java 上传文件-生成文件首页缩略图 生成pdf 抓取图片

时间：2023-03-08 19:27:27

方法：1、文件转换成pdf（采用openoffice或者jacob）

　　   2、抓取pdf首页图

第一步：采用jacob：

a、下载jacob  注意区分32位，64位，否则不能用
　　　　将dll文件放在java bin目录下即可
　　　　jar包引入项目

b、转换pdf

package cn.bnsr.edu_yun.util;

import java.io.File;  

import java.io.IOException;

import com.jacob.activeX.ActiveXComponent;

import com.jacob.com.ComThread;

import com.jacob.com.Dispatch;

import com.jacob.com.Variant;  

public class TestUtil {

	    static final int wdFormatPDF = 17;// PDF 格式

	    public void wordToPDF(String sfileName,String toFileName){    

	        System.out.println("启动Word...");

	        long start = System.currentTimeMillis();

	        ActiveXComponent app = null;

	        Dispatch doc = null;

	        try {

	            app = new ActiveXComponent("Word.Application");

	            app.setProperty("Visible", new Variant(false));

	            Dispatch docs = app.getProperty("Documents").toDispatch();

//	          doc = Dispatch.call(docs,  "Open" , sourceFile).toDispatch();

	            doc = Dispatch.invoke(docs,"Open",Dispatch.Method,new Object[] {

	               sfileName, new Variant(false),new Variant(true) }, new int[1]).toDispatch();

	            System.out.println("打开文档..." + sfileName);

	            System.out.println("转换文档到PDF..." + toFileName);

	            File tofile = new File(toFileName);

	            if (tofile.exists()) {

	                tofile.delete();

	            }

//	          Dispatch.call(doc, "SaveAs",  destFile,  17);

	            Dispatch.invoke(doc, "SaveAs", Dispatch.Method, new Object[] {

	                toFileName, new Variant(17) }, new int[1]);

	            long end = System.currentTimeMillis();

	            System.out.println("转换完成..用时：" + (end - start) + "ms.");

	        } catch (Exception e) {

	            e.printStackTrace();

	            System.out.println("========Error:文档转换失败：" + e.getMessage());

	        } finally {

	            Dispatch.call(doc,"Close",false);

	            System.out.println("关闭文档");

	            if (app != null)

	                app.invoke("Quit", new Variant[] {});

	            }

	          //如果没有这句话,winword.exe进程将不会关闭

	           ComThread.Release();

	    }

	    public static void main(String[] args) {

	    	TestUtil d = new TestUtil();

	        d.wordToPDF("D:\\work\\1111.docx", "d:\\work\\1111.pdf");

	    }  

}

第二步：抓取首页图：

　　

package cn.bnsr.edu_yun.util;

import java.awt.Image;

import java.awt.Rectangle;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.lang.reflect.Method;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

import java.security.AccessController;

import java.security.PrivilegedAction;

import com.sun.image.codec.jpeg.JPEGCodec;

import com.sun.image.codec.jpeg.JPEGImageEncoder;

import com.sun.pdfview.PDFFile;

import com.sun.pdfview.PDFPage;

public class PdfImageUtil {

		// 将PDF格式的文件转换为JPG格式的文件

	public static void pdfToJPG(String inputFile)throws IOException {

		// load a pdf from a byte buffer

		File file = new File(inputFile);

		RandomAccessFile raf = new RandomAccessFile(file, "r");

		FileChannel channel = raf.getChannel();

		//这句代码通道建立了map映射,如果要删除file那么得接触映射

		ByteBuffer buf = channel.map(FileChannel.MapMode.READ_ONLY, 0,

		channel.size());

		PDFFile pdffile = new PDFFile(buf);

		int totalpage =pdffile.getNumPages();

		for (int i = 1; i <= totalpage; i++) {

			if (i == 1) {

				// draw the first page to an image

				// 以图片的形式来描绘首页

				PDFPage page = pdffile.getPage(i);

				Rectangle rect = new Rectangle(0, 0, (int) page.getBBox().getWidth(), (int) page.getBBox().getHeight());

				// generate the image

				// 生成图片

				Image img = page.getImage(rect.width, rect.height, // width &

					// height

					rect, // clip rect

					null, // null for the ImageObserver

					true, // fill background with white

					true // block until drawing is done

					);

				BufferedImage tag = new BufferedImage(rect.width, rect.height,

				BufferedImage.TYPE_INT_RGB);

				tag.getGraphics().drawImage(img.getScaledInstance(rect.width, rect.height, Image.SCALE_SMOOTH), 0, 0, rect.width, rect.height,null);

				FileOutputStream out = new FileOutputStream( "D:\\work\\s111"+ ".jpg"); // 输出到文件流

				JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

				encoder.encode(tag); // JPEG编码

				// 关闭输出流

				out.close();

				break;

			}

		}

		buf.clear();

		channel.close();

		raf.close();

		unmap(buf);

		file.delete();

	}

		//解除map映射

	public static <T> void unmap(final Object buffer) {

		AccessController.doPrivileged(new PrivilegedAction<T>(){

			@Override

			public T run() {

				try {

					Method getCleanerMethod = buffer.getClass().getMethod("cleaner", new Class[0]);

					getCleanerMethod.setAccessible(true);

					sun.misc.Cleaner cleaner = (sun.misc.Cleaner) getCleanerMethod.invoke(buffer, new Object[0]);

					cleaner.clean();

				} catch(Exception e) {

					e.printStackTrace();

				}

				return null;

			}

		});

	}

}

　　

第三步、搞定，加入自己的业务逻辑，有问题欢迎提问。

　　

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