12. 单实例Singleton 示例
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view source <embed id="highlighter_35199_clipboard" title="copy to clipboard" type="application/x-shockwave-flash" width="16" height="16" src="http://cocre.com/wp-content/plugins/syntaxhighlighter/syntaxhighlighter/scripts/clipboard.swf" lk_media="yes" lk_mediaid="lk_juiceapp_mediaPopup_1243315889019" allowscriptaccess="always" wmode="transparent" flashvars="highlighterId=highlighter_35199" menu="false"></embed> print ? 01. 02. public class SimpleSingleton { 03. private static SimpleSingleton singleInstance = new SimpleSingleton(); 04. 05. //Marking default constructor private 06. //to avoid direct instantiation. 07. private SimpleSingleton() { 08. } 09. 10. //Get instance for class SimpleSingleton 11. public static SimpleSingleton getInstance() { 12. 13. return singleInstance; 14. } 15. }另一种实现
view source <embed id="highlighter_120550_clipboard" title="copy to clipboard" type="application/x-shockwave-flash" width="16" height="16" src="http://cocre.com/wp-content/plugins/syntaxhighlighter/syntaxhighlighter/scripts/clipboard.swf" lk_media="yes" lk_mediaid="lk_juiceapp_mediaPopup_1243315889023" allowscriptaccess="always" wmode="transparent" flashvars="highlighterId=highlighter_120550" menu="false"></embed> print ? 1. public enum SimpleSingleton { 2. INSTANCE; 3. public void doSomething() { 4. } 5. } 6. 7. //Call the method from Singleton: 8. SimpleSingleton.INSTANCE.doSomething();13. 抓屏程序
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view source <embed id="highlighter_817602_clipboard" title="copy to clipboard" type="application/x-shockwave-flash" width="16" height="16" src="http://cocre.com/wp-content/plugins/syntaxhighlighter/syntaxhighlighter/scripts/clipboard.swf" lk_media="yes" lk_mediaid="lk_juiceapp_mediaPopup_1243315889027" allowscriptaccess="always" wmode="transparent" flashvars="highlighterId=highlighter_817602" menu="false"></embed> print ? 01. import java.awt.Dimension; 02. import java.awt.Rectangle; 03. import java.awt.Robot; 04. import java.awt.Toolkit; 05. import java.awt.image.BufferedImage; 06. import javax.imageio.ImageIO; 07. import java.io.File; 08. 09. ... 10. 11. public void captureScreen(String fileName) throws Exception { 12. 13. Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); 14. Rectangle screenRectangle = new Rectangle(screenSize); 15. Robot robot = new Robot(); 16. BufferedImage image = robot.createScreenCapture(screenRectangle); 17. ImageIO.write(image, "png" , new File(fileName)); 18. 19. } 20. ...
14. 列出文件和目录
view source <embed id="highlighter_1356_clipboard" title="copy to clipboard" type="application/x-shockwave-flash" width="16" height="16" src="http://cocre.com/wp-content/plugins/syntaxhighlighter/syntaxhighlighter/scripts/clipboard.swf" lk_media="yes" lk_mediaid="lk_juiceapp_mediaPopup_1243315889031" allowscriptaccess="always" wmode="transparent" flashvars="highlighterId=highlighter_1356" menu="false"></embed> print ? 01. File dir = new File( "directoryName" ); 02. String[] children = dir.list(); 03. if (children == null ) { 04. // Either dir does not exist or is not a directory 05. } else { 06. for ( int i= 0 ; i < children.length; i++) { 07. // Get filename of file or directory 08. String filename = children[i]; 09. } 10. } 11. 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); 20. 21. // The list of files can also be retrieved as File objects 22. File[] files = dir.listFiles(); 23. 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);15. 创建ZIP和JAR文件
view source <embed id="highlighter_695137_clipboard" title="copy to clipboard" type="application/x-shockwave-flash" width="16" height="16" src="http://cocre.com/wp-content/plugins/syntaxhighlighter/syntaxhighlighter/scripts/clipboard.swf" lk_media="yes" lk_mediaid="lk_juiceapp_mediaPopup_1243315889035" allowscriptaccess="always" wmode="transparent" flashvars="highlighterId=highlighter_695137" menu="false"></embed> print ? 01. 02. import java.util.zip.*; 03. import java.io.*; 04. 05. public class ZipIt { 06. public static void main(String args[]) throws IOException { 07. if (args.length < 2 ) { 08. System.err.println( "usage: java ZipIt Zip.zip file1 file2 file3" ); 09. System.exit(- 1 ); 10. } 11. File zipFile = new File(args[ 0 ]); 12. if (zipFile.exists()) { 13. System.err.println( "Zip file already exists, please try another" ); 14. System.exit(- 2 ); 15. } 16. FileOutputStream fos = new FileOutputStream(zipFile); 17. ZipOutputStream zos = new ZipOutputStream(fos); 18. int bytesRead; 19. byte [] buffer = new byte [ 1024 ]; 20. CRC32 crc = new CRC32(); 21. for ( int i= 1 , n=args.length; i < n; i++) { 22. String name = args[i]; 23. File file = new File(name); 24. if (!file.exists()) { 25. System.err.println( "Skipping: " + name); 26. continue ; 27. } 28. BufferedInputStream bis = new BufferedInputStream( 29. new FileInputStream(file)); 30. crc.reset(); 31. while ((bytesRead = bis.read(buffer)) != - 1 ) { 32. crc.update(buffer, 0 , bytesRead); 33. } 34. bis.close(); 35. // Reset to beginning of input stream 36. bis = new BufferedInputStream( 37. new FileInputStream(file)); 38. ZipEntry entry = new ZipEntry(name); 39. entry.setMethod(ZipEntry.STORED); 40. entry.setCompressedSize(file.length()); 41. entry.setSize(file.length()); 42. entry.setCrc(crc.getValue()); 43. zos.putNextEntry(entry); 44. while ((bytesRead = bis.read(buffer)) != - 1 ) { 45. zos.write(buffer, 0 , bytesRead); 46. } 47. bis.close(); 48. } 49. zos.close(); 50. } 51. }16. 解析/读取XML 文件
XML文件
view source <embed id="highlighter_879090_clipboard" title="copy to clipboard" type="application/x-shockwave-flash" width="16" height="16" src="http://cocre.com/wp-content/plugins/syntaxhighlighter/syntaxhighlighter/scripts/clipboard.swf" lk_media="yes" lk_mediaid="lk_juiceapp_mediaPopup_1243315889039" allowscriptaccess="always" wmode="transparent" flashvars="highlighterId=highlighter_879090" menu="false"></embed> print ? 01. <? xml version = "1.0" ?> 02. < students > 03. < student > 04. < name >John</ name > 05. < grade >B</ grade > 06. < age >12</ age > 07. </ student > 08. < student > 09. < 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 >Java代码
view source <embed id="highlighter_40476_clipboard" title="copy to clipboard" type="application/x-shockwave-flash" width="16" height="16" src="http://cocre.com/wp-content/plugins/syntaxhighlighter/syntaxhighlighter/scripts/clipboard.swf" lk_media="yes" lk_mediaid="lk_juiceapp_mediaPopup_1243315889043" allowscriptaccess="always" wmode="transparent" flashvars="highlighterId=highlighter_40476" menu="false"></embed> print ? 01. 02. package net.viralpatel.java.xmlparser; 03. 04. import java.io.File; 05. import javax.xml.parsers.DocumentBuilder; 06. import javax.xml.parsers.DocumentBuilderFactory; 07. 08. import org.w3c.dom.Document; 09. import org.w3c.dom.Element; 10. import org.w3c.dom.Node; 11. import org.w3c.dom.NodeList; 12. 13. public class XMLParser { 14. 15. public void getAllUserNames(String fileName) { 16. try { 17. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); 18. DocumentBuilder db = dbf.newDocumentBuilder(); 19. File file = new File(fileName); 20. if (file.exists()) { 21. Document doc = db.parse(file); 22. Element docEle = doc.getDocumentElement(); 23. 24. // Print root element of the document 25. System.out.println( "Root element of the document: " 26. + docEle.getNodeName()); 27. 28. NodeList studentList = docEle.getElementsByTagName( "student" ); 29. 30. // Print total student elements in document 31. System.out 32. .println( "Total students: " + studentList.getLength()); 33. 34. if (studentList != null && studentList.getLength() > 0 ) { 35. for ( int i = 0 ; i < studentList.getLength(); i++) { 36. 37. Node node = studentList.item(i); 38. 39. if (node.getNodeType() == Node.ELEMENT_NODE) { 40. 41. System.out 42. .println( "=====================" ); 43. 44. Element e = (Element) node; 45. NodeList nodeList = e.getElementsByTagName( "name" ); 46. System.out.println( "Name: " 47. + nodeList.item( 0 ).getChildNodes().item( 0 ) 48. .getNodeValue()); 49. 50. nodeList = e.getElementsByTagName( "grade" ); 51. System.out.println( "Grade: " 52. + nodeList.item( 0 ).getChildNodes().item( 0 ) 53. .getNodeValue()); 54. 55. nodeList = e.getElementsByTagName( "age" ); 56. System.out.println( "Age: " 57. + nodeList.item( 0 ).getChildNodes().item( 0 ) 58. .getNodeValue()); 59. } 60. } 61. } else { 62. System.exit( 1 ); 63. } 64. } 65. } catch (Exception e) { 66. System.out.println(e); 67. } 68. } 69. public static void main(String[] args) { 70. 71. XMLParser parser = new XMLParser(); 72. parser.getAllUserNames( "c:\\test.xml" ); 73. } 74. }相关资源：敏捷开发V1.0.pptx
