文章目录

1. 1. dom4j的xpath接口
1. 1.1. 读入xml
2. 1.2. dom4j 输出
3. 1.3. xpath实际案例
2. 2. scala xml 操作
1. 2.1. 加载和导出xml
2. 2.2. 查询
3. 2.3. CRUD

dom4j的xpath接口

dom4j具体操作, 猛击

• document.selectNodes("") 查找多个匹配的节点

• document.selectSingleNode("") 查找只有一个匹配的节点, 如果没有返回null

• node.valueOf("@name"); 获取节点中name属性的值

xpath	意义
//BBB	选择所有的BBB
//DDD/BBB	选择所有DDD下面的BBB
/AAA/CCC/DDD/*	选择/AAA/CCC/DDD 下面所有的标签
/*/*/*/DDD	选择第四个层次的DDD
//* 所有的标签
/AAA/BBB[1]	选择第1个节点
/AAA/BBB[last()]
//@id	选择所有的id属性
//BBB[@name]	选择所有有name属性的BBB节点
//BBB[@*]	选择所有有属性的BBB节点
//BBB[not(@*)]	选择所有没有属性的BBB节点
//[@id='b1']	选择所有属性id=bi的属性
//*[count(BBB)=2]	选择有两个BBB子节点的节点
//*[count(*)=2]	选择由两个子节点的节点
//*[contains(name(), "AAA")]
//*[string-length(name(),3)]
/AAA/EEE //DDD/CCC	集合起来

读入xml

SAXReader reader = new RAXReader();
Document document = reader.read("*.xml");

dom4j 输出

org.dom4j.io.OutputFormat format = OutputFormat.createCompactFormat();
format.setEncoding("UTF-8");
XMLWriter writer = new XMLWriter(new FileOutputStream(), format);
writer.write(document);
writer.close();

xpath实际案例

<books>
    <book>
        <author>
        </author>
    </book>
</books>

Node node = document.selectSingleNode("//book[2]/author"); // 会选中其中一个
node.getText();

Node node = document.selectSingleNode("//book[2]");
node.valueOf("@id");  // 获取属性ID

scala xml 操作

加载和导出xml

val bookstore =
      <bookstore>
        <book>
          <title lang="eng">Harry Potter</title>
          <price>29.99</price>
        </book>
        <book>
          <title lang="eng">Learning XML</title>
          <price>39.95</price>
        </book>
      </bookstore>
XML.save("bookstore1.xml", bookstore, "utf-8", true, null) // 第三个参数明是否要写xml头
// 加载
XML.loadFile("bookstore.xml")

查询

由于scala.xml.Node 继承于 Seq[Node], 所以可以用 scala 的 Seq 中的方法来操作xml,

详细继承图,及案例

val bookstore = XML.loadFile("bookstore.xml")
val price =
  bookstore match {
    case <bookstore>{ books @ _* }</bookstore> =>
      books.collectFirst {
        case book @ <book>{ _* }</book> if (book \ "title").text == "Learning XML" =>
          (book \ "price").text
        }
    }

CRUD

注: 还有另一种更新方法, 感觉不是很直观, 有兴趣的可以猛击我

  it should "append xml" in {
    val bookstore = XML.loadFile("bookstore.xml")
    val book =
      <book>
        <title lang="zh">Learn Scala</title>
        <price>40.11</price>
      </book>
    bookstore \ "book" ++ book
  }

  it should "remove child" in {
    val bookstore = XML.loadFile("bookstore.xml")
    val afterDel = bookstore.child.filter(node => (node \ "price").text == "29.99")
  }

  it should "update xml" in {
    val bookstore = XML.loadFile("bookstore.xml")
    val updated =
      (bookstore \ "book") map {
        _ match {
          case book @ <book> { _* }</book> if (book \ "title").text == "Learning XML" =>
            <book><title>{ (book \ "title").text }</title><price>3</price></book>
          case x => x
        }
      }
  }