Java if 条件检查空值和空值

Question

如何在 java 中为 web 服务请求编写条件，在我的 web 服务请求中，我传递了一个具有 SpeedInfo 的元素。在SpeedInfo 元素中有两个子元素Bandwidth 和AccessSpeed。

这是我在 SoapUI 中的请求：

 <sch:SpeedInfo>
    <ns:Bandwidth xmlns:ns="http://lpp.att.com/logical/classofservice/schema/v1">4000000</ns:Bandwidth>
    <ns:AccessSpeed xmlns:ns="http://lpp.att.com/logical/classofservice/schema/v1">4000000</ns:AccessSpeed>
 </sch:SpeedInfo>

我的 Java 条件：

if (request.getSpeedInfo() == null || (request.getSpeedInfo() == null && request.getSpeedInfo().getBandwidth() == null)){
    throw new Exception(" SpeedInfo Bandwidth must be passed in the request ");
}

我需要我的条件来检查 3 个场景：

 1. if <speedInfo> itself is not present

 2. <sch:SpeedInfo> is present, but bandwidth not present:

  <sch:SpeedInfo>
      <ns:AccessSpeed xmlns:ns="http://lpp.att.com/logical/classofservice/schema/v1">40000000</ns:AccessSpeed>
  </sch:SpeedInfo>

 3. Bandwidth is present but no value  
   <sch:SpeedInfo>
      <ns:Bandwidth xmlns:ns="http://lpp.att.com/logical/classofservice/schema/v1"></ns:Bandwidth>
      <ns:AccessSpeed xmlns:ns="http://lpp.att.com/logical/classofservice/schema/v1">40000000</ns:AccessSpeed>
   </sch:SpeedInfo>

我得到的错误：

2016-02-02 09:45:48,349  WARN http-bio-8080-exec-3--[c0a8381152a2a943f51] c0a8381152a2a943f51 fw.ws.MessageInInterceptor:49 - Content input stream is NOT null, nothing to log in handleFault()?
2016-02-02 09:45:48,351  WARN http-bio-8080-exec-3--[c0a8381152a2a943f51] c0a8381152a2a943f51 cxf.phase.PhaseInterceptorChain:452 - Interceptor for {http://lpp.att.com/logical/v1}LogicalService#{http://lpp.att.com/logical/v1}classOfServiceAllocation has thrown exception, unwinding now
org.apache.cxf.interceptor.Fault: Unmarshalling Error: cvc-datatype-valid.1.2.1: '' is not a valid value for 'integer'. 
at    org.apache.cxf.jaxb.JAXBEncoderDecoder.unmarshall(JAXBEncoderDecoder.java:908)
at org.apache.cxf.jaxb.JAXBEncoderDecoder.unmarshall(JAXBEncoderDecoder.java:712)

Answer 1

if (request.getSpeedInfo() == null || (request.getSpeedInfo() == null && request.getSpeedInfo().getBandwidth() == null)){

对getSpeedInfo() 测试两次null 是没有意义的。这当然很明显？这并不能测试 getBandwidth() 单独为空的情况。

根据您的要求：

1. 如果<speedInfo> 本身不存在

request.getSpeedInfo() == null

1. <sch:SpeedInfo> 存在，但带宽不存在：

|| request.getSpeedInfo().getBandwidth() == null

1. 存在带宽但没有值

|| request.getSpeedInfo().getBandwidth().isEmpty() // or whatever API call is appropriate to the datatype

把它们放在一起：

if (request.getSpeedInfo() == null
||
request.getSpeedInfo().getBandwidth() == null
||
request.getSpeedInfo().getBandwidth().isEmpty())
{
    // request is invalid
}
else
    // request is valid ...

Answer 2

SpeedInfo speedInfo = request.getSpeedInfo();
if (speedInfo == null ||                // short circuit here means
    speedInfo.getBandwidth() == null || // that here speedInfo is not null
    speedInfo.getBandwidth().isEmpty()) { // Assuming getBandwidth() is a String or similar

        throw new Exception(" SpeedInfo Bandwidth must be passed in the request ");
}