![]() ![]() Which signals that the previous call to the plugin was not successful Through which the application can retrieve the result of the plugins work, i.e. Which lets the hosting application set a parameter for the plugin to work with Which returns the name of the plugin, so that it can be displayed to the user in some way In the example, we require plugins to implement the PluginFunction interface. The methods of the interface can be thought of as ”lifecycle“ methods - operations the host application calls to initialize a plugin, set parameters, execute it, get results and shut it down. In order for the host application to treat all plugins the same way, we define an interface which the plugins need to implement. write a SecurityManager that governs what plugins are allowed to doįigure 1 shows the various pieces of code that help implement all of this.įigure 1: Components of the plugin mechanism PluginDemo is an example application that shows the various pieces in action Step 1: Defining the API.write a ClassLoader that loads the plugin classes.determine how the host application gets to know which plugins are available, and where to find them.a Java interface, for the plugin to implement Generally speaking, there are four steps involved in the process. ![]() These are atypical, though, and what is described here is more like what Photoshop does.) (Examples of Java plugins in a broader sense would also be the Applet API in web browsers, and the Servlet API in web servers. This article shows how a plugin API can be added to Java applications. While Photoshop plugins are written in C, the mechanism is really language-independent, although it is constrained by the language the host application is written in. One application whose plugin API is very successful is Adobe Photoshop, which even spawned a market for commercially available plugins. One way of doing so is through plugins: chunks of external code that are accessed through the application, and use its API to perform a function that the application itself can't. Another option would be to extend the application by using its API, if it provides one. One solution might be to export the data, work on it with a different application which has the desired functionality, and then re-import it. Even worse, it might be something really specialized that only she needs, and which will never be added by the software vendor. No matter how many functions an application has, there are times when a user wants to do something that the original developers have not foreseen, and which is not included in the application. ![]()
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