apache commons 使用說明

1、(轉)Apache Commons工具集簡介Apache Commons包含了很多開源的工具，用于解決平時編程經常會遇到的問題，減少重復勞動。我選了一些比較常用的項目做簡單介紹。文中用了很多網上現成的東西，我只是做了一個匯總整理。一、Commons BeanUtils/commons/beanutils/index.html說明：針對Bean的一個工具集。由于Bean往往是有一堆get和set組成，所以BeanUtils也是在此基礎上進行一些包裝。使用示例：功能有很多，網站上有詳細介紹。一個比較常用的功能是Bean Copy，也就是copy be

2、an的屬性。如果做分層架構開發(fā)的話就會用到，比如從PO（Persistent Object）拷貝數據到VO（Value Object）。傳統(tǒng)方法如下：/得到TeacherFormTeacherForm teacherForm=(TeacherForm)form;/構造Teacher對象Teacher teacher=new Teacher();/賦值teacher.setName(teacherForm.getName();teacher.setAge(teacherForm.getAge();teacher.setGender(teacherForm.getGender();teacher.

3、setMajor(teacherForm.getMajor();teacher.setDepartment(teacherForm.getDepartment();/持久化Teacher對象到數據庫HibernateDAO= ;HibernateDAO.save(teacher);使用BeanUtils后，代碼就大大改觀了，如下所示：/得到TeacherFormTeacherForm teacherForm=(TeacherForm)form;/構造Teacher對象Teacher teacher=new Teacher();/賦值BeanUtils.copyProperties(teache

4、r,teacherForm);/持久化Teacher對象到數據庫HibernateDAO= ;HibernateDAO.save(teacher);二、Commons CLI/commons/cli/index.html說明：這是一個處理命令的工具。比如main方法輸入的string需要解析。你可以預先定義好參數的規(guī)則，然后就可以調用CLI來解析。使用示例：/ create Options objectOptions options = new Options();/ add t option, option is the command par

5、ameter, false indicates that/ this parameter is not required.options.addOption(“t”, false, “display current time”);options.addOption("c", true, "country code");CommandLineParser parser = new PosixParser();CommandLine cmd = parser.parse( options, args);if(cmd.hasOption("t&quo

6、t;)    / print the date and timeelse    / print the date/ get c option valueString countryCode = cmd.getOptionValue("c");if(countryCode = null)     / print default dateelse     / print date for country specified by countryCode三、Co

7、mmons Codec/commons/codec/index.html說明：這個工具是用來編碼和解碼的，包括Base64，URL，Soundx等等。用這個工具的人應該很清楚這些，我就不多介紹了。四、Commons Collections/commons/collections/說明：你可以把這個工具看成是java.util的擴展。使用示例：舉一個簡單的例子OrderedMap map = new LinkedMap();map.put("FIVE", "5"

8、);map.put("SIX", "6");map.put("SEVEN", "7");map.firstKey(); / returns "FIVE"map.nextKey("FIVE"); / returns "SIX"map.nextKey("SIX"); / returns "SEVEN"五、Commons Configuration/commons/confi

9、guration/說明：這個工具是用來幫助處理配置文件的，支持很多種存儲方式1. Properties files2. XML documents3. Property list files (.plist)4. JNDI5. JDBC Datasource6. System properties7. Applet parameters8. Servlet parameters使用示例：舉一個Properties的簡單例子# perties, definining the GUI,colors.background = #FFFFFFcolors.foreground =

10、 #000080window.width = 500window.height = 300 PropertiesConfiguration config = new PropertiesConfiguration("perties");config.setProperty("colors.background", "#000000);config.save();config.save("perties);/save a copyInteger integer = co

11、nfig.getInteger("window.width");Commons DBCP/commons/dbcp/說明：Database Connection pool, Tomcat就是用的這個，不用我多說了吧，要用的自己去網站上看說明。六、Commons DbUtils/commons/dbutils/說明：我以前在寫數據庫程序的時候，往往把數據庫操作單獨做一個包。DbUtils就是這樣一個工具，以后開發(fā)不用再重復這樣的工作了。值得一體的是，這個工具并不是現在流行的OR-M

12、apping工具（比如Hibernate），只是簡化數據庫操作，比如QueryRunner run = new QueryRunner(dataSource);/ Execute the query and get the results back from the handlerObject result = (Object) run.query("SELECT * FROM Person WHERE name=?", "John Doe");七、Commons FileUpload/commons/fi

13、leupload/說明：jsp的上傳文件功能怎么做呢？使用示例：/ Create a factory for disk-based file itemsFileItemFactory factory = new DiskFileItemFactory();/ Create a new file upload handlerServletFileUpload upload = new ServletFileUpload(factory); / Parse the requestList /* FileItem */ items = upload.parseRequest(request

14、);/ Process the uploaded itemsIterator iter = items.iterator();while (iter.hasNext()      FileItem item = (FileItem) iter.next();     if (item.isFormField()         processFormField(item);    

15、60; else         processUploadedFile(item);     八、Commons HttpClient/commons/httpclient/說明：這個工具可以方便通過編程的方式去訪問網站。使用示例：最簡單的Get操作GetMethod get = new GetMethod("");/ execute method

16、and handle any error responses.InputStream in = get.getResponseBodyAsStream();/ Process the data from the input stream.get.releaseConnection();九、Commons IO/commons/io/說明：可以看成是java.io的擴展，我覺得用起來非常方便。使用示例：1讀取Stream標準代碼：InputStream in = new URL( "&quo

17、t; ).openStream();try        InputStreamReader inR = new InputStreamReader( in );       BufferedReader buf = new BufferedReader( inR );       String line;       whil

18、e ( ( line = buf.readLine() ) != null )           System.out.println( line );          finally     in.close();  使用IOUtilsInputStream in = new URL( "http:/jakarta.apache.o

19、rg" ).openStream();try     System.out.println( IOUtils.toString( in ) ); finally     IOUtils.closeQuietly(in);2讀取文件File file = new File("/commons/io/perties");List lines = FileUtils.readLines(file, "UTF-8");3察看剩余空間long freeSpace

20、= FileSystemUtils.freeSpace("C:/");十、Commons JXPath/commons/jxpath/說明：Xpath你知道吧，那么JXpath就是基于Java對象的Xpath，也就是用Xpath對Java對象進行查詢。這個東西還是很有想像力的。使用示例：Address address = (Address)JXPathContext.newContext(vendor).getValue("locationsaddress/zipCode='90210'/addres

21、s");上述代碼等同于Address address = null;Collection locations = vendor.getLocations();Iterator it = locations.iterator();while (it.hasNext()    Location location = (Location)it.next();    String zipCode = location.getAddress().getZipCode();    if

22、(zipCode.equals("90210")       address = location.getAddress();        break;    十一、Commons Lang/commons/lang/說明：這個工具包可以看成是對java.lang的擴展。提供了諸如StringUtils, StringEscapeUtil

23、s, RandomStringUtils, Tokenizer, WordUtils等工具類。十二、Commons Logging/commons/logging/說明：你知道Log4j嗎？十三、Commons Math/commons/math/說明：看名字你就應該知道這個包是用來干嘛的了吧。這個包提供的功能有些和Commons Lang重復了，但是這個包更專注于做數學工具，功能更強大。十四、Commons Net/commons/net/說明：這個

24、包還是很實用的，封裝了很多網絡協議。1. FTP2. NNTP3. SMTP4. POP35. Telnet6. TFTP7. Finger8. Whois9. rexec/rcmd/rlogin10. Time (rdate) and Daytime11. Echo12. Discard13. NTP/SNTP使用示例：TelnetClient telnet = new TelnetClient();telnet.connect( "9", 23 );InputStream in = telnet.getInputStream();PrintStre

25、am out = new PrintStream( telnet.getOutputStream() );.telnet.close();十五、Commons Validator/commons/validator/說明：用來幫助進行驗證的工具。比如驗證Email字符串，日期字符串等是否合法。使用示例：/ Get the Date validatorDateValidator validator = DateValidator.getInstance();/ Validate/Convert the dateDate fooDate = vali

26、dator.validate(fooString, "dd/MM/yyyy");if (fooDate = null)     / error.not a valid date    return;十六、Commons Virtual File System/commons/vfs/說明：提供對各種資源的訪問接口。支持的資源類型包括1. CIFS2. FTP3. Local Files4. HTTP and HTTPS5. SFTP6. Temporary Files7. WebDAV8. Z