java 上传文件-生成文件首页缩略图 生成pdf 抓取图片

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。