How to do PDF conversion in Golang

In the Internet era, PDF has become a very important document format. With the popularity of PDF, more and more programmers are beginning to pay attention to how to add PDF support to their projects. In Golang, the demand for conversion to PDF is also growing, so this article will introduce how to convert PDF in Golang.

1. Use third-party libraries

First of all, we can use third-party libraries in Golang to achieve PDF conversion. Among them, the most commonly used one is go-fpdf. It is a lightweight third-party library that can be used to fully code dynamic graphics in Golang. For Golang developers, use this library to quickly generate PDF documents.

The following is the basic code for generating PDF documents using the go-fpdf library:

package main

import (
    "github.com/jung-kurt/gofpdf"
)

func main() {
    pdf := gofpdf.New("P", "mm", "A4", "") //创建PDF对象
    pdf.AddPage() //添加一页
    pdf.SetFont("Times", "B", 16) //设置字体格式
    pdf.Cell(40, 10, "Hello, world!") //写入文本

    err := pdf.OutputFileAndClose("hello.pdf") //保存并关闭文件
    if err != nil {
        panic(err)
    }
}

This code generates a PDF file and writes the text "Hello, world!" in it.

2. Use HTML/CSS to convert PDF

Another method is to use a third-party tool to convert HTML and CSS documents into PDF. In Windows and Linux systems, wkhtmltopdf is a very good PDF conversion tool.

In Golang, we can use the os/exec library to call the command line to convert HTML/CSS documents to PDF format. The code is as follows:

package main

import (
    "os/exec"
)

func main() {
    command := exec.Command("wkhtmltopdf", "index.html", "output.pdf") //调用命令行
    err := command.Run()
    if err != nil {
        panic(err)
    }
}

Here we use the command line tool wkhtmltopdf to convert the HTML file index.html to the PDF file output.pdf. It should be noted that when using this method, you need to install the corresponding third-party tools.

3. Use cloud services

The last method is to use cloud services to achieve PDF conversion. There are many cloud services available on the market. For example, CloudConvert is a popular cloud service that provides conversion between various formats, including PDF.

In Golang, we can use a third-party library to call the API of the CloudConvert cloud service to achieve PDF conversion. The code is as follows:

package main

import (
    "fmt"
    "github.com/cloudconvert/cloudconvert-go/sdk"
    "github.com/cloudconvert/cloudconvert-go/sdk/operations"
)

func main() {
    // 创建API客户端
    client, err := sdk.NewClient("<API KEY>")
    if err != nil {
        panic(err)
    }

    // 配置操作
    op := operations.NewConvertOperation()
    op.SetInput("upload", "a.pdf")

    // 设置输出格式
    op.SetOutputFormat("pdf")

    // 执行操作并检查错误
    conversion, err := client.Convert(op)
    if err != nil {
        panic(err)
    }

    // 打印输出URL
    fmt.Println(conversion.Output.Url)
}

The above code uses the CloudConvert cloud service to convert a.pdf file into pdf format.

Summary

This article introduces three different methods for converting PDF in Golang. Developers can choose one of the conversion methods based on their needs and preferences. However, it should be noted that when using third-party libraries and cloud services, you need to read the relevant documents and understand the related risks.

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