我想List<Map<String,Object>>
在 XML 中表示一个实例,如下所示:
<row>
<entry key="key1" xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">value1</entry>
<entry key="key2" xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">value2</entry>
<entry key="key3" />
<entry key="keyDate" xsi:type="xs:dateTime" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">2012-08-19T13:00:59.412-04:00</entry>
</row>
wherekey1
和key2
是字符串,key3
是 nil,并且keyDate
是日期。
我可以使用以下实现来接近XmlAdapter
这一点:
package net.parkerson.test1;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class JAXBMapAdapter extends XmlAdapter<JAXBMapAdapter.JAXBMap, Map<String, Object>>
{
@Override
public JAXBMap marshal(Map<String, Object> map) throws Exception
{
JAXBMap jaxbMap = new JAXBMap();
for (Entry<String, Object> entry : map.entrySet())
{
jaxbMap.entry.add(new JAXBMapEntry(entry));
}
return jaxbMap;
}
@Override
public Map<String, Object> unmarshal(JAXBMapAdapter.JAXBMap mappedObject) throws Exception
{
HashMap<String, Object> map = new HashMap<String, Object>();
for (JAXBMapEntry entry : mappedObject.entry)
{
map.put(entry.key, entry.value);
}
return map;
}
public static class JAXBMapEntry
{
@XmlAttribute
public String key;
@XmlElement
public Object value;
public JAXBMapEntry()
{
}
public JAXBMapEntry(Map.Entry<String, Object> entry)
{
key = entry.getKey();
value = entry.getValue();
}
}
public static class JAXBMap
{
public List<JAXBMapAdapter.JAXBMapEntry> entry = new ArrayList<JAXBMapAdapter.JAXBMapEntry>();
}
}
和以下测试代码:
package net.parkerson.test1;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.xml.bind.JAXB;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElements;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import net.parkerson.test1.JAXBMapAdapter;
public class Test1
{
@XmlRootElement
public static class Thingy
{
@XmlElements(@XmlElement(name = "row"))
@XmlJavaTypeAdapter(type=Map.class, value=JAXBMapAdapter.class)
public List<Map<String,Object>> rows;
}
public static void main(String[] args) throws Exception
{
Test1.Thingy thingy = new Test1.Thingy();
Map<String,Object> thing1 = new HashMap<String,Object>();
thing1.put("foo", "bar");
thing1.put("date", new Date());
Map<String,Object> thing2 = new HashMap<String,Object>();
thing2.put("foo", "baz");
thing2.put("date", new Date());
List<Map<String,Object>> things = new ArrayList<Map<String,Object>>();
things.add(thing1);
things.add(thing2);
thingy.rows = things;
java.io.StringWriter sw = new java.io.StringWriter();
JAXB.marshal(thingy, sw);
System.out.print(sw.toString());
}
}
这会产生:
<thingy>
<row>
<entry key="foo">
<value xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">bar</value>
</entry>
<entry key="date">
<value xsi:type="xs:dateTime" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">2012-08-19T13:20:57.484-04:00</value>
</entry>
</row>
<row>
<entry key="foo">
<value xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">baz</value>
</entry>
<entry key="date">
<value xsi:type="xs:dateTime" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">2012-08-19T13:20:57.484-04:00</value>
</entry>
</row>
</thingy>
我真正想要的是放弃value
条目内的嵌套标签。我天真的假设是我可以将@XmlElement
注释替换value
为@XmlValue
. 但是,这会导致 JAXB 吐得满地都是:
Exception in thread "main" java.lang.NullPointerException
at com.sun.xml.internal.bind.v2.runtime.reflect.TransducedAccessor.get(TransducedAccessor.java:154)
at com.sun.xml.internal.bind.v2.runtime.property.ValueProperty.<init>(ValueProperty.java:66)
at com.sun.xml.internal.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:95)
at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:145)
at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:479)
at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:498)
at com.sun.xml.internal.bind.v2.runtime.property.ArrayElementProperty.<init>(ArrayElementProperty.java:97)
at com.sun.xml.internal.bind.v2.runtime.property.ArrayElementNodeProperty.<init>(ArrayElementNodeProperty.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.sun.xml.internal.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:113)
at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:145)
at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:479)
at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:498)
at com.sun.xml.internal.bind.v2.runtime.property.ArrayElementProperty.<init>(ArrayElementProperty.java:97)
at com.sun.xml.internal.bind.v2.runtime.property.ArrayElementNodeProperty.<init>(ArrayElementNodeProperty.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.sun.xml.internal.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:113)
at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:145)
at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:479)
at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:305)
at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1100)
at com.sun.xml.internal.bind.v2.ContextFactory.createContext(ContextFactory.java:143)
at com.sun.xml.internal.bind.v2.ContextFactory.createContext(ContextFactory.java:110)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:202)
at javax.xml.bind.ContextFinder.find(ContextFinder.java:376)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:574)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:522)
at javax.xml.bind.JAXB$Cache.<init>(JAXB.java:87)
at javax.xml.bind.JAXB.getContext(JAXB.java:114)
at javax.xml.bind.JAXB._marshal(JAXB.java:538)
at javax.xml.bind.JAXB.marshal(JAXB.java:431)
at net.parkerson.test1.Test1.main(Test1.java:49)
我确信有一种方法可以使用XmlAdapter
基于我的代码来做到这一点,但我想我已经盯着这个太久了,无法想出它!