Apereo cas 的代理功能是非常常用和重要的，尤其是企业内部系统，各个系统间的无缝安全切换全部依靠这个代理功能，cas从4升级到5的转变就是配置更新可以及时生效，完全取消了xml等诸多的配置。
Apereo cas 的代理功能是非常常用和重要的，尤其是企业内部系统，各个系统间的无缝安全切换全部依靠这个代理功能，cas从4升级到5的转变就是配置更新可以及时生效，完全取消了xml等诸多的配置。在配置代理功能时遇到了不小的坑，千万不要依赖官方文档！！，这里有很多次的失败和尝试，希望他人千万不要掉进去。
官方说明，举例如下：
RegexA proxy policy that only allows proxying to PGT urls that match the specified regex pattern.{ "@class" : "org.apereo.cas.services.RegexRegisteredService", "serviceId" : "testId", "name" : "testId", "id" : 1, "proxyPolicy" : { "@class" : "org.apereo.cas.services.RegexMatchingRegisteredServiceProxyPolicy", "pattern" : "^https?://.*" }}我们重点看这个参数：pattern ，依据官方给的样例是个正则表达式字符串，如果你按照这个配置就惨了，
启动cas时你会遇到这个错误：
Caused by: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [java.util.regex.Pattern] at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:324) at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:206) at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:187) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getPotentiallyConvertedSimpleRead(MappingMongoConverter.java:829) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1220) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.access$200(MappingMongoConverter.java:85) at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1166) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getValueInternal(MappingMongoConverter.java:877) at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:290) at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:278) at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:330) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:278) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:238) at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1218)如果你把pattern字段取消或者改名，那么你会遇到这个错误：
java.lang.NullPointerException: null at org.apereo.cas.services.RegexMatchingRegisteredServiceProxyPolicy.hashCode(RegexMatchingRegisteredServiceProxyPolicy.java:62) ~[cas-server-core-services-5.1.2.jar!/:5.1.2] at org.apache.commons.lang3.builder.HashCodeBuilder.append(HashCodeBuilder.java:851) ~[commons-lang3-3.5.jar!/:3.5] at org.apereo.cas.services.AbstractRegisteredService.hashCode(AbstractRegisteredService.java:260) ~[cas-server-core-services-5.1.2.jar!/:5.1.2] at org.apache.commons.lang3.builder.HashCodeBuilder.append(HashCodeBuilder.java:851) ~[commons-lang3-3.5.jar!/:3.5] at org.apereo.cas.authentication.HttpBasedServiceCredential.hashCode(HttpBasedServiceCredential.java:91) ~[cas-server-core-authentication-5.1.2.jar!/:5.1.2] at java.util.HashMap.hash(HashMap.java:338) ~[?:1.8.0_121] at java.util.HashMap.put(HashMap.java:611) ~[?:1.8.0_121] at java.util.HashSet.add(HashSet.java:219) ~[?:1.8.0_121] at java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169) ~[?:1.8.0_121] at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175) ~[?:1.8.0_121] at java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948) ~[?:1.8.0_121] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[?:1.8.0_121] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[?:1.8.0_121] at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[?:1.8.0_121] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_121] at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[?:1.8.0_121] at org.apereo.cas.authentication.AuthenticationTransaction.sanitizeCredentials(AuthenticationTransaction.java:99) ~[cas-server-core-api-authentication-5.1.2.jar!/:5.1.2] at org.apereo.cas.authentication.AuthenticationTransaction.wrap(AuthenticationTransaction.java:50) ~[cas-server-core-api-authentication-5.1.2.jar!/:5.1.2] at org.apereo.cas.authentication.DefaultAuthenticationSystemSupport.handleAuthenticationTransaction(DefaultAuthenticationSystemSupport.java:54) ~[cas-server-core-authentication-5.1.2.jar!/:5.1.2]好吧，我们回到 org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [java.util.regex.Pattern] 这个错上上，一看错误就知道属性值转换器问题，查看源代码并测试如下：
在这个包下 package org.apereo.cas.util.spring 有个自定义转换器Converters.java,我们添加一个Pattern转换器试试：
/** * string to Pattern converter * turns a {@link Pattern} into a formatted string. */ public static class StringToPatternConverter implements Converter<String, Pattern> { @Override public Pattern convert(final String pgtUrlPattern) { return Pattern.compile(pgtUrlPattern, Pattern.CASE_INSENSITIVE); } }然后编译后，运行debug，查看转换器加载完毕了，但是错误依然存在，转换器没起作用。好吧，我忍了。这个cas我采用的是mongodb作为存储，那么这个注册服务的驱动用的是spring-data-mongodb组件，查看了官方文档，发现可以自定义转换器;好吧，弄它试试！在包 package org.apereo.cas.services.convert 下面建立一个StringToPatternConverter.java,然后放入org.apereo.cas.config.MongoDbServiceRegistryConfiguration中的这个方法中（其实官方的注释上标明了是排除转换器）：
@Override public CustomConversions customConversions() { return new CustomConversions(Arrays.asList( new BaseConverters.LoggerConverter(), new BaseConverters.ClassConverter(), new BaseConverters.CommonsLogConverter(), new BaseConverters.PersonAttributesConverter(), new BaseConverters.CacheLoaderConverter(), new BaseConverters.RunnableConverter(), new BaseConverters.ReferenceQueueConverter(), new BaseConverters.ThreadLocalConverter(), new BaseConverters.CertPathConverter(), new BaseConverters.CacheConverter() )); }编译后启动测试，发现问题依然存在，弯路走了不少。
原来错误的是这个样子的：
"proxyPolicy" : { "_class" : "org.apereo.cas.services.RegexMatchingRegisteredServiceProxyPolicy", "pattern" : "^(http|https)?://.*/eccl/proxyUrl.?.*" },最终正确的是这个样子的：
"proxyPolicy" : { "_class" : "org.apereo.cas.services.RegexMatchingRegisteredServiceProxyPolicy", "pattern" : /^(http|https)?:////.*//eccl//proxyUrl.?.*/i },为了取得真经，中间饶了十八弯，其中包含配置控制面板dashboard,包含配置CAS server that management app,中间的各种配置参数的组合，头大的很，主要是官方没有明确的每个参数的说明和例子，你自己猜着看。
