jwt验证登录信息

为什么要告别session？有这样一个场景，系统的数据量达到千万级，需要几台服务器部署，当一个用户在其中一台服务器登录后，用session保存其登录信息，其他服务器怎么知道该用户登录了？（单点登录），当然解决办法有，可以用spring-session。如果该系统同时为移动端服务呢？移动端通过url向后台要数据，如果用session，通过sessionId识别用户，万一sessionId被截获了，别人可以利用sessionId向后台要数据，就有安全隐患了。所以有必要跟session说拜拜了。服务端不需要存储任何用户的信息，用户的验证应该放在客户端，jwt就是这种方式！

什么是jwt？

最详细的是官网：https://jwt.io/

这里以java的ssm框架为例，集成jwt。

1.pom.xml 导入jwt的包

 

 

 

 

 

 

 <!-- jwt -->

   <!-- https://mvnrepository.com/artifact/com.auth0/java-jwt -->

   <dependency>

    <groupId>com.auth0</groupId>

    <artifactId>java-jwt</artifactId>

    <version>2.2.0</version>

   </dependency>

 

2.编写jwt的工具类，有加密解密功能就好

 

 

 

 

 

import com.auth0.jwt.JWTSigner;

import com.auth0.jwt.JWTVerifier;

import com.auth0.jwt.internal.com.fasterxml.jackson.databind.ObjectMapper;

​

import java.util.HashMap;

import java.util.Map;

​

public class JWT {

    private static final String SECRET = "XX#$%()(#*!()!KL<><MQLMNQNQJQK sdfkjsdrow32234545fdf>?N<:{LWPW";

​

    private static final String EXP = "exp";

​

    private static final String PAYLOAD = "payload";

​

    //加密，传入一个对象和有效期

    public static <T> String sign(T object, long maxAge) {

        try {

            final JWTSigner signer = new JWTSigner(SECRET);

            final Map<String, Object> claims = new HashMap<String, Object>();

            ObjectMapper mapper = new ObjectMapper();

            String jsonString = mapper.writeValueAsString(object);

            claims.put(PAYLOAD, jsonString);

            claims.put(EXP, System.currentTimeMillis() + maxAge);

            return signer.sign(claims);

        } catch(Exception e) {

            return null;

        }

    }

​

    //解密，传入一个加密后的token字符串和解密后的类型

    public static<T> T unsign(String jwt, Class<T> classT) {

        final JWTVerifier verifier = new JWTVerifier(SECRET);

        try {

            final Map<String,Object> claims= verifier.verify(jwt);

            if (claims.containsKey(EXP) && claims.containsKey(PAYLOAD)) {

                long exp = (Long)claims.get(EXP);

                long currentTimeMillis = System.currentTimeMillis();

                if (exp > currentTimeMillis) {

                    String json = (String)claims.get(PAYLOAD);

                    ObjectMapper objectMapper = new ObjectMapper();

                    return objectMapper.readValue(json, classT);

                }

            }

            return null;

        } catch (Exception e) {

            return null;

        }

 

    }

​

}

 

3.jwt有了，ssm要如何去利用，用户验证的第一步是登录，登录时根据用户传来的username和password到数据库验证身份，如果合法，便给该用户jwt加密生成token

 

 

 

 

 

//处理登录

    @RequestMapping(value="login", produces = "application/json; charset=utf-8")

    public @ResponseBody ResponseData login(HttpServletRequest request, @RequestParam( "email") String email,

            @RequestParam("password") String password) {

        Login login = new Login();

        login.setEmail(email);

        login.setPassword(password);

        ResponseData responseData = ResponseData.ok();

        //先到数据库验证

        Integer loginId = userService.checkLogin(login);

        if(null != loginId) {

            User user = userService.getUserByLoginId(loginId);

            login.setId(loginId);

            //给用户jwt加密生成token

            String token = JWT.sign(login, 60L* 1000L* 30L);

            //封装成对象返回给客户端

            responseData.putDataValue("loginId", login.getId());

            responseData.putDataValue("token", token);

            responseData.putDataValue("user", user);

 

        }

        else{

            responseData =  ResponseData.customerError();

        }   

        return responseData;

    }

 

4.在用户登录时，把loginId和token返回给前台，以后用户每次请求时，都得带上这两个参数，后台拿到token后解密出loginId，与用户传递过来的loginId比较，如果相同，则说明用户身份合法。因为是每个登录过后的每个请求，这里用springmvc的拦截器做

 

 

 

 

 

<mvc:interceptors>    

    <mvc:interceptor>    

        <!-- 匹配的是url路径， 如果不配置或/**,将拦截所有的Controller -->  

        <mvc:mapping path="/**" />  

        <!-- /register 和 /login 不需要拦截-->  

        <mvc:exclude-mapping path="/register" />

        <mvc:exclude-mapping path="/login" />

 

        <bean class="com.xforce.charles.interceptor.TokenInterceptor"></bean>    

    </mvc:interceptor>  

    <!-- 当设置多个拦截器时，先按顺序调用preHandle方法，然后逆序调用每个拦截器的postHandle和afterCompletion方法 -->  

    </mvc:interceptors> 

 

5.拦截器代码

 

 

 

 

 

import java.io.PrintWriter;

​

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

​

import org.springframework.web.servlet.HandlerInterceptor;

import org.springframework.web.servlet.ModelAndView;

​

import com.alibaba.fastjson.JSONObject;

import com.xforce.charles.model.Admin;

import com.xforce.charles.model.Login;

import com.xforce.charles.util.JWT;

import com.xforce.charles.util.ResponseData;

​

public class TokenInterceptor implements HandlerInterceptor{

​

    public void afterCompletion(HttpServletRequest request,

            HttpServletResponse response, Object handler, Exception arg3)

            throws Exception {

    }

​

    public void postHandle(HttpServletRequest request, HttpServletResponse response,

            Object handler, ModelAndView model) throws Exception {

    }

​

    //拦截每个请求

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response,

            Object handler) throws Exception {

        response.setCharacterEncoding("utf-8");

        String token = request.getParameter("token");

        ResponseData responseData = ResponseData.ok();

        //token不存在

        if(null != token) {

            Login login = JWT.unsign(token, Login.class);

            String loginId = request.getParameter("loginId");

            //解密token后的loginId与用户传来的loginId不一致，一般都是token过期

            if(null != loginId && null != login) {

                if(Integer.parseInt(loginId) == login.getId()) {

                    return true;

                }

                else{

                    responseData = ResponseData.forbidden();

                    responseMessage(response, response.getWriter(), responseData);

                    return false;

                }

            }

            else

            {

                responseData = ResponseData.forbidden();

                responseMessage(response, response.getWriter(), responseData);

                return false;

            }

        }

        else

        {

            responseData = ResponseData.forbidden();

            responseMessage(response, response.getWriter(), responseData);

            return false;

        }

    }

​

    //请求不通过，返回错误信息给客户端

    private void responseMessage(HttpServletResponse response, PrintWriter out, ResponseData responseData) {

        responseData = ResponseData.forbidden();

        response.setContentType("application/json; charset=utf-8");  

        String json = JSONObject.toJSONString(responseData);

        out.print(json);

        out.flush();

        out.close();

    }

​

 

}

 

6.注意点：用@ResponseBody返回json数据时，有时会有乱码，需要在springmvc的配置文件里面加以下配置（spring4以上）

 

 

 

 

 

<mvc:annotation-driven>

     <mvc:message-converters register-defaults="true">

    <bean class="org.springframework.http.converter.StringHttpMessageConverter">

 

      <property name="supportedMediaTypes" value = "text/plain;charset=UTF-8" />

    </bean>

   </mvc:message-converters>

     </mvc:annotation-driven>  

 

7.最后分享一个类，用于返回给客户端的万能类，我觉得它可以满足一般的接口

 

 

 

 

 

import java.util.HashMap;

import java.util.Map;

​

public class ResponseData {

​

    private final String message;

    private final int code;

    private final Map<String, Object> data = new HashMap<String, Object>();

​

    public String getMessage() {

        return message;

    }

​

    public int getCode() {

        return code;

    }

​

    public Map<String, Object> getData() {

        return data;

    }

​

    public ResponseData putDataValue(String key, Object value) {

        data.put(key, value);

        return this;

    }

​

    private ResponseData(int code, String message) {

        this.code = code;

        this.message = message;

    }

​

    public static ResponseData ok() {

        return new ResponseData(200, "Ok");

    }

​

    public static ResponseData notFound() {

        return new ResponseData(404, "Not Found");

    }

​

    public static ResponseData badRequest() {

        return new ResponseData(400, "Bad Request");

    }

​

    public static ResponseData forbidden() {

        return new ResponseData(403, "Forbidden");

    }

​

    public static ResponseData unauthorized() {

        return new ResponseData(401, "unauthorized");

    }

​

    public static ResponseData serverInternalError() {

        return new ResponseData(500, "Server Internal Error");

    }

​

    public static ResponseData customerError() {

        return new ResponseData(1001, "customer Error");

    }

}