{"id":450,"date":"2007-12-12T14:34:12","date_gmt":"2007-12-12T20:34:12","guid":{"rendered":"http:\/\/www.mooreds.com\/wordpress\/archives\/000450"},"modified":"2008-04-01T16:22:45","modified_gmt":"2008-04-01T22:22:45","slug":"gwt-mini-pattern-configuration-reader","status":"publish","type":"post","link":"https:\/\/www.mooreds.com\/wordpress\/archives\/450","title":{"rendered":"GWT Mini Pattern: Configuration Reader"},"content":{"rendered":"

I’ve written about configuration options to GWT widgets before<\/a>. Basically, the idea is that you have some configuration that lets the widget change behavior without redeploying or compiling code. In fact, nontechnical users (like designers) can change configuration, if it’s documented. These are the ways I know to specify configuration:<\/p>\n

Meta tags<\/strong><\/p>\n

In the page:
\n<\/p>\n

<meta content=\"bar\" name=\"foo\" id=\"foo\" \/><\/pre>\n
Updated 4\/1\/2008, to have id in the meta tag attbute.<\/em><\/p>\n
In your code:
\n<\/p>\n
String var = DOM.getElementProperty(DOM.getElementById(\"foo\"), \"content\");<\/pre>\n
You can also request only Boolean and Int:
\n<\/p>\n
String var = DOM.getElementPropertyInt(DOM.getElementById(\"foo\"), \"content\");<\/pre>\n
This is simple, all browsers ignore these tags, and you can place them anywhere in a page and get them read.  However, attributes can only contain strings.<\/p>\n
Hidden spans<\/strong><\/p>\n
In the page:<\/p>\n
<\/p>\n
<span id=\"foo\" style=\"display: none\">bar<\/span><\/pre>\n
In your code:<\/p>\n
<\/p>\n
String var = DOM.getInnerHTML(DOM.getElementById(\"foo\"));<\/pre>\n
This is a good choice if you want configuration to be more structured than what a tag attribute can provide--you can parse the 'var' string further.<\/p>\n
Javascript using jsni<\/strong><\/p>\n
<\/p>\n
<script type=\"text\/javascript\">\r\nvar ID = 'bar';\r\n<\/script><\/pre>\n
And in your code:<\/p>\n
<\/p>\n
private native String getIDAsString()\/*-{\r\nif ($wnd.ID == undefined) {\r\nreturn \"\";\r\n} else {\r\nreturn $wnd.ID;\r\n}\r\n}-*\/;\r\n\r\nprivate Integer getID() {\r\nInteger id = new Integer(-1);\r\ntry {\r\nid = Integer.valueOf(getIDAsString());\r\n} catch (NumberFormatException ignore) {}\r\nreturn id;\r\n}\r\n\r\nInteger foo = getID();<\/pre>\n
This method is great when you have variables that are used by other javascript components that you'd like to leverage for your GWT component, or if you have a really complex configuration that is multiple levels in structure.<\/p>\n
Javascript using dictionary<\/strong><\/p>\n
(As outlined here<\/a> and here<\/a>.)
\nIn the page:<\/p>\n
<\/p>\n
<script type=\"text\/javascript\">\r\nvar dictionary = {\r\nfoo: \"bar\"\r\n};\r\n<\/script><\/pre>\n
In your code:
\n<\/p>\n
Dictionary theme = Dictionary.getDictionary(\"dictionary\");\r\nString bar = theme.get(\"foo\");<\/pre>\n
This is good for simple hash datastructures.  I haven't tried it, but from the documentation, it doesn't look like it supports anything past String key value pairs, and your module must inherit from com.google.gwt.i18n.I18N.<\/p>\n
Regardless of your configuration method, I've found myself using a ConfigReader to isolate this logic.  It looks something like this:<\/p>\n
<\/p>\n
public class ConfigReader{\r\n\r\nprivate final boolean opt1;\r\nprivate final String opt2;\r\n\r\npublic ConfigReader(){\r\n\/\/ init opt1 and opt2 using one of the four methods above.\r\n}\r\n\r\npublic boolean isOpt1() {\r\nreturn opt1;\r\n}\r\n\r\npublic String getOpt2() {\r\nreturn opt2;\r\n}\r\n}<\/pre>\n","protected":false},"excerpt":{"rendered":"
I’ve written about configuration options to GWT widgets before. Basically, the idea is that you have some configuration that lets the widget change behavior without redeploying or compiling code. In […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18,30],"tags":[],"class_list":["post-450","post","type-post","status-publish","format-standard","hentry","category-gwt","category-gwt-mini-patterns"],"_links":{"self":[{"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/posts\/450","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/comments?post=450"}],"version-history":[{"count":0,"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/posts\/450\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/media?parent=450"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/categories?post=450"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.mooreds.com\/wordpress\/wp-json\/wp\/v2\/tags?post=450"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}