go解析xml的三種方式
之前項目中用到過xml解析，在這里記錄一下。
小文件簡單解析
demo.xml
<?xml version="1.0" encoding="UTF-8"?>
<config>
<smtpServer>smtp.163.com</smtpServer>
<smtpPort>25</smtpPort>
<sender>user@163.com</sender>
<senderPasswd>123456</senderPasswd>
<receivers flag="true">
<age>16</age>
<user>Mike_Zhang@live.com</user>
<user>test1@qq.com</user>
<script>
<![CDATA[
function matchwo(a,b) {
if (a < b && a < 0) then {
return 1;
} else {
return 0;
}
}
]]>
</script>
</receivers>
</config>
main.go
package main
import (
"fmt"
"io/ioutil"
"encoding/xml"
)
/*
https://studygolang.com/static/pkgdoc/pkg/encoding_xml.htm
*/
// 定義結構體映射xml結構
type SConfig struct {
XMLName xml.Name `xml:"config"` // 指定最外層的標簽為config
SmtpServer string `xml:"smtpServer"` // 讀取smtpServer配置項，並將結果保存到SmtpServer變量中
SmtpPort int `xml:"smtpPort"`
Sender string `xml:"sender"`
SenderPasswd string `xml:"senderPasswd"`
Receivers SReceivers `xml:"receivers"` // 讀取receivers標簽下的內容，以結構方式獲取
}
type SReceivers struct {
Age int `xml:"age"`
Flag string `xml:"flag,attr"` // 讀取flag屬性
User []string `xml:"user"` // 讀取user數組
Script string `xml:"script"` // 讀取 <![CDATA[ xxx ]]> 數據
}
func readXml(path string) {
// 不用管理打開和關閉，ioutil 在內部已經處理過了
data, err := ioutil.ReadFile(path)
if err != nil {
fmt.Println("讀文件出錯！", err)
return
}
// fmt.Println(string(bytes))
v := SConfig{}
err = xml.Unmarshal(data, &v)
if err != nil {
fmt.Printf("error: %v", err)
return
}
//fmt.Println(v)
fmt.Println("SmtpServer : ",v.SmtpServer)
fmt.Println("SmtpPort : ",v.SmtpPort)
fmt.Println("Sender : ",v.Sender)
fmt.Println("SenderPasswd : ",v.SenderPasswd)
fmt.Println("Receivers.Flag : ",v.Receivers.Flag)
fmt.Println("Receivers.Age : ",v.Receivers.Age)
fmt.Println("Receivers.Script : ",v.Receivers.Script)
for i,element := range v.Receivers.User {
fmt.Println(i,element)
}
}
func main() {
readXml("demo.xml")
}
輸出：
SmtpServer : smtp.163.com
SmtpPort : 25
Sender : user@163.com
SenderPasswd : 123456
Receivers.Flag : true
Receivers.Age : 16
Receivers.Script :
function matchwo(a,b) {
if (a < b && a < 0) then {
return 1;
} else {
return 0;
}
}
0 Mike_Zhang@live.com
1 test1@qq.com
大文件解析
對於超大xml文件的讀取采用事件驅動的方式節省內存提高效率：
demo.xml
<?xml version="1.0" encoding="UTF-8"?>
<config>
<smtpServer>smtp.163.com</smtpServer>
<smtpPort>25</smtpPort>
<sender>user@163.com</sender>
<senderPasswd>123456</senderPasswd>
<receivers flag="true">
<age>16</age>
<user>Mike_Zhang@live.com</user>
<user>test1@qq.com</user>
<script>
<![CDATA[
function matchwo(a,b) {
if (a < b && a < 0) then {
return 1;
} else {
return 0;
}
}
]]>
</script>
</receivers>
</config>
main.go
package main
import (
"fmt"
"encoding/xml"
"bufio"
"os"
"io"
)
/*
解析超大 xml 文件
https://studygolang.com/static/pkgdoc/pkg/encoding_xml.htm
*/
// 定義結構體映射xml結構
type SConfig struct {
XMLName xml.Name `xml:"config"` // 指定最外層的標簽為config
SmtpServer string `xml:"smtpServer"` // 讀取smtpServer配置項，並將結果保存到SmtpServer變量中
SmtpPort int `xml:"smtpPort"`
Sender string `xml:"sender"`
SenderPasswd string `xml:"senderPasswd"`
Receivers SReceivers `xml:"receivers"` // 讀取receivers標簽下的內容，以結構方式獲取
}
type SReceivers struct {
Age int `xml:"age"`
Flag string `xml:"flag,attr"` // 讀取flag屬性
User []string `xml:"user"` // 讀取user數組
Script string `xml:"script"` // 讀取 <![CDATA[ xxx ]]> 數據
}
func readXml(path string) {
file, errOpen := os.Open(path) // 打開文件
if errOpen != nil {
fmt.Println("打開文件異常！", errOpen)
return
}
defer file.Close() // 關閉文件
// 創建帶緩存的 Reader
reader := bufio.NewReader(file)
decoder := xml.NewDecoder(reader)
for t, err := decoder.Token(); err == nil || err == io.EOF; t, err = decoder.Token() {
switch token := t.(type) {
case xml.StartElement:
name := token.Name.Local
fmt.Println(name)
if name == "config" {
// 解析 config
var sConfig = SConfig{}
configErr := decoder.DecodeElement(&sConfig, &token)
if configErr != nil {
fmt.Println("解析錯誤：")
fmt.Println(configErr)
} else {
fmt.Println(sConfig)
}
return
}
}
}
}
func main() {
readXml("demo.xml")
}
輸出：
config
{{ config} smtp.163.com 25 user@163.com 123456 {16 true [Mike_Zhang@live.com test1@qq.com]
function matchwo(a,b) {
if (a < b && a < 0) then {
return 1;
} else {
return 0;
}
}
}}
復雜結構解析
有的時候xml文件很復雜，嵌套很深，這個時候如果我們使用struct來映射就會很麻煩，好在開源了一個很方便的解析工具etree。這個etree和python的etree的api幾乎一樣，用起來簡單好用。
bookstores.xml
<bookstore xmlns:p="urn:schemas-books-com:prices">
<book category="COOKING">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<p:price>30.00</p:price>
</book>
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<p:price>29.99</p:price>
</book>
<book category="WEB">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<p:price>49.99</p:price>
</book>
<book category="WEB">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<p:price>39.95</p:price>
</book>
</bookstore>
main.go
package main
/*
使用 etree 解析復雜結構的 xml 文件
https://godoc.org/github.com/beevik/etree
https://pkg.go.dev/github.com/beevik/etree?tab=doc
https://github.com/beevik/etree
*/
import (
"fmt"
"github.com/beevik/etree"// go get github.com/beevik/etree
)
func readXml(path string) {
doc := etree.NewDocument()
if err := doc.ReadFromFile(path); err != nil {
panic(err)
}
root := doc.SelectElement("bookstore")
fmt.Println("ROOT element:", root.Tag)
for _, book := range root.SelectElements("book") {
fmt.Println("CHILD element:", book.Tag)
if title := book.SelectElement("title"); title != nil {
lang := title.SelectAttrValue("lang", "unknown")
fmt.Printf(" TITLE: %s (%s)\n", title.Text(), lang)
}
for _, attr := range book.Attr {
fmt.Printf(" ATTR: %s=%s\n", attr.Key, attr.Value)
}
}
}
func main() {
readXml("bookstores.xml")
}
輸出：
ROOT element: bookstore
CHILD element: book
TITLE: Everyday Italian (en)
ATTR: category=COOKING
CHILD element: book
TITLE: Harry Potter (en)
ATTR: category=CHILDREN
CHILD element: book
TITLE: XQuery Kick Start (en)
ATTR: category=WEB
CHILD element: book
TITLE: Learning XML (en)
ATTR: category=WEB