搭建shiro时，出现了这个bug，找了好久，结合自己的情况加上网上几个，说明一下。

报错情况：

[org.apache.shiro.authc.AbstractAuthenticator] - Authentication failed for token submission [org.apache.shiro.authc.UsernamePasswordToken - admin01, rememberMe=false (0:0:0:0:0:0:0:1)]. Possible unexpected error? (Typical or expected login exceptions should extend from AuthenticationException).java.lang.IllegalArgumentException: Argument for byte conversion cannot be null. at org.apache.shiro.codec.CodecSupport.toBytes(CodecSupport.java:197) at org.apache.shiro.authc.credential.HashedCredentialsMatcher.getCredentials(HashedCredentialsMatcher.java:347) at org.apache.shiro.authc.credential.HashedCredentialsMatcher.doCredentialsMatch(HashedCredentialsMatcher.java:380) at org.apache.shiro.realm.AuthenticatingRealm.assertCredentialsMatch(AuthenticatingRealm.java:597) at org.apache.shiro.realm.AuthenticatingRealm.getAuthenticationInfo(AuthenticatingRealm.java:578) at org.apache.shiro.authc.pam.ModularRealmAuthenticator.doSingleRealmAuthentication(ModularRealmAuthenticator.java:180) at org.apache.shiro.authc.pam.ModularRealmAuthenticator.doAuthenticate(ModularRealmAuthenticator.java:267) at org.apache.shiro.authc.AbstractAuthenticator.authenticate(AbstractAuthenticator.java:198) at org.apache.shiro.mgt.AuthenticatingSecurityManager.authenticate(AuthenticatingSecurityManager.java:106) at org.apache.shiro.mgt.DefaultSecurityManager.login(DefaultSecurityManager.java:270) at org.apache.shiro.subject.support.DelegatingSubject.login(DelegatingSubject.java:256) at org.apache.shiro.web.filter.authc.AuthenticatingFilter.executeLogin(AuthenticatingFilter.java:53) at org.apache.shiro.web.filter.authc.FormAuthenticationFilter.onAccessDenied(FormAuthenticationFilter.java:154) at com.cn.demo.shiro.UserFormAuthenticationFilter.onAccessDenied(UserFormAuthenticationFilter.java:29) at org.apache.shiro.web.filter.AccessControlFilter.onAccessDenied(AccessControlFilter.java:133) at org.apache.shiro.web.filter.AccessControlFilter.onPreHandle(AccessControlFilter.java:162) at org.apache.shiro.web.filter.PathMatchingFilter.isFilterChainContinued(PathMatchingFilter.java:203) at org.apache.shiro.web.filter.PathMatchingFilter.preHandle(PathMatchingFilter.java:178) at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:131) at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66) at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449) at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365) at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90) at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83) at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383) at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362) at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:491) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:764) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1388) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Unknown Source)

首先，这个错误就是认证失败，而原因有以下几种：

1、数据库数据加密了，但shiro对toke没有进行加密

2、数据库没有进行加密，但shiro对toke进行了加密

3、你用来匹配认证的信息不完整（我的就是这个原因）。

先说我的解决方法：

在编写realm域模块时，supports我采用UsernamePasswordToken形式。而写doGetAuthenticationInfo（认证）时，通过用户名（usercode）获取用户信息，刚开始，我只获取了一次，即只写了sysUser时（没有active_user对象），我直接把 user , user.getPassword() ,this.getName() 三个参数给了 SimpleAuthenticationInfo ，所以一直报错。但是user里面是封装了password的。

后面我又获取了一次用户信息，封装到active_user。之后把 user.getPassword()改成 active_user.getPassword()。然后问题就解决了。也就是说，刚开始，我没有成功的把密码给到SimpleAuthenticationInfo进行匹配认证。

然后1、2种情况：

首先先检查你的shiro配置文件 applicationContext-shiro.xml , 看是否在自定义 Realm时注入了加密模块

可以看到，我的realm是注入了加密模块了的，而加密方式为md5，也就是说，shiro获取到表单数据后会对password进行md5加密，之后把加密的password和数据库进行匹配认证。

如果你没有注入这个模块，而你的数据库数据却是加密了的。你可以注入这个模块或者取消数据库加密。（该方法借鉴于：https://blog.csdn.net/geniusle201/article/details/70493517）