深入理解Go语言encoding/xml包：正确处理XML属性

package main

import (
    "encoding/xml"
    "fmt"
    "io"
    "strings"
)

// parseXMLWithAttributes 演示如何使用xml.Decoder.Token()解析XML并提取属性
func parseXMLWithAttributes(r io.Reader) error {
    xd := xml.NewDecoder(r)

    fmt.Println("--- 开始解析XML令牌 ---")
    for {
        token, err := xd.Token()
        if err == io.EOF {
            break // 文件结束
        }
        if err != nil {
            return fmt.Errorf("解析XML错误: %w", err)
        }

        // 使用类型断言的switch语句处理不同类型的令牌，更符合Go语言习惯
        switch t := token.(type) {
        case xml.StartElement:
            fmt.Printf("START: <%s", t.Name.Local)
            if t.Name.Space != "" {
                fmt.Printf(" (命名空间: %s)", t.Name.Space)
            }
            // 遍历并打印所有属性
            if len(t.Attr) > 0 {
                fmt.Println("\n  属性:")
                for _, attr := range t.Attr {
                    attrName := attr.Name.Local
                    if attr.Name.Space != "" {
                        attrName = fmt.Sprintf("%s:%s", attr.Name.Space, attrName)
                    }
                    fmt.Printf("    - %s = \"%s\"\n", attrName, attr.Value)
                }
            } else {
                fmt.Println(" (无属性)")
            }
            fmt.Println(">") // 结束StartElement的打印
        case xml.EndElement:
            fmt.Printf("END: </%s>\n", t.Name.Local)
        case xml.CharData:
            data := strings.TrimSpace(string(t))
            if len(data) > 0 {
                fmt.Printf("CDATA: \"%s\"\n", data)
            }
        case xml.Comment:
            fmt.Printf("COMMENT: <!-- %s -->\n", string(t))
        case xml.ProcInst:
            fmt.Printf("PROC_INST: <?%s %s?>\n", t.Target, string(t.Inst))
        case xml.Directive:
            fmt.Printf("DIRECTIVE: <!%s>\n", string(t))
        default:
            fmt.Printf("未知令牌类型: %T\n", t)
        }
    }
    fmt.Println("--- XML解析结束 ---")
    return nil
}

func main() {
    // 示例XML数据，包含命名空间和属性
    xmlData := `<?xml version="1.0" encoding="UTF-8"?>
<root xmlns:ex="http://example.com/ns" version="1.0">
    <!-- 这是一个根元素注释 -->
    <ex:item id="123" type="book">
        <title lang="en">Go Programming</title>
        <author>Gopher</author>
    </ex:item>
    <ex:item id="456" type="magazine"/>
</root>`

    reader := strings.NewReader(xmlData)
    if err := parseXMLWithAttributes(reader); err != nil {
        fmt.Printf("XML解析失败: %v\n", err)
    }
}

--- 开始解析XML令牌 ---
PROC_INST: <?xml version="1.0" encoding="UTF-8"?>
START: <root (命名空间: )
  属性:
    - xmlns:ex = "http://example.com/ns"
    - version = "1.0"
>
CDATA: ""
COMMENT: <!-- 这是一个根元素注释 -->
CDATA: ""
START: <item (命名空间: http://example.com/ns)
  属性:
    - id = "123"
    - type = "book"
>
CDATA: ""
START: <title (命名空间: )
  属性:
    - lang = "en"
>
CDATA: "Go Programming"
END: </title>
CDATA: ""
START: <author (命名空间: ) (无属性)
>
CDATA: "Gopher"
END: </author>
CDATA: ""
END: </item>
CDATA: ""
START: <item (命名空间: http://example.com/ns)
  属性:
    - id = "456"
    - type = "magazine"
>
END: </item>
CDATA: ""
END: </root>
--- XML解析结束 ---