SimpleXML :对多个类型使用id属性
SimpleXML :对多个类型使用id属性
提问于 2014-06-23 11:37:37
我使用SimpleXML将XML解析为Java对象，但无法解析该文件：
<pets>
<cats>
<cat id="0" talk="miaou" />
<cat id="1" talk="MIWAOUHAUOHou" />
</cats>
<dogs>
<dog id="0"/>
</dogs>
<mine>
<cat ref="1"/>
</mine>
</pets>使用这个Java类：
@Default
@Root(name = "pets")
public class SimpleIds
{
@ElementList(required = false)
public ArrayList<Cat> cats;
@ElementList(required = false)
public ArrayList<Dog> dogs;
@Root(name = "cat")
public static class Cat
{
@Attribute
public String talk;
public void talk()
{
System.out.println(talk);
}
}
@Root(name = "dog")
public static class Dog
{
}
@Element
public Mine mine;
@Root(name = "mine")
public static class Mine
{
@Element
public Cat cat;
}
}而这个序列化器：
Strategy strategy = new CycleStrategy("id", "ref");
Serializer serializer = new Persister(strategy);
SimpleIds xml = serializer.read(SimpleIds.class, new File("simpleIds.xml"));
xml.mine.cat.talk();这让我很不友好：
org.simpleframework.xml.strategy.CycleException: Element '0' already exists在SimpleXML中不可能使用这种xml文件吗？还是它只是一种糟糕的xml格式？
编辑：如果我把cat id="0"改成cat id="2"，它的效果就像魅力.
Stack Overflow用户
回答已采纳
发布于 2014-06-26 13:19:55
最后，我在W3C推荐上找到了一个答案：
文档中all attributes类型为“id”(其中包括所有xml:id属性)的值是唯一的。
这意味着我输入的XML是不正确的。
我不能更改它，因为我从软件中接收到它，但是我必须在读取它之前对它进行格式化(并反向写入)才能得到这样的结果：
<pets>
<cats>
<cat id="cat-0" talk="miaou" />
<cat id="cat-1" talk="MIWAOUHAUOHou" />
</cats>
<dogs>
<dog id="dog-0"/>
</dogs>
<mine>
<cat ref="cat-1"/>
</mine>
</pets>编辑：下面是可以在SimpleXML中为您自动完成这些工作的代码：
/*
* Copyright (C) 2014, Mathieu Lavigne <bludwarf@gmail.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package org.simpleframework.xml.strategy;
import static org.simpleframework.xml.strategy.Name.*;
import java.util.Map;
import org.simpleframework.xml.core.Persister;
import org.simpleframework.xml.stream.Node;
import org.simpleframework.xml.stream.NodeMap;
/**
* CycleStrategy for SimpleXML allowing having duplicate IDs on nodes from different types.
*
* <p>Known limitations : </p>
*
* <ul>
* <li>as for Legacy CycleStrategy, new ids are generated for <b>every node</b> when calling {@link Persister#write(Object, java.io.File)}
* </ul>
*
* @author bludwarf@gmail.com
* @since 26 juin 2014
*/
public class TypedCycleStrategy extends CycleStrategy
{
private String mark;
private String refer;
public TypedCycleStrategy()
{
this(MARK, REFER, LABEL, LENGTH);
}
public TypedCycleStrategy(String mark, String refer)
{
this(mark, refer, LABEL, LENGTH);
}
public TypedCycleStrategy(String mark, String refer, String label)
{
this(mark, refer, label, LENGTH);
}
public TypedCycleStrategy(String mark, String refer, String label, String length)
{
super(mark, refer, label, length);
this.mark = mark;
this.refer = refer;
}
public Value read(Type type, NodeMap node, Map map)
throws Exception
{
// Unique id
makeUniqueAttribute(mark, node, type);
// Unique ref
makeUniqueAttribute(refer, node, type);
return super.read(type, node, map);
}
/**
* @param attribute mark OR refer
* @param node current node
* @param type node type
* @return the uniqueId created
* @throws Exception
*/
public static String makeUniqueAttribute(String attribute, NodeMap node, Type type) throws Exception
{
final Node entry = node.remove(attribute);
String uniqueId = null;
// Attribute found ?
if (entry != null)
{
// Replace it to make it unique
final String id = entry.getValue();
uniqueId = type.getType().getName() + "-" + id;
node.put(attribute, uniqueId);
}
return uniqueId;
}
}注意：不更改包声明!
以及相应的序列化程序：
Strategy strategy = new TypedCycleStrategy("id", "ref");
Serializer serializer = new Persister(strategy);
SimpleIds xml = serializer.read(SimpleIds.class, new File("simpleIds.xml"));
xml.mine.cat.talk();页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/24364936
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