Xstream

最新推荐文章于 2024-05-26 20:48:22 发布

ywmahl

最新推荐文章于 2024-05-26 20:48:22 发布

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文章标签： function object class getter string setter

本文链接：https://blog.youkuaiyun.com/ywmahl/article/details/2154276

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About XStream

XStream is a simple library to serialize objects to XML and back again.

1 Requirement

xstream.jar

2.example

xml:

<Function>
<description>this is a simple test></descripion>
     <cases>
     <case type="single">single value check</case>
     <case type="duplicate">duplicate value check</case>
   <cases>
</Function>

Analysis:

according to the xml structure, we should define a class named Function (no need the same name whatever, but it is better to use the same one to identify).

Class Function{

private String description;

private List cases; // since cases node include a case list

getter and setter method...

}

The following question is how we fetch the case info. if we define it as a string, we could only get the text value, we couldn't get the attribute type. So let's define a Type to manage it.

Class FunctionCase{

private String typedescriptor;

private String value;

getter and setter method...

}

so, what to do next, parse it directly? ok, let's try:

Xstream stream = new Xstream(new DomDriver());

stream.alias("Function", Function.class);

stream.alias("case", FunctionCase.class);

stream.aliasAttribute(FunctionCase.class, "typedescriptor", "type"); // since type is defined as an attribute in class FunctionCase.

Function fun = stream.fromXML(new InputStream(...));

then we can get description by fun.getDescription(); get the cases by iterate list fun.getCases();

we can get type but we can't get value. the xstream can't parse the text value directly into value fields.

As mentioned above, if we do stream.alias("case", String.class); then we can only get the text.

The problem can be resovled by ading a converter:

public class FunctionCaseConverter implements Converter{

public void marshal(Object object, HierarchicalStreamWriter writer, MarshallingContext context) {

  FunctionCase io = (FunctionCase) object;
  writer.startNode("case");
  writer.setValue(io.getValue());
  writer.addAttribute("type", io.getType());
  writer.endNode();

}

public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {

FunctionCase entryIO = new FunctionCase();

  entryIO.setValue(reader.getValue());
  entryIO.setType(reader.getAttribute("type"));
  return entryIO;

}

public boolean canConvert(Class type) {

return type.equals(FunctionCase.class);
}
}

Then we should tell the xstream when it meets FunctionCase, it should convert it to our defined way:

stream.registerConverter(new FunctionCaseConverter());

OK, everything get done. Test it:)

3 Above is example from xml to object, the reverse opration works the same way.