在 Java 中将 XML 转换为 JSON（没有额外的 <e> 和 <o> 元素）

Question

我正在使用 json-lib 库中的 XMLSerializer，以便在 JSON 和 XML 之间来回转换。

有没有办法避免生成<e> 和<a> 节点？这很不方便被路径表达式破坏？

考虑下面的例子：

{"store": {
  "book":   [
        {
      "category": "reference",
      "author": "Nigel Rees",
      "title": "Sayings of the Century",
      "price": 8.95
    },
        {
      "category": "fiction",
      "author": "Evelyn Waugh",
      "title": "Sword of Honour",
      "price": 12.99
    },
        {
      "category": "fiction",
      "author": "Herman Melville",
      "title": "Moby Dick",
      "isbn": "0-553-21311-3",
      "price": 8.99
    },
        {
      "category": "fiction",
      "author": "J. R. R. Tolkien",
      "title": "The Lord of the Rings",
      "isbn": "0-395-19395-8",
      "price": 22.99
    }
  ],
  "bicycle":   {
    "color": "red",
    "price": 19.95
  }
}}

被序列化为：

<?xml version="1.0" encoding="UTF-8"?>
<o>
  <store class="object">
    <bicycle class="object">
      <color type="string">red</color>
      <price type="number">19.95</price>
    </bicycle>
    <book class="array">
      <e class="object">
        <author type="string">Nigel Rees</author>
        <category type="string">reference</category>
        <price type="number">8.95</price>
        <title type="string">Sayings of the Century</title>
      </e>
      <e class="object">
        <author type="string">Evelyn Waugh</author>
        <category type="string">fiction</category>
        <price type="number">12.99</price>
        <title type="string">Sword of Honour</title>
      </e>
      <e class="object">
        <author type="string">Herman Melville</author>
        <category type="string">fiction</category>
        <isbn type="string">0-553-21311-3</isbn>
        <price type="number">8.99</price>
        <title type="string">Moby Dick</title>
      </e>
      <e class="object">
        <author type="string">J. R. R. Tolkien</author>
        <category type="string">fiction</category>
        <isbn type="string">0-395-19395-8</isbn>
        <price type="number">22.99</price>
        <title type="string">The Lord of the Rings</title>
      </e>
    </book>
  </store>
</o>

http://jsontoxml.utilities-online.info/ 提供的东西正是我所追求的，但似乎在 Java 中不可用。

Answer 1

您可以通过 StAX 使用 StAXON - JSON 来执行此操作。 StAXON 实现 XML 的 Streaming API，但读取和写入 JSON。也就是说，您可以使用标准 XML 工具来完成这项工作。

复制 XML 的一个常见“技巧”是使用身份 XML 转换 (XSLT)。

这里有一些代码：

InputStream input = ... // your JSON input;
OutputStream output = System.out;
try {
    /*
     * Create source.
     */
    XMLInputFactory inputFactory = new JsonXMLInputFactory();
    inputFactory.setProperty(JsonXMLInputFactory.PROP_MULTIPLE_PI, false);
    Source source = new StAXSource(inputFactory.createXMLStreamReader(input));

    /*
     * Create result.
     */
    XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
    XMLStreamWriter writer = outputFactory.createXMLStreamWriter(output);
    writer = new PrettyXMLStreamWriter(writer); // format output
    Result result = new StAXResult(writer);

    /*
     * Transform (copy).
     */
    TransformerFactory transformerFactory = TransformerFactory.newInstance();
    transformerFactory.newTransformer().transform(source, result);
} finally {
    /*
     * As per StAX specification, XMLStreamReader/Writer.close() doesn't close
     * the underlying stream.
     */
    output.close();
    input.close();
}

用你的例子运行它会产生：

<?xml version="1.0" ?>
<store>
    <book>
        <category>reference</category>
        <author>Nigel Rees</author>
        <title>Sayings of the Century</title>
        <price>8.95</price>
    </book>
    <book>
        <category>fiction</category>
        <author>Evelyn Waugh</author>
        <title>Sword of Honour</title>
        <price>12.99</price>
    </book>
    <book>
        <category>fiction</category>
        <author>Herman Melville</author>
        <title>Moby Dick</title>
        <isbn>0-553-21311-3</isbn>
        <price>8.99</price>
    </book>
    <book>
        <category>fiction</category>
        <author>J. R. R. Tolkien</author>
        <title>The Lord of the Rings</title>
        <isbn>0-395-19395-8</isbn>
        <price>22.99</price>
    </book>
    <bicycle>
        <color>red</color>
        <price>19.95</price>
    </bicycle>
</store>

注意：如果输出属性PROP_MULTIPLE_PI设置为true，StAXON会生成<xml-multiple>处理指令。在转换回 JSON 以触发数组启动时，StAXON 可以使用这些。如果您不需要返回 JSON，请将此设置保留为 false。