java-如何使用Simple从自定义Converter访问字段注释？

我正在使用简单(http://simple.sourceforge.net/)库在Java中封送/拆封XML数据.对于某些更复杂的数据结构,我需要编写自己的Converters.例如,说我有一个List< List< String>>我需要编组.我写了以下内容：

class WorldObject {

   @Element(name="vector-names")
   @Convert(ListListConverter.class)
   private List<List<String>> vectorNames;

   /** Constructor and other details ... **/

}

与ListListConverter一起(我暂时不考虑解组器)：

class ListListConverter implements Converter<List<List<String>>> {

   @Override
   public List<List<String>> read(InputNode node) throws Exception {
      // stub
      return null;
   }   

   @Override
   public void write(OutputNode node, List<List<String>> value)
         throws Exception {

      node.setName("list-list-string");

      for (List<String> list : value) {
         OutputNode subList = node.getChild("list-string");

         for (String str : list) {
            OutputNode stringNode = subList.getChild("string");
            stringNode.setValue(str);
         }

         subList.commit();
      }

      node.commit();

   }

}

此设置工作正常,并生成我想要的XML.但是,我想访问@Element批注的名称字段,以便可以给标签指定名称(在这种情况下为“ vector-names”),而不是默认名称(“ list-list-string” ).这就是Simple对开箱即用处理的所有类型进行编组的方式,因此必须有一种从自定义Converter访问该数据的方法.

我该怎么做？

解决方法:

您无法以这种方式获取注释,因为无法通过字段转换器中的字段进行访问.
解决方案是编写一个WorldObject-Converter-即使您只想编写一个字段.

WorldObject类：

@Root
@Convert(WorldObjectConverter.class) // specify converter for this class
public class WorldObject
{
    @Element(name = "vector-names")
    private List<List<String>> vectorNames;

    // only for the example below - write whatever constructor(s) you need
    public WorldObject()
    {
        this.vectorNames = new ArrayList<>();
    }

    // constructor, getter / setter, etc.


    // a getter is required to access the field in the converter.
    public List<List<String>> getVectorNames()
    {
        return vectorNames;
    }
}

WorldObjectConverter类：

public class WorldObjectConverter implements Converter<WorldObject>
{
    @Override
    public WorldObject read(InputNode node) throws Exception
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }


    @Override
    public void write(OutputNode node, WorldObject value) throws Exception
    {
        final Field f = value.getClass().getDeclaredField("vectorNames"); // get the field 'vectorNames' of the 'WorldObject' class
        final Element elementAnnotation = f.getAnnotation(Element.class); // get the 'Element' annotation of the Field

        final String name = elementAnnotation.name(); // get the 'name'-value of the annotation
        node.setName(name); // set Nodename


        for( List<String> list : value.getVectorNames() )
        {
            OutputNode subList = node.getChild("list-string");

            for( String str : list )
            {
                OutputNode stringNode = subList.getChild("string");
                stringNode.setValue(str);
            }

            subList.commit();
        }

        node.commit();
    }
}

例：

final File f = new File("test.xml"); // output file

WorldObject wo = new WorldObject(); // the object to serialize

// some testdata ...
List<String> l = new ArrayList<>();
l.add("a");
l.add("b");
wo.getVectorNames().add(l);

l = new ArrayList<>();
l.add("c");
l.add("d");
wo.getVectorNames().add(l);


// create the serializer - dont forget the AnnotationStrategy!
Serializer ser = new Persister(new AnnotationStrategy());
ser.write(wo, f); // serialize it to file

输出：

<vector-names>
   <list-string>
      <string>a</string>
      <string>b</string>
   </list-string>
   <list-string>
      <string>c</string>
      <string>d</string>
   </list-string>
</vector-names>

完成！

标签：java,xml,simple-framework
来源： https://codeday.me/bug/20191012/1898552.html