Category: JAVA

IDEA 2019.02.07注册码

N757JE0KCT-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-AE3x5sRpDellY4SmQVy2Pfc2IT7y1JjZFmDA5JtOv4K5gwVdJOLw5YGiOskZTuGu6JhOi50nnd0WaaNZIuVVVx3T5MlXrAuO3kb2qPtLtQ6/n3lp4fIv+6384D4ciEyRWijG7NA9exQx39Tjk7/xqaGk7ooKgq5yquIfIA+r4jlbW8j9gas1qy3uTGUuZQiPB4lv3P5OIpZzIoWXnFwWhy7s//mjOWRZdf/Du3RP518tMk74wizbTeDn84qxbM+giNAn+ovKQRMYHtLyxntBiP5ByzfAA9Baa5TUGW5wDiZrxFuvBAWTbLrRI0Kd7Nb/tB9n1V9uluB2WWIm7iMxDg==-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

使用NIO进行快速的文件拷贝

  1. public static void fileCopy( File in, File out )
  2.             throws IOException
  3.     {
  4.         FileChannel inChannel = new FileInputStream( in ).getChannel();
  5.         FileChannel outChannel = new FileOutputStream( out ).getChannel();
  6.         try
  7.         {
  8. //          inChannel.transferTo(0, inChannel.size(), outChannel);      // original — apparently has trouble copying large files on Windows  
  10.             // magic number for Windows, 64Mb – 32Kb)  
  11.             int maxCount = (64 * 1024 * 1024) – (32 * 1024);
  12.             long size = inChannel.size();
  13.             long position = 0;
  14.             while ( position < size )
  15.             {
  16.                position += inChannel.transferTo( position, maxCount, outChannel );
  17.             }
  18.         }
  19.         finally
  20.         {
  21.             if ( inChannel != null )
  22.             {
  23.                inChannel.close();
  24.             }
  25.             if ( outChannel != null )
  26.             {
  27.                 outChannel.close();
  28.             }
  29.         }
  30.     }

列出文件和目录

  1. File dir = new File(“directoryName”);
  2.   String[] children = dir.list();
  3.   if (children == null) {
  4.       // Either dir does not exist or is not a directory  
  5.   } else {
  6.       for (int i=0; i < children.length; i++) {
  7.           // Get filename of file or directory  
  8.           String filename = children[i];
  9.       }
  10.   }
  12.   // It is also possible to filter the list of returned files.  
  13.   // This example does not return any files that start with `.’.  
  14.   FilenameFilter filter = new FilenameFilter() {
  15.       public boolean accept(File dir, String name) {
  16.           return !name.startsWith(“.”);
  17.       }
  18.   };
  19.   children = dir.list(filter);
  21.   // The list of files can also be retrieved as File objects  
  22.   File[] files = dir.listFiles();
  24.   // This filter only returns directories  
  25.   FileFilter fileFilter = new FileFilter() {
  26.       public boolean accept(File file) {
  27.           return file.isDirectory();
  28.       }
  29.   };
  30.   files = dir.listFiles(fileFilter);

创建ZIP和JAR文件 create zip jar

  1. import java.util.zip.*;
  2. import java.io.*;
  4. public class ZipIt {
  5.     public static void main(String args[]) throws IOException {
  6.         if (args.length < 2) {
  7.             System.err.println(“usage: java ZipIt Zip.zip file1 file2 file3”);
  8.             System.exit(-1);
  9.         }
  10.         File zipFile = new File(args[0]);
  11.         if (zipFile.exists()) {
  12.             System.err.println(“Zip file already exists, please try another”);
  13.             System.exit(-2);
  14.         }
  15.         FileOutputStream fos = new FileOutputStream(zipFile);
  16.         ZipOutputStream zos = new ZipOutputStream(fos);
  17.         int bytesRead;
  18.         byte[] buffer = new byte[1024];
  19.         CRC32 crc = new CRC32();
  20.         for (int i=1, n=args.length; i < n; i++) {
  21.             String name = args[i];
  22.             File file = new File(name);
  23.             if (!file.exists()) {
  24.                 System.err.println(“Skipping: “ + name);
  25.                 continue;
  26.             }
  27.             BufferedInputStream bis = new BufferedInputStream(
  28.                 new FileInputStream(file));
  29.             crc.reset();
  30.             while ((bytesRead = bis.read(buffer)) != –1) {
  31.                 crc.update(buffer, 0, bytesRead);
  32.             }
  33.             bis.close();
  34.             // Reset to beginning of input stream  
  35.             bis = new BufferedInputStream(
  36.                 new FileInputStream(file));
  37.             ZipEntry entry = new ZipEntry(name);
  38.             entry.setMethod(ZipEntry.STORED);
  39.             entry.setCompressedSize(file.length());
  40.             entry.setSize(file.length());
  41.             entry.setCrc(crc.getValue());
  42.             zos.putNextEntry(entry);
  43.             while ((bytesRead = bis.read(buffer)) != –1) {
  44.                 zos.write(buffer, 0, bytesRead);
  45.             }
  46.             bis.close();
  47.         }
  48.         zos.close();
  49.     }
  50. }

解析/读取XML 文件

  1. <?xml version=“1.0”?>
  2. <students>
  3.     <student>
  4.         <name>John</name>
  5.         <grade>B</grade>
  6.         <age>12</age>
  7.     </student>
  8.     <student>
  9.         <name>Mary</name>
  10.         <grade>A</grade>
  11.         <age>11</age>
  12.     </student>
  13.     <student>
  14.         <name>Simon</name>
  15.         <grade>A</grade>
  16.         <age>18</age>
  17.     </student>
  18. </students>
  1. package net.viralpatel.java.xmlparser;
  3. import java.io.File;
  4. import javax.xml.parsers.DocumentBuilder;
  5. import javax.xml.parsers.DocumentBuilderFactory;
  7. import org.w3c.dom.Document;
  8. import org.w3c.dom.Element;
  9. import org.w3c.dom.Node;
  10. import org.w3c.dom.NodeList;
  12. public class XMLParser {
  14.     public void getAllUserNames(String fileName) {
  15.         try {
  16.             DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
  17.             DocumentBuilder db = dbf.newDocumentBuilder();
  18.             File file = new File(fileName);
  19.             if (file.exists()) {
  20.                 Document doc = db.parse(file);
  21.                 Element docEle = doc.getDocumentElement();
  23.                 // Print root element of the document  
  24.                 System.out.println(“Root element of the document: “
  25.                         + docEle.getNodeName());
  27.                 NodeList studentList = docEle.getElementsByTagName(“student”);
  29.                 // Print total student elements in document  
  30.                 System.out
  31.                         .println(“Total students: “ + studentList.getLength());
  33.                 if (studentList != null && studentList.getLength() > 0) {
  34.                     for (int i = 0; i < studentList.getLength(); i++) {
  36.                         Node node = studentList.item(i);
  38.                         if (node.getNodeType() == Node.ELEMENT_NODE) {
  40.                             System.out
  41.                                     .println(“=====================”);
  43.                             Element e = (Element) node;
  44.                             NodeList nodeList = e.getElementsByTagName(“name”);
  45.                             System.out.println(“Name: “
  46.                                     + nodeList.item(0).getChildNodes().item(0)
  47.                                             .getNodeValue());
  49.                             nodeList = e.getElementsByTagName(“grade”);
  50.                             System.out.println(“Grade: “
  51.                                     + nodeList.item(0).getChildNodes().item(0)
  52.                                             .getNodeValue());
  54.                             nodeList = e.getElementsByTagName(“age”);
  55.                             System.out.println(“Age: “
  56.                                     + nodeList.item(0).getChildNodes().item(0)
  57.                                             .getNodeValue());
  58.                         }
  59.                     }
  60.                 } else {
  61.                     System.exit(1);
  62.                 }
  63.             }
  64.         } catch (Exception e) {
  65.             System.out.println(e);
  66.         }
  67.     }
  68.     public static void main(String[] args) {
  70.         XMLParser parser = new XMLParser();
  71.         parser.getAllUserNames(“c:\\test.xml”);
  72.     }
  73. }

使用iText JAR生成PDF

  1. import java.io.File;
  2. import java.io.FileOutputStream;
  3. import java.io.OutputStream;
  4. import java.util.Date;
  6. import com.lowagie.text.Document;
  7. import com.lowagie.text.Paragraph;
  8. import com.lowagie.text.pdf.PdfWriter;
  10. public class GeneratePDF {
  12.     public static void main(String[] args) {
  13.         try {
  14.             OutputStream file = new FileOutputStream(new File(“C:\\Test.pdf”));
  16.             Document document = new Document();
  17.             PdfWriter.getInstance(document, file);
  18.             document.open();
  19.             document.add(new Paragraph(“Hello Kiran”));
  20.             document.add(new Paragraph(new Date().toString()));
  22.             document.close();
  23.             file.close();
  25.         } catch (Exception e) {
  27.             e.printStackTrace();
  28.         }
  29.     }
  30. }

创建图片的缩略图 createThumbnail

  1. private void createThumbnail(String filename, int thumbWidth, int thumbHeight, int quality, String outFilename)
  2.         throws InterruptedException, FileNotFoundException, IOException
  3.     {
  4.         // load image from filename  
  5.         Image image = Toolkit.getDefaultToolkit().getImage(filename);
  6.         MediaTracker mediaTracker = new MediaTracker(new Container());
  7.         mediaTracker.addImage(image, 0);
  8.         mediaTracker.waitForID(0);
  9.         // use this to test for errors at this point: System.out.println(mediaTracker.isErrorAny());  
  11.         // determine thumbnail size from WIDTH and HEIGHT  
  12.         double thumbRatio = (double)thumbWidth / (double)thumbHeight;
  13.         int imageWidth = image.getWidth(null);
  14.         int imageHeight = image.getHeight(null);
  15.         double imageRatio = (double)imageWidth / (double)imageHeight;
  16.         if (thumbRatio < imageRatio) {
  17.             thumbHeight = (int)(thumbWidth / imageRatio);
  18.         } else {
  19.             thumbWidth = (int)(thumbHeight * imageRatio);
  20.         }
  22.         // draw original image to thumbnail image object and  
  23.         // scale it to the new size on-the-fly  
  24.         BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
  25.         Graphics2D graphics2D = thumbImage.createGraphics();
  26.         graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
  27.         graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
  29.         // save thumbnail image to outFilename  
  30.         BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFilename));
  31.         JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
  32.         JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(thumbImage);
  33.         quality = Math.max(0, Math.min(quality, 100));
  34.         param.setQuality((float)quality / 100.0f, false);
  35.         encoder.setJPEGEncodeParam(param);
  36.         encoder.encode(thumbImage);
  37.         out.close();
  38.     }