /**
   * @Description TODO
   * @Author 丁帅帅
   * @Date 21/08/10 10:11
   * @Version 1.0
   */
  public class ShowServlet extends HttpServlet {
  
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  
          resp.getWriter().write("你好 ，世界！");
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          super.doGet(req, resp);
      }
  }
  
  

• 注解实现

• Filter

• package com.ding.filter;
  
  import javax.servlet.*;
  import javax.servlet.annotation.WebFilter;
  import java.io.IOException;
  
  /**
   * @Description 过滤器处理乱码
   * @Author 丁帅帅
   * @Date 21/08/10 10:02
   * @Version 1.0
   */
  @WebFilter("/fun/*")
  public class CharacterEncodingFilter_2 implements Filter {
      @Override
      public void init(FilterConfig filterConfig) throws ServletException {
  
      }
  
      @Override
      public void doFilter(ServletRequest Request, ServletResponse Response, FilterChain filterChain) throws IOException, ServletException {
                 //处理中文乱码
                  Request.setCharacterEncoding("UTF-8");
                  Response.setCharacterEncoding("UTF-8");
                  Response.setContentType("text/html;charset=utf-8");
  
                  filterChain.doFilter(Request,Response);
      }
  
      @Override
      public void destroy() {
  
      }
  }
  
  

• package com.ding.servlet;
  
  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 java.io.IOException;
  
  /**
   * @Description TODO
   * @Author 丁帅帅
   * @Date 21/08/10 10:11
   * @Version 1.0
   */
  @WebServlet(urlPatterns = {"/fun","/funn"})
  public class ShowServlet_2 extends HttpServlet {
  
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  
          resp.getWriter().write("你好 ，世界！");
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          super.doGet(req, resp);
      }
  }
  
  

• pom

• <?xml version="1.0" encoding="UTF-8"?>
  <project xmlns="http://maven.apache.org/POM/4.0.0"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
      <modelVersion>4.0.0</modelVersion>
  
      <groupId>org.example</groupId>
      <artifactId>javaweb-filter</artifactId>
      <version>1.0-SNAPSHOT</version>
      <packaging>war</packaging>
      <properties>
          <maven.compiler.source>8</maven.compiler.source>
          <maven.compiler.target>8</maven.compiler.target>
      </properties>
  
      <dependencies>
          <!-- servlet3.0规范的坐标 -->
          <dependency>
              <groupId>javax.servlet</groupId>
              <artifactId>javax.servlet-api</artifactId>
              <version>3.1.0</version>
              <scope>provided</scope>
          </dependency>
  
          <!--jsp坐标-->
          <dependency>
              <groupId>javax.servlet.jsp</groupId>
              <artifactId>jsp-api</artifactId>
              <version>2.1</version>
              <scope>provided</scope>
          </dependency>
          <!-- JSTL表达式的依赖 -->
          <dependency>
              <groupId>javax.servlet.jsp.jstl</groupId>
              <artifactId>jstl</artifactId>
              <version>1.2</version>
          </dependency>
          <!-- standard标签库 -->
          <dependency>
              <groupId>taglibs</groupId>
              <artifactId>standard</artifactId>
              <version>1.1.2</version>
          </dependency>
          <!-- 数据库 -->
          <dependency>
              <groupId>mysql</groupId>
              <artifactId>mysql-connector-java</artifactId>
              <version>5.1.47</version>
          </dependency>
      </dependencies>
  
  
  
      <!--构建-->
      <build>
          <!--设置插件-->
          <plugins>
              <!--具体的插件配置-->
              <plugin>
                  <groupId>org.apache.tomcat.maven</groupId>
                  <artifactId>tomcat7-maven-plugin</artifactId>
                  <version>2.1</version>
                  <configuration>
                      <port>80</port>
                      <path>/</path>
                  </configuration>
              </plugin>
          </plugins>
      </build>
  
  </project>
  

2.验证用户登录

用户登录之后才能进入主页！用户注销后就不能进入主页了！

• login

• <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  <html>
  <head>
      <title>登录</title>
  </head>
  <body>
  <h1>登录</h1>
  <form action="/servlet/login">
      <input type="text" name="username">
      <input type="submit">
  </form>
  </body>
  </html>
  
  

• error

• <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  <html>
  <head>
      <title>error</title>
  </head>
  <body>
  <h1>错误</h1>
  <h3>没有权限，或用户名错误</h3>
  
  <a href="/login.jsp">返回登录页面</a>
  </body>
  </html>
  
  

• success

• <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  <html>
  <head>
      <title>Title</title>
  </head>
  <body>
  <h1>主页</h1>
  <p>
      <a href="/servlet/logout">注销</a>
  </p>
  </body>
  </html>
  
  

• LoginFilter

• package com.ding.filter;
  
  import com.ding.util.Constant;
  
  import javax.servlet.*;
  import javax.servlet.annotation.WebFilter;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  /**
   * @Description TODO
   * @Author 丁帅帅
   * @Date 21/08/11 00:14
   * @Version 1.0
   */
  @WebFilter("/sys/*")
  public class LoginFilter implements Filter {
      @Override
      public void init(FilterConfig filterConfig) throws ServletException {
  
      }
  
      @Override
      public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
          HttpServletRequest request = (HttpServletRequest) req;
          HttpServletResponse response = (HttpServletResponse) resp;
          //如果没有登录，则重定向到错误页面
          Object userSession = request.getSession().getAttribute(Constant.USER_SESSION);
          if (userSession == null) {
              response.sendRedirect("/error.jsp");
          }
          chain.doFilter(req, resp);
      }
  
      @Override
      public void destroy() {
  
      }
  }
  
  

• LoginServlet

• package com.ding.servlet;
  
  import com.ding.util.Constant;
  
  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 java.io.IOException;
  
  /**
   * @Description TODO
   * @Author 丁帅帅
   * @Date 21/08/10 23:50
   * @Version 1.0
   */
  @WebServlet("/servlet/login")
  public class LoginServlet extends HttpServlet {
  
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          //获取前端请求的参数
          String username = req.getParameter("username");
          if (username.equals("admin")) {
              //登录成功，保存sessionId到session中
              req.getSession().setAttribute(Constant.USER_SESSION, req.getSession().getId());
              //重定向到成功页面
              resp.sendRedirect("/sys/success.jsp");
          } else {
              //登录失败，重定向到错误页面
              resp.sendRedirect("/error.jsp");
          }
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          doGet(req, resp);
      }
  }
  

• Logout

• package com.ding.servlet;
  
  import com.ding.util.Constant;
  
  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 java.io.IOException;
  
  /**
   * @Description TODO
   * @Author 丁帅帅
   * @Date 21/08/11 00:18
   * @Version 1.0
   */
  @WebServlet("/servlet/logout")
  public class LogoutServlet extends HttpServlet {
  
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          Object userSession = req.getSession().getAttribute(Constant.USER_SESSION);
          if (userSession != null) {
              //注销登录
              req.getSession().removeAttribute(Constant.USER_SESSION);
              //重定向回登录页面
              resp.sendRedirect("/login.jsp");
          }
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          doGet(req, resp);
      }
  }
  

• util

• package com.ding.util;
  
  /**
   * @Description 常量单独放到一个类中,容易后期更改
   * @Author 丁帅帅
   * @Date 21/08/11 00:19
   * @Version 1.0
   */
  public class Constant {
      private Constant() {
      }
  
      public static final String USER_SESSION = "USER_SESSION";
  }