第一种，设置环境变量：

func init() {
	//设置中文字体:解决中文乱码问题
	fontPaths := findfont.List()
	for _, path := range fontPaths {
		if strings.Contains(path, "msyh.ttf") ||
			strings.Contains(path, "simhei.ttf") ||
			strings.Contains(path, "simsun.ttc") ||
			strings.Contains(path, "simkai.ttf") {

			os.Setenv("FYNE_FONT", path)
			break
		}
	}
}

第二种，导入这个包，自动加载系统中的字体文件：

package main

import (
	_ "github.com/lengzhao/font/autoload"
)

第三种，使用fyne主题方法：

func main() {

	myApp := app.New()
	t := &myTheme{}
	t.SetFonts("./font\\xxx.ttf", "")
	myApp.Settings().SetTheme(t)
	
    //...

}

type myTheme struct {
	regular, bold, italic, boldItalic, monospace fyne.Resource
}

func (t *myTheme) Color(name fyne.ThemeColorName, variant fyne.ThemeVariant) color.Color {
	return theme.DefaultTheme().Color(name, variant)
}

func (t *myTheme) Icon(name fyne.ThemeIconName) fyne.Resource {
	return theme.DefaultTheme().Icon(name)
}

func (m *myTheme) Font(style fyne.TextStyle) fyne.Resource {
	if style.Monospace {
		return m.monospace
	}
	if style.Bold {
		if style.Italic {
			return m.boldItalic
		}
		return m.bold
	}
	if style.Italic {
		return m.italic
	}
	return m.regular
}

func (m *myTheme) Size(name fyne.ThemeSizeName) float32 {
	return theme.DefaultTheme().Size(name)
}

func (t *myTheme) SetFonts(regularFontPath string, monoFontPath string) {
	t.regular = theme.TextFont()
	t.bold = theme.TextBoldFont()
	t.italic = theme.TextItalicFont()
	t.boldItalic = theme.TextBoldItalicFont()
	t.monospace = theme.TextMonospaceFont()

	if regularFontPath != "" {
		t.regular = loadCustomFont(regularFontPath, "Regular", t.regular)
		t.bold = loadCustomFont(regularFontPath, "Bold", t.bold)
		t.italic = loadCustomFont(regularFontPath, "Italic", t.italic)
		t.boldItalic = loadCustomFont(regularFontPath, "BoldItalic", t.boldItalic)
	}
	if monoFontPath != "" {
		t.monospace = loadCustomFont(monoFontPath, "Regular", t.monospace)
	} else {
		t.monospace = t.regular
	}
}

func loadCustomFont(env, variant string, fallback fyne.Resource) fyne.Resource {
	variantPath := strings.Replace(env, "Regular", variant, -1)

	res, err := fyne.LoadResourceFromPath(variantPath)
	if err != nil {
		fyne.LogError("Error loading specified font", err)
		return fallback
	}

	return res
}

更新，以上方法编译的时候发现问题，静态资源并没有打包，因此需要用到

fyne bundle

但是，我尝试了打包字体文件后，go文件太大， 导致编译和开发的时候非常慢。

经过我努力的搜搜后找到了完美的解决方法

package main

import (
	_ "embed"

	"GoV2App/frame"
	"image/color"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/theme"
)

var (
	//go:embed resource/font/siyuanyuanti.ttf
	NotoSansSC []byte
)


func main() {

	myApp := app.New()

	myApp.Settings().SetTheme(&MyTheme{})

	//...

}

type MyTheme struct{}

var _ fyne.Theme = (*MyTheme)(nil)

// StaticName 为 fonts 目录下的 ttf 类型的字体文件名
func (m MyTheme) Font(fyne.TextStyle) fyne.Resource {
	return &fyne.StaticResource{
		StaticName:    "siyuanyuanti.ttf",
		StaticContent: NotoSansSC,
	}
}

func (*MyTheme) Color(n fyne.ThemeColorName, v fyne.ThemeVariant) color.Color {
	return theme.DefaultTheme().Color(n, v)
}

func (*MyTheme) Icon(n fyne.ThemeIconName) fyne.Resource {
	return theme.DefaultTheme().Icon(n)
}

func (*MyTheme) Size(n fyne.ThemeSizeName) float32 {
	return theme.DefaultTheme().Size(n)
}