通过反射写BaseServlet

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package ming.stop.base;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;import java.lang.reflect.Method;/** * Created by Ming on 2017/8/22. */@WebServlet(name = "BaseServlet",urlPatterns = {"/base"})public class BaseServlet extends HttpServlet {    protected   void   doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // action名就是方法名b        String action = request.getParameter("action");        if(action != null && !action.equals("")) {            Class aClass = this.getClass();            //反射执行这个方法            try {                Method method = aClass.getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class);                method.invoke(this, request, response);            } catch (Exception e) {                System.out.println("没有这个方法: "+action);                e.printStackTrace();                throw new RuntimeException(e);            }        }    }    protected  void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        doPost(request,response);    }}

子类DEMO：

package ming.stop.biz.front.web;import ming.stop.base.BaseServlet;import ming.stop.biz.front.service.UserService;import ming.stop.biz.front.service.impl.UserServiceImpl;import ming.stop.entity.User;import ming.stop.utils.CommonUtils;import ming.stop.utils.MD5Utils;import javax.servlet.annotation.WebServlet;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.text.SimpleDateFormat;import java.util.Date;/** * Created by Ming on 2017/8/24.f */@WebServlet(urlPatterns = {"/user"})public class UserServlet extends BaseServlet {    UserService userService = new UserServiceImpl();    //注册业务    public void register(HttpServletRequest request, HttpServletResponse response){        try {            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-DD HH:mm:SS");            User user = CommonUtils.copyToBean(request,User.class);            user.setUid(CommonUtils.getUUID());            user.setState(0);            user.setCode(CommonUtils.getUUID64());            user.setRegistertime(new Date());            System.out.println(user);            boolean isRegisterSuccess = false;            isRegisterSuccess = userService.register(user);            //判断是否注册成功            if(isRegisterSuccess){                //注册成功                response.sendRedirect(request.getContextPath()+"/registerSuccess.jsp");            }else {                //注册失败                response.sendRedirect(request.getContextPath()+"/registerFail.jsp");            }            //处理异常        } catch (Exception e) {            request.setAttribute("msg",e.getMessage());            e.printStackTrace();        }    }    //激活业务    public void active(HttpServletRequest request,HttpServletResponse response){        //激活码        String code = request.getParameter("code");        try {            boolean activeFlag = userService.activeUser(code);            if(activeFlag){                //激活成功                System.out.println("激活成功！");                response.sendRedirect(request.getContextPath()+"/login.jsp");            }else {                System.out.println("激活失败！可能你超过了有效期！或服务繁忙请稍后再试试！");            }        } catch (Exception e) {            e.printStackTrace();        }    }    //登录业务    public void login(HttpServletRequest request,HttpServletResponse response){        String username = request.getParameter("username");        String password = request.getParameter("password");        password = MD5Utils.md5(password);        String autoLogin = request.getParameter("autoLogin");        String saveUsername = request.getParameter("saveUsername");        try {            User user = userService.queryUserByUsername(username);            if(user != null && user.getState() == 1){                //用户不为空就判断密码                if( !user.getPassword().equals(password)){                    request.setAttribute("msg_password","密码错误");                    request.getRequestDispatcher("/login.jsp").forward(request,response);                    return;                }else{                    HttpSession session = request.getSession();                    session.setAttribute("user",user);                    session.setAttribute("loginTime",new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));                    //判断是否 记住用户名                    if(saveUsername != null){                        Cookie cookie = new Cookie("username",username);                        cookie.setMaxAge(60*30);                        response.addCookie(cookie);                    }else {                        Cookie cookie = new Cookie("username","");                        cookie.setMaxAge(0);                        response.addCookie(cookie);                    }                    //判断是否自动登录                    if(autoLogin != null){                        Cookie cookie_uid = new Cookie("cookie_uid",user.getUid());                        Cookie cookie_pwd = new Cookie("cookie_pwd",user.getPassword());                        cookie_uid.setMaxAge(60*15);                        cookie_pwd.setMaxAge(60*15);                        response.addCookie(cookie_uid);                        response.addCookie(cookie_pwd);                    }                    response.sendRedirect(request.getContextPath());                    System.out.println("登录成功！");                }            }else {                request.setAttribute("msg_username","没有此用户");                request.getRequestDispatcher("/login.jsp").forward(request,response);            }        } catch (Exception e) {            e.printStackTrace();        }    }    //退出登录    public void logout(HttpServletRequest request,HttpServletResponse response){        HttpSession session = request.getSession(false);        if(session != null)        session.invalidate();        Cookie username = new Cookie("username","");        username.setMaxAge(0);        Cookie cookie_uid = new Cookie("cookie_uid","");        cookie_uid.setMaxAge(0);        response.addCookie(username);response.addCookie(cookie_uid);        Cookie cookie_pwd = new Cookie("cookie_pwd","");        cookie_pwd.setMaxAge(0);        response.addCookie(username);response.addCookie(cookie_pwd);        try {            request.getRequestDispatcher("/login.jsp").forward(request,response);        } catch (Exception e) {            e.printStackTrace();        }    }    // 检查用户名是否重复 业务    public void checkUsername(HttpServletRequest request,HttpServletResponse response){        String username = request.getParameter("username");        try {            User user = userService.queryUserByUsername(username);            if(user != null){                response.getWriter().write("{\"isExist\":true}");            }else {                response.getWriter().write("{\"isExist\":false}");            }        } catch (Exception e) {            e.printStackTrace();        }    }}

可以看出一个Servlet 应该处理一个业务，

编写多个方法，访问时候只需要 http://localhost:8080/项目名/user?action=方法名

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