XStream 如何忽略 未知节点?

NND, 该死的ZF， 把google搜索老是屏蔽！

百度牛掰？又不见你百度给我找出正确答案？！！要是有一天“百度他M”能知道就好了。。。

 

以下是以备需要， 还没有测试成功！

 

Omit Unexpected XML Elements With XStream

Posted January 8, 2009
Filed under: Java, XML |

XStream is a Java xml library,
which nicely serializes Java objects to XML and vice versa. It can easily deal
with missing (i.e. optional) XML elements. The corresponding Java
fields will just be left blank.

<user>
    <name>Peter Voss<name>
</user>

can be read into the Java object:

public class User {
    private String name;
    private String role;

    // getter and setter methods are here
}

 

In this case the optional <role> field is missing in the XML
and the corresponding field in the User Java object will be left null when
deserializing the XML.

But once if you have decided on your XML API, you might want to
question if it is flexible enough. Just consider you have built software based
on this XML spec. Can you still add optional XML elements without breaking the
applications that you have already shipped? Consider you want to add more
information, like a <department> element. Will your clients be able to
just ignore this piece of
information? The short answer is: No. XStream will throw a
ConversionException if it finds an element that has no corresponding Java field.
The Jira ticket XSTR-30 is an improvement
request related to this topic. But so far XStream has no simple switch to
turn off complaining about unknown elements.

But you could easily tweak XStream to ignore additional elements by adding your own custom
mapper that ignores the field. The following snippet creates an XStream instance that ignores
additional fields. It is grabbed from the
CustomMapperTest.testCanBeUsedToOmitUnexpectedElements() unit test that is part
of the XStream source code:

XStream xstream = new XStream() {
  @Override
  protected MapperWrapper wrapMapper(MapperWrapper next) {
    return new MapperWrapper(next) {
      @Override
      public boolean shouldSerializeMember(Class definedIn,
              String fieldName) {
        if (definedIn == Object.class) {
          return false;
        }
        return super.shouldSerializeMember(definedIn, fieldName);
      }
    };
  }
};

I just wanted to write this down, because a solution for this common
problem is somewhat difficult to find right now.