How Groovy Helps Ken Kousen Kousen IT, Inc. http://www.kousenit.com [email_address] http://kousenit.wordpress.com

What is Groovy? From Scott Davis, Groovy Recipes: Groovy is what Java would look like had it been written in the 21 st century. Groovy is a new breed of language. It doesn’t replace old technology as much as enhances it … this isn’t a “Hey guys, let’s rewrite our application from the ground up” … this is a “Let’s use a language that seamlessly integrates with our existing codebase” approach

From Scott Davis, Groovy Recipes:

Groovy is what Java would look like had it been written in the 21 st century.

Groovy is a new breed of language. It doesn’t replace old technology as much as enhances it … this isn’t a “Hey guys, let’s rewrite our application from the ground up” … this is a “Let’s use a language that seamlessly integrates with our existing codebase” approach

Groovy Programming language with new features Optional typing Closures Builders Compiles to the JVM Compiled, not interpreted Interacts transparently with Java If you don’t know the Groovy way, use Java Scripts as well as classes Open source project

Programming language with new features

Optional typing

Closures

Builders

Compiles to the JVM

Compiled, not interpreted

Interacts transparently with Java

If you don’t know the Groovy way, use Java

Scripts as well as classes

Open source project

Groovy Features Additions and simplifications to Java Special features of its own Lists and Maps as part of the language Everything is an object Metaprogramming makes it easy to create Domain Specific Languages Like Grails 

Additions and simplifications to Java

Special features of its own

Lists and Maps as part of the language

Everything is an object

Metaprogramming makes it easy to create Domain Specific Languages

Like Grails 

Installing Groovy Need a JVM first JDK 1.5+ preferred, others still work Download Groovy from http://groovy.codehaus.org Run installer (Windows) or just unzip and set GROOVY_HOME variable Add the bin directory to your path That’s all there is to it

Need a JVM first

JDK 1.5+ preferred, others still work

Download Groovy from http://groovy.codehaus.org

Run installer (Windows) or just unzip and set GROOVY_HOME variable

Add the bin directory to your path

That’s all there is to it

Groovy Editors Groovy comes with groovysh command line client groovyconsole Swing GUI Plug-ins for most major IDEs Eclipse Netbeans JetGroovy plugin for IntelliJ IDEA Favored by most of the core team members

Groovy comes with

groovysh command line client

groovyconsole Swing GUI

Plug-ins for most major IDEs

Eclipse

Netbeans

JetGroovy plugin for IntelliJ IDEA

Favored by most of the core team members

Three Sample Problems Google Chart is a web service that generates plots based on encoded data RESTful web service Major League Baseball provides game information online XML processing and networking Analyze training days data Database access, closures, and ranges

Google Chart is a web service that generates plots based on encoded data

RESTful web service

Major League Baseball provides game information online

XML processing and networking

Analyze training days data

Database access, closures, and ranges

Google Chart API The Google Chart API is a web service located at http://code.google.com/apis/chart/ So-called “RESTful” web service URL with query string to generate response Lots of different chart types can be generated Data must be “encoded”

The Google Chart API is a web service located at http://code.google.com/apis/chart/

So-called “RESTful” web service

URL with query string to generate response

Lots of different chart types can be generated

Data must be “encoded”

Google Chart API Three types of encoding Simple encoding uses alphanumeric characters A to Z, a to z, 0 to 9 62 unique values Text encoding uses floating point numbers 0.0 to 100.0 with a single decimal place 1000 unique values Extended encoding uses pairs of alphanumeric characters 4096 unique values

Three types of encoding

Simple encoding uses alphanumeric characters A to Z, a to z, 0 to 9

62 unique values

Text encoding uses floating point numbers 0.0 to 100.0 with a single decimal place

1000 unique values

Extended encoding uses pairs of alphanumeric characters

4096 unique values

Google Chart API Typical request: http://chart.apis.google.com/chart? chs=200x125 &chd=s:helloWorld &cht=lc &chxt=x,y &chxl=0:|Mar|Apr|May|June|July|1:||50+Kb

Typical request:

http://chart.apis.google.com/chart? chs=200x125 &chd=s:helloWorld &cht=lc &chxt=x,y &chxl=0:|Mar|Apr|May|June|July|1:||50+Kb

My Application Create pie chart of categories of training classes delivered in 2007 To do so Iterate over list of courses For each course, choose a category and increment the number of courses in that category Encode the map into a string required by Google Chart Create the required URL and access Google Chart

Create pie chart of categories of training classes delivered in 2007

To do so

Iterate over list of courses

For each course, choose a category and increment the number of courses in that category

Encode the map into a string required by Google Chart

Create the required URL and access Google Chart

My Application More important, illustrate various aspects of Groovy programming Groovy scripts and classes Lists and maps as native data structures Regular expressions Groovy Strings Ranges URL creation and access Groovy bean properties

More important, illustrate various aspects of Groovy programming

Groovy scripts and classes

Lists and maps as native data structures

Regular expressions

Groovy Strings

Ranges

URL creation and access

Groovy bean properties

Groovy Scripts and Classes Groovy uses classes just as Java does Classes assumed to be public Groovy also uses scripts Scripts become classes internally Can mix script code and classes in the same source code file

Groovy uses classes just as Java does

Classes assumed to be public

Groovy also uses scripts

Scripts become classes internally

Can mix script code and classes in the same source code file

google_chart.groovy package chart class Chart { def base = 'http://chart.apis.google.com/chart' def url = base + '?cht=p3&chs=500x150' def imageTag // … more code to come … } def chart = new Chart() chart.encodeMap() println chart.imageTag

Interesting Features No semicolons! Actually, they’re optional Groovy code organized in packages Class is public by default Fields are private by default Methods are public by default Optional data typing def means untyped Can declare a type if you want

No semicolons!

Actually, they’re optional

Groovy code organized in packages

Class is public by default

Fields are private by default

Methods are public by default

Optional data typing

def means untyped

Can declare a type if you want

Interesting Features Strings can use either single or double quotes Single quotes imply regular Strings Double quotes are “GStrings” and can do variable replacement Script code shown in same file Accesses the imageTag property Define a property, automatically get a public getter and a public setter method

Strings can use either single or double quotes

Single quotes imply regular Strings

Double quotes are “GStrings” and can do variable replacement

Script code shown in same file

Accesses the imageTag property

Define a property, automatically get a public getter and a public setter method

More Fields def data = [ 'Spring and Hibernate', 'EJB', 'J2EE', 'J2EE', 'Spring', 'XML', 'Spring', 'Spring', 'XML', 'XML', 'J2EE', 'WS', 'Struts', 'Spring', 'JS', 'WS', 'Ajax', 'WS', 'Portlets', 'Hibernate and EJB3', 'J2EE', 'OOAD', 'Java', 'Ajax', 'Ajax', 'Spring', 'Struts 2', 'XML and Java', 'Ajax and Java', 'Securing WS', 'JSF', 'Ajax', 'Ajax and Java', 'Ajax', 'J2EE', 'WS'] def map = [:]

Lists and Maps Lists and Maps are native data structures Lists declared using array syntax Default implementation is an ArrayList Maps are defined using [key:value] Default implementation is a HashMap

Lists and Maps are native data structures

Lists declared using array syntax

Default implementation is an ArrayList

Maps are defined using [key:value]

Default implementation is a HashMap

Constructor Code Chart() { data. each { name -> if (name =~ (/Spring|Hibernate|Struts/)) { addToMap('Open Source') } if (name =~ (/Ajax|JS/)) { addToMap('Ajax') } // … other categories … } }

Constructor Code List’s each method takes a Closure as an argument Each element of the list is passed into the closure as the variable name If closure is the last argument of a method, can be placed after the method Closure is a block of code and the context in which it runs Can be assigned to variables, passed into methods, and so on

List’s each method takes a Closure as an argument

Each element of the list is passed into the closure as the variable name

If closure is the last argument of a method, can be placed after the method

Closure is a block of code and the context in which it runs

Can be assigned to variables, passed into methods, and so on

Constructor Code Regular expression declared inside forward slashes Known as “slashy” syntax Any string can be defined that way The =~ is the “find” operator Operator ==~ is the “match” operator Operator ~ is the pattern operator

Regular expression declared inside forward slashes

Known as “slashy” syntax

Any string can be defined that way

The =~ is the “find” operator

Operator ==~ is the “match” operator

Operator ~ is the pattern operator

addToMap(label) def addToMap(label) { map[label] = map.get(label,0) + 1 }

addToMap(label) Method signature uses def as return type Can return a value, or not Dummy argument doesn’t require a type definition get(label,0) Search for the value under the key label Return it if it exists, assign it with the default value 0 if not Either way, increment the value and assign it back into the map under the label key Can access a value using get method or using array syntax map[label]

Method signature uses def as return type

Can return a value, or not

Dummy argument doesn’t require a type definition

get(label,0)

Search for the value under the key label

Return it if it exists, assign it with the default value 0 if not

Either way, increment the value and assign it back into the map under the label key

Can access a value using get method or using array syntax map[label]

addToMap(label) Resulting map of categories is [“Open Source”:9, “J2EE”:12, “Web Services”:9, “Ajax”:9, “Other”:1] (some courses appear in more than one category)

Resulting map of categories is

[“Open Source”:9, “J2EE”:12, “Web Services”:9, “Ajax”:9, “Other”:1]

(some courses appear in more than one category)

Encoding Data values are all integers less than 64 Can always scale the data if not Use the Google Chart simple encoding Values from 0 to 25 are the letters A to Z Values from 26 to 51 are the letters a to z Values from 52 to 61 are the numbers 0 to 9 Encode each value, then concatenate the results into a string which will be added as a query parameter

Data values are all integers less than 64

Can always scale the data if not

Use the Google Chart simple encoding

Values from 0 to 25 are the letters A to Z

Values from 26 to 51 are the letters a to z

Values from 52 to 61 are the numbers 0 to 9

Encode each value, then concatenate the results into a string which will be added as a query parameter

encodeMap() def encodeMap() { List list = (('A'..'Z')+('a'..'z')+(0..9)) as List String s = &quot;&chd=s:&quot; List keys = [] map. each { k,v -> keys << k s += list[v] } // … more to come …

encodeMap() Values separated by two dots are Ranges Each range concatenated together The as operator “coerces” the Range into a List Could also use the toList() method The each method iterates over map entries and passes each to the closure Closure declares keys as k , values as v Each k is appended to the keys list, using the << operator Values are used as an index to the range list, which returns the proper encoded value

Values separated by two dots are Ranges

Each range concatenated together

The as operator “coerces” the Range into a List

Could also use the toList() method

The each method iterates over map entries and passes each to the closure

Closure declares keys as k , values as v

Each k is appended to the keys list, using the << operator

Values are used as an index to the range list, which returns the proper encoded value

encodeMap() String labels = &quot;&chl=&quot; + keys. collect { URLEncoder.encode(it,&quot;UTF-8&quot;) }. join ('|') url += s // the query string, defined in the code above url += labels println url // might as well see it String urle = url.replaceAll(/&/,'&amp;') imageTag = &quot;<img src='${urle}' alt='Course distribution'/>&quot;

encodeMap() Lots going on here  Need to get the labels for the pie chart The labels will be the keys from the map Encoding requires the labels to be concatenated into a single string using | as a separator The collect method passes each element of a collection through the closure Since no dummy variable was defined for the closure this time, the default value “ it ” is used The src attribute set as a GString between ${…}

Lots going on here 

Need to get the labels for the pie chart

The labels will be the keys from the map

Encoding requires the labels to be concatenated into a single string using | as a separator

The collect method passes each element of a collection through the closure

Since no dummy variable was defined for the closure this time, the default value “ it ” is used

The src attribute set as a GString between ${…}

encodeMap() Each label is passed through the standard Java URLEncoder.encode() method If you don’t have a specifically Groovy way to do something, use Java Total URL is fine, but if it is the argument to the src attribute of an img tag, it can’t include & Have to encode & using the entity reference &amp; The replaceAll method replaces each string that matches the regular expression with the supplied value

Each label is passed through the standard Java URLEncoder.encode() method

If you don’t have a specifically Groovy way to do something, use Java

Total URL is fine, but if it is the argument to the src attribute of an img tag, it can’t include &

Have to encode & using the entity reference &amp;

The replaceAll method replaces each string that matches the regular expression with the supplied value

Result <img src='http://chart.apis.google.com/chart?cht=p3 &amp;chs=500x150 &amp;chd=s:JMJJB &amp;chl=Open+Source|J2EE|Web+Services|Ajax|Other' alt='Course distribution'/> The chart type is p3 (a 3D pie chart) The chart size ( chs ) is 500x150 pixels The encoded chart data was JMJJB (9, 12, 9, 9, 1) The s: indicates the simple encoding scheme The chart labels are in the URL encoded string after chl

<img src='http://chart.apis.google.com/chart?cht=p3 &amp;chs=500x150 &amp;chd=s:JMJJB &amp;chl=Open+Source|J2EE|Web+Services|Ajax|Other' alt='Course distribution'/>

The chart type is p3 (a 3D pie chart)

The chart size ( chs ) is 500x150 pixels

The encoded chart data was JMJJB (9, 12, 9, 9, 1)

The s: indicates the simple encoding scheme

The chart labels are in the URL encoded string after chl

Result

Google Chart Builder Zan Thrash has created a full builder called the Google Chart Builder See his blog posting at http://zanthrash.blogspot.com/2008/01/groovy-chart-builder.html Source code is available and instructive Grails has a Google Chart plugin at http://grails.org/Google+Chart+Plugin Either of those are excellent for real work 

Zan Thrash has created a full builder called the Google Chart Builder

See his blog posting at http://zanthrash.blogspot.com/2008/01/groovy-chart-builder.html

Source code is available and instructive

Grails has a Google Chart plugin at http://grails.org/Google+Chart+Plugin

Either of those are excellent for real work 

Baseball Data Publicly accessible in XML format Base URL is http://gd2.mlb.com/components/game/mlb Games are filed by year, month, and day Game directory uses team abbreviations 2007 World Series Game 4: year_2007/month_10/day_28/gid_2007_10_28_bosmlb_colmlb_1/boxscore.xml

Publicly accessible in XML format

Base URL is http://gd2.mlb.com/components/game/mlb

Games are filed by year, month, and day

Game directory uses team abbreviations

2007 World Series Game 4:

year_2007/month_10/day_28/gid_2007_10_28_bosmlb_colmlb_1/boxscore.xml

boxscore.xml Typical boxscore includes Root element is <boxscore> Child elements <linescore> <pitching> for home and away teams <pitcher> element for each pitcher <batting> for home and away teams <batter> element for each batter Assorted <note>, <text_data>, <game_info> elements

Typical boxscore includes

Root element is <boxscore>

Child elements

<linescore>

<pitching> for home and away teams

<pitcher> element for each pitcher

<batting> for home and away teams

<batter> element for each batter

Assorted <note>, <text_data>, <game_info> elements

Java Approach Consider the Java code to access the data Open a URL and a URLConnection Get a DocumentBuilderFactory Get a DocumentBuilder Invoke the parse method using an InputStream from the URLConnection Either traverse the tree or call getElementByTagName to retrieve the data Don’t forget all the try/catch blocks

Consider the Java code to access the data

Open a URL and a URLConnection

Get a DocumentBuilderFactory

Get a DocumentBuilder

Invoke the parse method using an InputStream from the URLConnection

Either traverse the tree or call getElementByTagName to retrieve the data

Don’t forget all the try/catch blocks

Groovy Approach Use XmlParser or XmlSlurper Very similar classes with mostly the same methods Parser returns a list of nodes to navigate Slurper returns GPathResults , which are like XPath but groovier Just to keep things simple, since the data isn’t massive, we’ll use the parser

Use XmlParser or XmlSlurper

Very similar classes with mostly the same methods

Parser returns a list of nodes to navigate

Slurper returns GPathResults , which are like XPath but groovier

Just to keep things simple, since the data isn’t massive, we’ll use the parser

GetGameData.groovy class GetGameData { def day def month def year def base = 'http://gd2.mlb.com/components/game/mlb/' // all teams in actual file def abbrevs = [ ana:&quot;Los Angeles (A)&quot;,ari:&quot;Arizona&quot;,atl:&quot;Atlanta&quot;, bal:&quot;Baltimore&quot;,bos:&quot;Boston&quot;,cha:&quot;Chicago (A)&quot;, chn:&quot;Chicago (N)&quot;,cin:&quot;Cincinnati&quot;,cle:&quot;Cleveland&quot;, col:&quot;Colorado&quot;, was:&quot;Washington&quot;]

getGame() void getGame(away, home, num) { println &quot;$away at $home on ${month}/${day}/${year}&quot; def url = base + &quot;year_${year}/month_${month}/day_${day}/&quot; def game = &quot;gid_${year}_${month}_${day}_&quot; + &quot;${away}mlb_${home}mlb_${num}/boxscore.xml&quot; def boxscore = new XmlParser().parse(url + game)

getGame() def awayName = boxscore.'@away_fname' def awayScore = boxscore.linescore[0].'@away_team_runs' def homeName = boxscore.'@home_fname' def homeScore = boxscore.linescore[0].'@home_team_runs' println &quot;$awayName $awayScore, $homeName $homeScore (game $num)&quot;

getGame() def pitchers = boxscore.pitching.pitcher pitchers. each { p -> if (p.'@note' && p.'@note' =~ /W|L|S/) { println &quot; ${p.'@name'} ${p.'@note'}&quot; } }

Interesting Features GStrings simplify string handling Java would have to use concatenation to mix strings and variables XmlParser has a parse method that takes a URL Result is a DOM tree Child elements found using dot notation boxscore.pitching.pitcher selects all pitchers Attribute values use @ notation

GStrings simplify string handling

Java would have to use concatenation to mix strings and variables

XmlParser has a parse method that takes a URL

Result is a DOM tree

Child elements found using dot notation

boxscore.pitching.pitcher selects all pitchers

Attribute values use @ notation

Result (so far) bos at col on 10/28/2007 Boston Red Sox 4, Colorado Rockies 3 (game 1) Lester (W, 1-0) Papelbon (S, 3) Cook (L, 0-1)

Process the Data def batters = boxscore.batting.batter for (b in batters) { println &quot;${b.'@name'} went ${b.'@h'} for ${b.'@ab'}&quot; } println batters. size () + &quot; total batters&quot; println 'Total hits: ' + batters.'@h'*. toInteger ().sum()

Notes Groovy prefers for/in loop Could use batters.each here instead NodeList has size() method So does List , String , arrays, etc. Spread-dot operator, *. Applies function after dot to each element of a list

Groovy prefers for/in loop

Could use batters.each here instead

NodeList has size() method

So does List , String , arrays, etc.

Spread-dot operator, *.

Applies function after dot to each element of a list

More Processing println &quot;Batters with at least one hit:&quot; println batters. findAll { it.'@h'. toInteger () > 0 }. collect { it.'@name' + '(' + it.'@h' + ')' } }

List Processing List has a findAll method that takes a closure Default reference to each element is “ it ” List also has collect method Applies closure to each element and returns a list containing the results Many other list processing methods available each, every, unique, sort, join, flatten, reverse, intersect, +, -

List has a findAll method that takes a closure

Default reference to each element is “ it ”

List also has collect method

Applies closure to each element and returns a list containing the results

Many other list processing methods available

each, every, unique, sort, join, flatten, reverse, intersect, +, -

XML Builder Groovy implements Builder pattern Uses metaprogramming to intercept “pseudo” method calls Builders already included NodeBuilder for XML AntBuilder for creating Ant scripts SwingBuilder for GUIs BuilderSupport for creating your own

Groovy implements Builder pattern

Uses metaprogramming to intercept “pseudo” method calls

Builders already included

NodeBuilder for XML

AntBuilder for creating Ant scripts

SwingBuilder for GUIs

BuilderSupport for creating your own

Create HTML void writeHtml(node) { def away = node.'@away_sname‘ def home = node.'@home_sname' def name = &quot;$away at $home&quot; new File(&quot;${away}${home}.html&quot;). withWriter { w -> def builder = new MarkupBuilder(w)

Notes File has withWriter method that creates a Writer and automatically closes it when done MarkupBuilder overloaded to take a Writer Default writes to standard out

File has withWriter method that creates a Writer and automatically closes it when done

MarkupBuilder overloaded to take a Writer

Default writes to standard out

Building HTML builder.html { head { title name } body { h1 name h2 node.'@date' node.batting. each { batters -> def team = batters.'@team_flag' + '_sname' h2 node.&quot;@${team}&quot;

Notes Looks like HTML Each HTML term is intercepted Builder then creates XML node with that name Closure after node indicates child node Argument in parentheses is attribute Can freely mix regular Groovy variables and the builder nodes

Looks like HTML

Each HTML term is intercepted

Builder then creates XML node with that name

Closure after node indicates child node

Argument in parentheses is attribute

Can freely mix regular Groovy variables and the builder nodes

More HTML table (border:'2') { tr { th 'Batter'; th 'AB'; th 'R'; th 'H' th 'RBI'; th 'BB'; th 'SO' } batters.batter. findAll { it.'@pos' != 'P' }. each { b -> tr { td b.'@name' + ' (' + b.'@pos' + ')' td b.'@ab'; td b.'@r'; td b.'@h' td b.'@rbi'; td b.'@bb'; td b.'@so' } }

Table, continued tr { td(style:'font-weight:bold','Totals') td batters.batter.'@ab'*. toInteger ().sum() td batters.batter.'@r'*. toInteger ().sum() td batters.batter.'@h'*. toInteger ().sum() td batters.batter.'@rbi'*. toInteger ().sum() td batters.batter.'@bb'*. toInteger ().sum() td batters.batter.'@so'*. toInteger ().sum() } }

Results HTML output file Generating XML just as easy Swing GUIs are fun, too

HTML output file

Generating XML just as easy

Swing GUIs are fun, too

HTML Boxscore

Screen Scraping Want all games for a given date MLB web page lists games in subdirectories, as discussed above Can’t just use XML Parser HTML not necessarily well-formed Without a schedule, don’t know which games played on each day Grab page and screen scrape

Want all games for a given date

MLB web page lists games in subdirectories, as discussed above

Can’t just use XML Parser

HTML not necessarily well-formed

Without a schedule, don’t know which games played on each day

Grab page and screen scrape

Games for 5/5/2007

Find Games on Date void getGames() { println &quot;Games for ${month}/${day}/${year}&quot; def url = base + &quot;year_${year}/month_${month}/day_${day}/&quot; def gamePage = new URL(url).text def pattern = /&quot;gid_${year}_${month}_${day}_(w*)mlb_(w*)mlb_(d)/

Notes URL class has getText() method Invoked using text property Retrieves entire page for processing Could use eachLine() method instead Processes line by line Available in any File Works for URLs, too, by duck typing Each game in a link with the above pattern Also in text, so include the leading quotes to distinguish between the two Groups (w*) contain the team abbreviations

URL class has getText() method

Invoked using text property

Retrieves entire page for processing

Could use eachLine() method instead

Processes line by line

Available in any File

Works for URLs, too, by duck typing

Each game in a link with the above pattern

Also in text, so include the leading quotes to distinguish between the two

Groups (w*) contain the team abbreviations

Process HTML Page def m = gamePage =~ pattern if (m) { (0..<m. count ).eachWithIndex { line, i -> def away = m[line][1] def home = m[line][2] def num = m[line][3] try { getGame(away,home,num) } catch (Exception e) { println abbrevs[away] + &quot; at &quot; + abbrevs[home] + &quot; not started yet&quot; } } }

Notes Matcher’s count property tells how many matches Range (0..<x) is from 0 up to but not including x Iterator eachWithIndex available Index not actually used here, just shown for illustration

Matcher’s count property tells how many matches

Range (0..<x) is from 0 up to but not including x

Iterator eachWithIndex available

Index not actually used here, just shown for illustration

Results Games for 05/05/2007 Boston at Minnesota on 05/05/2007 Boston Red Sox 1, Minnesota Twins 2 (game 1) Tavarez (L, 1-3) Santana (W, 4-2) Nathan (S, 8) Chicago (A) at Los Angeles (A) on 05/05/2007 Chicago White Sox 6, Los Angeles Angels 3 (game 1) Garland (W, 1-2) Jenks (S, 9) Lackey (L, 4-3) …

Database Data Groovy simplifies database access groovy.sql.Sql class Can do inserts, updates, deletes, and queries Includes many convenience methods

Groovy simplifies database access

groovy.sql.Sql class

Can do inserts, updates, deletes, and queries

Includes many convenience methods

Training Data Sample data from training company Want to determine teaching days and revenue Three tables Location id, city, state, version (for optimistic locking) latitude, longitude (computed from web service) Client id, name, version Course id, title, start_date, end_date, rate, version location_id FK to Location.id client_id FK to Client.id

Sample data from training company

Want to determine teaching days and revenue

Three tables

Location

id, city, state, version (for optimistic locking)

latitude, longitude (computed from web service)

Client

id, name, version

Course

id, title, start_date, end_date, rate, version

location_id FK to Location.id

client_id FK to Client.id

Training Data Data stored in MySQL database Use MySQL JDBC driver Note length of course is dependent variable Computed from start_date and end_date Revenue adding in rate for each day, since course may have calendar gaps Lots of annoying Java calendar processing

Data stored in MySQL database

Use MySQL JDBC driver

Note length of course is dependent variable

Computed from start_date and end_date

Revenue adding in rate for each day, since course may have calendar gaps

Lots of annoying Java calendar processing

Side Issues Initial insert into database done by collecting data in spreadsheet Can access spreadsheet directly using Scriptom library Alternative is to save as CSV and process file Need latitude and longitude for each city, state in order to create Google Map

Initial insert into database done by collecting data in spreadsheet

Can access spreadsheet directly using Scriptom library

Alternative is to save as CSV and process file

Need latitude and longitude for each city, state in order to create Google Map

Sample CSV Data 75,5/14/2007,5/18/2007,Java Web Services,Lancaster,PA 76,5/21/2007,5/25/2007,Ajax and Struts,Philadelphia,PA 77,6/4/2007,6/12/2007,Java Web Services,McLean,VA 78,6/25/2007,6/29/2007,Portal Dev. Using RAD6,Enola,PA 80,7/9/2007,7/14/2007,Hibernate EJB3,Atlanta,GA 81,8/23/2007,8/23/2007,J2EE for Managers,Marlborough,CT

Process CSV Data class Record { int num; String startDate; String endDate String title; String city; String state Record(String[] s) { num = s[0].startsWith(&quot;#&quot;) ? 0 : s[0]. toInteger () startDate = s[1]; endDate = s[2] title = s[3]; city = s[4]; state = s[6] } String toString() { &quot;$title ($startDate -- $endDate) $city, $state&quot; } }

Process CSV Data def records = [] try { def dataFile = new File('Course_locations.csv') def lines = dataFile. readLines () for (line in lines) { elements = line.trim().split(',') records << new Record(*elements) } } catch (FileNotFoundException e) { println e } records.each { println it }

GroovyBeans GroovyBeans declare properties Put in fields, accessors automatically generated (Groovy calls both gets and sets accessors) Map constructor generated, too new Record(title:”Groovy”,…) assigns value to title, etc.

GroovyBeans declare properties

Put in fields, accessors automatically generated

(Groovy calls both gets and sets accessors)

Map constructor generated, too

new Record(title:”Groovy”,…) assigns value to title, etc.

Notes File has readLines method Closure argument applies to each line Can use String methods like split and trim Spread operator takes list and splits it into input arguments Again, not really necessary here since constructor takes an array, but interesting nevertheless Note toString method does not require a return keyword Value of closure returned by default

File has readLines method

Closure argument applies to each line

Can use String methods like split and trim

Spread operator takes list and splits it into input arguments

Again, not really necessary here since constructor takes an array, but interesting nevertheless

Note toString method does not require a return keyword

Value of closure returned by default

Geocoding Geocoders available as web services Google has one So does the USGS Return information as XML or CSV

Geocoders available as web services

Google has one

So does the USGS

Return information as XML or CSV

Using Google Geocoder def key = ‘long_ugly_key' def base = 'http://maps.google.com/maps/geo' def city = 'Marlborough' def state = 'CT' def query = &quot;q=${city},+${state}&output=csv&key=${key}&quot; def url_string = base + '?q=' + ',+' + URLEncoder.encode(city,&quot;UTF-8&quot;) + ',+' + state + &quot;&output=csv&key=${key}&quot; def results = new URL(url_string).text.split(',') def latitude = results[-2].toDouble(); def longitude = results[-1].toDouble(); println &quot;(${latitude},${longitude})&quot; assert &quot;(41.63256,-72.46315) == (${latitude},${longitude})&quot;

Google Geocoder When csv parameter included, result is four strings HTTP status code (hopefully 200) Accuracy (magnification level) Latitude Longitude Note use in script of indices -1, -2 to grab two elements from the end

When csv parameter included, result is four strings

HTTP status code (hopefully 200)

Accuracy (magnification level)

Latitude

Longitude

Note use in script of indices -1, -2 to grab two elements from the end

USGS Geocoder def partialCsvRequest = &quot;http://geocoder.us/service/csv/geocode?address=&quot; def address = &quot;11 Emily Road, Marlborough, CT&quot; def csvUrl = new URL(partialCsvRequest + URLEncoder.encode(address)) def csvResponse = csvUrl.text def tokens = csvResponse.split(&quot;,&quot; ) println &quot;Latitude: [${tokens[0]}]&quot; println &quot;Longitude: [${tokens[1]}]&quot; println &quot;Address: [${tokens[2]}]&quot; println &quot;City: [${tokens[3]}]&quot; println &quot;State: [${tokens[4]}]&quot; println &quot;Zip: [${tokens[5]}]&quot;

TrainingCourse class TrainingCourse { String title; Date startDate; Date endDate; double rate String toString() { def nf = NumberFormat.currencyInstance &quot;(${title},(${startDate} - ${endDate}),${nf.format(rate)})&quot; } int getLength() { (startDate..endDate). size () } double getRevenue() { length * rate } }

Notes Can provide get methods as necessary Dates are a range now..then size() returns number of days Can add, subtract days

Can provide get methods as necessary

Dates are a range

now..then

size() returns number of days

Can add, subtract days

CourseProcessor.groovy class CourseProcessor { def courses = [] def courseYearMap = new TreeMap() def cal = Calendar.instance CourseProcessor() { def USER = ‘xxx‘; def PASS = ‘xxx’; def URL = ‘xxx‘; def DRIVER = ‘xxx' def conn = Sql.newInstance(URL,USER,PASS,DRIVER) conn.eachRow('select * from course') { row -> courses << new TrainingCourse( title:row.title,startDate:row.start_date, endDate:row.end_date,rate:row.rate) }

Continuing… courses. each { c -> cal.time = c.startDate def year = cal.get(Calendar.YEAR) courseYearMap[year] = courseYearMap.get(year,[]) + c } }

Notes Want to sort courses by year Current approach is to add them to a map Using TreeMap instead of [:] means courses automatically sorted by key on add Map contains Years as keys List of courses as values

Want to sort courses by year

Current approach is to add them to a map

Using TreeMap instead of [:] means courses automatically sorted by key on add

Map contains

Years as keys

List of courses as values

Printing Courses def printYearMap() { def nf = NumberFormat.currencyInstance courseYearMap. each { year,courseList -> def monthlyDays = new int [12] def monthlyRev = new double [12] courseList. each { course -> cal.time = course.startDate def month = cal.get(Calendar.MONTH) for (date in course.startDate..course.endDate) { monthlyDays[month] += 1 monthlyRev[month] += course.rate } }

Continuing def days = (courseList*.length).sum() def rev = (courseList*.revenue).sum() println &quot;Totals for $year : ${days} days, ${nf.format(rev)}&quot;

Testing Testing assert keyword used everywhere GroovyTestCase extends JUnit TestCase assertArrayEquals assertContains(int, int[]) assertLength assertScript(String script) Asserts script runs without exceptions shouldFail(Closure) assert closure fails when run

Testing

assert keyword used everywhere

GroovyTestCase extends JUnit TestCase

assertArrayEquals

assertContains(int, int[])

assertLength

assertScript(String script)

Asserts script runs without exceptions

shouldFail(Closure) assert closure fails when run

Testing Can execute any GroovyTestCase as regular Groovy script Runs as though it has main method Mocks and Stubs built in, too

Can execute any GroovyTestCase as regular Groovy script

Runs as though it has main method

Mocks and Stubs built in, too

Miscellaneous I see I’ve left out lots of cool topics Safe dereferencing operator ?. a?.b?.c checks for null a and b Templates look like JSPs, but run with Groovy scripts Will discuss with Grails Metaprogramming (the red pill) Great for creating DSLs Heredocs def doc = '''This is a multiline script written over several lines''‘ Grails!

I see I’ve left out lots of cool topics

Safe dereferencing operator ?.

a?.b?.c checks for null a and b

Templates look like JSPs, but run with Groovy scripts

Will discuss with Grails

Metaprogramming (the red pill)

Great for creating DSLs

Heredocs

def doc = '''This is a multiline script written over several lines''‘

Grails!

References Groovy home is http://groovy.codehaus.org Lots of info, plug-ins, details Mailing lists at http://groovy.codehaus.org/Mailing+Lists News portal at http://aboutgroovy.com Lots of samples at http://pleac.sourceforge.net/pleac_groovy/

Groovy home is http://groovy.codehaus.org

Lots of info, plug-ins, details

Mailing lists at http://groovy.codehaus.org/Mailing+Lists

News portal at http://aboutgroovy.com

Lots of samples at http://pleac.sourceforge.net/pleac_groovy/