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Manuel Smeria 4.4 1 {{box cssClass="floatinginfobox" title="**Contents**"}}
2 {{toc/}}
3 {{/box}}
Silvia Macovei 4.1 4
Manuel Smeria 4.4 5 {{warning}}
6 Plugins are the old way of writing XWiki extensions. The new way is to [[write a Component>>platform:DevGuide.WritingComponents]].
7 {{/warning}}
Vincent Massol 3.1 8
Vincent Massol 4.3 9 Plugins are quite handy when you want to interact with third-party code from the Velocity context. Check the [[Extensions wiki>>extensions:Main.WebHome]] for a list of existing plugins.
Vincent Massol 1.1 10
Manuel Smeria 4.4 11 Here are the steps to develop a "Hello World" plugin and more.
Vincent Massol 1.1 12
Silvia Macovei 4.2 13 = The plugin architecture =
Vincent Massol 1.1 14
15 Basically, a plugin is composed of two parts:
16
Manuel Smeria 4.4 17 * The **plugin** itself: it must implement the [[XWikiPluginInterface>>https://fisheye2.atlassian.com/browse/xwiki/xwiki-platform/core/trunk/xwiki-core/src/main/java/com/xpn/xwiki/plugin/XWikiPluginInterface.java]] interface. For simplicity you can also extend the [[XWikiDefaultPlugin>>https://fisheye2.atlassian.com/browse/xwiki/xwiki-platform/core/trunk/xwiki-core/src/main/java/com/xpn/xwiki/plugin/XWikiDefaultPlugin.java]] class which is an adapter to the XWikiPluginInterface. The plugin contains the core functions of your plugin. They will not be accessible from scripting (without programming rights).
18 * Its **API**: it should extend the [[Api>>https://fisheye2.atlassian.com/browse/xwiki/xwiki-platform/core/trunk/xwiki-core/src/main/java/com/xpn/xwiki/api/Api.java]] class. Will contain all the public methods, accessible from scripting.
Silvia Macovei 4.2 19
Silvia Macovei 4.1 20 Although you can write the functionality inside the API, this is not recommended; the plugin functionality is written in the //hidden// part ("hidden" as in "not publicly accessible"), and the API can filter the access to privileged users, beautify the method names or parameter list, etc., or simply forward the call to the hidden part.
Vincent Massol 1.21 21
Silvia Macovei 4.2 22 == Plugin lifecycle ==
Sergiu Dumitriu 1.24 23
Silvia Macovei 4.2 24 When the XWiki engine is initialized, the Plugin Manager calls the class constructor for all the enabled plugins (classes implementing the com.xpn.xwiki.plugin.XWikiPluginInterface). For each plugin the class constructor is called only once, and the plugin manager calls the init(XWikiContext) method of the plugin. Each time a plugin is referenced by a Velocity script, for example, when you call a method served by the plugin API:
jeanvivienmaurice 1.14 25
Vincent Massol 5.1 26 {{code}}#set($helloWorldText = "$xwiki.helloworld.hello()"){{/code}}
Silvia Macovei 4.2 27
jeanvivienmaurice 1.14 28 or when you ask the XWiki instance for the plugin API object :
Silvia Macovei 4.1 29
30 {{code}}
jeanvivienmaurice 1.14 31 #set($pluginObject = $xwiki.getPlugin("helloworld")
32
33 #* the name given as argument of getPlugin() should be
34 the one returned by the getName() method of the Plugin class.
35 *#
Silvia Macovei 4.1 36 {{/code}}
37
Manuel Smeria 4.4 38 XWiki calls the getPluginApi() method for the plugin's instance, which itself creates an instance of the class com.xpn.xwiki.plugin.PluginApi. This is why you should not store things in fields of the class extending PluginApi in your plugin, since the usual behavior for the getPluginApi() method is to create a new instance of the PluginApi class every time Velocity needs to access the API for your plugin. This is not true if you store the returned plugin API in a variable, for example:
jeanvivienmaurice 1.14 39
Manuel Smeria 4.4 40 {{code}}
41 #set($myPluginApi = $xwiki.helloworld)
42 {{/code}}
43
Silvia Macovei 4.2 44 The myPluginApi variable will point to the same object as long as the variable exists. You can declare fields in your plugin class instead, since there is only one instance of this class, whose lifecycle spans over the entire servlet's lifecycle.
Sergiu Dumitriu 1.24 45
Silvia Macovei 4.2 46 = Write the plugin =
47
Silvia Macovei 4.1 48 First of all let's **declare our plugin class**:
Vincent Massol 1.1 49
Manuel Smeria 4.4 50 {{code language="java"}}
51 public class HelloWorldPlugin extends XWikiDefaultPlugin {...}
52 {{/code}}
Vincent Massol 1.1 53
Silvia Macovei 4.1 54 Then let's **implement the needed constructor**:
Vincent Massol 1.1 55
Silvia Macovei 4.1 56 {{code language="java"}}
Vincent Massol 1.1 57 public HelloWorldPlugin(String name, String className, XWikiContext context) {
58 super(name,className,context);
Silvia Macovei 4.1 59 }
60 {{/code}}
Vincent Massol 1.1 61
Manuel Smeria 4.4 62 **Set a method to get the name of the plugin**. That's how we will call it from Velocity. For example, we will be able to use our plugin with ##$xwiki.helloworld.myMethod()##;
Vincent Massol 1.1 63
Silvia Macovei 4.1 64 {{code language="java"}}
Vincent Massol 1.1 65 public String getName() {
66 return "helloworld";
67 }
Silvia Macovei 4.1 68 {{/code}}
Vincent Massol 1.1 69
Silvia Macovei 4.1 70 **Write a method to get the plugin API**. Don't forget to cast the plugin.
Vincent Massol 1.1 71
Silvia Macovei 4.1 72 {{code language="java"}}
Vincent Massol 1.1 73 public Api getPluginApi(XWikiPluginInterface plugin, XWikiContext context) {
74 return new HelloWorldPluginApi((HelloWorldPlugin) plugin, context);
75 }
Silvia Macovei 4.1 76 {{/code}}
Vincent Massol 1.1 77
Manuel Smeria 4.4 78 **Overload the cache flush method** (optional):
Vincent Massol 1.1 79
Manuel Smeria 4.4 80 {{code language="java"}}
81 public void flushCache() {}
82 {{/code}}
Vincent Massol 1.1 83
Manuel Smeria 4.4 84 Optionally, we can **create a [[log4j>>http://logging.apache.org/log4j/1.2/apidocs/index.html]] instance** for the plugin:
Vincent Massol 1.1 85
Manuel Smeria 4.4 86 {{code language="java"}}
87 private static final Log LOG = LogFactory.getLog(HelloWorldPlugin.class);
88 {{/code}}
Silvia Macovei 4.1 89
Vincent Massol 1.1 90 This is very useful for debugging. The logger could be invoked from any method like:
Silvia Macovei 4.1 91
92 {{code language="java"}}
Vincent Massol 1.1 93 public String getName() {
Sergiu Dumitriu 1.30 94 LOG.debug("Entered method getName");
Vincent Massol 1.1 95 return "helloworld";
96 }
Silvia Macovei 4.1 97 {{/code}}
Vincent Massol 1.1 98
Manuel Smeria 4.4 99 Then, to enable logging at a specific level for your plugin, edit //webapps/xwiki/WEB-INF/classes/log4j.properties// and add, for example:
Vincent Massol 1.1 100
Manuel Smeria 4.4 101 {{code}}
102 log4j.com.xpn.xwiki.plugin.helloworld.HelloWorldPlugin=debug
103 {{/code}}
Silvia Macovei 4.1 104
Manuel Smeria 4.4 105 You'll then be able to follow your plugin's log messages by tailing your ##xwiki.log## file. Note that you'll need to restart the app server for changes to ##log4j.properties## to take effect.
Silvia Macovei 4.2 106
Manuel Smeria 4.4 107 And finally, **write a method to init the context**:
Vincent Massol 1.1 108
Silvia Macovei 4.1 109 {{code language="java"}}
Vincent Massol 1.1 110 public void init(XWikiContext context) {
111 super.init(context);
112 }
Silvia Macovei 4.1 113 {{/code}}
Vincent Massol 1.1 114
115 Here is the code you should have now:
116
Silvia Macovei 4.1 117 {{code language="java"}}
Vincent Massol 1.1 118 package com.xpn.xwiki.plugin.helloworld;
119
120 import org.apache.commons.logging.Log;
121 import org.apache.commons.logging.LogFactory;
122
123 import com.xpn.xwiki.XWikiContext;
124 import com.xpn.xwiki.api.Api;
125 import com.xpn.xwiki.plugin.XWikiDefaultPlugin;
126 import com.xpn.xwiki.plugin.XWikiPluginInterface;
127
128 public class HelloWorldPlugin extends XWikiDefaultPlugin {
129
Sergiu Dumitriu 1.30 130 private static Log LOG = LogFactory.getLog(HelloWorldPlugin.class);
Vincent Massol 1.1 131
132 public HelloWorldPlugin(String name, String className, XWikiContext context) {
133 super(name,className,context);
134 init(context);
135 }
Sergiu Dumitriu 1.30 136
Vincent Massol 1.1 137 public String getName() {
138 return "helloworld";
139 }
140
141 public Api getPluginApi(XWikiPluginInterface plugin, XWikiContext context) {
142 return new HelloWorldPluginApi((HelloWorldPlugin) plugin, context);
143 }
144
145 public void flushCache() {
146 }
147
148 public void init(XWikiContext context) {
149 super.init(context);
150 }
151 }
Silvia Macovei 4.1 152 {{/code}}
Vincent Massol 1.1 153
Silvia Macovei 4.2 154 = Write the API =
Sergiu Dumitriu 1.29 155
Vincent Massol 1.1 156 Let's write the API class which will contain the methods that can be called from Velocity.
Silvia Macovei 4.2 157
Silvia Macovei 4.1 158 Firstly, **class declaration**:
Vincent Massol 1.1 159
Manuel Smeria 4.4 160 {{code language="java"}}
161 public class HelloWorldPluginApi extends Api {...}
162 {{/code}}
Vincent Massol 1.1 163
Silvia Macovei 4.1 164 Then, **plugin field declaration**. It will let our API to call backend methods.
Vincent Massol 1.1 165
Manuel Smeria 4.4 166 {{code language="java"}}
167 private HelloWorldPlugin plugin;
168 {{/code}}
Vincent Massol 1.1 169
Silvia Macovei 4.1 170 **Required constructor**
Vincent Massol 1.1 171
Silvia Macovei 4.1 172 {{code language="java"}}
Vincent Massol 1.1 173 public HelloWorldPluginApi(HelloWorldPlugin plugin, XWikiContext context) {
Sergiu Dumitriu 1.31 174 super(context);
175 setPlugin(plugin);
Vincent Massol 1.1 176 }
Silvia Macovei 4.1 177 {{/code}}
Vincent Massol 1.1 178
Silvia Macovei 4.1 179 Classic **plugin getter and setter**. These methods are not required at all, on the contrary, they should not be defined, unless they are really needed.
Vincent Massol 1.1 180
Silvia Macovei 4.1 181 {{code language="java"}}
Vincent Massol 1.1 182 public HelloWorldPlugin getPlugin(){
Sergiu Dumitriu 1.31 183 return (hasProgrammingRights() ? plugin : null);
184 // Uncomment for allowing unrestricted access to the plugin
185 // return plugin;
Vincent Massol 1.1 186 }
187
188 public void setPlugin(HelloWorldPlugin plugin) {
Sergiu Dumitriu 1.31 189 this.plugin = plugin;
Vincent Massol 1.1 190 }
Silvia Macovei 4.1 191 {{/code}}
Vincent Massol 1.1 192
Silvia Macovei 4.1 193 Here is the key **API method**. Here is the one that you will call from velocity. You can define any number of them and call your plugin backend from them.
194
195 {{code language="java"}}
Vincent Massol 1.1 196 public String hello() {
197 return "Hello World!";
198 }
Silvia Macovei 4.1 199 {{/code}}
200
Manuel Smeria 4.4 201 You can also have void methods:
202
Silvia Macovei 4.1 203 {{code language="java"}}
jeanvivienmaurice 1.9 204 public void updatePage() {
205 //...
Silvia Macovei 4.1 206 }
207 {{/code}}
Vincent Massol 1.1 208
209 Here is the complete API code:
210
Silvia Macovei 4.1 211 {{code language="java"}}
Vincent Massol 1.1 212 package com.xpn.xwiki.plugin.helloworld;
213
214 import com.xpn.xwiki.XWikiContext;
215 import com.xpn.xwiki.api.Api;
216
217 public class HelloWorldPluginApi extends Api {
218 private HelloWorldPlugin plugin;
219
Sergiu Dumitriu 1.31 220 public HelloWorldPluginApi(HelloWorldPlugin plugin, XWikiContext context) {
221 super(context);
222 setPlugin(plugin);
223 }
Vincent Massol 1.1 224
Sergiu Dumitriu 1.32 225 public HelloWorldPlugin getPlugin(){
226 return (hasProgrammingRights() ? plugin : null);
227 // Uncomment for allowing unrestricted access to the plugin
228 // return plugin;
229 }
jeanvivienmaurice 1.9 230
Sergiu Dumitriu 1.31 231 public void setPlugin(HelloWorldPlugin plugin) {
232 this.plugin = plugin;
233 }
234
235 public String hello() {
236 return "Hello World!";
237 }
238
239 public void updatePage() {
240 //...
241 }
Vincent Massol 1.1 242 }
Silvia Macovei 4.1 243 {{/code}}
Vincent Massol 1.1 244
Silvia Macovei 4.2 245 = Integrate the plugin in your XWiki installation =
jeanvivienmaurice 1.9 246
Manuel Smeria 4.4 247 First of all you need to **copy your classes to the XWiki servlet installation**. Don't forget to be consistent with your package tree. With a Linux Tomcat installation, you'll need to follow these steps which you should be able to reproduce easily in your favourite operating system:
Sergiu Dumitriu 1.32 248
Silvia Macovei 4.1 249 {{code}}
Sergiu Dumitriu 1.33 250 go to the tomcat installation folder (or whatever container you are using)
Vincent Massol 1.1 251 $ cd myTomcatInstallation
252 go to the xwiki WEB-INF directory
253 $ cd webapps/xwiki/WEB-INF
254 create the classes tree, compliant to the "package" directive that you set in the plugin source files
255 $ mkdir classes/com/xpn/xwiki/plugin/helloworld
256 And then copy the class files to this location
Sergiu Dumitriu 1.33 257 $ cp myPluginsFolder/HelloWorldPlugin.class classes/com/xpn/xwiki/plugin/helloworld
258 $ cp myPluginsFolder/HelloWorldPluginAPI.class classes/com/xpn/xwiki/plugin/helloworld
Silvia Macovei 4.1 259 {{/code}}
Vincent Massol 1.1 260
Manuel Smeria 4.4 261 Alternatively, you can jar up your classes (with the required directory structure) and place the jar in //webapps/xwiki/WEB-INF/lib//. This is a more agreeable way of distributing your plugin.
Silvia Macovei 4.2 262
Manuel Smeria 4.4 263 Finally you need to **register your plugin** in the ##xwiki.cfg## file located in //WEB-INF//:
Vincent Massol 1.1 264
Silvia Macovei 4.1 265 {{code}}
Sergiu Dumitriu 1.33 266 xwiki.plugins=com.xpn.xwiki.plugin.calendar.CalendarPlugin,\
267 ...,\
268 com.xpn.xwiki.plugin.helloworld.HelloWorldPlugin
Silvia Macovei 4.1 269 {{/code}}
Vincent Massol 1.1 270
Sergiu Dumitriu 1.34 271 Don't forget to restart your servlet container after this. XWiki has to re-read the configuration file.
Vincent Massol 1.1 272
Silvia Macovei 4.2 273 = Use the plugin =
Vincent Massol 1.1 274
Manuel Smeria 4.4 275 Here is the simplest part. Edit a page and write: {{code}}My plugin says: "$xwiki.helloworld.hello()"{{/code}}.
276 It should be rendered like this: {{code}}My plugin says: "Hello World!"{{/code}}.
Silvia Macovei 4.2 277 You can also call void methods specified in the API class :
Silvia Macovei 4.1 278
279 {{code}}
jeanvivienmaurice 1.8 280 $xwiki.helloworld.updatePage()
Sergiu Dumitriu 1.35 281 The page has been updated.
Silvia Macovei 4.1 282 {{/code}}
jeanvivienmaurice 1.6 283
Silvia Macovei 4.2 284 = Examples =
Sergiu Dumitriu 1.35 285
Vincent Massol 5.3 286 Here are some examples of what you can do with plugins. You should actually check the [[API Guide>>platform:DevGuide.APIGuide]], since it contains examples on how to use the XWiki API. The examples in the API Guide are written in Velocity, and are thus easily applicable to Java.
jeanvivienmaurice 1.6 287
Silvia Macovei 4.2 288 == Accessing pages, objects and object properties from pages ==
jeanvivienmaurice 1.6 289
jeanvivienmaurice 1.36 290 This is something you can do from Velocity as well, but when you need to perform complex treatments on your XWiki pages, you need to do it from a java plugin.
291
Manuel Smeria 4.4 292 The class representing a document in the XWiki Java model is ##com.xpn.xwiki.doc.XWikiDocument##. The class representing an object in the XWiki Java model is ##com.xpn.xwiki.objects.BaseObject##.
Silvia Macovei 4.2 293
Manuel Smeria 4.4 294 If you need to access existing documents from your plugin, you use the XWiki class, ##com.xpn.xwiki.XWiki##, which has a getDocument() method. You can retrieve the current Xwiki instance by using the ##com.xpn.xwiki.XWikiContext## class, which has a getWiki() method.
Silvia Macovei 4.2 295
Manuel Smeria 4.4 296 The rule, in plugin programming, is to pass the current context as a ##com.xpn.xwiki.XWikiContext## function parameter, between the different methods of your plugin class. The plugin API class also has a context property pointing to the current context.
Silvia Macovei 4.2 297
Silvia Macovei 4.1 298 {{code}}
Vincent Massol 1.19 299 // You need the current context, which you always have in a plugin anyway
300 com.xpn.xwiki.doc.XWikiDocument doc = context.getDoc(); // current document;
301 com.xpn.xwiki.doc.XWikiDocument doc = context.getWiki().getDocument("theSpace.theDoc", context); // any document
jeanvivienmaurice 1.6 302 com.xpn.xwiki.objects.BaseObject meta;
303 meta = doc.getObject("fooSpace.fooClass");
304 String docType = (String)meta.getStringValue("type"); //if the class of the object has a property named "type", which can accept a text value...
Vincent Massol 1.19 305 meta.set("type", "newValue", context);
Silvia Macovei 4.1 306 {{/code}}
jeanvivienmaurice 1.6 307
Silvia Macovei 4.2 308 If you need to access the parent of an XWiki document, you should use the getDocument() method of the XWiki class, as seen in the example above, with, as parameter value, the parent's full name returned by the getParent() method of the XWikiDocument class.
Silvia Macovei 4.1 309
Manuel Smeria 4.4 310 {{code}}
311 com.xpn.xwiki.doc.XWikiDocument parentDocument = context.getWiki().getDocument(childDocument.getParent());
312 {{/code}}
Silvia Macovei 4.1 313
Manuel Smeria 4.4 314 You should not use ##XWikiDocument.getParentDoc## since it only returns a blank XWikiDocument object set with the same full name as the parent's full name.

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