使用代码生成插件工程，脱离eclipse本身的新建工程向导（3）

    在第二步中需要有个PluginClassCodeGenerator类，是用来生产插件工程的启动类Activator，在eclipse源码中，也需要依赖向导中保存的一些上下文信息，也需要进行改造，改造后如下。

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;
import org.eclipse.pde.core.plugin.IPluginReference;
import org.eclipse.pde.internal.build.IPDEBuildConstants;
import org.eclipse.pde.internal.core.util.CoreUtility;
import org.eclipse.pde.ui.templates.PluginReference;

/**
 * 
 * @author aquarion
 * @version 1.0
 *
 */
@SuppressWarnings("restriction")
public class PluginClassCodeGenerator {
	private IProject fProject;
	private String fQualifiedClassName;
	private String id;

	public PluginClassCodeGenerator(IProject project,
			String qualifiedClassName, String id) {
		fProject = project;
		fQualifiedClassName = qualifiedClassName;
		this.id = id;
	}

	public IFile generate() throws CoreException {
		int nameloc = fQualifiedClassName.lastIndexOf('.');
		String packageName = (nameloc == -1) ? "" : fQualifiedClassName.substring(0, nameloc); //$NON-NLS-1$
		String className = fQualifiedClassName.substring(nameloc + 1);

		IPath path = new Path(packageName.replace('.', '/'));
		path = new Path("src").append(path);

		CoreUtility.createFolder(fProject.getFolder(path));

		IFile file = fProject.getFile(path.append(className + ".java")); //$NON-NLS-1$
		StringWriter swriter = new StringWriter();
		PrintWriter writer = new PrintWriter(swriter);
		// only generate/extend plug-in classes if it's a IU plug-in
		generatePluginClass(packageName, className, writer);
		writer.flush();
		try {
			swriter.close();
			ByteArrayInputStream stream = new ByteArrayInputStream(swriter
					.toString().getBytes(fProject.getDefaultCharset()));
			if (file.exists())
				file.setContents(stream, false, true, null);
			else
				file.create(stream, false, null);
			stream.close();
		} catch (IOException e) {

		}
		return file;
	}

	private void generatePluginClass(String packageName, String className,
			PrintWriter writer) {
		if (!packageName.equals("")) { //$NON-NLS-1$
			writer.println("package " + packageName + ";"); //$NON-NLS-1$ //$NON-NLS-2$
			writer.println();
		}
		writer.println("import org.eclipse.ui.plugin.AbstractUIPlugin;"); //$NON-NLS-1$
		writer.println("import org.osgi.framework.BundleContext;"); //$NON-NLS-1$
		writer.println();
		writer.println("/**"); //$NON-NLS-1$
		writer.println(" * The activator class controls the plug-in life cycle"); //$NON-NLS-1$
		writer.println(" */"); //$NON-NLS-1$
		writer.println("public class " + className + " extends AbstractUIPlugin {"); //$NON-NLS-1$ //$NON-NLS-2$
		writer.println();
		writer.println("\t// The plug-in ID"); //$NON-NLS-1$
		writer.println("\tpublic static final String PLUGIN_ID = \"" + id + "\"; //$NON-NLS-1$"); //$NON-NLS-1$ //$NON-NLS-2$
		writer.println();
		writer.println("\t// The shared instance"); //$NON-NLS-1$
		writer.println("\tprivate static " + className + " plugin;"); //$NON-NLS-1$ //$NON-NLS-2$
		writer.println("\t"); //$NON-NLS-1$
		writer.println("\t/**"); //$NON-NLS-1$
		writer.println("\t * The constructor"); //$NON-NLS-1$
		writer.println("\t */"); //$NON-NLS-1$
		writer.println("\tpublic " + className + "() {"); //$NON-NLS-1$ //$NON-NLS-2$
		writer.println("\t}"); //$NON-NLS-1$
		writer.println();

		writer.println("\t/*"); //$NON-NLS-1$
		writer.println("\t * (non-Javadoc)"); //$NON-NLS-1$
		writer.println("\t * @see org.eclipse.ui.plugin.AbstractUIPlugin#start(org.osgi.framework.BundleContext)"); //$NON-NLS-1$
		writer.println("\t */"); //$NON-NLS-1$
		writer.println("\tpublic void start(BundleContext context) throws Exception {"); //$NON-NLS-1$
		writer.println("\t\tsuper.start(context);"); //$NON-NLS-1$
		writer.println("\t\tplugin = this;"); //$NON-NLS-1$
		writer.println("\t}"); //$NON-NLS-1$
		writer.println();

		writer.println("\t/*"); //$NON-NLS-1$
		writer.println("\t * (non-Javadoc)"); //$NON-NLS-1$
		writer.println("\t * @see org.eclipse.ui.plugin.AbstractUIPlugin#stop(org.osgi.framework.BundleContext)"); //$NON-NLS-1$
		writer.println("\t */"); //$NON-NLS-1$
		writer.println("\tpublic void stop(BundleContext context) throws Exception {"); //$NON-NLS-1$
		writer.println("\t\tplugin = null;"); //$NON-NLS-1$
		writer.println("\t\tsuper.stop(context);"); //$NON-NLS-1$
		writer.println("\t}"); //$NON-NLS-1$
		writer.println();

		writer.println("\t/**"); //$NON-NLS-1$
		writer.println("\t * Returns the shared instance"); //$NON-NLS-1$
		writer.println("\t *"); //$NON-NLS-1$
		writer.println("\t * @return the shared instance"); //$NON-NLS-1$
		writer.println("\t */"); //$NON-NLS-1$
		writer.println("\tpublic static " + className + " getDefault() {"); //$NON-NLS-1$ //$NON-NLS-2$
		writer.println("\t\treturn plugin;"); //$NON-NLS-1$
		writer.println("\t}"); //$NON-NLS-1$
		writer.println();
		writer.println("}"); //$NON-NLS-1$
	}

	@SuppressWarnings({ "rawtypes", "unchecked", "restriction" })
	public IPluginReference[] getDependencies() {
		ArrayList result = new ArrayList();
		result.add(new PluginReference("org.eclipse.ui", null, 0)); //$NON-NLS-1$
		result.add(new PluginReference(IPDEBuildConstants.BUNDLE_CORE_RUNTIME,
				null, 0));
		return (IPluginReference[]) result.toArray(new IPluginReference[result
				.size()]);
	}

	// public String[] getImportPackages() {
	//		return fPluginData.getOSGiFramework() != null ? new String[] { "org.osgi.framework;version=\"1.3.0\"" } //$NON-NLS-1$
	// : new String[0];
	// }

}

    经过这三步，能生产最基础的插件工程，用处其实不大，需要进一步的定制特别的插件工程内容来满足需求。