Apache Commons 工具类介绍及简单使用

迈不过友情╰ 2022-10-29 01:45 183阅读 0赞

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。

<table> 
 <tbody> 
  <tr> 
   <td><strong>组件</strong></td> 
   <td><strong>功能介绍</strong></td> 
  </tr> 
  <tr> 
   <td>BeanUtils</td> 
   <td>提供了对于JavaBean进行各种操作，克隆对象,属性等等.</td> 
  </tr> 
  <tr> 
   <td>Betwixt</td> 
   <td>XML与Java对象之间相互转换.</td> 
  </tr> 
  <tr> 
   <td>Codec</td> 
   <td>处理常用的编码方法的工具类包&nbsp;例如DES、SHA1、MD5、Base64等.</td> 
  </tr> 
  <tr> 
   <td>Collections</td> 
   <td>java集合框架操作.</td> 
  </tr> 
  <tr> 
   <td>Compress</td> 
   <td>java提供文件打包 压缩类库.</td> 
  </tr> 
  <tr> 
   <td>Configuration</td> 
   <td>一个java应用程序的配置管理类库.</td> 
  </tr> 
  <tr> 
   <td>DBCP</td> 
   <td>提供数据库连接池服务.</td> 
  </tr> 
  <tr> 
   <td>DbUtils</td> 
   <td>提供对jdbc&nbsp;的操作封装来简化数据查询和记录读取操作.</td> 
  </tr> 
  <tr> 
   <td>Email</td> 
   <td>java发送邮件 对javamail的封装.</td> 
  </tr> 
  <tr> 
   <td>FileUpload</td> 
   <td>提供文件上传功能.</td> 
  </tr> 
  <tr> 
   <td>HttpClien</td> 
   <td>提供HTTP客户端与服务器的各种通讯操作. 现在已改成HttpComponents</td> 
  </tr> 
  <tr> 
   <td>IO</td> 
   <td>io工具的封装.</td> 
  </tr> 
  <tr> 
   <td>Lang</td> 
   <td>Java基本对象方法的工具类包 如：StringUtils,ArrayUtils等等.</td> 
  </tr> 
  <tr> 
   <td>Logging</td> 
   <td>提供的是一个Java 的日志接口.</td> 
  </tr> 
  <tr> 
   <td>Validator</td> 
   <td>提供了客户端和服务器端的数据验证框架.</td> 
  </tr> 
 </tbody> 
</table>

**1、BeanUtils** 提供了对于JavaBean进行各种操作， 比如对象,属性复制等等。

public class Person {  
        private String name = "";  
        private String email = "";  
      
        private int age;  
        //省略 set,get方法  
        }  
      
    //  再创建一个Test类，其中在main方法中代码如下：  
        import java.lang.reflect.InvocationTargetException;  
        import java.util.HashMap;  
        import java.util.Map;  
        import org.apache.commons.beanutils.BeanUtils;  
        import org.apache.commons.beanutils.ConvertUtils;  
        public class Test {  
      
        /** 
     
        * @param args 
     
        */  
        public static void main(String[] args) {  
        Person person = new Person();  
        person.setName("tom");  
        person.setAge(21);  
        try {  
                //克隆  
            Person person2 =  (Person)BeanUtils.cloneBean(person);  
            System.out.println(person2.getName()+">>"+person2.getAge());  
        } catch (IllegalAccessException e) {  
            e.printStackTrace();  
        } catch (InstantiationException e) {  
            e.printStackTrace();  
        } catch (InvocationTargetException e) {  
            e.printStackTrace();  
        } catch (NoSuchMethodException e) {  
            e.printStackTrace();  
      
        }  
      
        }  
      
        }  
      
    //  原理也是通过Java的反射机制来做的。  
    //  2、 将一个Map对象转化为一个Bean  
    //  这个Map对象的key必须与Bean的属性相对应。  
        Map map = new HashMap();  
        map.put("name","tom");  
        map.put("email","tom@");  
        map.put("age","21");  
        //将map转化为一个Person对象  
        Person person = new Person();  
        BeanUtils.populate(person,map);  
    //  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 map = BeanUtils.describe(person)

## **2、Betwixt  ** ##

XML与Java对象之间相互转换。

public class Person{  
            private String name;  
            private int age;  
            /** Need to allow bean to be created via reflection */  
            public PersonBean() {  
            }  
            public PersonBean(String name, int age) {  
                this.name = name;  
                this.age = age;  
            }  
            //省略set, get方法  
            public String toString() {  
                return "PersonBean[name='" + name + "',age='" + age + "']";  
            }  
        }  
          
        //再创建一个WriteApp类：  
        import java.io.StringWriter;  
        import org.apache.commons.betwixt.io.BeanWriter;  
        public class WriteApp {  
        /** 
        * 创建一个例子Bean，并将它转化为XML. 
        */  
        public static final void main(String [] args) throws Exception {  
            // 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′ ?>\n”);  
            // 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 PersonBean(“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();  
            }  
        }  
    //2、 将XML转化为JavaBean  
        import java.io.StringReader;  
        import org.apache.commons.betwixt.io.BeanReader;  
        public class ReadApp {  
        public static final void main(String args[]) throws Exception{  
            // 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", PersonBean.class);  
            //现在我们对XML进行解析  
            PersonBean person = (PersonBean) beanReader.parse(xmlReader);  
            //输出结果  
            System.out.println(person);  
            }  
        }

## **3、Codec**  ##

提供了一些公共的编解码实现，比如Base64, Hex, MD5,Phonetic and URLs等等。

private static String encodeTest(String str){  
            Base64 base64 = new Base64();  
            try {  
                str = base64.encodeToString(str.getBytes("UTF-8"));  
            } catch (UnsupportedEncodingException e) {  
                e.printStackTrace();  
            }  
                System.out.println("Base64 编码后："+str);  
            return str;  
        }  
      
        private static void decodeTest(String str){  
            Base64 base64 = new Base64();  
            //str = Arrays.toString(Base64.decodeBase64(str));  
            str = new String(Base64.decodeBase64(str));  
            System.out.println("Base64 解码后："+str);  
        }

## **4、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

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、Compress ** ##

commons compress中的打包、压缩类库。

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、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

# usergui.properties  
    colors.background = #FFFFFF  
    colors.foreground = #000080  
    window.width = 500  
    window.height = 300  
      
    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、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 javax.sql.DataSource;  
    import java.sql.Connection;  
    import java.sql.Statement;  
    import java.sql.ResultSet;  
    import java.sql.SQLException;  
      
    import org.apache.commons.pool.ObjectPool;  
    import org.apache.commons.pool.impl.GenericObjectPool;  
    import org.apache.commons.dbcp.ConnectionFactory;  
    import org.apache.commons.dbcp.PoolingDataSource;  
    import org.apache.commons.dbcp.PoolableConnectionFactory;  
    import org.apache.commons.dbcp.DriverManagerConnectionFactory;  
    //官方示例  
    public class PoolingDataSources {  
      
        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("\t" + 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);  
      
            //获取GenericObjectPool 连接的实例  
            ObjectPool connectionPool = new GenericObjectPool(  
                    poolableConnectionFactory);  
      
            // 创建 PoolingDriver  
            PoolingDataSource dataSource = new PoolingDataSource(connectionPool);  
              
            return dataSource;  
        }  
    }

## **8、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 org.apache.commons.dbutils.DbUtils;  
    import org.apache.commons.dbutils.QueryRunner;  
    import org.apache.commons.dbutils.handlers.BeanListHandler;  
    import java.sql.Connection;  
    import java.sql.DriverManager;  
    import java.sql.SQLException;  
    import java.util.List;  
    //转换成list  
    public class BeanLists {  
        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);  
            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("id:" + p.getId() + ",name:" + p.getName());  
                }  
            } catch (SQLException e) {  
                e.printStackTrace();  
            } finally {  
                DbUtils.closeQuietly(conn);  
            }  
        }  
    }  
      
    public class Person{  
        private Integer id;  
        private String name;  
      
       //省略set, get方法  
    }  
      
    import org.apache.commons.dbutils.DbUtils;  
    import org.apache.commons.dbutils.QueryRunner;  
    import org.apache.commons.dbutils.handlers.MapListHandler;  
      
    import java.sql.Connection;  
    import java.sql.DriverManager;  
    import java.sql.SQLException;  
      
    import java.util.List;  
    import java.util.Map;  
    //转换成map  
    public class MapLists {  
        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);  
            try {  
                conn = DriverManager.getConnection(url, user, password);  
                QueryRunner qr = new QueryRunner();  
                List results = (List) qr.query(conn, "select id,name from person", new MapListHandler());  
                for (int i = 0; i < results.size(); i++) {  
                    Map map = (Map) results.get(i);  
                    System.out.println("id:" + map.get("id") + ",name:" + map.get("name"));  
                }  
            } catch (SQLException e) {  
                e.printStackTrace();  
            } finally {  
                DbUtils.closeQuietly(conn);  
            }  
        }  
    }

## **9、Email ** ##

提供的一个开源的API，是对javamail的封装。

public static void main(String args[]){  
            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、FileUpload** ##

** **java web文件上传功能。

boolean isMultipart = ServletFileUpload.isMultipartContent(request);  
      
        //现在我们得到了items的列表  
      
        //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：  
        // Create a factory for disk-based file items  
        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 /* FileItem */ 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。  
        // Process the uploaded items  
        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：  
        // processFormField  
        if (item.isFormField()) {  
            String name = item.getFieldName();  
            String value = item.getString();  
            //...省略步骤  
        }  
      
        //如果是提交的文件：  
        // processUploadedFile  
        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  
        // Process a file upload  
        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：  
        // Process a file upload in memory  
        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  
        //Create a progress listener  
        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、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 GetSample{  
        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();  
            }  
        }  
    }  
      
    //POST方法  
    import java.io.IOException;  
    import org.apache.commons.httpclient.*;  
    import org.apache.commons.httpclient.methods.PostMethod;  
    import org.apache.commons.httpclient.params.HttpMethodParams;  
      
    public class PostSample{  
        public static void main(String[] args) {  
            // 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、IO ** ##

对java.io的扩展 操作文件非常方便。

InputStream in = new URL( "http://jakarta.apache.org" ).openStream();  
    try {  
           InputStreamReader inR = new InputStreamReader( in );  
           BufferedReader buf = new BufferedReader( inR );  
           String line;  
           while ( ( line = buf.readLine() ) != null ) {  
              System.out.println( line );  
           }  
      } finally {  
        in.close();  
      }  
      
    //使用IOUtils  
      
    InputStream in = new URL( "http://jakarta.apache.org" ).openStream();  
    try {  
        System.out.println( IOUtils.toString( in ) );  
    } 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、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。

![6779093a9b1aa7c2eb0761d27da0a4c9.png][]

private static void testArr() {  
            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());  
      
        }  
        //2 截取从from开始字符串  
        StringUtils.substringAfter("SELECT * FROM PERSON ", "from");  
        //3 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  
        //4.取得类名  
           System.out.println(ClassUtils.getShortClassName(Test.class));  
           //取得其包名  
           System.out.println(ClassUtils.getPackageName(Test.class));  
            
           //5.NumberUtils  
           System.out.println(NumberUtils.stringToInt("6"));  
           //6.五位的随机字母和数字  
           System.out.println(RandomStringUtils.randomAlphanumeric(5));  
           //7.StringEscapeUtils  
           System.out.println(StringEscapeUtils.escapeHtml("<html>"));  
           //输出结果为<html>  
           System.out.println(StringEscapeUtils.escapeJava("String"));  
            
           //8.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(test,","));  
           //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));  
           System.out.println(NumberUtils.stringToInt("33"));

## **14、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 CommonLogTest {  
         private static Log log = LogFactory.getLog(CommonLogTest.class);  
         //日志打印  
         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

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

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");

//配置文件中使用验证
    <form-validation>  
       <global>  
           <validator name="required"  
              classname="org.apache.commons.validator.TestValidator"  
              method="validateRequired"  
              methodParams="java.lang.Object, org.apache.commons.validator.Field"/>  
        </global>  
        <formset>  
        </formset>  
    </form-validation>  
      
    添加姓名验证.  
      
    <form-validation>  
       <global>  
           <validator name="required"  
              classname="org.apache.commons.validator.TestValidator"  
              method="validateRequired"  
              methodParams="java.lang.Object, org.apache.commons.validator.Field"/>  
        </global>  
        <formset>  
           <form name="nameForm">  
              <field property="firstName" depends="required">  
                 <arg0 key="nameForm.firstname.displayname"/>  
              </field>  
              <field property="lastName" depends="required">  
                 <arg0 key="nameForm.lastname.displayname"/>  
              </field>  
           </form>  
        </formset>  
    </form-validation>

// 验证类
    Excerpts from org.apache.commons.validator.RequiredNameTest  
    //加载验证配置文件  
    InputStream in = this.getClass().getResourceAsStream("validator-name-required.xml");  
      
    ValidatorResources resources = new ValidatorResources(in);  
    //这个是自己创建的bean 我这里省略了  
    Name name = new Name();  
      
    Validator validator = new Validator(resources, "nameForm");  
    //设置参数  
    validator.setParameter(Validator.BEAN_PARAM, name);  
      
      
    Map results = null;  
    //验证  
    results = validator.validate();  
      
    if (results.get("firstName") == null) {  
        //验证成功  
    } else {  
        //有错误     int errors = ((Integer)results.get("firstName")).intValue();  
    }

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[6779093a9b1aa7c2eb0761d27da0a4c9.png]: /images/20221024/63290f6db6f3457899b32d3d4dcb580f.png
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