Question

我有一个子类孩子，它派生自基类父。我想在Base Class的属性周围添加一个Wrapper。

Parent.java

10-12 16:59:37.427  25539-25539/com.gpslocmex.locmex E/AndroidRuntime﹕ FATAL EXCEPTION: main
    android.util.AndroidRuntimeException: { what=0 when=-1ms } This message is already in use.
            at android.os.MessageQueue.enqueueMessage(MessageQueue.java:285)
            at android.os.Handler.sendMessageAtTime(Handler.java:473)
            at android.os.Handler.postAtTime(Handler.java:285)
            at com.google.maps.api.android.lib6.d.cm.c(Unknown Source)
            at com.google.maps.api.android.lib6.d.cm.b(Unknown Source)
            at com.google.maps.api.android.lib6.d.et.a(Unknown Source)
            at com.google.android.gms.maps.internal.j.onTransact(SourceFile:167)
            at android.os.Binder.transact(Binder.java:326)
            at com.google.android.gms.maps.internal.IGoogleMapDelegate$zza$zza.addMarker(Unknown Source)
            at com.google.android.gms.maps.GoogleMap.addMarker(Unknown Source)
            at com.gpslocmex.locmex.Mapa_activity.renovarmarcador(Mapa_activity.java:218)
            at com.gpslocmex.locmex.Mapa_activity$4$1.handleMessage(Mapa_activity.java:161)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4745)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)

Child.java

package test;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Parent {

    int a;
    int b;

    String name;

    public Parent() {
    }

    public int getA() {
        return a;
    }

    public void setA(int a) {
        this.a = a;
    }

    public int getB() {
        return b;
    }

    public void setB(int b) {
        this.b = b;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

的Output.xml

package test;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Child extends Parent {

    private String foo;

    public Child() {

    }

    public String getFoo() {
        return foo;
    }

    public void setFoo(String foo) {
        this.foo = foo;
    }
}

但我想要这样的事情：

<child>
    <a>1</a>
    <b>3</b>
    <name>name</name>
    <foo>foo</foo>
</child>

我希望有人可以帮助我。

Answer 1

你想做的事情是可行的，但可能不值得麻烦。您需要为Child课程实施XmlAdapter，

package test;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public final class ChildAdapter extends
XmlAdapter<PrintedType, Child> {

    @Override
    public Child unmarshal(PrintedType v) throws Exception {
        Child ret = new Child();
        ret.setFoo(v.foo);
        ret.setA(v.parent.getA());
        ret.setB(v.parent.getB());
        ret.setName(v.parent.getName());
        return ret;
    }

    @Override
    public PrintedType marshal(Child v) throws Exception {
        PrintedType ret = new PrintedType();
        ret.parent = v;
        ret.foo = v.getFoo();
        return ret;
    }
}

以及生成您想要的XML表示的值类型：

package test;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="child")
@XmlAccessorType(XmlAccessType.FIELD)
public class PrintedType {
    String foo;
    Parent parent;
}

然后，如果你想编组一个Child的实例作为根元素（而不是在其他类中有一个Child成员字段，并且编组该类），你实际上有首先将Child转换为PrintedType（https://stackoverflow.com/a/11967459/4854749）。所以样本测试类可能是

package test;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class Demo {
    public static void main(String[] args) throws JAXBException {
        Child child = new Child();
        child.setA(1);
        child.setB(3);
        child.setName("name");
        child.setFoo("foo");

        JAXBContext jc = JAXBContext.newInstance(PrintedType.class);
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);

        PrintedType ret = new PrintedType();
        ret.parent = child;
        ret.foo = child.getFoo();

        marshaller.marshal(ret, System.out);
    }
}

您确定这对您要解决的问题有意义吗？我不知道你的背景，但问问自己哪种听起来更合适：Child 是 Parent，或Child 包含 Parent？如果是后者，则可以通过取消继承和使用合成来使事情变得更加简单（使Child 包含一个Parent字段）。那么你就不需要适配器类了，而Child会以你想要的方式编组。

Jaxb附加包装arround基类

1 个答案: