C#/VB.NET如何创建、读取PDF文档

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一、创建PDF文档

C#

using Spire.Pdf;using Spire.Pdf.Graphics;using System.Drawing;namespace CreatePDF_PDF{    class Program    {        static void Main(string[] args)        {            //初始化一个PdfDocument类实例            PdfDocument document = new PdfDocument();            //声明 PdfUnitConvertor和PdfMargins类对象            PdfUnitConvertor unitCvtr = new PdfUnitConvertor();            PdfMargins margins = new PdfMargins();            //设置页边距            margins.Top = unitCvtr.ConvertUnits(2.54f, PdfGraphicsUnit.Centimeter, PdfGraphicsUnit.Point);            margins.Bottom = margins.Top;            margins.Left = unitCvtr.ConvertUnits(3.17f, PdfGraphicsUnit.Centimeter, PdfGraphicsUnit.Point);            margins.Right = margins.Left;            //新添加一个A4大小的页面            PdfPageBase page = document.Pages.Add(PdfPageSize.A4, margins);            //自定义PdfTrueTypeFont、PdfPen实例，设置字体类型、字号和字体颜色            PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("楷体", 11f),true);            PdfPen pen = new PdfPen(Color.Black);            //调用DrawString()方法在指定位置写入文本            string text = ("《蝶恋花 送春》 \n 楼外垂杨千万缕，欲系青春，少住春还去。犹自风前飘柳絮，随春且看归何处？\n 绿满山川闻杜宇，便作无情，莫也愁人苦。把酒送春春不语，黄昏却下潇潇雨。");            page.Canvas.DrawString(text, font, pen, 15, 13);            //加载图片，并调用DrawImage()方法在指定位置绘入图片            PdfImage image = PdfImage.FromFile("image1.jpg");            float width = image.Width * 0.55f;            float height = image.Height * 0.55f;            float y = (page.Canvas.ClientSize.Width - width) / 3;            page.Canvas.DrawImage(image, y, 60, width, height);            //保存并打开文档            document.SaveToFile("PDF创建.pdf");            System.Diagnostics.Process.Start("PDF创建.pdf");        }    }}

创建结果：

VB.NET

Imports Spire.PdfImports Spire.Pdf.GraphicsImports System.DrawingNamespace CreatePDF_PDF    Class Program        Private Shared Sub Main(ByVal args As String())            Dim document As PdfDocument = New PdfDocument()            Dim unitCvtr As PdfUnitConvertor = New PdfUnitConvertor()            Dim margins As PdfMargins = New PdfMargins()            margins.Top = unitCvtr.ConvertUnits(2.54F, PdfGraphicsUnit.Centimeter, PdfGraphicsUnit.Point)            margins.Bottom = margins.Top            margins.Left = unitCvtr.ConvertUnits(3.17F, PdfGraphicsUnit.Centimeter, PdfGraphicsUnit.Point)            margins.Right = margins.Left            Dim page As PdfPageBase = document.Pages.Add(PdfPageSize.A4, margins)            Dim font As PdfTrueTypeFont = New PdfTrueTypeFont(New Font("楷体", 11F), True)            Dim pen As PdfPen = New PdfPen(Color.Black)            Dim text As String =("《蝶恋花 送春》 " & vbLf & " 楼外垂杨千万缕，欲系青春，少住春还去。犹自风前飘柳絮，随春且看归何处？" & vbLf & " 绿满山川闻杜宇，便作无情，莫也愁人苦。把酒送春春不语，黄昏却下潇潇雨。")            page.Canvas.DrawString(text, font, pen, 15, 13)            Dim image As PdfImage = PdfImage.FromFile("image1.jpg")            Dim width As Single = image.Width * 0.55F            Dim height As Single = image.Height * 0.55F            Dim y As Single =(page.Canvas.ClientSize.Width - width) / 3            page.Canvas.DrawImage(image, y, 60, width, height)            document.SaveToFile("PDF创建.pdf")            System.Diagnostics.Process.Start("PDF创建.pdf")        End Sub    End ClassEnd Namespace

这里创建PDF文档，Spire.PDF支持直接生成PDF文档并同时实现添加文本、图片、图形、水印、表格、页眉页脚、页码等操作，这里示例代码以添加文本、图片为例，有需要可以参见以下博客：

• C# 添加PDF水印

• C# 创建PDF表格

  二、 读取PDF文档

  测试文档：
  

  1. 读取PDF文本

  1.1读取全部文本

  C#

using Spire.Pdf;using System;using System.IO;using System.Text;namespace ExtractText_PDF{    class Program    {        static void Main(string[] args)        {            //实例化PdfDocument类对象，并加载PDF文档            PdfDocument doc = new PdfDocument();            doc.LoadFromFile("sample.pdf");            //实例化一个StringBuilder 对象            StringBuilder content = new StringBuilder();            //遍历文档所有PDF页面，提取文本            foreach (PdfPageBase page in doc.Pages)            {                content.Append(page.ExtractText());            }            //将提取到的文本写为.txt格式并保存到本地路径            String fileName = "获取文本.txt";            File.WriteAllText(fileName, content.ToString());            System.Diagnostics.Process.Start("获取文本.txt");        }    }}

读取结果：

VB.NET

Imports Spire.PdfImports SystemImports System.IOImports System.TextNamespace ExtractText_PDF    Class Program        Private Shared Sub Main(ByVal args As String())            Dim doc As PdfDocument = New PdfDocument()            doc.LoadFromFile("sample.pdf")            Dim content As StringBuilder = New StringBuilder()            For Each page As PdfPageBase In doc.Pages                content.Append(page.ExtractText())            Next            Dim fileName As String = "获取文本.txt"            File.WriteAllText(fileName, content.ToString())            System.Diagnostics.Process.Start("获取文本.txt")        End Sub    End ClassEnd Namespace

1.2 读取指定区域文本

C#

using Spire.Pdf;using System.IO;using System.Text;using System.Drawing;namespace ExtractText1_PDF{    class Program    {        static void Main(string[] args)        {            //创建PdfDocument类实例，并加载PDF文档            PdfDocument pdf = new PdfDocument();             pdf.LoadFromFile("sample.pdf");            //获取PDF第一页              PdfPageBase page = pdf.Pages[0];            //从第一页的指定矩形区域内提取文本              string text = page.ExtractText(new RectangleF(50, 50, 500, 170));            //保存文本到.txt文件，并打开文档            StringBuilder sb = new StringBuilder();            sb.AppendLine(text);            File.WriteAllText("Extract.txt", sb.ToString());            System.Diagnostics.Process.Start("Extract.txt");        }    }}

读取结果：
（此时读取的就只是指定区域内的文本）

VB.NET

Imports Spire.PdfImports System.IOImports System.TextImports System.DrawingNamespace ExtractText1_PDF    Class Program        Private Shared Sub Main(ByVal args As String())            Dim pdf As PdfDocument = New PdfDocument()            pdf.LoadFromFile("sample.pdf")            Dim page As PdfPageBase = pdf.Pages(0)            Dim text As String = page.ExtractText(New RectangleF(50, 50, 500, 170))            Dim sb As StringBuilder = New StringBuilder()            sb.AppendLine(text)            File.WriteAllText("Extract.txt", sb.ToString())            System.Diagnostics.Process.Start("Extract.txt")        End Sub    End ClassEnd Namespace

2. 读取PDF图片

C#

using Spire.Pdf;using System.Collections.Generic;using System.Drawing;namespace ExtractImages_PDF{    class Program    {        static void Main(string[] args)        {            //创建一个PdfDocument类对象，加载PDF测试文档            PdfDocument doc = new PdfDocument();             doc.LoadFromFile("sample.pdf");            //声明List类对象            List ListImage = new List();            //遍历PDF文档所有页面            for (int i = 0; i < doc.Pages.Count; i++)            {                //获取文档所有页，并提取页面中的所有图片                PdfPageBase page = doc.Pages[i];                Image[] images = page.ExtractImages();                if (images != null && images.Length > 0)                {                    ListImage.AddRange(images);                }            }            //将获取到的图片保存到本地路径            if (ListImage.Count > 0)            {                for (int i = 0; i < ListImage.Count; i++)                {                    Image image = ListImage[i];                    image.Save("image" + (i + 1).ToString() + ".png", System.Drawing.Imaging.ImageFormat.Png);                }                //打开获取到的图片                System.Diagnostics.Process.Start("image1.png");            }        }    }}

读取结果：

VB.NET

Imports Spire.PdfImports System.Collections.GenericImports System.DrawingNamespace ExtractImages_PDF    Class Program        Private Shared Sub Main(ByVal args As String())            Dim doc As PdfDocument = New PdfDocument()            doc.LoadFromFile("sample.pdf")            Dim ListImage As List(Of Image) = New List(Of Image)()            For i As Integer = 0 To doc.Pages.Count - 1                Dim page As PdfPageBase = doc.Pages(i)                Dim images As Image() = page.ExtractImages()                If images IsNot Nothing AndAlso images.Length > 0 Then                    ListImage.AddRange(images)                End If            Next            If ListImage.Count > 0 Then                For i As Integer = 0 To ListImage.Count - 1                    Dim image As Image = ListImage(i)                    image.Save("image" & (i + 1).ToString() & ".png", System.Drawing.Imaging.ImageFormat.Png)                Next                System.Diagnostics.Process.Start("image1.png")            End If        End Sub    End ClassEnd Namespace

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