java 文件类型转换

 

PDF转JPG

1、提高转换后JPG文件清晰度（清晰度降低、图片质量压缩也用的此方法）

  示例为pdf转换jpg  在转换的过程中清晰度会下降、红色部分为提高清晰度

        File file = new File("D:\\workspace\\word2pdf\\src\\tests.doc.pdf");        RandomAccessFile raf = new RandomAccessFile(file, "r");        FileChannel channel = raf.getChannel();        ByteBuffer buf = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel                .size());        PDFFile pdffile = new PDFFile(buf);        System.out.println("页数： " + pdffile.getNumPages());        String getPdfFilePath = System.getProperty("user.dir") + "\\pdfPicFile";        System.out.println("getPdfFilePath is  :" + getPdfFilePath);        for (int i = 1; i <= pdffile.getNumPages(); i++) {            // draw the first page to an image            PDFPage page = pdffile.getPage(i);

            Rectangle rect = new Rectangle(0, 0, (int) page.getBBox()                    .getWidth(), (int) page.getBBox().getHeight());            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, 0, 0, rect.width, rect.height, null);            // 输出到文件流            FileOutputStream out = new FileOutputStream(getPdfFilePath + "\\"                    + i + ".jpg");            System.out.println("成功保存图片到:" + getPdfFilePath + "\\" + i + ".jpg");            /*             * JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);             * encoder.encode(tag); // JPEG编码 out.close();             */            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);            JPEGEncodeParam param2 = encoder.getDefaultJPEGEncodeParam(tag);            param2.setQuality(1f, false);// 1f是提高生成的图片质量             encoder.setJPEGEncodeParam(param2);            encoder.encode(tag); // JPEG编码            out.close();        }    }}