今天在配置spring-security.xml配置文件时出错
错误如下:

严重: Servlet.service() for servlet [security] in context with path [] threw exception
java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"
    at org.springframework.security.crypto.password.DelegatingPasswordEncoder$UnmappedIdPasswordEncoder.matches(DelegatingPasswordEncoder.java:238)
    at org.springframework.security.crypto.password.DelegatingPasswordEncoder.matches(DelegatingPasswordEncoder.java:198)
    at org.springframework.security.authentication.dao.DaoAuthenticationProvider.additionalAuthenticationChecks(DaoAuthenticationProvider.java:86)
    at org.springframework.security.authentication.dao.AbstractUserDetailsAuthenticationProvider.authenticate(AbstractUserDetailsAuthenticationProvider.java:166)
    at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:174)
    at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:199)
    at org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter.attemptAuthentication(UsernamePasswordAuthenticationFilter.java:94)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:124)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:66)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:357)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:270)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

正确配置

<!--配置用户认证信息-->
    <security:authentication-manager>
        <security:authentication-provider>
            <security:user-service>
                <!--配置用户信息，说明：
                       name：用户名称
                       password：用户密码。细节：指定加密的方式，{noop}是不加密的。
                       authorities：角色列表
                -->

                <security:user name="user" password="{noop}user" authorities="ROLE_USER" />
                <security:user name="admin" password="{noop}admin" authorities="ROLE_ADMIN" />
            </security:user-service>
        </security:authentication-provider>
    </security:authentication-manager>

配置用户密码时指定加密的方式，{noop}是不加密的。在配置密码时没有加上导致错误.

java.lang.IllegalArgumentException: There is no PasswordEncoder mapped for the id "null"