简介
说明
本文用示例介绍如何解决拦截器中注入Bean失败的问题。
场景
Token拦截器中需要用@Autowired注入JavaJwtUtil类，结果发现注入的JavaJwtUtil为Null。
原因
拦截器的配置类是以new JwtInterceptor的方式使用的，那么这个JwtInterceptor不受Spring管理。因此，里边@Autowired注入JavaJwtUtil是不会注入进去的。
问题重现
代码
application.yml
server:
port: 8080
spring:
application:
name: springboot-jwt
config:
jwt:
# 密钥
secret: abcd1234
# token过期时间（5分钟）。单位：毫秒.
expire: 300000
拦截器配置
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new JwtInterceptor());
}
}拦截器
package com.example.demo.interceptor;
import com.example.demo.util.JavaJwtUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.annotation.PostConstruct;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Arrays;
import java.util.List;
@Slf4j
@Component
public class JwtInterceptor implements HandlerInterceptor {
@Autowired
JavaJwtUtil javaJwtUtil;
List<String> whiteList = Arrays.asList(
"/auth/login",
"/error"
);
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
Object handler) throws Exception {
// 如果不是映射到方法直接通过
if (!(handler instanceof HandlerMethod)) {
return true;
}
//放过不需要验证的页面。
String uri = request.getRequestURI();
if (whiteList.contains(uri)) {
return true;
}
// 头部和参数都查看一下是否有token
String token = request.getHeader("token");
if (StringUtils.isEmpty(token)) {
token = request.getParameter("token");
if (StringUtils.isEmpty(token)) {
throw new RuntimeException("token是空的");
}
}
if (!javaJwtUtil.verifyToken(token)) {
log.error("token无效");
return false;
}
String userId = javaJwtUtil.getUserIdByToken(token);
log.info("userId:" userId);
String userName = javaJwtUtil.getUserNameByToken(token);
log.info("userName:" userName);
return true;
}
}Jwt工具类
package com.example.demo.util;
import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTDecodeException;
import com.auth0.jwt.exceptions.JWTVerificationException;
import com.auth0.jwt.interfaces.DecodedJWT;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import java.util.Date;
@Component
public class JavaJwtUtil {
//过期时间
@Value("${config.jwt.expire}")
private Long EXPIRE_TIME;
//密钥
@Value("${config.jwt.secret}")
private String SECRET;
// 生成Token，五分钟后过期
public String createToken(String userId) {
try {
Date date = new Date(System.currentTimeMillis() EXPIRE_TIME);
Algorithm algorithm = Algorithm.HMAC256(SECRET);
return JWT.create()
// 将 user id 保存到 token 里面
.withAudience(userId)
// date之后，token过期
.withExpiresAt(date)
// token 的密钥
.sign(algorithm);
} catch (Exception e) {
return null;
}
}
// 根据token获取userId
public String getUserIdByToken(String token) {
try {
String userId = JWT.decode(token).getAudience().get(0);
return userId;
} catch (JWTDecodeException e) {
return null;
}
}
// 根据token获取userName
public String getUserNameByToken(String token) {
try {
String userName = JWT.decode(token).getSubject();
return userName;
} catch (JWTDecodeException e) {
return null;
}
}
//校验token
public boolean verifyToken(String token) {
try {
Algorithm algorithm = Algorithm.HMAC256(SECRET);
JWTVerifier verifier = JWT.require(algorithm)
// .withIssuer("auth0")
// .withClaim("username", username)
.build();
DecodedJWT jwt = verifier.verify(token);
return true;
} catch (JWTVerificationException exception) {
// throw new RuntimeException("token 无效，请重新获取");
return false;
}
}
}Controller
package com.example.demo.controller;
import com.example.demo.util.JavaJwtUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/auth")
public class AuthController {
@Autowired
JavaJwtUtil javaJwtUtil;
@RequestMapping("/login")
public String login() {
// 验证userName，password和数据库中是否一致，如不一致，直接返回失败
// 通过userName，password从数据库中获取userId
String userId = 5 "";
String token = javaJwtUtil.createToken(userId);
System.out.println("token:" token);
return token;
}
//需要token验证
@RequestMapping("/info")
public String info() {
return "验证通过";
}
}测试
访问：http://localhost:8080/auth/login
前端结果：一串token字符串
访问：http://localhost:8080/auth/info(以token作为header或者参数）
后端结果
java.lang.NullPointerException: null at com.example.demo.interceptor.JwtInterceptor.preHandle(JwtInterceptor.java:55) ~[main/:na]
解决方案
方案简述
配置类中将new JwtInterceptor()改为Bean的方式
配置类
package com.example.demo.interceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(getJwtInterceptor());
}
@Bean
JwtInterceptor getJwtInterceptor() {
return new JwtInterceptor();
}
}拦截器（此时无需@Component）
package com.example.demo.interceptor;
import com.example.demo.util.JavaJwtUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.StringUtils;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Arrays;
import java.util.List;
@Slf4j
public class JwtInterceptor implements HandlerInterceptor {
@Autowired
JavaJwtUtil javaJwtUtil;
List<String> whiteList = Arrays.asList(
"/auth/login",
"/error"
);
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
Object handler) throws Exception {
// 如果不是映射到方法直接通过
if (!(handler instanceof HandlerMethod)) {
return true;
}
//放过不需要验证的页面。
String uri = request.getRequestURI();
if (whiteList.contains(uri)) {
return true;
}
// 头部和参数都查看一下是否有token
String token = request.getHeader("token");
if (StringUtils.isEmpty(token)) {
token = request.getParameter("token");
if (StringUtils.isEmpty(token)) {
throw new RuntimeException("token是空的");
}
}
if (!javaJwtUtil.verifyToken(token)) {
log.error("token无效");
return false;
}
String userId = javaJwtUtil.getUserIdByToken(token);
log.info("userId:" userId);
String userName = javaJwtUtil.getUserNameByToken(token);
log.info("userName:" userName);
return true;
}
}到此这篇关于Spring拦截器中注入Bean失败解放方案详解的文章就介绍到这了,更多相关Spring Bean内容请搜索Devmax以前的文章或继续浏览下面的相关文章希望大家以后多多支持Devmax！