没有属性的JAXB元素

2 回答

• 0

  您可以执行以下操作并利用 XmlAdapter 将 Boolean 转换为空对象以获取所需的XML表示形式 .

  Java模型

  Root

  该属性是 boolean ，但我们将使字段 Boolean ，以便我们可以应用 XmlAdapter . 我们还将指定我们希望JAXB映射到该字段（请参阅：http://blog.bdoughan.com/2011/06/using-jaxbs-xmlaccessortype-to.html） .

  import javax.xml.bind.annotation.*;
  import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
  
  @XmlRootElement
  @XmlAccessorType(XmlAccessType.FIELD)
  public class Root {
  
      @XmlJavaTypeAdapter(BooleanAdapter.class)
      private Boolean foo = false;
  
      @XmlJavaTypeAdapter(BooleanAdapter.class)
      private Boolean bar = false;
  
      public boolean isFoo() {
          return foo;
      }
  
      public void setFoo(boolean foo) {
          this.foo = foo;
      }
  
      public boolean isBar() {
          return bar;
      }
  
      public void setBar(boolean bar) {
          this.bar = bar;
      }
  
  }
  

  BooleanAdapter

  import javax.xml.bind.annotation.adapters.XmlAdapter;
  
  public class BooleanAdapter extends XmlAdapter<BooleanAdapter.AdaptedBoolean, Boolean> {
  
      public static class AdaptedBoolean {
      }
  
      @Override
      public Boolean unmarshal(AdaptedBoolean v) throws Exception {
          return null != v;
      }
  
      @Override
      public AdaptedBoolean marshal(Boolean v) throws Exception {
          if(v) {
              return new AdaptedBoolean();
          } else {
              return null;
          }
      }
  
  }
  

  演示代码

  下面是一些演示代码，您可以运行以查看一切正常 .

  Demo

  import javax.xml.bind.*;
  
  public class Demo {
  
      public static void main(String[] args) throws Exception {
          JAXBContext jc = JAXBContext.newInstance(Root.class);
  
          Root foo = new Root();
          foo.setFoo(true);
          foo.setBar(false);
  
          Marshaller marshaller = jc.createMarshaller();
          marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
          marshaller.marshal(foo, System.out);
      }
  
  }
  

  Output

  <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
  <root>
      <foo/>
  </root>
  

  回复于 2024-05-05T09:28:32+08:00
• 0

  您可以通过设置空字符串来伪造空节点，为此您需要将 boolean s转换为 String s .

  @XmlRootElement
  public static  class Structure {
      @XmlElement String type;
      @XmlElement Automaton automaton;
      public Structure() { automaton = new Automaton(); }
      Structure(String t) { this(); type = t; }
  }
  
  public static class Automaton {
      @XmlElement List<State> state;
      public Automaton() { state = new ArrayList<>(); }
      State addState(State s) {state.add(s); return s;};
  }
  
  public static class State {
      @XmlAttribute String id, name;
      @XmlElement double x, y;
      @XmlElement String initial;
      @XmlElement(name="final") String final_;
      public State() {};
      State(String id, String n, double x, double y)
      {this.id = id; name = n; this.x = x; this.y = y;};
  }
  

  创建一些数据并封送它：

  @Test
  public void jaxbEmptyEmlements() throws JAXBException {
      JAXBContext c = JAXBContext.newInstance(Structure.class);
      Marshaller m = c.createMarshaller();
      m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
      m.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
      Structure o = new Structure("fa");
      o.automaton.addState(new State("0", "q0", 160d, 151d)).initial = "";
      o.automaton.addState(new State("1", "q1", 369d, 94d)).final_ = "";
      m.marshal(o, System.out);
  }
  

  这将输出

  <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
  <structure>
      <type>fa</type>
      <automaton>
          <state id="0" name="q0">
              <x>160.0</x>
              <y>151.0</y>
              <initial></initial>
          </state>
          <state id="1" name="q1">
              <x>369.0</x>
              <y>94.0</y>
              <final></final>
          </state>
      </automaton>
  </structure>
  

  请注意 <initial></initial> 与 <initial/> 相同， final 相同 .

  或者，您可以重新考虑状态类型的节点并创建一个元素<state-type>并使用值enum设置它，例如enum StateType {INITIAL，FINAL}或者只是将其设置为字符串initial或final .

  EDIT
  

  回复于 2024-05-05T09:28:32+08:00