java - 在java中合并XML，多个节点的标签名称与子节点相同？

Question

我在合并两个 XML 字符串或文件时遇到问题。

XML1.

<?xml version="1.0" encoding="UTF-8"?>
<Specification>
	<item>
		<id>PS1</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P1</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P2</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR1</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR2</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
	<item>
		<id>PS2</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P3</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P4</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR3</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR4</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
</Specification>

XML2.

<?xml version="1.0" encoding="UTF-8"?>
<Specification>
	<item>
		<id>PS3</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P5</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P6</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR5</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR6</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
	<item>
		<id>PS1</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P7</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P8</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR3</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR4</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
</Specification>

预期输出：

<?xml version="1.0" encoding="UTF-8"?>
<Specification>
	<item>
		<id>PS1</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P1</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P2</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR1</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR2</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
	<item>
		<id>PS2</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P3</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P4</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR3</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR4</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
	<item>
		<id>PS3</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P5</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P6</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR5</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR6</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
	<item>
		<id>PS1</id>
		<startDate> 21 Oct 2016</startDate>
		<Product>
			<item>
				<id>P7</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
			<item>
				<id>P8</id>
				<startDate> 21 Oct 2016</startDate>
			</item>
		</Product>
		<CompositePrice>
			<item>
				<id>PR3</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>1.0</Price>
			</item>
			<item>
				<id>PR4</id>
				<startDate> 21 Oct 2016</startDate>
				<Price>2.0</Price>
			</item>
		</Price>
	</item>
</Specification>

我尝试运行 java 代码，但是当第二个代码在规范下有多个项目时无法合并。当第二个只有一个项目时运行正常，即使第一个有多个项目在规范下也是如此。