各位大神速来求助，我在过滤器里面拿到redis数据库的值，总是报空指针

Question

过滤器：
package com.orhonit.ipb.portal.configuration;import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;public class PwTfTempUserFilter implements Filter{
@Autowired
private RedisTemplate<String, Object> redisTemplate;

@Override
public void destroy() {
// TODO Auto-generated method stub

} @Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
// TODO Auto-generated method stub
System.err.println("过滤器执行了");
HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse rep = (HttpServletResponse) response;
        String token = req.getHeader("token");
        if(token == null){
         rep.sendError(401, "没有token");
         return;
        }
       
     System.out.println(token);
     String id = (String) redisTemplate.opsForValue().get("PwTfTempUser:"+token);
    
     System.out.println(id);
     req.getSession().setAttribute("TempUser", id);
        chain.doFilter(request, response);

        
} @Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub

}}String id = (String) redisTemplate.opsForValue().get("PwTfTempUser:"+token);这句一直报空指针
依赖注入没问题，我在别的地方这个方法就可以用，为什么？

Answer 1

贴出错误信息； debug模式一步一步找，看看 redisTemplate.opsForValue().get("PwTfTempUser:"+token);这里面一个对象、一个方法是否都注入了可以调用。

Answer 2

在web.xml的过滤器替换成这个
<filter>
<filter-name>pwTfTempUserFilter</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
PwTfTempUserFilter类上加@Component注解
确保PwTfTempUserFilter被扫描到

Answer 3

java.lang.NullPointerException: null
at com.orhonit.ipb.portal.configuration.PwTfTempUserFilter.doFilter(PwTfTempUserFilter.java:43) ~[classes/:na]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at com.github.ag.core.a.c.doFilter(XXFilter.java:28) ~[jwt-core-2.0-SNAPSHOT.jar:na]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:110) ~[spring-boot-actuator-1.5.4.RELEASE.jar:1.5.4.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at org.springframework.cloud.sleuth.instrument.web.TraceFilter.doFilter(TraceFilter.java:153) ~[spring-cloud-sleuth-core-1.2.1.RELEASE.jar:1.2.1.RELEASE]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:106) ~[spring-boot-actuator-1.5.4.RELEASE.jar:1.5.4.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43) ~[undertow-core-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46) ~[undertow-core-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60) ~[undertow-core-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43) ~[undertow-core-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43) ~[undertow-core-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43) ~[undertow-core-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48) [undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43) [undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81) ~[undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104) [undertow-servlet-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:211) [undertow-core-1.4.15.Final.jar:1.4.15.Final]
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:809) [undertow-core-1.4.15.Final.jar:1.4.15.Final]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_161]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_161]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_161]这是报错信息，springBoot架构 没有web.xml

Answer 4

目测redisTemplate没有注入，类上加上@Component