Java 使用xstream生成子类从xml解组
我正在尝试使用XStream将XML转换为对象树。我希望基于属性创建一个特定的子类 我该怎么做呢Java 使用xstream生成子类从xml解组,java,xstream,Java,Xstream,我正在尝试使用XStream将XML转换为对象树。我希望基于属性创建一个特定的子类 我该怎么做呢 <items> <item> <event type="aaa"> <timestamp>2014-04-10 15:58:08 UTC</timestamp> </event> <event type="bbb">
<items>
<item>
<event type="aaa">
<timestamp>2014-04-10 15:58:08 UTC</timestamp>
</event>
<event type="bbb">
<timestamp>2014-04-03 11:58:08 UTC</timestamp>
</event>
</item>
</items>
但是,我希望XStream为每个事件类型创建一个不同的类。
我有两个类EventAAA和EventBBB,它们都是从抽象事件扩展而来的。如何让XStream在解组时考虑到这一点?XStream当前总是尝试实例化事件,但由于它是抽象的,所以失败了
干杯 执行所需操作(及更多操作)的示例代码:
import com.thoughtworks.xstream.xstream;
导入com.thoughtworks.xstream.converters.Converter;
导入com.thoughtworks.xstream.converters.MarshallingContext;
导入com.thoughtworks.xstream.converters.UnmarshallingContext;
导入com.thoughtworks.xstream.io.HierarchycalStreamReader;
导入com.thoughtworks.xstream.io.HierarchycalStreamWriter;
导入java.util.ArrayList;
导入java.util.array;
/**
* http://stackoverflow.com/posts/23792750
*/
公共类应用程序{
公共静态类项目{
私人ArrayList e;
公共项目(ArrayList e){
这个。e=e;
}
}
公共静态类项{
私人ArrayList e;
公共项目(ArrayList e){
这个。e=e;
}
}
公共静态void main(字符串[]args){
项目=新项目(
新阵列列表(
Arrays.asList(
新项目(
新阵列列表(
Arrays.asList(新的EventAAA(),新的EventBBB())
)
)
)
)
);
XStream xs=新的XStream();
registerConverter(新的EventConverter());
registerConverter(newitemconverter());
别名(“item”,item.class);
附加材料(项目类别“e”);
别名(“items”,items.class);
X.addImplicitArray(Items.class,“e”);
System.out.println(“序列化单个事件对象:”);
System.out.println(xs.toXML(neweventaaa());
System.out.println(xs.toXML(neweventbbb());
System.out.println(“反序列化单个事件对象:”);
System.out.println(xs.fromXML(xs.toXML(neweventaaa()).toString());
System.out.println(xs.fromXML(xs.toXML(neweventAAA()).getClass().getName());
System.out.println(xs.fromXML(xs.toXML(neweventbbb()).toString());
System.out.println(xs.fromXML(xs.toXML(neweventbbb()).getClass().getName());
System.out.println(“显示ArrayList项的序列化:”);
System.out.println(xs.toXML(items));
System.out.println(“显示ArrayList项的反序列化:”);
System.out.println(xs.fromXML(xs.toXML(items));
System.out.println(“为e:”中的元素反序列化显示正确的类型信息”);
Items items2=(Items)xs.fromXML(xs.toXML(Items));
用于(项目i:项目2.e){
对于(事件e:即){
System.out.println(e.getClass().getName());
}
}
}
公共静态类时间戳{
公共时间戳(字符串时间戳){
}
}
公共静态抽象类事件{
公共抽象字符串getTypeName();
私有时间戳时间戳=新时间戳(“”);
公共无效设置时间戳(时间戳t){
this.timestamp=t;
}
公共时间戳getTimestamp(){
返回时间戳;
}
}
公共静态类EventAAA扩展事件{
@凌驾
公共字符串getTypeName(){
返回“aaa”;
}
}
公共静态类EventBBB扩展事件{
@凌驾
公共字符串getTypeName(){
返回“bbb”;
}
}
公共静态类ItemConverter实现转换器{
@凌驾
公共无效封送处理(对象o、HierarchycalStreamWriter编写器、封送上下文mc){
第i项=第o项;
对于(事件e:即){
作者:startNode(“事件”);
mc.另一(e);
writer.endNode();
}
}
@凌驾
公共对象解组(HierarchycalStreamReader阅读器,解组上下文uc){
项目i=新项目(新ArrayList());
while(reader.hasMoreChildren()){
i、 添加((事件)uc.convertOther(i,事件类));
}
返回i;
}
@凌驾
公共布尔canConvert(类类型){
返回(type.equals(Item.class));
}
}
公共静态类EventConverter实现转换器{
公共布尔canConvert(类clazz){
返回Event.class.isAssignableFrom(clazz);
}
公共无效封送处理(对象值、HierarchycalStreamWriter编写器、,
编组(上下文){
事件e=(事件)值;
writer.addAttribute(“type”,例如getTypeName());
writer.startNode(“时间戳”);
writer.setValue(例如getTimestamp().toString());
writer.endNode();
}
公共对象解组(HierarchycalStreamReader,
解组(上下文){
字符串类型=reader.getAttribute(“类型”);
事件e;
if(类型等于(“aaa”)){
e=新事件AAA();
}else if(类型等于(“bbb”)){
e=新事件bbb();
}否则{
抛出新的IllegalArgumentException(“遇到非法类型的事件:“+type”);
}
reader.moveDown();
e、 setTimestamp(新的时间戳(reader.getValue());
reader.moveUp();
返回e;
}
}
}
Ou
xstream.alias("items", Items.class);
xstream.alias("event", Event.class);
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
/**
* http://stackoverflow.com/posts/23792750
*/
public class App {
public static class Items {
private ArrayList<Item> e;
public Items(ArrayList<Item> e) {
this.e = e;
}
}
public static class Item {
private ArrayList<Event> e;
public Item(ArrayList<Event> e) {
this.e = e;
}
}
public static void main(String[] args) {
Items items = new Items(
new ArrayList<Item>(
Arrays.asList(
new Item(
new ArrayList(
Arrays.<Event>asList(new EventAAA(), new EventBBB())
)
)
)
)
);
XStream xs = new XStream();
xs.registerConverter(new EventConverter());
xs.registerConverter(new ItemConverter());
xs.alias("item", Item.class);
xs.addImplicitArray(Item.class, "e");
xs.alias("items", Items.class);
xs.addImplicitArray(Items.class, "e");
System.out.println("Serialize individual event objects:");
System.out.println(xs.toXML(new EventAAA()));
System.out.println(xs.toXML(new EventBBB()));
System.out.println("De-serialize individual event objects:");
System.out.println(xs.fromXML(xs.toXML(new EventAAA())).toString());
System.out.println(xs.fromXML(xs.toXML(new EventAAA())).getClass().getName());
System.out.println(xs.fromXML(xs.toXML(new EventBBB())).toString());
System.out.println(xs.fromXML(xs.toXML(new EventBBB())).getClass().getName());
System.out.println("Show serialization of ArrayList<Item> items:");
System.out.println(xs.toXML(items));
System.out.println("Show de-serialization of ArrayList<Item> items:");
System.out.println(xs.fromXML(xs.toXML(items)));
System.out.println("Show correct type information in de-serialization for elements in e:");
Items items2 = (Items) xs.fromXML(xs.toXML(items));
for (Item i : items2.e) {
for (Event e : i.e) {
System.out.println(e.getClass().getName());
}
}
}
public static class Timestamp {
public Timestamp(String timestamp) {
}
}
public static abstract class Event {
public abstract String getTypeName();
private Timestamp timestamp = new Timestamp("");
public void setTimestamp(Timestamp t) {
this.timestamp = t;
}
public Timestamp getTimestamp() {
return timestamp;
}
}
public static class EventAAA extends Event {
@Override
public String getTypeName() {
return "aaa";
}
}
public static class EventBBB extends Event {
@Override
public String getTypeName() {
return "bbb";
}
}
public static class ItemConverter implements Converter {
@Override
public void marshal(Object o, HierarchicalStreamWriter writer, MarshallingContext mc) {
Item i = (Item) o;
for (Event e : i.e) {
writer.startNode("event");
mc.convertAnother(e);
writer.endNode();
}
}
@Override
public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext uc) {
Item i = new Item(new ArrayList<>());
while (reader.hasMoreChildren()) {
i.e.add((Event) uc.convertAnother(i, Event.class));
}
return i;
}
@Override
public boolean canConvert(Class type) {
return (type.equals(Item.class));
}
}
public static class EventConverter implements Converter {
public boolean canConvert(Class clazz) {
return Event.class.isAssignableFrom(clazz);
}
public void marshal(Object value, HierarchicalStreamWriter writer,
MarshallingContext context) {
Event e = (Event) value;
writer.addAttribute("type", e.getTypeName());
writer.startNode("timestamp");
writer.setValue(e.getTimestamp().toString());
writer.endNode();
}
public Object unmarshal(HierarchicalStreamReader reader,
UnmarshallingContext context) {
String type = reader.getAttribute("type");
Event e;
if (type.equals("aaa")) {
e = new EventAAA();
} else if (type.equals("bbb")) {
e = new EventBBB();
} else {
throw new IllegalArgumentException("Encountered illegal type of event: " + type);
}
reader.moveDown();
e.setTimestamp(new Timestamp(reader.getValue()));
reader.moveUp();
return e;
}
}
}
Serialize individual event objects:
<App_-EventAAA type="aaa">
<timestamp>App$Timestamp@184cf7cf</timestamp>
</App_-EventAAA>
<App_-EventBBB type="bbb">
<timestamp>App$Timestamp@5bfa9431</timestamp>
</App_-EventBBB>
De-serialize individual event objects:
App$EventAAA@48fa0f47
App$EventAAA
App$EventBBB@161479c6
App$EventBBB
Show serialization of ArrayList<Item> items:
<items>
<item>
<event type="aaa">
<timestamp>App$Timestamp@5c909414</timestamp>
</event>
<event type="bbb">
<timestamp>App$Timestamp@65466a6a</timestamp>
</event>
</item>
</items>
Show de-serialization of ArrayList<Item> items:
App$Items@3eb7fc54
Show correct type information in de-serialization for elements in e:
App$EventAAA
App$EventBBB