xml 生成/解析

项目地址：
https://github.com/beevik/etree

用法：

1. 生成：

    package main
    import (
        "fmt"
        "github.com/beevik/etree"
    )
    func main() {
        doc := etree.NewDocument()
        doc.CreateProcInst("xml", `version="1.0" encoding="UTF-8"`)
        doc.CreateProcInst("xml-stylesheet", `type="text/xsl" href="style.xsl"`)
        people := doc.CreateElement("People")
        people.CreateComment("These are all known people")
        jon := people.CreateElement("Person")
        jon.CreateAttr("name", "Jon")
        sally := people.CreateElement("Person")
        sally.CreateAttr("name", "Sally")
        doc.Indent(2)
        output,_ := doc.WriteToString()
        fmt.Println(output)
    }
    // 输出
    <?xml version="1.0" encoding="UTF-8"?>
    <?xml-stylesheet type="text/xsl" href="style.xsl"?>
    <People>
      <!--These are all known people-->
      <Person name="Jon"/>
      <Person name="Sally"/>
    </People>

2. 解析：

    package main
    import (
        "fmt"
        "github.com/beevik/etree"
    )
    func main() {
        xml := `
    <?xml version="1.0" encoding="UTF-8"?>
    <?xml-stylesheet type="text/xsl" href="style.xsl"?>
    <People>
      <!--These are all known people-->
      <Person name="Jon"/>
      <Person name="Sally"/>
    </People>
    `
        doc := etree.NewDocument()
        if err := doc.ReadFromString(xml); err != nil {
            fmt.Println("解析出错：",err)
        }
        root := doc.SelectElement("People")
        fmt.Println("根元素名：", root.Tag)
        for _, ele := range root.SelectElements("Person") {
            fmt.Println("子元素：", ele.Tag)
            for _, attr := range ele.Attr {
                fmt.Println(attr.Key, attr.Value)
            }
        }
    }
    // 输出
    根元素名： People
    子元素： Person
    name Jon
    子元素： Person
    name Sally