Apache Utilities At Work V5

Apache Utilities at Work

Tom Marrs

2 © 2008 CIBER, Inc. All rights reserved

Who am I?

• Background– Co-author of JBoss At Work: A Practical Guide

(O’Reilly, November 2005)• Currently working on 2nd ed.

– User Groups• Founding President of DOSUG

• Past President of DJUG

– Related Experience• I’ve been on several bad projects

• I hate re-inventing the wheel


Learning Objectives

• As a result of this presentation you will learn:– To research Open Source utilities before coding– To avoid re-inventing the wheel– What common utilities are available on Apache– How to use Apache utilities on your project– How to hide the details


Prerequisites

• Core Java SE• The right mindset

– Leverage existing utilities


Session Non-Agenda

In this Session, we will not discuss:

• JavaEE• A full-blown application• Other cool Apache projects:

– Web Services (Axis 2)– CXF– XMLBeans– Geronimo– ServiceMix– ActiveMQ– Camel– Struts– Beehive


Session Agenda

In this Session we will discuss:

• Commons Lang• Commons Configuration• Commons Logging and Log4J• POI• Commons Email• Velocity• HttpClient• Commons IO • Summary


Session Roadmap

Where are we?



Like Nails on a Blackboard …

if (myString == null || myString.length() == 0) { // Ugh!!

…

}

// OR only slightly better.

public class MyUtils {

…

public static boolean isNullOrEmpty(String stringToCheck) {

boolean retValue = false;

if (stringToCheck == null) {

retValue = true;

} else if (stringToCheck.length() == 0) {

retValue = true;

}

return retVal;

}


Commons Lang Overview

• Enhanced methods and classes for core Java SE (java.lang)– http://commons.apache.org/lang

• Includes String, numerical, date/time methods• Useful: StopWatch (simple timing test)• My favorite – StringUtils:

– isBlank()– isEmpty()– isNotBlank()– isNotEmpty()


With StringUtils

// Usage

if (StringUtils.isEmpty(myString)) {

…

}

if (StringUtils.isBlank(myString)) {

…

}


Session Roadmap

Where are we?



Getting Properties – What we want

String emailTo = MyPropertyUtil.getProperty(EMAIL_TO);


Rolling Your Own Properties

public class MyPropertyUtil { private static final String MY_PROPS_FILE_NAME = “…”; // Use –D to set this at startup.

…

public static String getProperty(String key) throws MyPropertyUtilException { Properties props = null; String value = “”, propsFileName = System.getProperty(MY_PROPS_FILE_NAME);

if (StringUtils.isNotBlank(key) && StringUtils.isNotBlank(propsFileName) { try { // FIXMEE: Move Props File Name & Properties Load to static initializer.

// The Thread Context ClassLoader is the ClassLoader used by the creator // of the Thread that runs your code. By using the Thread Context ClassLoader, // we’re guaranteed to load the resource (class or property file) as long as // it's on the application's CLASSPATH.

ClassLoader myClassLoader = Thread.currentThread().getContextClassLoader(); URL myUrl = myClassLoader.getResource(name); props.load(url.openStream());

value = props.getProperty(key); } catch (Throwable th) { … } }

return value; }


Commons Configuration Overview

• A clean way to configure your application– http://commons.apache.org/configuration

• It loads the configuration data for you• Configuration/Factory (main class) can work

with:– Properties files– XML files– JNDI– JDBC DataSource– System Properties (JVM)– .INI files (Windows)


Commons Configuration Overview … Cont’d

• It can handle hierarchical data• It can combine multiple data sources

(composite):

CompositeConfiguration config = new CompositeConfiguration(); config.addConfiguration(new SystemConfiguration()); config.addConfiguration(new

PropertiesConfiguration("application.properties"));


Properties with Commons Configuration

public class MyPropertyUtil { private static final String MY_PROPS_FILE_NAME = “…”; // Use –D to set this at startup.

…

public static String getProperty(String key) throws MyPropertyUtilException { Properties props = null; String value = “”, propsFileName = System.getProperty(MY_PROPS_FILE_NAME);

if (StringUtils.isNotBlank(key) && StringUtils.isNotBlank(propsFileName) { try { // FIXMEE: Move Props File Name & Constructor call to static initializer. Configuration config = new PropertiesConfiguration(propsFileName);

value = props.getString(key); } catch (Throwable th) { … } }

return value; }}


Session Roadmap

Where are we?



Session Roadmap

Where are we?



POI Overview

• API to access MS file formats– Word– PowerPoint– Outlook– Visio– Publisher– Excel (HSSF)– http://poi.apache.org


Generate an Excel File with POI

private static void populateExcelWorksheet(Collection rows, FileOutputStream fileOut) { try { if (rows.size() > 0) { HSSFWorkbook workBook = new HSSFWorkbook(); HSSFSheet workSheet = workBook.createSheet(); //Create new workSheet Iterator rowDataIterator = rows.iterator(); int rowNum = 0, maxColumnSize = 0;

while (rowDataIterator.hasNext()) { LinkedList rowStringsList = (LinkedList) rowDataIterator.next(); if (rowStringsList.size() > 0) { HSSFRow row = workSheet.createRow(rowNum); // Create header ONLY once if (rowNum == 0) { maxColumnSize = ExcelUtil.createColumnHeaders(rowStringsList, workBook, row); } else { maxColumnSize = ExcelUtil.fillRowCellValue(rowStringsList, workBook, row); } rowNum++; } }


Generate an Excel File with POI … Cont’d

workBook.write(fileOut);

}

}

catch (IOException e) {

...

}

}



private static short createColumnHeaders(LinkedList stringList, HSSFWorkbook workBook, HSSFRow row) { short columnNum = 0; Iterator iter = stringList.iterator(); while (iter.hasNext()) { String value = (String) iter.next();

// Create a new font and alter it. HSSFFont font = workBook.createFont(); //Customize font customizeExcelFont(font); // Fonts are set into a style so create a new one to use. HSSFCellStyle style = workBook.createCellStyle(); style.setFont(font);

HSSFCell cell = null;

cell = row.createCell(columnNum); cell.setCellStyle(style); cell.setCellValue(value); columnNum++; } return columnNum; }



private static short fillRowCellValue(LinkedList stringList, HSSFWorkbook workBook, HSSFRow row) { short columnNum = 0; Iterator iter = stringList.iterator(); while (iter.hasNext()) { String value = (String) iter.next(); HSSFCellStyle style = workBook.createCellStyle(); HSSFCell cell = null; // Set background color with light "foreground" // foreground being the filled, not the font color. style.setFillForegroundColor(HSSFColor.LIGHT_GREEN.index); style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);

cell = row.createCell(columnNum); cell.setCellStyle(style); cell.setCellValue(value); columnNum++; } return columnNum; }


Session Roadmap

Where are we?



Commons Email Overview

• Simple API for sending email– http://commons.apache.org/email

• Based on JavaMail API (but easier to use)• Key Areas:

– Text– HTML– Attachments


Using JavaMail

public void send(MyEmailParams emailParams) throws EmailException { // Send Text try { Session session = getDefaultSession(); InternetAddress[] recipientsArr = (InternetAddress[]) emailParams.getRecipients().toArray(new InternetAddress[0]);

MimeMessage msg = new MimeMessage(session); msg.setFrom(emailParams.getSender());

msg.setRecipients(Message.RecipientType.TO, recipientsArr); if (!emailParams.getCcRecipients.isEmpty(){ InternetAddress[] ccRecipientsArr = (InternetAddress[])

emailParams.getCcRecipients().toArray(newInternetAddress[0]); msg.setRecipients(Message.RecipientType.CC, ccRecipientsArr); }


Using JavaMail … Cont’d

msg.setSubject(emailParams.getSubject()); msg.setText(emailParams.getBody()); Transport.send(msg); // Send message } catch (MessagingException me) { … } }

private Session getDefaultSession() throws EmailException { Properties props = new Properties(); String mailSmtpHost = MyPropertyUtil.getProperty(MAIL_SMTP_HOST), mailSmtpPort = MyPropertyUtil.getProperty(MAIL_SMTP_PORT), mailDebug = MyPropertyUtil.getProperty(MAIL_DEBUG, FALSE);

props.setProperty(MAIL_TRANSPORT_PROTOCOL, SMTP); props.setProperty(MAIL_SMTP_HOST, mailSmtpPort); props.setProperty(MAIL_SMTP_HOST, mailSmtpHost); props.setProperty(MAIL_DEBUG, mailDebug);

Session session = Session.getDefaultInstance(props);

return session; }


Using Commons Email

public static void sendSimpleEmail(EmailParams emailParams) throws MyEmailUtilException { // Send text.

try { SimpleEmail email = new SimpleEmail(); String hostName = MyPropertyUtil.getProperty(MY_SMTP_SERVER); Iterator toAddrIter = emailParams.getToRecipients().iterator(), ccAddrIter = emailParams.getCcRecipients().iterator(); email.setHostName(hostName); email.setFrom(emailParams.getFromEmailAddr(), emailParams.getFromName()); while (toAddrIter.hasNext()) { email.addTo((String) toAddrIter.next()); } while (ccAddrIter.hasNext()) { email.addCc((String) ccAddrIter.next()); }

email.setSubject(emailParams.getSubject()); email.setMsg(emailParams.getMessage()); email.send(); } catch (EmailException e) { … } }


Session Roadmap

Where are we?



Velocity Overview

• Templating Engine– http://velocity.apache.org

• Other good tools exist:– FreeMarker – http://freemarker.sourceforge.net/


Using the Velocity API

VelocityEngine velocityEngine = new VelocityEngine();Properties props = new Properties();Template template = null;VelocityContext velocityContext = new VelocityContext(); props.setProperty(VelocityEngine.RESOURCE_LOADER, "classpath");props.setProperty("classpath." + VelocityEngine.RESOURCE_LOADER + ".class", ClasspathResourceLoader.class.getName());

velocityEngine.init(props);

try { StringWriter writer = new StringWriter(); template = velocityEngine.getTemplate(MY_TEMPLATE);

velocityContext.put(RECIPIENT_NAME, recipientName); velocityContext.put(POLICY_NUMBER, policyNumber); velocityContext.put(REFUND_AMOUNT, refundAmount);

template.merge(velocityContext, writer);} catch (…) { …}


Velocity Template

<HTML><BODY> <p> Dear $recipientName, Due to your safe driving record, we are refunding $refundAmount on

your auto policy ($policyNumber). </p></BODY></HTML>


Session Roadmap

Where are we?



Commons HttpClient Overview

• API to help develop an HTTP Client– GET / POST– Authentication– Redirect– Proxy– Encodings– Cookies

• In its final release (3.x)– http://hc.apache.org/httpclient-3.x/index.html

• To be replaced by HttpComponents:– http://hc.apache.org– Still in Beta– “Not yet, grasshopper”


HttpClient Example

public class MyHttpClient {… public static String sendPostRequest(MyRequestDto myRequestDto) throws MyHttpClientException {

String responseString = null; PostMethod httpPost = null; HttpClient httpClient = new HttpClient(); MyHttpClient.setupProxy(httpClient); try { // Create and send the HTTP Request. httpPost = MyHttpClient.setupHttpPostRequest(myRequestDto); httpClient.executeMethod(httpPost);

// Get the HTTP Status. if (httpPost.getStatusCode() == HttpStatus.SC_MOVED_TEMPORARILY) { MyHttpClient.handleRedirect(httpClient, httpPost); } //Get HTTP response. responseString = MyHttpClient.getHttpResponse(httpPost); …


HttpClient Example … Cont’d

} catch (HttpException he) { … } catch (IOException ioe) { … } finally { httpPost.releaseConnection(); } return responseString; }

private static void setupProxy(HttpClient httpClient) { // Tunnel through a proxy. String useProxy = MyPropertyUtil.getProperty(USE_PROXY); if (StringUtils.isNotBlank(useProxy) && useProxy.equalsIgnoreCase(YES)) { String proxyHost = MyPropertyUtil.getProperty(MY_PROXY_HOST), proxyPort = MyPropertyUtil.getProperty(MY_PROXY_PORT), proxyRealm = MyPropertyUtil.getProperty(MY_PROXY_REALM), proxyUser = MyPropertyUtil.getProperty(MY_PROXY_USER), proxyPassword = MyPropertyUtil.getProperty(MY_PROXY_PASSWORD);

httpClient.getHostConfiguration().setProxy(proxyHost, Integer.parseInt(proxyPort));

httpClient.getState().setProxyCredentials(proxyRealm, proxyHost, new UsernamePasswordCredentials(proxyUser, proxyPassword));

} }



private static PostMethod setupHttpPostRequest(MyRequestDto myRequestDto) { String myUrl = MyPropertyUtil.getProperty(ConfigConstants.CONFIG_MY_URL); PostMethod httpPost = new PostMethod(myUrl); // Populate HTTP Post Parameters. httpPost.addParameter(REDIR_KEY, REDIR_VALUE); httpPost.addParameter(FIRST_NAME_KEY, myRequestDto.getFirstName()); …

return httpPost; }

private static void handleRedirect(HttpClient httpclient, PostMethod httpPost) throws MyHttpClientException { try { Header locationHeader = httpPost.getResponseHeader(HTTP_RESPONSE_LOCATION_HEADER);

if locationHeader != null) { String redirectLocation = locationHeader.getValue(); httpPost.setURI(redirectLocation); httpClient.executeMethod(httpPost); } } catch (URIException ue) { … } // 2 others – HttpException, IOException }



private static String getHttpResponse(PostMethod httpPost) throws MyHttpClientException { String responseString = null; InputStream is = null;

try { is = httpPost.getResonseBodyAsStream(); BufferedReader br = new BufferedReader(new InputStreamReader(is)); StringBuffer responseBuffer = new StringBuffer(); String line = null; boolean done = false;

while (!done) { line = br.readLine(); done = (line == null); if (!done) { responseBuffer.append(line); } }

responseString – responseBuffer.toString().trim(); } catch (IOException ioe) { …



} finally {

if (is != null) {

try {

is.close();

} catch (…) {

…

}

}

}

return responseString;

}

}


Session Roadmap

Where are we?



Commons IO Overview

• API to simplify IO processing– http://commons.apache.org/io

• Key Areas– Utility classes – Perform common tasks– Filters – File filter implementations– Comparators – For comparing lists of files– Streams – Stream, Reader and Writer

implementations

• My Favorite – IOUtils


Stream I/O without Commons IO

private static String getHttpResponse(PostMethod httpPost) throws MyHttpClientException { String responseString = null; InputStream is = null;

try { is = httpPost.getResonseBodyAsStream(); BufferedReader br = new BufferedReader(new InputStreamReader(is)); StringBuffer responseBuffer = new StringBuffer(); String line = null; boolean done = false;

while (!done) { line = br.readLine(); done = (line == null); if (!done) { responseBuffer.append(line); } }

responseString – responseBuffer.toString().trim(); } catch (IOException ioe) { …


Stream I/O without Commons IO … Cont’d

} finally {

if (is != null) {

try {

is.close();

} catch (…) {

…

}

}

}


}

}


Stream I/O with Commons IO

private static String getHttpResponse(PostMethod httpPost)

throws MyHttpClientException {

String responseString = null;

InputStream is = null;

try {

is = httpPost.getResonseBodyAsStream();

responseString = IOUtils.toString(is);

} catch (IOExeception ioe) {

…

} finally {

IOUtils.closeQuietly(is);

}


}


Session Roadmap

Where are we?


– Conclusions– Questions– Resources


Conclusions

• Apache has a wealth of useful APIs• SourceForge (and others) also have great APIs• Use thin wrappers to hide the details• Research Open Source before coding

– Don’t re-invent the wheel– Google, anyone?


Questions?

Tom Marrs

Principal Architect

[email protected]


Resources

• Apache Main Page: http://www.apache.org• Apache Commons: http://commons.apache.org

– Lang: http://commons.apache.org/lang– Configuration: http://commons.apache.org/configuration– Logging: http://commons.apache.org/logging– Email: http://commons.apache.org/email– IO: http://commons.apache.org/io– HttpClient: http://hc.apache.org/httpclient-3.x/index.html

• Apache Log4J: http://logging.apache.org/log4j/1.2/index.html• Apache Velocity: http://velocity.apache.org• FreeMarket: http://freemarker.sourceforge.net• Apache POI: http://poi.apache.org• Apache HttpComponents: http://hc.apache.org

Technology

Apache Utilities At Work V5