How to convert EPUB in golang (code example)

With the popularity of electronic publications, EPUB has become a very popular e-book format. Golang is a very popular programming language that is particularly good at handling concurrency and high-concurrency situations. Therefore, this article will introduce how to use Golang to implement a tool to convert EPUB files to other formats.

1. Introduction to EPUB format

First of all, let’s take a look at the EPUB format. EPUB (Electronic Publication) is an XML-based e-book format widely used on smartphones, tablets and other devices for reading digital books. EPUB files can contain images, text and HTML, and support search and bookmark functions.

2. Introduction to Golang

Golang is a statically typed, compiled language developed by Google. Golang is excellent at handling high concurrency and distributed systems, and has a rich standard library and third-party libraries. The advantages of Golang include:

1. Easy to learn: Golang syntax is simple and easy to understand, and the code is clear and easy to read.
2. Excellent performance: Golang is much faster than Python and Node.js.
3. Concurrency processing: Golang supports coroutines and channels, which is excellent in high concurrency situations.

3. Use Golang for EPUB conversion

In order to implement a tool to convert EPUB files to other formats, we need to master the following steps.

1. Parsing EPUB files: Using Go's archive/zip package and xml package, we can easily parse EPUB files.
2. Parse content: In EPUB format, each chapter is usually stored in a separate HTML file. Therefore, we need to parse the content in each HTML file.
3. Convert format: Convert the parsed HTML content into the required format, such as PDF, MOBI, TXT, etc.

The following is a simple Golang program for converting EPUB files into PDF format.

package main

import (
    "os"
    "io/ioutil"
    "archive/zip"
    "encoding/xml"
    "fmt"
    "github.com/jung-kurt/gofpdf"
)

type chapter struct {
    FileName string `xml:"file-name,attr"`
    Content  string `xml:",innerxml"`
}

func main() {
    // 读取EPUB文件
    file, _ := os.Open("sample.epub")
    defer file.Close()

    // 解压缩EPUB文件
    r, _ := zip.NewReader(file, file.Size())
    for _, f := range r.File {
        // 检查文件类型
        if f.Name[len(f.Name)-5:] == ".html" {
            // 读取HTML文件中的内容
            htmlFile, _ := f.Open()
            defer htmlFile.Close()
            htmlContent, _ := ioutil.ReadAll(htmlFile)

            // 解析HTML内容
            var c chapter
            xml.Unmarshal(htmlContent, &c)

            // 将HTML内容转换为PDF格式
            pdf := gofpdf.New("P", "mm", "A4", "")
            pdf.AddPage()
            pdf.Write(5, c.Content)
            pdf.OutputFileAndClose(fmt.Sprintf("%s.pdf", c.FileName))
        }
    }
}

The above code loops through all HTML files in the EPUB file and converts them to PDF format. We can modify the code according to our needs and convert HTML text to other formats, such as MOBI, TXT, etc.

4. Summary

The above is a simple example of using Golang to implement a tool to convert EPUB files to other formats. Using Golang to implement EPUB conversion is very simple, the amount of code is also very small, and it is suitable for developers of all levels. Hope this article helps you!

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