Xml SAX 解析模式使用

如下代码展示了通过实现 SaxHandler 接口来完成 SAX 模式解析的操作示例。

import std.collection.*
import encoding.xml.*

let latestMovie = """
<collection shelf="New Arrivals">
<movie title="Movie 2021">
   <score>7.4</score>
   <year>2021-3</year>
   <description>This is a virtual film released in 2021 for testing.</description>
</movie>
<movie title="Movie 2022">
   <type>Anime, Science Fiction</type>
   <score>7</score>
   <year>2022-2</year>
   <description>This is a virtual film released in 2022 for testing.</description>
</movie>
<movie title="Movie 2023">
   <score>6.5</score>
   <year>2023-4</year>
   <description>This is a virtual film released in 2023 for testing.</description>
</movie>
</collection>
"""

// 实现 SaxHandler 接口
class MovieHandler <: SaxHandler {
    private var curTag: String
    private var title: String
    private var score: String
    private var year: String

    init() {
        curTag = ""
        title = ""
        score = ""
        year = ""
    }

    public func startDocument(): Unit {
        println("Start Parsing.")
    }
    public func endDocument(): Unit {
        println("End Parsing.")
    }
    public func startElement(name: String, attrs: ArrayList<XmlAttr>): Unit {
        curTag = name
        if (name == "movie") {
            title = attrs[0].content
            println("Title: ${title}")
        }
    }
    public func endElement(name: String): Unit {
        if (curTag == "score") {
            println("Score: ${score}")
        } else if (curTag == "year") {
            println("Year: ${year}")
        }
    }
    public func characters(content: String): Unit {
        if (curTag == "score") {
            score = content
        } else if (curTag == "year") {
            year = content
        }
    }
}
main() {
    // 初始化 SaxHandler，并通过它初始化 XmlParser
    var handler = MovieHandler()
    let x: XmlParser = XmlParser(handler)

    // 调用 XmlParser 的 parse 方法进行解析
    x.parse(latestMovie)
    return 0
}

运行结果如下:

Start Parsing.
Title: Movie 2021
Score: 7.4
Year: 2021-3
Title: Movie 2022
Score: 7
Year: 2022-2
Title: Movie 2023
Score: 6.5
Year: 2023-4
End Parsing.