Go-Excelize API源码阅读（二十三）——SetDocProps、GetDocProps

Go-Excelize API源码阅读（二十三）——SetDocProps、GetDocProps

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一、Go-Excelize简介

Excelize 是 Go 语言编写的用于操作 Office Excel 文档基础库，基于 ECMA-376，ISO/IEC 29500 国际标准。可以使用它来读取、写入由 Microsoft Excel™ 2007 及以上版本创建的电子表格文档。支持 XLAM / XLSM / XLSX / XLTM / XLTX 等多种文档格式，高度兼容带有样式、图片(表)、透视表、切片器等复杂组件的文档，并提供流式读写 API，用于处理包含大规模数据的工作簿。可应用于各类报表平台、云计算、边缘计算等系统。使用本类库要求使用的 Go 语言为 1.15 或更高版本。

二、 SetDocProps(docProperties *DocProperties)

func (f *File) SetDocProps(docProperties *DocProperties) error
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设置工作簿的核心属性。可以设置的属性包括:

下面举一个使用例子：

err := f.SetDocProps(&excelize.DocProperties{
    Category:       "category",
    ContentStatus:  "Draft",
    Created:        "2019-06-04T22:00:10Z",
    Creator:        "Go Excelize",
    Description:    "This file created by Go Excelize",
    Identifier:     "xlsx",
    Keywords:       "Spreadsheet",
    LastModifiedBy: "Go Author",
    Modified:       "2019-06-04T22:00:10Z",
    Revision:       "0",
    Subject:        "Test Subject",
    Title:          "Test Title",
    Language:       "en-US",
    Version:        "1.0.0",
})
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然后直接上源码：

func (f *File) SetDocProps(docProperties *DocProperties) (err error) {
	var (
		core               *decodeCoreProperties
		newProps           *xlsxCoreProperties
		fields             []string
		output             []byte
		immutable, mutable reflect.Value
		field, val         string
	)

	core = new(decodeCoreProperties)
	if err = f.xmlNewDecoder(bytes.NewReader(namespaceStrictToTransitional(f.readXML(defaultXMLPathDocPropsCore)))).
		Decode(core); err != nil && err != io.EOF {
		err = fmt.Errorf("xml decode error: %s", err)
		return
	}
	newProps, err = &xlsxCoreProperties{
		Dc:             NameSpaceDublinCore,
		Dcterms:        NameSpaceDublinCoreTerms,
		Dcmitype:       NameSpaceDublinCoreMetadataInitiative,
		XSI:            NameSpaceXMLSchemaInstance,
		Title:          core.Title,
		Subject:        core.Subject,
		Creator:        core.Creator,
		Keywords:       core.Keywords,
		Description:    core.Description,
		LastModifiedBy: core.LastModifiedBy,
		Language:       core.Language,
		Identifier:     core.Identifier,
		Revision:       core.Revision,
		ContentStatus:  core.ContentStatus,
		Category:       core.Category,
		Version:        core.Version,
	}, nil
	if core.Created != nil {
		newProps.Created = &xlsxDcTerms{Type: core.Created.Type, Text: core.Created.Text}
	}
	if core.Modified != nil {
		newProps.Modified = &xlsxDcTerms{Type: core.Modified.Type, Text: core.Modified.Text}
	}
	fields = []string{
		"Category", "ContentStatus", "Creator", "Description", "Identifier", "Keywords",
		"LastModifiedBy", "Revision", "Subject", "Title", "Language", "Version",
	}
	immutable, mutable = reflect.ValueOf(*docProperties), reflect.ValueOf(newProps).Elem()
	for _, field = range fields {
		if val = immutable.FieldByName(field).String(); val != "" {
			mutable.FieldByName(field).SetString(val)
		}
	}
	if docProperties.Created != "" {
		newProps.Created = &xlsxDcTerms{Type: "dcterms:W3CDTF", Text: docProperties.Created}
	}
	if docProperties.Modified != "" {
		newProps.Modified = &xlsxDcTerms{Type: "dcterms:W3CDTF", Text: docProperties.Modified}
	}
	output, err = xml.Marshal(newProps)
	f.saveFileList(defaultXMLPathDocPropsCore, output)

	return
}
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这个API的实现看起来很复杂，我们来对他进行拆解：

	core = new(decodeCoreProperties)
	if err = f.xmlNewDecoder(bytes.NewReader(namespaceStrictToTransitional(f.readXML(defaultXMLPathDocPropsCore)))).
		Decode(core); err != nil && err != io.EOF {
		err = fmt.Errorf("xml decode error: %s", err)
		return
	}
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这部分的作用是对defaultXMLPathDocPropsCore文件进行读取，即docProps/core.xml文件：

	defaultXMLPathDocPropsCore  = "docProps/core.xml"
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然后对xml文件进行解码。

	newProps, err = &xlsxCoreProperties{
		Dc:             NameSpaceDublinCore,
		Dcterms:        NameSpaceDublinCoreTerms,
		Dcmitype:       NameSpaceDublinCoreMetadataInitiative,
		XSI:            NameSpaceXMLSchemaInstance,
		Title:          core.Title,
		Subject:        core.Subject,
		Creator:        core.Creator,
		Keywords:       core.Keywords,
		Description:    core.Description,
		LastModifiedBy: core.LastModifiedBy,
		Language:       core.Language,
		Identifier:     core.Identifier,
		Revision:       core.Revision,
		ContentStatus:  core.ContentStatus,
		Category:       core.Category,
		Version:        core.Version,
	}, nil
		if core.Created != nil {
		newProps.Created = &xlsxDcTerms{Type: core.Created.Type, Text: core.Created.Text}
	}
	if core.Modified != nil {
		newProps.Modified = &xlsxDcTerms{Type: core.Modified.Type, Text: core.Modified.Text}
	}
		fields = []string{
		"Category", "ContentStatus", "Creator", "Description", "Identifier", "Keywords",
		"LastModifiedBy", "Revision", "Subject", "Title", "Language", "Version",
	}
	immutable, mutable = reflect.ValueOf(*docProperties), reflect.ValueOf(newProps).Elem()
	for _, field = range fields {
		if val = immutable.FieldByName(field).String(); val != "" {
			mutable.FieldByName(field).SetString(val)
		}
	}
	if docProperties.Created != "" {
		newProps.Created = &xlsxDcTerms{Type: "dcterms:W3CDTF", Text: docProperties.Created}
	}
	if docProperties.Modified != "" {
		newProps.Modified = &xlsxDcTerms{Type: "dcterms:W3CDTF", Text: docProperties.Modified}
	}
	output, err = xml.Marshal(newProps)
	f.saveFileList(defaultXMLPathDocPropsCore, output)
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将获取的信息创建一个新的xlsxCoreProperties结构体。然后将结构体序列化之后保存为配置文件即可。

三、GetDocProps()

下面介绍工作簿的最后一个API：GetDocProps()

// GetDocProps provides a function to get document core properties.
func (f *File) GetDocProps() (ret *DocProperties, err error) {
	core := new(decodeCoreProperties)

	if err = f.xmlNewDecoder(bytes.NewReader(namespaceStrictToTransitional(f.readXML(defaultXMLPathDocPropsCore)))).
		Decode(core); err != nil && err != io.EOF {
		err = fmt.Errorf("xml decode error: %s", err)
		return
	}
	ret, err = &DocProperties{
		Category:       core.Category,
		ContentStatus:  core.ContentStatus,
		Creator:        core.Creator,
		Description:    core.Description,
		Identifier:     core.Identifier,
		Keywords:       core.Keywords,
		LastModifiedBy: core.LastModifiedBy,
		Revision:       core.Revision,
		Subject:        core.Subject,
		Title:          core.Title,
		Language:       core.Language,
		Version:        core.Version,
	}, nil
	if core.Created != nil {
		ret.Created = core.Created.Text
	}
	if core.Modified != nil {
		ret.Modified = core.Modified.Text
	}
	return
}

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逻辑很简单，读取并解码xml文件，将获得的结果core中的变量放入ret，其也是一个DocProperties结构体，最后返回即可。