JAVA：Apache Commons工具集简介, BeanUtils, FileUpload, IO, Validator, Compress

//举一个Properties的简单例子
# 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。

//用commons email发送邮件
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。

//官方示例：
//* 检查请求是否含有上传文件
	// Check that we have a file upload request
	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、HttpClien 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。

//GET方法
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。

//1．读取Stream

//标准代码：
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。

	// 1 合并两个数组: org.apache.commons.lang. ArrayUtils
		// 有时我们需要将两个数组合并为一个数组，用ArrayUtils就非常方便，示例如下：
		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&lt;html&gt;
        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

// 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");

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();
}

更多参考：