Apache Utilities At Work V5

Apache Utilities at Work Tom Marrs

Who am I?

Background

Co-author of JBoss At Work: A Practical Guide (O’Reilly, November 2005)

Currently working on 2 nd 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?

Commons Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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?

Commons Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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?

Commons Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

Session Roadmap

Where are we?

Commons Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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 Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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?

Commons Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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 Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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)

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)

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();

…

} finally {

if (is != null) {

try {

is.close();

} catch (…) {

…

}

}

}

}

}

Session Roadmap

Where are we?

Commons Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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

try {

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();

…

Stream I/O without Commons IO … Cont’d

} finally {

if (is != null) {

try {

is.close();

} catch (…) {

…

}

}

}

}

}

Stream I/O with Commons IO

try {

responseString = IOUtils.toString(is);

} catch (IOExeception ioe) {

…

} finally {

IOUtils.closeQuietly(is);

}

}

Session Roadmap

Where are we?

Commons Lang

POI

Commons Email

Velocity

HttpClient

Commons IO

Summary

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_address]

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

Apache Utilities At Work V5

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