Hudson 插件开发 （Part 2: 插件结构解读 I ）

经过前一篇文章的步骤，在我们的指定目录下已经生成了一个Hudson 插件的项目文件夹。在Eclipse中导入这个项目，我们可以看见项目有如下的结构：

+ src
    + main
        + java
             +  full.package.name
                    +- HelloWorldBuilder.java
                    +- PluginImpl.java
+resources
             +  full.package.name
                    +- config.jelly
                    +- global.jelly
                +- index.jelly
        + webapp
            +- help-globalConfig.html
            +- help-projectConfig.html

PluginImpl.java：
这个类是用于插件注册扩展点（Extension points）的一个类，在这里，我们注册了一个Builder。其实在Hudson 中有很多不同种类的扩展点，比如Publisher、Recorder 等等。详细的说明可以参考Hudson 的网站。

public class PluginImpl extends Plugin {
    public void start() throws Exception {
       
        BuildStep.BUILDERS.add(HelloWorldBuilder.DESCRIPTOR);
    }
}

HelloWorldBuilder.java
这个类就是具体实现某一扩展点的一个类，在这里由于要扩展Builder这个扩展点，所以继承了 Builder 这个类

public class HelloWorldBuilder extends Builder {

    private final String name;

    @DataBoundConstructor
    public HelloWorldBuilder(String name) {
        this.name = name;
    }

    /**
     * We'll use this from the <tt>config.jelly</tt>.
     */
    public String getName() {
        return name;
    }

    public boolean perform(Build build, Launcher launcher, BuildListener listener) {
        // this is where you 'build' the project
        // since this is a dummy, we just say 'hello world' and call that a build

        // this also shows how you can consult the global configuration of the builder
        if(DESCRIPTOR.useFrench())
            listener.getLogger().println("Bonjour, "+name+"!");
        else
            listener.getLogger().println("Hello, "+name+"!");
        return true;
    }

    public Descriptor<Builder> getDescriptor() {
        // see Descriptor javadoc for more about what a descriptor is.
        return DESCRIPTOR;
    }

    /**
     * Descriptor should be singleton.
     */
    public static final DescriptorImpl DESCRIPTOR = new DescriptorImpl();

    /**
     * Descriptor for {@link HelloWorldBuilder}. Used as a singleton.
     * The class is marked as public so that it can be accessed from views.
     *
     * <p>
     * See <tt>views/hudson/plugins/hello_world/HelloWorldBuilder/*.jelly</tt>
     * for the actual HTML fragment for the configuration screen.
     */
    public static final class DescriptorImpl extends Descriptor<Builder> {
        /**
         * To persist global configuration information,
         * simply store it in a field and call save().
         *
         * <p>
         * If you don't want fields to be persisted, use <tt>transient</tt>.
         */
        private boolean useFrench;

        DescriptorImpl() {
            super(HelloWorldBuilder.class);
        }

        /**
         * Performs on-the-fly validation of the form field 'name'.
         *
         * @param value
         *      This receives the current value of the field.
         */
        public void doCheckName(StaplerRequest req, StaplerResponse rsp, @QueryParameter final String value) throws IOException, ServletException {
            new FormFieldValidator(req,rsp,null) {
                /**
                 * The real check goes here. In the end, depending on which
                 * method you call, the browser shows text differently.
                 */
                protected void check() throws IOException, ServletException {
                    if(value.length()==0)
                        error("Please set a name");
                    else
                    if(value.length()<4)
                        warning("Isn't the name too short?");
                    else
                        ok();

                }
            }.process();
        }

        /**
         * This human readable name is used in the configuration screen.
         */
        public String getDisplayName() {
            return "Say hello world";
        }

        public boolean configure(StaplerRequest req, JSONObject o) throws FormException {
            // to persist global configuration information,
            // set that to properties and call save().
            useFrench = o.getBoolean("useFrench");
            save();
            return super.configure(req);
        }

        /**
         * This method returns true if the global configuration says we should speak French.
         */
        public boolean useFrench() {
            return useFrench;
        }
    }
}

是不是看得有点头晕，呵呵，下面我来逐步分析这些代码

@DataBoundConstructor
    public HelloWorldBuilder(String name) {
        this.name = name;
    }

    /**
     * We'll use this from the <tt>config.jelly</tt>.
     */
    public String getName() {
        return name;
    }

这段代码用于构造这个Bulider并且从相应的config.jelly中获取相应的参数。Hudson使用了一种叫structured form submission的技术，使得可以使用这种方式活动相应的参数。

public boolean perform(Build build, Launcher launcher, BuildListener listener) {
        // this is where you 'build' the project
        // since this is a dummy, we just say 'hello world' and call that a build

        // this also shows how you can consult the global configuration of the builder
        if(DESCRIPTOR.useFrench())
            listener.getLogger().println("Bonjour, "+name+"!");
        else
            listener.getLogger().println("Hello, "+name+"!");
        return true;
    }

方法perform（）是个很重要的方法，当插件运行的的时候这个方法会被调用。相应的业务逻辑也可以在这里实现。比如这个perform（）方法就实现了怎么说　“Hello”

接下来，在HelloBuilder 这个类里面有一个叫 DescriptorImpl 的内部类，它继承了Descriptor。在Hudson 的官方说明文档里说Descriptor包含了一个配置实例的元数据。打个比方，我们在工程配置那里对插件进行了配置，这样就相当于创建了一个插脚的实例，这时候就需要一个类来存储插件的配置数据，这个类就是Descriptor。

public String getDisplayName() {
            return "Say hello world";
        }

如上面的代码，可以在Descriptor的这个方法下设置插件在工程配置页面下现实的名字

public boolean configure(StaplerRequest req, JSONObject o) throws FormException {
            // to persist global configuration information,
            // set that to properties and call save().
            useFrench = o.getBoolean("useFrench");
            save();
            return super.configure(req);
        }

如同注释属所说，这个方法用于将全局配置存储到项目中

快下班了，待续，呵呵

评论

5 楼 daxiaoli123 2012-08-20  

怎么生成的啊
我下载了maven2   mvn -cpu hpi:create


C:\Documents and Settings\Administrator>mvn hpi:create
Error reading settings.xml: start tag not allowed in epilog but got s (position:
END_TAG seen ...</settings>\n\n\n<s... @260:3)

4 楼 classtwo5367 2009-07-08  

juvenshun 写道

国人不乏使用开源软件的文章和经验
但是如何扩展，这方面的资料很少，LZ能去做并共享出来，很的很好

哎..这也是我实习公司要求我做的..现学现卖..哈哈..

3 楼 juvenshun 2009-07-08  

国人不乏使用开源软件的文章和经验
但是如何扩展，这方面的资料很少，LZ能去做并共享出来，很的很好

2 楼 classtwo5367 2009-07-08  

juvenshun 写道

这类文章要支持的

呵呵，能力有限，也就能写成这样，献丑了，

1 楼 juvenshun 2009-07-08  

这类文章要支持的