Apache Commons包含了很多开源的工具，用于解决平时编程经常会遇到的问题，减少重复劳动。下面是我这几年做开发过程中自己用过的工具类做简单介绍。
Commons简介
| 组件 | 功能介绍 |
| commons-beanutils | 提供了对于JavaBean进行各种操作，克隆对象,属性等等. |
| commons-betwixt | XML与Java对象之间相互转换. |
| commons-codec | 处理常用的编码方法的工具类包 例如DES、SHA1、MD5、Base64等. |
| commons-collections | java集合框架操作. |
| commons-compress | java提供文件打包 压缩类库. |
| commons-configuration | 一个java应用程序的配置管理类库. |
| commons-dbcp | 提供数据库连接池服务. |
| commons-dbutils | 提供对jdbc 的操作封装来简化数据查询和记录读取操作. |
| commons-email | java发送邮件 对javamail的封装. |
| commons-fileupload | 提供文件上传功能. |
| commons-httpclient | 提供HTTP客户端与服务器的各种通讯操作. 现在已改成HttpComponents |
| commons-io | io工具的封装. |
| commons-lang | Java基本对象方法的工具类包 如：StringUtils,ArrayUtils,DateUtils,DateFormatUtils等等. |
| commons-logging | 提供的是一个Java 的日志接口. |
| commons-validator | 提供了客户端和服务器端的数据验证框架. |
Maven依赖
<!-- https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils --> <dependency> <groupId>commons-beanutils</groupId> <artifactId>commons-beanutils</artifactId> <version>1.9.3</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-betwixt/commons-betwixt --> <dependency> <groupId>commons-betwixt</groupId> <artifactId>commons-betwixt</artifactId> <version>0.8</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-codec/commons-codec --> <dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.10</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-collections4</artifactId> <version>4.1</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-collections/commons-collections --> <dependency> <groupId>commons-collections</groupId> <artifactId>commons-collections</artifactId> <version>3.2.1</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-compress --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-compress</artifactId> <version>1.18</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-configuration2 --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-configuration2</artifactId> <version>2.2</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-configuration/commons-configuration --> <dependency> <groupId>commons-configuration</groupId> <artifactId>commons-configuration</artifactId> <version>1.10</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-dbcp2 --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-dbcp2</artifactId> <version>2.1.1</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-dbcp/commons-dbcp --> <dependency> <groupId>commons-dbcp</groupId> <artifactId>commons-dbcp</artifactId> <version>1.4</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-dbutils/commons-dbutils --> <dependency> <groupId>commons-dbutils</groupId> <artifactId>commons-dbutils</artifactId> <version>1.6</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-email --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-email</artifactId> <version>1.4</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-email/commons-email --> <dependency> <groupId>commons-email</groupId> <artifactId>commons-email</artifactId> <version>1.0</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload --> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3.1</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient --> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.12</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-httpclient/commons-httpclient --> <dependency> <groupId>commons-httpclient</groupId> <artifactId>commons-httpclient</artifactId> <version>3.1</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-io/commons-io --> <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.6</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-io --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-io</artifactId> <version>1.3.2</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 --> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.9</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-lang/commons-lang --> <dependency> <groupId>commons-lang</groupId> <artifactId>commons-lang</artifactId> <version>2.6</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-logging/commons-logging --> <dependency> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> <version>1.2</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-validator/commons-validator --> <dependency> <groupId>commons-validator</groupId> <artifactId>commons-validator</artifactId> <version>1.6</version> </dependency>
1、commons-beanutils
提供了对于JavaBean进行各种操作， 比如对象,属性复制等等。
import java.util.HashMap; import java.util.Map; import org.apache.commons.beanutils.BeanUtils; import org.apache.commons.beanutils.PropertyUtils; public class CommonsBeanUtils { public static void main(String[] args) throws Exception { // **************************************************************************** Person person = new Person(); person.setName("tom"); person.setAge(21); // 克隆对象 Person person2 = (Person) BeanUtils.cloneBean(person); System.out.println(person2.getName() + ">>" + person2.getAge()); // **************************************************************************** Map<String, String> map = new HashMap<String, String>(); map.put("name", "tom"); map.put("email", "tom@"); map.put("age", "21"); // 将map转化为一个Person对象 Person person3 = new Person(); BeanUtils.populate(person3, map); System.out.println(person3.getName() + ">>" + person3.getAge()); // 通过上面的一行代码，此时person的属性就已经具有了上面所赋的值了。 // 将一个Bean转化为一个Map对象了，如下： Map<String, String> map2 = BeanUtils.describe(person3); System.out.println(map2.get("name") + ">>" + map2.get("age")); // **************************************************************************** Person person4 = new Person(); person4.setName("andy"); // 反射调用get方法 String name = (String) PropertyUtils.getProperty(person4, "name"); System.out.println(name); // 反射调用set方法 PropertyUtils.setProperty(person4, "age", 25); System.out.println(person4.getAge()); } }
2、commons-betwixt
XML与Java对象之间相互转换。
import java.io.StringReader; import java.io.StringWriter; import org.apache.commons.betwixt.io.BeanReader; import org.apache.commons.betwixt.io.BeanWriter; public class CommonsBetwixt { public static void main(String[] args) throws Exception { // ****************************创建一个例子Bean，并将它转化为XML ************************************************ // 先创建一个StringWriter，我们将把它写入为一个字符串 StringWriter outputWriter = new StringWriter(); // Betwixt在这里仅仅是将Bean写入为一个片断 // 所以如果要想完整的XML内容，我们应该写入头格式 outputWriter.write("<?xml version=’1.0′ encoding=’UTF-8′ ?> "); // 创建一个BeanWriter，其将写入到我们预备的stream中 BeanWriter beanWriter = new BeanWriter(outputWriter); // 配置betwixt // 更多详情请参考java docs 或最新的文档 beanWriter.getXMLIntrospector().getConfiguration().setAttributesForPrimitives(false); beanWriter.getBindingConfiguration().setMapIDs(false); beanWriter.enablePrettyPrint(); // 如果这个地方不传入XML的根节点名，Betwixt将自己猜测是什么 // 但是让我们将例子Bean名作为根节点吧 beanWriter.write("person", new Person("John Smith", 21)); // 输出结果 System.out.println(outputWriter.toString()); // Betwixt写的是片断而不是一个文档，所以不要自动的关闭掉writers或者streams， // 但这里仅仅是一个例子，不会做更多事情，所以可以关掉 outputWriter.close(); // ****************************将XML转化为JavaBean ************************************************ // 先创建一个XML，由于这里仅是作为例子，所以我们硬编码了一段XML内容 StringReader xmlReader = new StringReader("<?xml version='1.0' encoding='UTF-8' ?> <person><age>25</age><name>James Smith</name></person>"); // 创建BeanReader BeanReader beanReader = new BeanReader(); // 配置reader beanReader.getXMLIntrospector().getConfiguration().setAttributesForPrimitives(false); beanReader.getBindingConfiguration().setMapIDs(false); // 注册beans，以便betwixt知道XML将要被转化为一个什么Bean beanReader.registerBeanClass("person", Person.class); // 现在我们对XML进行解析 Person person = (Person) beanReader.parse(xmlReader); // 输出结果 System.out.println(person); } }
3、commons-codec
公共的编解码实现，比如Base64, Hex, MD5,Phonetic and URLs等等。
import org.apache.commons.codec.binary.Base64; public class CommonsCodec { public static void main(String[] args) throws Exception { Base64 base64 = new Base64(); String encodestr = base64.encodeToString("abcd".getBytes("UTF-8")); System.out.println("Base64 编码后：" + encodestr); String decodestr = new String(Base64.decodeBase64("YWJjZA==")); System.out.println("Base64 解码后："+decodestr); } }
4、commons-collections
对java.util的扩展封装，处理数据还是挺灵活的。
org.apache.commons.collections – Commons Collections自定义的一组公用的接口和工具类
org.apache.commons.collections.bag – 实现Bag接口的一组类
org.apache.commons.collections.bidimap – 实现BidiMap系列接口的一组类
org.apache.commons.collections.buffer – 实现Buffer接口的一组类
org.apache.commons.collections.collection – 实现java.util.Collection接口的一组类
org.apache.commons.collections.comparators – 实现java.util.Comparator接口的一组类
org.apache.commons.collections.functors – Commons Collections自定义的一组功能类
org.apache.commons.collections.iterators – 实现java.util.Iterator接口的一组类
org.apache.commons.collections.keyvalue – 实现集合和键/值映射相关的一组类
org.apache.commons.collections.list – 实现java.util.List接口的一组类
org.apache.commons.collections.map – 实现Map系列接口的一组类
org.apache.commons.collections.set – 实现Set系列接口的一组类
import java.util.ArrayList; import java.util.Collection; import java.util.List; import org.apache.commons.collections.BidiMap; import org.apache.commons.collections.CollectionUtils; import org.apache.commons.collections.OrderedMap; import org.apache.commons.collections.bidimap.TreeBidiMap; import org.apache.commons.collections.map.LinkedMap; public class CommonsCollections { public static void main(String[] args) { //得到集合里按顺序存放的key之后的某一Key OrderedMap map = new LinkedMap (); map.put("FIVE", "5"); map.put("SIX", "6"); map.put("SEVEN", "7"); map.firstKey(); // returns "FIVE" map.nextKey("FIVE"); // returns "SIX" map.nextKey("SIX"); // returns "SEVEN" //通过key得到value 通过value得到key 将map里的key和value对调 BidiMap bidi = new TreeBidiMap(); bidi.put("SIX", "6"); bidi.get("SIX"); // returns "6" bidi.getKey("6"); // returns "SIX" // bidi.removeValue("6"); // removes the mapping BidiMap inverse = bidi.inverseBidiMap(); // returns a map with keys and values swapped System.out.println(inverse); //得到两个集合中相同的元素 List<String> list1 = new ArrayList<String>(); list1.add("1"); list1.add("2"); list1.add("3"); List<String> list2 = new ArrayList<String>(); list2.add("2"); list2.add("3"); list2.add("5"); Collection c = CollectionUtils.retainAll(list1, list2); System.out.println(c); } }
5、commons-compress
commons compress中的打包、压缩类库。
import java.io.File; import java.io.FileInputStream; import org.apache.commons.compress.archivers.zip.ZipArchiveEntry; import org.apache.commons.compress.archivers.zip.ZipArchiveOutputStream; public class CommonsCompress { public static void main(String[] args) throws Exception { // 创建压缩对象 ZipArchiveEntry entry = new ZipArchiveEntry("CompressTest"); // 要压缩的文件 File f = new File("e:\test.pdf"); FileInputStream fis = new FileInputStream(f); // 输出的对象 压缩的文件 ZipArchiveOutputStream zipOutput = new ZipArchiveOutputStream(new File("e:\test.zip")); zipOutput.putArchiveEntry(entry); int i = 0, j; while ((j = fis.read()) != -1) { zipOutput.write(j); i++; System.out.println(i); } zipOutput.closeArchiveEntry(); zipOutput.close(); fis.close(); } }
6、commons-configuration
用来帮助处理配置文件的，支持很多种存储方式。
1. Properties files
2. XML documents
3. Property list files (.plist)
4. JNDI
5. JDBC Datasource
6. System properties
7. Applet parameters
8. Servlet parameters
PropertiesConfiguration config = new PropertiesConfiguration("usergui.properties"); config.setProperty("colors.background", "#000000); config.save(); config.save("usergui.backup.properties);//save a copy Integer integer = config.getInteger("window.width");
7、commons-dbcp
(Database Connection Pool)是一个依赖Jakarta commons-pool对象池机制的数据库连接池,Tomcat的数据源使用的就是DBCP。
import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import javax.sql.DataSource; import org.apache.commons.dbcp.ConnectionFactory; import org.apache.commons.dbcp.DriverManagerConnectionFactory; import org.apache.commons.dbcp.PoolableConnectionFactory; import org.apache.commons.dbcp.PoolingDataSource; import org.apache.commons.pool.ObjectPool; import org.apache.commons.pool.impl.GenericObjectPool; public class CommonsDbcp { public static void main(String[] args) { System.out.println("加载jdbc驱动"); try { Class.forName("oracle.jdbc.driver.OracleDriver"); } catch (ClassNotFoundException e) { e.printStackTrace(); } System.out.println("Done."); // System.out.println("设置数据源"); DataSource dataSource = setupDataSource("jdbc:oracle:thin:@localhost:1521:test"); System.out.println("Done."); // Connection conn = null; Statement stmt = null; ResultSet rset = null; try { System.out.println("Creating connection."); conn = dataSource.getConnection(); System.out.println("Creating statement."); stmt = conn.createStatement(); System.out.println("Executing statement."); rset = stmt.executeQuery("select * from person"); System.out.println("Results:"); int numcols = rset.getMetaData().getColumnCount(); while (rset.next()) { for (int i = 0; i <= numcols; i++) { System.out.print(" " + rset.getString(i)); } System.out.println(""); } } catch (SQLException e) { e.printStackTrace(); } finally { try { if (rset != null) rset.close(); } catch (Exception e) { } try { if (stmt != null) stmt.close(); } catch (Exception e) { } try { if (conn != null) conn.close(); } catch (Exception e) { } } } public static DataSource setupDataSource(String connectURI) { // 设置连接地址 ConnectionFactory connectionFactory = new DriverManagerConnectionFactory(connectURI, null); // 创建连接工厂 PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory, null, null, connectURI, false, false); // 获取GenericObjectPool 连接的实例 ObjectPool connectionPool = new GenericObjectPool(poolableConnectionFactory); // 创建 PoolingDriver PoolingDataSource dataSource = new PoolingDataSource(connectionPool); return dataSource; } }
8、commons-dbutils
Apache组织提供的一个资源JDBC工具类库，它是对JDBC的简单封装，对传统操作数据库的类进行二次封装，可以把结果集转化成List。，同时也不影响程序的性能。
DbUtils类：启动类
ResultSetHandler接口：转换类型接口
MapListHandler类：实现类，把记录转化成List
BeanListHandler类：实现类，把记录转化成List，使记录为JavaBean类型的对象
Qrery Runner类：执行SQL语句的类
import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.util.List; import java.util.Map; import org.apache.commons.dbutils.DbUtils; import org.apache.commons.dbutils.QueryRunner; import org.apache.commons.dbutils.handlers.BeanListHandler; import org.apache.commons.dbutils.handlers.MapListHandler; public class CommonsDbutils { public static void main(String[] args) { Connection conn = null; String url = "jdbc:mysql://localhost:3306/ptest"; String jdbcDriver = "com.mysql.jdbc.Driver"; String user = "root"; String password = "ptest"; DbUtils.loadDriver(jdbcDriver); //****************************转换成list ************************************ try { conn = DriverManager.getConnection(url, user, password); QueryRunner qr = new QueryRunner(); List results = (List) qr.query(conn, "select id,name from person",new BeanListHandler(Person.class)); for (int i = 0; i < results.size(); i++) { Person p = (Person) results.get(i); System.out.println("age:" + p.getAge() + ",name:" + p.getName()); } } catch (SQLException e) { e.printStackTrace(); } finally { DbUtils.closeQuietly(conn); } //****************************转换成map ************************************ try { conn = DriverManager.getConnection(url, user, password); QueryRunner qr = new QueryRunner(); List results = (List) qr.query(conn, "select age,name from person",new MapListHandler()); for (int i = 0; i < results.size(); i++) { Map map = (Map) results.get(i); System.out.println("age:" + map.get("age") + ",name:"+ map.get("name")); } } catch (SQLException e) { e.printStackTrace(); } finally { DbUtils.closeQuietly(conn); } } }
9、commons-email
提供的一个开源的API，是对javamail的封装。
import org.apache.commons.mail.DefaultAuthenticator; import org.apache.commons.mail.Email; import org.apache.commons.mail.EmailException; import org.apache.commons.mail.SimpleEmail; public class CommosEmail { public static void main(String[] args) throws EmailException { Email email = new SimpleEmail(); email.setHostName("smtp.googlemail.com"); email.setSmtpPort(465); email.setAuthenticator(new DefaultAuthenticator("username", "password")); email.setSSLOnConnect(true); email.setFrom("user@gmail.com"); email.setSubject("TestMail"); email.setMsg("This is a test mail ... :-)"); email.addTo("foo@bar.com"); email.send(); } }
10、commons-fileupload
java web文件上传功能。
//检查请求是否含有上传文件 boolean isMultipart = ServletFileUpload.isMultipartContent(request); //如果你的应用近于最简单的情况，上面的处理就够了。但我们有时候还是需要更多的控制。 //下面提供了几种控制选择 DiskFileItemFactory factory = new DiskFileItemFactory(); // Set factory constraints factory.setSizeThreshold(yourMaxMemorySize); factory.setRepository(yourTempDirectory); // Create a new file upload handler ServletFileUpload upload = new ServletFileUpload(factory); // 设置最大上传大小 upload.setSizeMax(yourMaxRequestSize); // 解析所有请求 List items = upload.parseRequest(request); // Create a factory for disk-based file items DiskFileItemFactory factory = new DiskFileItemFactory( yourMaxMemorySize, yourTempDirectory); //一旦解析完成，你需要进一步处理item的列表。 Iterator iter = items.iterator(); while (iter.hasNext()) { FileItem item = (FileItem) iter.next(); if (item.isFormField()) { processFormField(item); } else { processUploadedFile(item); } } //区分数据是否为简单的表单数据，如果是简单的数据 if (item.isFormField()) { String name = item.getFieldName(); String value = item.getString(); //...省略步骤 } //如果是提交的文件： if (!item.isFormField()) { String fieldName = item.getFieldName(); String fileName = item.getName(); String contentType = item.getContentType(); boolean isInMemory = item.isInMemory(); long sizeInBytes = item.getSize(); //...省略步骤 } //对于这些item，我们通常要把它们写入文件，或转为一个流 if (writeToFile) { File uploadedFile = new File(...); item.write(uploadedFile); } else { InputStream uploadedStream = item.getInputStream(); //...省略步骤 uploadedStream.close(); } //或转为字节数组保存在内存中 byte[] data = item.get(); //...省略步骤 //如果这个文件真的很大，你可能会希望向用户报告到底传了多少到服务端，让用户了解上传的过程 ProgressListener progressListener = new ProgressListener(){ public void update(long pBytesRead, long pContentLength, int pItems) { System.out.println("We are currently reading item " + pItems); if (pContentLength == -1) { System.out.println("So far, " + pBytesRead + " bytes have been read."); } else { System.out.println("So far, " + pBytesRead + " of " + pContentLength + " bytes have been read."); } } }; upload.setProgressListener(progressListener);
11、commons-httpclient
基于HttpCore实 现的一个HTTP/1.1兼容的HTTP客户端，它提供了一系列可重用的客户端身份验证、HTTP状态保持、HTTP连接管理module。
import java.io.IOException; import org.apache.commons.httpclient.*; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.params.HttpMethodParams; public class CommonsHttpclient { public static void main(String[] args) { // 构造HttpClient的实例 HttpClient httpClient = new HttpClient(); // 创建GET方法的实例 GetMethod getMethod = new GetMethod("http://www.ibm.com"); // 使用系统提供的默认的恢复策略 getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler()); try { // 执行getMethod int statusCode = httpClient.executeMethod(getMethod); if (statusCode != HttpStatus.SC_OK) { System.err.println("Method failed: " + getMethod.getStatusLine()); } // 读取内容 byte[] responseBody = getMethod.getResponseBody(); // 处理内容 System.out.println(new String(responseBody)); } catch (HttpException e) { // 发生致命的异常，可能是协议不对或者返回的内容有问题 System.out.println("Please check your provided http address!"); e.printStackTrace(); } catch (IOException e) { // 发生网络异常 e.printStackTrace(); } finally { // 释放连接 getMethod.releaseConnection(); } // 构造HttpClient的实例 HttpClient httpClient = new HttpClient(); // 创建POST方法的实例 String url = "http://www.oracle.com/"; PostMethod postMethod = new PostMethod(url); // 填入各个表单域的值 NameValuePair[] data = { new NameValuePair("id", "youUserName"), new NameValuePair("passwd", "yourPwd") }; // 将表单的值放入postMethod中 postMethod.setRequestBody(data); // 执行postMethod int statusCode = httpClient.executeMethod(postMethod); // HttpClient对于要求接受后继服务的请求，象POST和PUT等不能自动处理转发 // 301或者302 if (statusCode == HttpStatus.SC_MOVED_PERMANENTLY || statusCode == HttpStatus.SC_MOVED_TEMPORARILY) { // 从头中取出转向的地址 Header locationHeader = postMethod.getResponseHeader("location"); String location = null; if (locationHeader != null) { location = locationHeader.getValue(); System.out.println("The page was redirected to:" + location); } else { System.err.println("Location field value is null."); } return; } } }
12、commons-io
对java.io的扩展 操作文件非常方便。
import java.io.BufferedReader; import java.io.File; import java.io.InputStream; import java.io.InputStreamReader; import java.net.URL; import java.util.List; import org.apache.commons.io.FileSystemUtils; import org.apache.commons.io.FileUtils; import org.apache.commons.io.IOUtils; public class CommonsIo { public static void main(String[] args) throws Exception { // 1．读取Stream // 标准代码： InputStream in = new URL("http://jakarta.apache.org").openStream(); InputStreamReader inR = new InputStreamReader(in); BufferedReader buf = new BufferedReader(inR); String line; while ((line = buf.readLine()) != null) { System.out.println(line); } in.close(); // 使用IOUtils InputStream in2 = new URL("http://jakarta.apache.org").openStream(); try { System.out.println(IOUtils.toString(in2)); } finally { IOUtils.closeQuietly(in); } // 2．读取文件 File file = new File("/commons/io/project.properties"); List lines = FileUtils.readLines(file, "UTF-8"); // 3．察看剩余空间 long freeSpace = FileSystemUtils.freeSpace("C:/"); } }
13、commos-lang
主要是一些公共的工具集合，比如对字符、数组的操作等等。
import java.util.Calendar; import java.util.Date; import org.apache.commons.lang.ArrayUtils; import org.apache.commons.lang.ClassUtils; import org.apache.commons.lang.RandomStringUtils; import org.apache.commons.lang.StringEscapeUtils; import org.apache.commons.lang.StringUtils; import org.apache.commons.lang.time.DateFormatUtils; import org.apache.commons.lang.time.DateUtils; public class CommonsLang { public static void main(String[] args) throws Exception { //********************************ArrayUtils*************************************** // 将两个数组合并为一个数组 String[] s1 = new String[] { "1", "2", "3" }; String[] s2 = new String[] { "a", "b", "c" }; String[] s = (String[]) ArrayUtils.addAll(s1, s2); for (int i = 0; i < s.length; i++) { System.out.println(s[i]); } String str = ArrayUtils.toString(s); str = str.substring(1, str.length() - 1); System.out.println(str + ">>" + str.length()); //********************************StringUtils*************************************** // 截取从from开始字符串 StringUtils.substringAfter("SELECT * FROM PERSON ", "from"); // 判断该字符串是不是为数字(0~9)组成，如果是，返回true 但该方法不识别有小数点和请注意 StringUtils.isNumeric("454534"); // 返回true // 取得类名 System.out.println(ClassUtils.getShortClassName(CommonsLang.class)); // 取得其包名 System.out.println(ClassUtils.getPackageName(CommonsLang.class)); // 五位的随机字母和数字 System.out.println(RandomStringUtils.randomAlphanumeric(5)); // StringEscapeUtils System.out.println(StringEscapeUtils.escapeHtml("<html>")); // 输出结果为<html> System.out.println(StringEscapeUtils.escapeJava("String")); // StringUtils,判断是否是空格字符 System.out.println(StringUtils.isBlank(" ")); // 将数组中的内容以,分隔 System.out.println(StringUtils.join(s1, ",")); // 在右边加下字符,使之总长度为6 System.out.println(StringUtils.rightPad("abc", 6, 'T')); // 首字母大写 System.out.println(StringUtils.capitalize("abc")); // Deletes all whitespaces from a String 删除所有空格 System.out.println(StringUtils.deleteWhitespace(" ab c ")); // 判断是否包含这个字符 System.out.println(StringUtils.contains("abc", "ba")); // 表示左边两个字符 System.out.println(StringUtils.left("abc", 2)); //********************************DateFormatUtils*************************************** System.out.println(DateFormatUtils.format(new Date(), "yyyy-MM-dd HH:mm:ss")); //直接将日期格式化为内置的固定格式 System.out.println(DateFormatUtils.ISO_DATE_FORMAT.format(new Date())); //字符型日期转化为Date System.out.println(DateUtils.parseDate("2014-11-11 11:11:11", new String[] { "yyyy-MM-dd HH:mm:ss", "yyyy-MM-dd HH:mm", "yyyy-MM-dd", "yyyy/MM/dd" })); //日期舍入与截整 System.out.println(DateUtils.truncate(new Date(), Calendar.DATE)); //判断是否是同一天 System.out.println(DateUtils.isSameDay(new Date(), new Date())); //加天数 System.out.println(DateUtils.addDays(new Date(), 10)); } }
14、commos-logging
提供的是一个Java 的日志接口,同时兼顾轻量级和不依赖于具体的日志实现工具。
import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public class CommosLogging { private static Log log = LogFactory.getLog(CommosLogging.class); public static void main(String[] args) { log.error("ERROR"); log.debug("DEBUG"); log.warn("WARN"); log.info("INFO"); log.trace("TRACE"); System.out.println(log.getClass()); } }
15、Validator
通用验证系统，该组件提供了客户端和服务器端的数据验证框架。
验证日期
// 获取日期验证 DateValidator validator = DateValidator.getInstance(); // 验证/转换日期 Date fooDate = validator.validate(fooString, "dd/MM/yyyy"); if (fooDate == null) { // 错误 不是日期 return; }
表达式验证
// 设置参数 boolean caseSensitive = false; String regex1 = "^([A-Z]*)(?:\-)([A-Z]*)*$" String regex2 = "^([A-Z]*)$"; String[] regexs = new String[] {regex1, regex1}; // 创建验证 RegexValidator validator = new RegexValidator(regexs, caseSensitive); // 验证返回boolean boolean valid = validator.isValid("abc-def"); // 验证返回字符串 String result = validator.validate("abc-def"); // 验证返回数组 String[] groups = validator.match("abc-def");