token令牌，过滤器，JWT，拦截器

令牌(token)技术

不需要在服务端去保留用户的认证信息或者会话信息。这就意味着基于token认证机制的应用不需要去考虑用户在哪一台服务器登录了

1.基本流程

用户使用用户名密码来请求服务器

服务器进行验证用户的信息

服务器通过验证发送给用户一个token

客户端存储token，并在每次请求时附送上这个token值

服务端验证token值，并返回数据

JWT （全称JSON WEB TOKEN）

1.导入jar包

<dependency><groupId>io.jsonwebtoken</groupId><artifactId>jjwt-api</artifactId><version>0.12.6</version>
</dependency>
<dependency><groupId>io.jsonwebtoken</groupId><artifactId>jjwt-impl</artifactId><version>0.12.6</version><scope>runtime</scope>
</dependency>
<dependency><groupId>io.jsonwebtoken</groupId><artifactId>jjwt-jackson</artifactId> <!-- or jjwt-gson if Gson is preferred --><version>0.12.6</version><scope>runtime</scope>
</dependency>

这个jar包包含了上面三个

<dependency><groupId>io.jsonwebtoken</groupId><artifactId>jjwt</artifactId><version>0.12.6</version>
</dependency>

2.官网（https://jwt.io/）

3.格式

以json格式传输共享数据（分为三部分,最后三个部分组成的完整json会使用Base64进行编码且以.分割）

Header(头)

用于记录令牌类型以及签名算法等信息

PayLoad(载荷)

存储Http共享数据

Signature(签名)

使用加密算法保证Header与PayLoad的安全性

4.如何使用jwt（生成，校验）

package com.lu.tlias84;import io.jsonwebtoken.*;
import io.jsonwebtoken.security.Keys;
import org.junit.jupiter.api.Test;import javax.xml.crypto.Data;
import java.util.Date;public class TestJwt {@Testpublic void testGenerateJwtToken(){//1. 构建jwt对象JwtBuilder builder = Jwts.builder();//2. 指定header(一般不指定)//省略使用默认的jwt头//3. 往payload放置http需要共享的信息,并且指定过期时间builder.claim("username","count-l");builder.claim("password","count-l");Date date = new Date();builder.issuedAt(date);//token生效时间builder.expiration(new Date(date.getTime()+60*1000));//指定过期时间//4. 进行数字签名String key = "febaa5b6-b818-440a-ad8a-9606ffaafd0c";//第一个参数是数字签名（需要自己生成）//第二个参数 加密的签名算法，新版需要保证一定强度（HS256至少要32字节，HS384至少需要84字节，HS512至少要64字节）builder.signWith(Keys.hmacShaKeyFor(key.getBytes()), Jwts.SIG.HS256);//生成tokenString compact = builder.compact();System.out.println(compact);}@Testpublic void testVerifyJwtToken(){String key = "febaa5b6-b818-440a-ad8a-9606ffaafd0c";String token = "eyJhbGciOiJIUzI1NiJ9.eyJ1c2VybmFtZSI6ImNvdW50LWwiLCJwYXNzd29yZCI6ImNvdW50LWwiLCJpYXQiOjE3MjQzMTUyODUsImV4cCI6MTcyNDMxNTM0NX0.olJzzamV5Pi5qdKCU3p0F19SX_vaD2rSkiLXfrxenVo";//1.构建jwt解析对象JwtParserBuilder parser = Jwts.parser();//2.指定数字签名JwtParser build = parser.verifyWith(Keys.hmacShaKeyFor(key.getBytes())).build();//3.指定tokenClaims payload = build.parseSignedClaims(token).getPayload();System.out.println(payload.get("username"));System.out.println(payload.get("password"));}
}

解析

public void testVerifyJwtToken(){String key = "febaa5b6-b818-440a-ad8a-9606ffaafd0c";String token = "eyJhbGciOiJIUzI1NiJ9.eyJ1c2VybmFtZSI6ImNvdW50LWwiLCJwYXNzd29yZCI6ImNvdW50LWwifQ.0HgzrDeIXEOixSV9-08lCLx0sX6m--3ShxYYUpJKhz4";//1.构建jwt解析对象JwtParserBuilder parser = Jwts.parser();//2.指定数字签名JwtParser build = parser.verifyWith(Keys.hmacShaKeyFor(key.getBytes())).build();//3.指定tokenClaims payload = build.parseSignedClaims(token).getPayload();System.out.println(payload.get("username"));System.out.println(payload.get("password"));
}

JWT工具类

package com.lu.tlias84.utils;import com.alibaba.fastjson.JSONObject;
import io.jsonwebtoken.Claims;
import io.jsonwebtoken.JwtParser;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.security.Keys;import java.util.Date;/*** jwt token 生成与验证（解析）*/
public class JwtUtil {private JwtUtil(){}private static final String SIG = "febaa5b6-b818-440a-ad8a-9606ffaafd0c";/*** 生成token* @param username payload-用户名* @param password payload-密码* @param minutes token过期时间，以分钟为单位* @return token*/public static String generateToken(String username,String password,long minutes){//1.构建jwt对象//2.指定header（一般省略）//3.放置payload，以及过期时间和生效时间//4.进行数字签名//第一个参数是数字签名（需要自己生成）//第二个参数 加密的签名算法，新版需要保证一定强度（HS256至少要32字节，HS384至少需要84字节，HS512至少要64字节）//5.生成tokenDate now = new Date();String token = Jwts.builder().claim("username", username).claim("password", password).issuedAt(now).expiration(new Date(now.getTime() + 60 * 1000 * minutes)).signWith(Keys.hmacShaKeyFor(SIG.getBytes()), Jwts.SIG.HS256).compact();return token;}/*** 验证token* @param token 生成的令牌* @return payload中的用户信息*/public static JSONObject verifyToken(String token){//1.构建解析对象//2.指定数字签名//3.指定被签名后的tokenJwtParser parser = Jwts.parser().verifyWith(Keys.hmacShaKeyFor(SIG.getBytes())).build();Claims payload = parser.parseSignedClaims(token).getPayload();JSONObject jsonObject = new JSONObject();jsonObject.put("username", payload.get("username"));jsonObject.put("password", payload.get("password"));//TODO: 还没有完成token失效的处理以及 token字符串不和法的处理return jsonObject;}
}

使用

package com.lu.tlias84.service.impl;import com.alibaba.fastjson.JSONObject;
import com.lu.tlias84.entity.Emp;
import com.lu.tlias84.mapper.EmpMapper;
import com.lu.tlias84.po.LoginParam;
import com.lu.tlias84.service.LoginService;
import com.lu.tlias84.utils.JwtUtil;
import com.lu.tlias84.utils.ResultUtil;
import jakarta.annotation.Resource;
import org.springframework.stereotype.Service;import java.util.Objects;@Service
public class LoginServiceImpl implements LoginService {@Resourceprivate EmpMapper empMapper;@Overridepublic ResultUtil login(LoginParam loginParam) {Emp emp = empMapper.selectEmpByUsername(loginParam.getUsername());if (Objects.isNull(emp) || !emp.getPassword().equals(loginParam.getPassword())) {return ResultUtil.fail("用户名或者密码不正确");}String token = JwtUtil.generateToken(loginParam.getUsername(), loginParam.getPassword(), 30);JSONObject json = new JSONObject();json.put("id", emp.getId());json.put("username", emp.getUsername());json.put("password", emp.getPassword());json.put("token", token);return ResultUtil.success(json);}
}

过滤器

1.filter

package com.lu.tlias84.filter;import com.alibaba.fastjson.JSONObject;
import com.lu.tlias84.entity.Emp;
import com.lu.tlias84.mapper.EmpMapper;
import com.lu.tlias84.utils.JwtUtil;
import com.lu.tlias84.utils.ResultUtil;
import jakarta.annotation.Resource;
import jakarta.servlet.*;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.apache.http.HttpStatus;
import org.springframework.stereotype.Component;import java.io.IOException;
import java.io.PrintWriter;
import java.util.Objects;/*** 登录过滤器，进行登录token拦截*/
@Slf4j
//@Component
public class LoginFilter implements Filter {@Resourceprivate EmpMapper empMapper;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {Filter.super.init(filterConfig);log.info("初始化过滤器");}@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {log.info("开始执行http请求过滤");//参数向下转型成HttpServletRequest以及HttpServletResponseHttpServletRequest sRequest = (HttpServletRequest) request;HttpServletResponse sResponse = (HttpServletResponse) response;//放行登录接口String uri = sRequest.getRequestURI();if (uri.contains("login")) {chain.doFilter(request, response);return;}//获取请求头中的tokenString token = sRequest.getHeader("token");//判断是否有token->是否绕过登录if (Objects.isNull(token)) {writeErrorResponse(sResponse,"请先登录");return;}//校验token是否过期或者错误JSONObject jsonObject =null;try {jsonObject = JwtUtil.verifyToken(token);} catch (Exception e) {writeErrorResponse(sResponse,"token不合法");return;}//TODO: 使用jwt工具类验证token中的数据是否正确Emp emp = empMapper.selectEmpByUsername(jsonObject.getString("username"));if (Objects.isNull(emp) || !emp.getPassword().equals(jsonObject.getString("password"))) {writeErrorResponse(sResponse,"校验不正确");return;}//过滤链对象执行完过滤逻辑之后放行http请求，把request，response重新交给controller（servlet）chain.doFilter(request, response);log.info("过滤完成");}private static void writeErrorResponse(HttpServletResponse sResponse,String msg) throws IOException {//设置UTF-8编码sResponse.setContentType("application/json;charset=utf-8");sResponse.setCharacterEncoding("UTF-8");//设置响应状态码sResponse.setStatus(HttpStatus.SC_UNAUTHORIZED);PrintWriter writer = sResponse.getWriter();ResultUtil fail = ResultUtil.fail(msg);//使用fastjson把对象转成json字符串writer.write(JSONObject.toJSONString(fail));}@Overridepublic void destroy() {Filter.super.destroy();}
}

2.流程图

拦截器

1.SpringBoot2.x

编写拦截器

实现HandlerInterceptorAdapter接口

配置拦截器

继承WebMvcConfigurer类器

2.SpringBoot3.x

编写拦截器

实现Handlerlnterceptor接口

package com.lu.tlias84.Interceptor;import com.alibaba.fastjson.JSONObject;
import com.lu.tlias84.entity.Emp;
import com.lu.tlias84.mapper.EmpMapper;
import com.lu.tlias84.utils.JwtUtil;
import com.lu.tlias84.utils.ResultUtil;
import jakarta.annotation.Resource;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.apache.http.HttpStatus;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;import java.io.IOException;
import java.io.PrintWriter;
import java.util.Objects;/*** springboot提供的登录拦截器*/
@Component
public class LoginInterceptor implements HandlerInterceptor {@Resourceprivate EmpMapper empMapper;@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String token = request.getHeader("token");if (Objects.isNull(token)) {writeErrorResponse(response,"请先登录");return false;}JSONObject jsonObject =null;try {jsonObject = JwtUtil.verifyToken(token);} catch (Exception e) {writeErrorResponse(response,"token不合法");return false;}Emp emp = empMapper.selectEmpByUsername(jsonObject.getString("username"));if (Objects.isNull(emp) || !emp.getPassword().equals(jsonObject.getString("password"))) {writeErrorResponse(response,"校验不正确");return false;}return true;}private static void writeErrorResponse(HttpServletResponse sResponse,String msg) throws IOException {//设置UTF-8编码sResponse.setContentType("application/json;charset=utf-8");sResponse.setCharacterEncoding("UTF-8");//设置响应状态码sResponse.setStatus(HttpStatus.SC_UNAUTHORIZED);PrintWriter writer = sResponse.getWriter();ResultUtil fail = ResultUtil.fail(msg);//使用fastjson把对象转成json字符串writer.write(JSONObject.toJSONString(fail));}
}

配置拦截器

继承WebMvcConfigurationSupport类

package com.lu.tlias84.config;import com.lu.tlias84.Interceptor.LoginInterceptor;
import jakarta.annotation.Resource;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;/*** springboot配置类* 一般用来配置拦截器或者跨域配置。。** 过滤器（filter） 与拦截器（Interceptor）的区别：* 相同点：执行都在controller（servlet）之前* 不同点：*      1.技术提供方：过滤器->servlet提供 拦截器 ->spring*      2.执行顺序：先执行过滤器 后执行拦截器*      3.拦截力度：过滤器拦截力度粗 ->编码转换，时间格式转化*                拦截器拦截力度细 ->登录认证，接口日志记录*                *                */
@Configuration
//如果继承 extends WebMvcConfigurationSupport springboot 会自己处理时间
//如果想使用自定义的时间格式 implements WebMvcConfigurer
//public class WebMvcConfig extends WebMvcConfigurationSupport {
public class WebMvcConfig implements WebMvcConfigurer {@ResourceLoginInterceptor loginInterceptor;@Overridepublic void addInterceptors(InterceptorRegistry registry) {//添加拦截器registry.addInterceptor(loginInterceptor)//添加拦截路径.addPathPatterns("/**")//排除路劲.excludePathPatterns("/login");}
}

面试题

1.过滤器和拦截器有什么区别

过滤器（filter）与拦截器（Interceptor）的区别：
相同点：执行都在controller（servlet）之前
不同点：
     1.技术提供方：过滤器->servlet提供拦截器 ->spring
     2.执行顺序：先执行过滤器后执行拦截器
     3.拦截力度：过滤器拦截力度粗 ->编码转换，时间格式转化
拦截器拦截力度细 ->登录认证，接口日志记录