推送时偶现 java.lang.NullPointerException 错误

服务端如出现下面错误：

java.lang.NullPointerException 
at com.aliyuncs.DefaultAcsClient.readError(DefaultAcsClient.java:262) 
at com.aliyuncs.DefaultAcsClient.parseAcsResponse(DefaultAcsClient.java:166) 
at com.aliyuncs.DefaultAcsClient.getAcsResponse(DefaultAcsClient.java:106) 
at com.svw.avacar.push.service.impl.AliPushServiceImpl.push(AliPushServiceImpl.java:77) 
at com.svw.avacar.push.service.impl.AliPushServiceImpl$$FastClassBySpringCGLIB$$a269edd.invoke() 
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) 
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738) 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) 
at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:62) 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:168) 
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:85) 
at com.svw.avacar.push.aop.AliPushAspect.saveUserMessage(AliPushAspect.java:33) 
at sun.reflect.GeneratedMethodAccessor314.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:498) 
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:629) 
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:618) 
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70) 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) 
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) 
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673) 
at com.svw.avacar.push.service.impl.AliPushServiceImpl$$EnhancerBySpringCGLIB$$d77811a5.push() 
at com.svw.avacar.push.job.TimelyJob.execute(TimelyJob.java:61) 
at org.quartz.core.JobRunShell.run(JobRunShell.java:202) 
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:573)

原因是：IAcsClient 是线程安全的， 可以共用一个。

PushRequest 是线程不安全的，建议每次推送都 new 一个，即可解决。