【Java】【MVC】一套完整的登陆注册逻辑

作者: JerichoPH | 来源:发表于2017-04-18 12:19 被阅读571次

一套完整的登陆注册业务逻辑

准备部分

基础工具类

Base

package com.jericho.tools;

import com.google.gson.Gson;

import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.Field;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class Base {

static Gson gson = new Gson();

private static Map<Object, Object> _makeReturnMap(boolean isSuccess) {
    Map<Object, Object> map = new HashMap<>();
    if (isSuccess) {
        map.put("err", 0);
    } else {
        map.put("err", 1);
    }
    return map;
}

/**
 * 生成成功返回结果信息
 *
 * @param message 描述
 * @return Map
 */
public static Map<Object, Object> returnSuccess(String message) {
    Map<Object, Object> map = Base._makeReturnMap(true);
    map.put("msg", message);
    return map;
}

/**
 * 生成成功返回结果信息
 *
 * @param map 描述
 * @return Map
 */
public static Map<Object, Object> returnSuccess(Map<Object, Object> map) {
    Map<Object, Object> res = Base._makeReturnMap(true);
    res.putAll(map);
    return res;
}

/**
 * 返回json格式成功信息
 *
 * @param message 描述
 * @return String
 */
public static String jsonSuccess(String message) {
    return Base.gson.toJson(Base.returnSuccess(message));
}

/**
 * 返回json格式成功信息
 *
 * @param map 描述
 * @return String
 */
public static String jsonSuccess(Map<Object, Object> map) {
    return Base.gson.toJson(Base.returnSuccess(map));
}

/**
 * 生成失败返回结果信息
 *
 * @param message 描述
 * @return Map
 */
public static Map<Object, Object> returnFail(String message) {
    Map<Object, Object> map = Base._makeReturnMap(false);
    map.put("msg", message);
    return map;
}

/**
 * 生成失败返回结果信息
 *
 * @param map 描述
 * @return Map
 */
public static Map<Object, Object> returnFail(Map<Object, Object> map) {
    Map<Object, Object> res = Base._makeReturnMap(false);
    res.putAll(map);
    return res;
}

/**
 * 生成json格式失败信息
 *
 * @param message 描述
 * @return String
 */
public static String jsonFail(String message) {
    return Base.gson.toJson(Base.returnFail(message));
}

/**
 * 生成json格式失败信息
 *
 * @param map 描述
 * @return String
 */
public static String jsonFail(Map<Object, Object> map) {
    return Base.gson.toJson(Base.returnFail(map));
}

/**
 * 生成md5
 *
 * @param str 待加密字符串
 * @return String
 * @throws NoSuchAlgorithmException
 */
public static String md5(Object str) throws NoSuchAlgorithmException {
    MessageDigest md5 = MessageDigest.getInstance("MD5");
    md5.update(str.toString().getBytes());
    return new BigInteger(1, md5.digest()).toString(16);
}

/**
 * 显示请求结果
 *
 * @param request 请求数据
 */
public static void showRequest(HttpServletRequest request) {
    Map<String, String[]> map = request.getParameterMap();
    for (Map.Entry<String, String[]> m :
            map.entrySet()) {
        String key = m.getKey();
        String[] values = m.getValue();
        System.out.print(key + ":");
        for (String value :
                values) {
            System.out.print(value + " ");
        }
        System.out.println();
    }
}

/**
 * 获取生成随机字符串
 *
 * @param length 生成字符串长度
 * @return String
 */
public static String getRandomString(int length) {
    String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";//含有字符和数字的字符串
    Random random;//随机类初始化
    random = new Random();
    StringBuffer sb = new StringBuffer();//StringBuffer类生成，为了拼接字符串

    for (int i = 0; i < length; ++i) {
        int number = random.nextInt(62);// [0,62)

        sb.append(str.charAt(number));
    }
    return sb.toString();
}

/**
 * 将请求表单保存到实体类
 *
 * @param entity  实体类
 * @param request 请求数据
 * @param <T>     T
 * @return T
 * @throws Exception
 */
public static <T> T requestToBean(Class<T> entity, HttpServletRequest request) throws Exception {
    Map<String, String[]> map = request.getParameterMap();
    T cls = entity.newInstance();
    Class<?> clsClass = cls.getClass();

    for (Map.Entry<String, String[]> m :
            map.entrySet()) {
        String key = m.getKey();
        String[] value = m.getValue();

        Field field = clsClass.getDeclaredField(key);
        field.setAccessible(true);
        if (value.length == 1) {
            field.set(cls, value[0]);
        } else {
            field.set(cls, (Object) value);
        }
    }
    return cls;
}

/**
 * 将请求表单保存到实体类
 *
 * @param entity    实体类
 * @param request   请求数据
 * @param exception 排除在外的字段
 * @param <T>       T
 * @return T
 * @throws Exception
 */
public static <T> T requestToBean(Class<T> entity, HttpServletRequest request, String exception) throws Exception {
    Map<String, String[]> map = request.getParameterMap();
    T cls = entity.newInstance();
    Class<?> clsClass = cls.getClass();

    for (Map.Entry<String, String[]> m :
            map.entrySet()) {
        String key = m.getKey();
        String[] value = m.getValue();

        if (exception.indexOf(key) != -1) {
            continue;
        } else {
            Field field = clsClass.getDeclaredField(key);
            field.setAccessible(true);
            if (value.length == 1) {
                field.set(cls, value[0]);
            } else {
                field.set(cls, (Object) value);
            }
        }
    }
    return cls;
}

public static <T> T resultSetToBean(ResultSet rs, Class<T> cls)
        throws Exception {
    T resultObject = null;
    int index = 1;

    ResultSetMetaData metaData = rs.getMetaData();
    int cols_len = metaData.getColumnCount();
    while (rs.next()) {
        // 通过反射机制创建一个实例
        resultObject = cls.newInstance();
        for (int i = 0; i < cols_len; i++) {
            String cols_name = metaData.getColumnName(i + 1);
            Object cols_value = rs.getObject(cols_name);

            if (cols_value == null) {
                cols_value = "";
            }
            Field field = cls.getDeclaredField(cols_name);
            field.setAccessible(true); // 打开javabean的访问权限
            field.set(resultObject, cols_value);
        }
    }

    return resultObject;
}
}

DbUtils

package com.yjzblog.web.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ResourceBundle;

/**
 * 数据库工具类
 */
public class DbUtils {

private static String driver = null;
private static String dns = null;
private static String user = null;
private static String pwd = null;

static {
    // 读取配置文件
    ResourceBundle rb = ResourceBundle.getBundle("db");
    DbUtils.driver = rb.getString("driver");
    DbUtils.dns = rb.getString("dns");
    DbUtils.user = rb.getString("user");
    DbUtils.pwd = rb.getString("pwd");

    // 获取数据库驱动
    // 获取数据库驱动
    try {
        Class.forName(DbUtils.driver);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

/**
 * 获取链接
 *
 * @return Connection
 * @throws Exception
 */
public static Connection getConn() throws Exception {
    return DriverManager.getConnection(dns, user, pwd);
}

/**
 * 关闭资源
 *
 * @param conn 链接
 * @param stmt 参数
 * @param rs   结果集
 * @throws Exception
 */
public static void kill(Connection conn, Statement stmt, ResultSet rs) throws Exception {
    if (conn != null) {
        conn.close();
    }
    if (stmt != null) {
        stmt.close();
    }
    if (rs != null) {
        rs.close();
    }
}
}

数据库配置db.properties

driver=com.mysql.jdbc.Driver
dns=jdbc:mysql://localhost:3306/yjzblog
user=root
pwd=1

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_3_1.xsd"
version="3.1">
<session-config>
<session-timeout>15</session-timeout>
</session-config>
<welcome-file-list>
<welcome-file>index</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>demo</welcome-file>
</welcome-file-list>

        <!--servlet-->
        <servlet>
            <servlet-name>Index</servlet-name>
            <servlet-class>com.yjzblog.web.servlet.IndexServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>Index</servlet-name>
            <url-pattern>/index</url-pattern>
        </servlet-mapping>
    
        <servlet>
            <servlet-name>Register</servlet-name>
            <servlet-class>com.yjzblog.web.servlet.RegisterServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>Register</servlet-name>
            <url-pattern>/register</url-pattern>
        </servlet-mapping>
    
        <servlet>
            <servlet-name>Login</servlet-name>
            <servlet-class>com.yjzblog.web.servlet.LoginServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>Login</servlet-name>
            <url-pattern>/login</url-pattern>
        </servlet-mapping>
    
        <servlet>
            <servlet-name>Welcome</servlet-name>
            <servlet-class>com.yjzblog.web.servlet.WelcomeServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>Welcome</servlet-name>
            <url-pattern>/welcome</url-pattern>
        </servlet-mapping>
    
        <servlet>
            <servlet-name>Demo</servlet-name>
            <servlet-class>com.yjzblog.web.servlet.DemoServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>Demo</servlet-name>
            <url-pattern>/demo</url-pattern>
        </servlet-mapping>
    
        <servlet>
            <servlet-name>Exit</servlet-name>
            <servlet-class>com.yjzblog.web.servlet.ExitServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>Exit</servlet-name>
            <url-pattern>/exit</url-pattern>
        </servlet-mapping>
    </web-app>
    ```
2. 实体类
    1. User
    ```js
    package com.yjzblog.web.domain;

    /**
     * user实体类
     */
    public class User {
    private long id;
    private String mobile_no;
    private String pwd;
    private String salt;
    private String nickname;
    
    @Override
    public String toString() {
        return "User{" +
                       "id=" + id +
                       ", mobile_no='" + mobile_no + '\'' +
                       ", pwd='" + pwd + '\'' +
                       ", salt='" + salt + '\'' +
                       ", nickname='" + nickname + '\'' +
                       '}';
    }
    
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
    
        User user = (User) o;
    
        if (id != user.id) return false;
        if (mobile_no != null ? !mobile_no.equals(user.mobile_no) : user.mobile_no != null) return false;
        if (pwd != null ? !pwd.equals(user.pwd) : user.pwd != null) return false;
        if (salt != null ? !salt.equals(user.salt) : user.salt != null) return false;
        return nickname != null ? nickname.equals(user.nickname) : user.nickname == null;
    
    }
    
    @Override
    public int hashCode() {
        int result = (int) (id ^ (id >>> 32));
        result = 31 * result + (mobile_no != null ? mobile_no.hashCode() : 0);
        result = 31 * result + (pwd != null ? pwd.hashCode() : 0);
        result = 31 * result + (salt != null ? salt.hashCode() : 0);
        result = 31 * result + (nickname != null ? nickname.hashCode() : 0);
        return result;
    }
    
    public long getId() {
    
        return id;
    }
    
    public void setId(long id) {
        this.id = id;
    }
    
    public String getMobile_no() {
        return mobile_no;
    }
    
    public void setMobile_no(String mobile_no) {
        this.mobile_no = mobile_no;
    }
    
    public String getPwd() {
        return pwd;
    }
    
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    
    public String getSalt() {
        return salt;
    }
    
    public void setSalt(String salt) {
        this.salt = salt;
    }
    
    public String getNickname() {
        return nickname;
    }
    
    public void setNickname(String nickname) {
        this.nickname = nickname;
    }
    }
    ```

业务实现

主页（引导页）

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>webStu</title>
    <script src="resource/ui/js/jquery-1.11.0.min.js"></script>
</head>
<body>
<h1>Hello Java</h1>
<a href="<%=request.getContextPath()%>/register">注册</a>
<a href="<%=request.getContextPath()%>/login">登陆</a>
</body>
</html>

IndexServlet

package com.yjzblog.web.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;
import java.io.PrintWriter;

@WebServlet(name = "IndexServlet")
public class IndexServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    this.doGet(request, response);
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    request.getRequestDispatcher("/index.jsp").forward(request, response);
}
}

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>注册</title>
    <script src="resource/ui/js/jquery-1.11.0.min.js"></script>
</head>
<body>
<h2>注册</h2>
<form id="frmRegister">
    <label>账号：<input type="text" placeholder="账号" name="mobile_no" value="13522178057"></label>
    <label>密码：<input type="password" placeholder="密码" name="pwd" value="123123"></label>
    <label>重复密码：<input type="password" placeholder="再次输入密码" name="repeat" value="123123"></label>
    <label>昵称：<input type="text" placeholder="昵称" name="nickname" value="JerichoPH"></label>
    <a href="javascript:" onclick="fnRegister()">注册</a>
</form>
</body>
<script>
    /**
     * 执行注册
     */
    fnRegister = function () {
        $.ajax({
            url: "<%=request.getContextPath()%>/register",
            type: "post",
            data: $("#frmRegister").serialize(),
            success: function (res) {
                console.log(res);
                res = $.parseJSON(res);
                console.log(res);
                if (res.err == 0) {
                    alert(res.msg);
                } else {
                    alert(res.msg);
                }
            }
        })
    };
</script>
</html>

RegisterServlet

package com.yjzblog.web.servlet;

import com.google.gson.Gson;
import com.jericho.tools.Base;
import com.yjzblog.web.domain.User;
import com.yjzblog.web.service.UserService;
import com.yjzblog.web.service.impl.UserServiceImpl;

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.io.PrintWriter;

@WebServlet(name = "RegisterServlet")
public class RegisterServlet extends HttpServlet {

UserService userService = new UserServiceImpl();
Gson gson = new Gson();

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    Base.showRequest(request);

    // 获取表单数据
    try {
        User user = Base.requestToBean(User.class, request, "repeat");
        String repeat = request.getParameter("repeat");

        // 判断两次密码是否一致
        if (user.getPwd().equals(repeat)) {
            // 两次密码一致,生成MD5密码
            user.setPwd(Base.md5(user.getPwd()));
            // 密码加盐
            user.setSalt(Base.getRandomString(4));
            user.setPwd(Base.md5(user.getPwd() + user.getSalt()));

            // 保存到数据库
            boolean register = this.userService.register(user);
            System.out.println(register);
            out.print(Base.jsonSuccess(register ? "注册成功" : "注册失败"));
        }

    } catch (Exception e) {
        e.printStackTrace();
    }
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    request.getRequestDispatcher("/register.jsp").forward(request, response);
}
}

UserDao

package com.yjzblog.web.dao;

import com.yjzblog.web.domain.User;

/**
 * user数据处理接口
 */
public interface UserDao {
/**
 * 创建信息用户
 *
 * @param user 用户信息
 * @return int
 * @throws Exception
 */
public int add(User user) throws Exception;

/**
 * 根据mobile_no查询数据
 *
 * @param mobile_no 手机号
 * @return User
 * @throws Exception
 */
public User readOneBymobile_no(String mobile_no) throws Exception;
}

UserDaoImpl

package com.yjzblog.web.dao.impl;

import com.jericho.tools.Base;
import com.yjzblog.web.dao.UserDao;
import com.yjzblog.web.domain.User;
import com.yjzblog.web.utils.DbUtils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

/**
 * user数据处理实现类
 */
public class UserDaoImpl implements UserDao {

/**
 * 创建新用户
 *
 * @param user 用户信息
 * @return int
 * @throws Exception
 */
@Override
public int add(User user) throws Exception {
    Connection conn = DbUtils.getConn();
    PreparedStatement ps = conn.prepareStatement("INSERT INTO `user` (mobile_no,pwd,salt,nickname) VALUES (?,?,?,?)");
    try {
        ps.setString(1, user.getMobile_no());
        ps.setString(2, user.getPwd());
        ps.setString(3, user.getSalt());
        ps.setString(4, user.getNickname());
        int i = ps.executeUpdate();
        return i;
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        DbUtils.kill(conn, ps, null);
    }
    return 0;
}

/**
 * 根据mobile_no 查询数据
 *
 * @param mobile_no 手机号
 * @return User
 * @throws Exception
 */
@Override
public User readOneBymobile_no(String mobile_no) throws Exception {
    Connection conn = DbUtils.getConn();
    PreparedStatement preparedStatement = conn.prepareStatement("SELECT * FROM user WHERE mobile_no = ?");
    ResultSet rs = null;
    // 获取用户数据
    try {
        preparedStatement.setString(1, mobile_no);
        rs = preparedStatement.executeQuery();
        return Base.resultSetToBean(rs, User.class);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        DbUtils.kill(conn, preparedStatement, rs);
    }
    return null;
}
}

UserService

package com.yjzblog.web.service;

import com.yjzblog.web.domain.User;

/**
 * 用户服务接口
 */
public interface UserService {
/**
 * 注册
 *
 * @param user 用户信息
 * @return boolean
 * @throws Exception
 */
public boolean register(User user) throws Exception;

/**
 * 登陆
 *
 * @param user 用户数据
 * @return User
 * @throws Exception
 */
public User login(User user) throws Exception;
}

UserServiceImpl

package com.yjzblog.web.service.impl;

import com.jericho.tools.Base;
import com.yjzblog.web.dao.UserDao;
import com.yjzblog.web.dao.impl.UserDaoImpl;
import com.yjzblog.web.domain.User;
import com.yjzblog.web.service.UserService;

/**
 * 用户服务实现类
 */
public class UserServiceImpl implements UserService {

UserDao userDao = new UserDaoImpl();

/**
 * 注册
 *
 * @param user 用户信息
 * @return boolean
 * @throws Exception
 */
@Override
public boolean register(User user) throws Exception {
    int add = this.userDao.add(user);
    return add > 0;
}

/**
 * 登陆
 *
 * @param user 用户数据
 * @return User
 * @throws Exception
 */
@Override
public User login(User user) throws Exception {
    // 获取数据库信息
    User userData = this.userDao.readOneBymobile_no(user.getMobile_no());

    // 密码加盐运算
    String pwd = Base.md5(Base.md5(user.getPwd()) + userData.getSalt());
    if (pwd.equals(userData.getPwd())) {
        // 密码正确
        userData.setSalt("");// 去掉多余字段
        return userData;
    } else {
        // 密码错误
        return null;
    }
}
}

登陆

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登陆</title>
    <script src="resource/ui/js/jquery-1.11.0.min.js"></script>
</head>
<body>
<h2>登陆</h2>
<form id="frmLogin">
    <label>账号：<input type="text" placeholder="账号" name="mobile_no"></label>
    <label>密码：<input type="password" placeholder="密码" name="pwd"></label>
    <a href="javascript:" onclick="fnLogin()">登陆</a>
</form>
</body>
<script>
    /**
     * 执行登陆
     */
    fnLogin = function () {
        $.ajax({
            url: "<%=request.getContextPath()%>/login",
            type: "post",
            data: $("#frmLogin").serialize(),
            success: function (res) {
                res = $.parseJSON(res);
                if (res.err == 0) {
                    alert(res.msg);
                    location.href = "/welcome";
                } else {
                    alert(res.msg);
                    location.reload();
                }
            }
        })
    };
</script>
</html>

LoginServlet

package com.yjzblog.web.servlet;

import com.google.gson.Gson;
import com.jericho.tools.Base;
import com.yjzblog.web.domain.User;
import com.yjzblog.web.service.UserService;
import com.yjzblog.web.service.impl.UserServiceImpl;

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.io.PrintWriter;

@WebServlet(name = "LoginServlet")
public class LoginServlet extends HttpServlet {

Gson gson = new Gson();
User user = null;
UserService userService = new UserServiceImpl();

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    try {
        // 获取表单数据
        this.user = Base.requestToBean(User.class, request, "id,salt,nickname");
        // 执行登陆
        User user = this.userService.login(this.user);
        if (user != null) {
            // 登陆成功,保存到session
            request.getSession().setAttribute("user", user);

            out.print(Base.jsonSuccess("登陆成功"));
        } else {
            out.print(Base.jsonFail("账号或密码错误"));
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    // 读取session数据,判断是否已经登陆
    User user = (User) request.getSession().getAttribute("user");
    if (user != null) {
        // 已登陆
        request.getRequestDispatcher("/welcome.jsp").forward(request, response);
    } else {
        // 未登陆
        request.getRequestDispatcher("/login.jsp").forward(request, response);
    }
}
}

欢迎页

welcome.jsp

<%@ page import="com.yjzblog.web.domain.User" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登陆成功</title>
    <script src="resource/ui/js/jquery-1.11.0.min.js"></script>
</head>
<body>
<h2>登陆成功</h2>
<%
    User user = (User) request.getSession().getAttribute("user");
%>
欢迎登陆：<%=user.getNickname()%>
<br>
<a href="javascript:" onclick="fnExit()">退出登陆</a>
</body>
<script>
    /**
     * 退出登录
     */
    fnExit = function () {
        $.ajax({
            url: "<%=request.getContextPath()%>/exit",
            success: function (res) {
                res = $.parseJSON(res);
                if (res.err == 0) {
                    alert(res.msg);
                    location.reload();
                } else {
                    alert(res.msg);
                    location.reload();
                }
            }
        })
    };
</script>
</html>

WelcomeServlet

package com.yjzblog.web.servlet;

import com.google.gson.Gson;

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.io.PrintWriter;

@WebServlet(name = "WelcomeServlet")
public class WelcomeServlet extends HttpServlet {

Gson gson = new Gson();

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    this.doGet(request, response);
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    Object user = request.getSession().getAttribute("user");
    if (user == null) {
        request.getRequestDispatcher("/login.jsp").forward(request, response);
    } else {
        request.getRequestDispatcher("/welcome.jsp").forward(request, response);
    }
}
}

退出登陆

ExitServlet

package com.yjzblog.web.servlet;

import com.google.gson.Gson;
import com.jericho.tools.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.io.PrintWriter;

@WebServlet(name = "ExitServlet")
public class ExitServlet extends HttpServlet {

Gson gson = new Gson();

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    this.doGet(request, response);
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    response.setCharacterEncoding("utf-8");
    PrintWriter out = response.getWriter();

    // 清除session
    request.getSession().invalidate();
    out.print(this.gson.toJson(Base.returnSuccess("退出成功")));
}
}

【Java】【MVC】一套完整的登陆注册逻辑

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