Springboot 如何实现filter拦截token验证和跨域

针对您的问题，我来为您详细讲解Spring Boot如何实现filter拦截token验证和跨域。

一、使用Filter拦截Token验证

1. 引入相关依赖

在pom.xml文件中引入以下相关依赖：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>

    <dependency>
        <groupId>io.jsonwebtoken</groupId>
        <artifactId>jjwt</artifactId>
        <version>0.9.1</version>
    </dependency>
</dependencies>

2. 编写TokenFilter

在项目中新建TokenFilter.java文件，继承OncePerRequestFilter类，并重写doFilterInternal方法。在该方法中，我们可以对请求头中的Token进行验证。

import com.fasterxml.jackson.databind.ObjectMapper;
import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.OncePerRequestFilter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Component
public class TokenFilter extends OncePerRequestFilter {

    @Value("${jwt.secret}")
    private String secret;

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        String token = request.getHeader("Authorization");
        if(StringUtils.isEmpty(token) || !token.startsWith("Bearer ")){
            filterChain.doFilter(request, response);
            return;
        }

        try {
            Claims claims = Jwts.parser()
                        .setSigningKey(secret)
                        .parseClaimsJws(token.replace("Bearer ", ""))
                        .getBody();
            request.setAttribute("claims", claims);
        } catch (SignatureException e) {
              response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Invalid Token!");
              return;
        }
        filterChain.doFilter(request, response);
    }
}

3. 配置TokenFilter

在Spring Boot中使用@WebFilter注解进行配置。在项目启动时，会自动加载该Filter进行处理。

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.filter.RequestContextFilter;

@Configuration
public class FilterConfig {

    @Bean
    public FilterRegistrationBean tokenFilter(){
        FilterRegistrationBean<TokenFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new TokenFilter());
        registrationBean.addUrlPatterns("/*");
        registrationBean.setName("TokenFilter");
        registrationBean.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registrationBean;
    }
}

至此，我们就已经完成了使用Filter拦截Token验证的过程。

二、使用Filter实现跨域请求

1. 编写CorsFilter

在项目中新建CorsFilter.java文件，继承OncePerRequestFilter类，并重写doFilterInternal方法。在该方法中，我们可以设置response的header，实现跨域请求。

import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Component
public class CorsFilter extends OncePerRequestFilter {

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "*");
        response.setHeader("Access-Control-Allow-Headers", "Content-Type,Access-Token");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Credentials", "true");
        response.setHeader("Access-Control-Expose-Headers", "*");
        if("OPTIONS".equalsIgnoreCase(request.getMethod())){
            response.setStatus(HttpServletResponse.SC_OK);
            return;
        }
        filterChain.doFilter(request, response);
    }
}

2. 配置CorsFilter

同样地，在Spring Boot中使用@WebFilter注解进行配置。在项目启动时，会自动加载该Filter进行处理。

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;

@Configuration
public class FilterConfig {

    @Bean
    public FilterRegistrationBean corsFilter(){
        FilterRegistrationBean<CorsFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new CorsFilter());
        registrationBean.addUrlPatterns("/*");
        registrationBean.setName("CorsFilter");
        registrationBean.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registrationBean;
    }
}

至此，我们就已经完成了使用Filter实现跨域请求的过程。

三、完整的配置文件

最后，如果您需要参考完整的配置文件，可以使用以下代码块进行配置。该配置文件中包含上述两种Filter的配置。

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.filter.RequestContextFilter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Configuration
public class FilterConfig {

    @Value("${jwt.secret}")
    private String secret;

    @Bean
    public FilterRegistrationBean tokenFilter(){
        FilterRegistrationBean<TokenFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new TokenFilter());
        registrationBean.addUrlPatterns("/*");
        registrationBean.setName("TokenFilter");
        registrationBean.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registrationBean;
    }

    @Bean
    public FilterRegistrationBean corsFilter(){
        FilterRegistrationBean<CorsFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new CorsFilter());
        registrationBean.addUrlPatterns("/*");
        registrationBean.setName("CorsFilter");
        registrationBean.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registrationBean;
    }

    private class TokenFilter extends OncePerRequestFilter {

        @Override
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
            String token = request.getHeader("Authorization");
            if(StringUtils.isEmpty(token) || !token.startsWith("Bearer ")){
                filterChain.doFilter(request, response);
                return;
            }

            try {
                Claims claims = Jwts.parser()
                        .setSigningKey(secret)
                        .parseClaimsJws(token.replace("Bearer ", ""))
                        .getBody();
                request.setAttribute("claims", claims);
            } catch (SignatureException e) {
                response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Invalid Token!");
                return;
            }
            filterChain.doFilter(request, response);
        }
    }

    private class CorsFilter extends OncePerRequestFilter {

        @Override
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
            response.setHeader("Access-Control-Allow-Origin", "*");
            response.setHeader("Access-Control-Allow-Methods", "*");
            response.setHeader("Access-Control-Allow-Headers", "Content-Type,Access-Token");
            response.setHeader("Access-Control-Max-Age", "3600");
            response.setHeader("Access-Control-Allow-Credentials", "true");
            response.setHeader("Access-Control-Expose-Headers", "*");
            if("OPTIONS".equalsIgnoreCase(request.getMethod())){
                response.setStatus(HttpServletResponse.SC_OK);
                return;
            }
            filterChain.doFilter(request, response);
        }
    }
}

至此，希望我这份攻略可以帮到您。如果还有任何问题，欢迎继续提问。

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