Provide a way to easily work with dates between Java and PHP

[belgattitude]

Hide the complexity of using dates when JavaVM and PHP timezones differs.

[belgattitude]

Before that tasks is finished it's interesting to have a look to the updated docs:

Working with dates

Dates are not (yet) automatically casted between Java and PHP. Keep in mind that internally the JVM
keeps tracks of milliseconds where PHP is limited to microseconds and that timezones might differs between
runtimes.

Ignoring deprecated constructors, the java.util.Date allows
creation of dates based on a timestamp expressed in milliseconds :

<?php

// $ba = new BridgeAdapter(...); 

$phpDate = \DateTime::createFromFormat('Y-m-d', '2016-12-21');
$milli = $phpDate->format('U') * 1000; // Internally the JVM handles milliseconds
                                       // In order to create a new Java date, 
                                       // php dates must be converted accordingly.
                                       // The 'U' allows formatting the date as
                                       // microseconds since epoch time, just multiply
                                       // by 1000 to get milliseconds.
                                       // Alternatively you can use 
                                       // $milli = strtotime('2016-12-21') * 1000;  
                                       
$javaDate = $ba->java('java.util.Date', $milli);

$simpleDateFormat= $ba->java("java.text.SimpleDateFormat", 'yyyy-MM-dd');

echo $simpleDateFormat->format($javaDate);

// Will print: "2016-12-21"

Alternatively you can use the java.text.SimpleDateFormatter object
to parse the date string without the php conversion.

<?php

// $ba = new BridgeAdapter(...); 

$date = '2016-12-21';
$simpleDateFormat = $ba->java("java.text.SimpleDateFormat", 'yyyy-MM-dd');
$javaDate = $simpleDateFormat->parse($date); // This is a Java date
echo $simpleDateFormat->format($javaDate);
// Will print: "2016-12-21"

Please be aware that timezones might differ from PHP and the JVM. In that case, dates between PHP and Java
are not guaranteed to be the same (think of 2016-12-31 23:00:00 in London and Paris)

In most cases those differences can be easily fixed by ensuring both the JVM and PHP configurations
use the same timezone.

Another option is to pass the current timezone in the formatter :

<?php
$pattern = "yyyy-MM-dd HH:mm";
$formatter = $ba->java("java.text.SimpleDateFormat", $pattern);
$tz = $ba->javaClass('java.util.TimeZone')->getTimezone("Europe/Paris");
$formatter->setTimeZone($tz);