步驟：
1. 建立一個org.eclipse.core.resources.IProject
2. 給該project設定description，也就是生成.project檔案
注意：a、JavaCore.NATURE_ID = "org.eclipse.jdt.core.javanature"表示是個java project
b、在將description置入project時，保證project是存在的並且開啟中。
3. 將org.eclipse.core.resources.IProject轉換為java project
IJavaProject javaProject=JavaCore.create(project);
4. 取得eclipse的jre路徑和當前project的路徑，設定原始碼的存放目錄以及*.class檔案的存放目錄
這塊生成的是.classPath檔案中的內容
5. 將一個字串編譯為java檔案和對應的.class檔案

例子:

package com.wisoft.magicube.codegenerator.popup.actions;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.eclipse.core.resources.ICommand;
import org.eclipse.core.resources.IFolder;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IProjectDescription;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.Path;
import org.eclipse.core.runtime.SubProgressMonitor;
import org.eclipse.jdt.core.IClasspathEntry;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.IPackageFragment;
import org.eclipse.jdt.core.IPackageFragmentRoot;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.ui.PreferenceConstants;
import org.eclipse.jface.action.IAction;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.ui.IObjectActionDelegate;
import org.eclipse.ui.IWorkbenchPart;

public class NewJavaProjectAction implements IObjectActionDelegate {

	public void run(IAction action) {
		// 獲取工作區
		IWorkspaceRoot root = ResourcesPlugin.getWorkspace().getRoot();

		// ///////////////////////////////////建立新專案///////////////////////////
		final IProject project = root.getProject("xyz");
		
		// 設定工程的位置
		// 為專案指定存放路徑,預設放在當前工作區
		IPath projectPath = new Path("g:/myplugIn");
		IWorkspace workspace = root.getWorkspace();
		final IProjectDescription description = workspace.newProjectDescription(project.getName());
		description.setLocation(projectPath);

		// 設定工程標記,即為java工程
		String[] javaNature = description.getNatureIds();
		String[] newJavaNature = new String[javaNature.length + 1];
		System.arraycopy(javaNature, 0, newJavaNature, 0, javaNature.length);
		newJavaNature[javaNature.length] = "org.eclipse.jdt.core.javanature"; // 這個標記證明本工程是Java工程
		description.setNatureIds(newJavaNature);

		// /////////////////////////////
		try {
			NullProgressMonitor monitor = new NullProgressMonitor();
			project.create(description, monitor);
			project.open(IResource.BACKGROUND_REFRESH, new SubProgressMonitor(monitor, 1000));
		} catch (CoreException e) {
			e.printStackTrace();
		}

		// 下面程式碼只在新建嚮導的情況下才可用
		/*
		 * //建立新專案,WorkspaceModifyOperation位於org.eclipse.ui.ide中
		 * WorkspaceModifyOperation workspaceModifyOperation = new
		 * WorkspaceModifyOperation() {
		 * 
		 * @Override protected void execute(IProgressMonitor monitor) throws
		 * CoreException, InvocationTargetException, InterruptedException { try
		 * { monitor.beginTask("", ); project.create(description, monitor);
		 * 
		 * if(monitor.isCanceled()){ throw new OperationCanceledException(); }
		 * 
		 * project.open(IResource.BACKGROUND_REFRESH, new
		 * SubProgressMonitor(monitor, )); } catch (Exception e) {
		 * e.printStackTrace(); } finally{ monitor.done(); } } };
		 * //接下來呼叫IWizard的getContainer().run()方法.
		 */

		// 轉化成java工程
		IJavaProject javaProject = JavaCore.create(project);
		// //////////////////////////////////新增JRE庫////////////////////////////
		try {
			// 獲取預設的JRE庫
			IClasspathEntry[] jreLibrary = PreferenceConstants.getDefaultJRELibrary();
			// 獲取原來的build path
			IClasspathEntry[] oldClasspathEntries = javaProject.getRawClasspath();
			List list = new ArrayList();
			list.addAll(Arrays.asList(jreLibrary));
			list.addAll(Arrays.asList(oldClasspathEntries));

			javaProject.setRawClasspath(list.toArray(new IClasspathEntry[list.size()]), null);
		} catch (JavaModelException e) {
			e.printStackTrace();
		}

		// //////////////////////////////////建立輸出路徑/////////////////////////////
		IFolder binFolder = javaProject.getProject().getFolder("bin");
		try {
			binFolder.create(true, true, null);
			javaProject.setOutputLocation(binFolder.getFullPath(), null);
		} catch (CoreException e) {
			e.printStackTrace();
		}

		// /////////////////////////設定Java生成器///////////////////////
		try {
			IProjectDescription description2 = javaProject.getProject().getDescription();
			ICommand command = description2.newCommand();
			command.setBuilderName("org.eclipse.jdt.core.javabuilder");
			description2.setBuildSpec(new ICommand[] { command });
			description2.setNatureIds(new String[] { "org.eclipse.jdt.core.javanature" });
			javaProject.getProject().setDescription(description2, null);
		} catch (CoreException e) {
			e.printStackTrace();
		}

		// /////////////////////////////建立原始碼資料夾//////////////////////////
		// ///////////原始檔夾和資料夾相似,只是使用PackageFragmentRoot進行了封裝////////
		IFolder srcFolder = javaProject.getProject().getFolder("src");
		try {
			srcFolder.create(true, true, null);
			// this.createFolder(srcFolder);
			// 建立SourceLibrary
			IClasspathEntry srcClasspathEntry = JavaCore.newSourceEntry(srcFolder.getFullPath());

			// 得到舊的build path
			IClasspathEntry[] oldClasspathEntries = javaProject.readRawClasspath();

			// 新增新的
			List list = new ArrayList();
			list.addAll(Arrays.asList(oldClasspathEntries));
			list.add(srcClasspathEntry);

			// 原來存在一個與工程名相同的原始檔夾,必須先刪除
			IClasspathEntry temp = JavaCore.newSourceEntry(new Path("/xyz"));
			if (list.contains(temp)) {
				list.remove(temp);
			}

			System.out.println(list.size());

			javaProject.setRawClasspath(list.toArray(new IClasspathEntry[list.size()]), null);
		} catch (CoreException e) {
			e.printStackTrace();
		}

		// ///////////////////////////////建立包//////////////////////////
		// IPackageFragmentRoot packageFragmentRoot = javaProject.getPackageFragmentRoot(javaProject.getResource());
		//此處得到的src目錄只讀

		try {
			// 先找指定的原始檔夾所在的IPackageFragmentRoot
			IPackageFragmentRoot packageFragmentRoot = javaProject.findPackageFragmentRoot(new Path("/xyz/src"));
			// 根據IPackageFragmentRoot建立IPackageFragment,IPackageFragment就是包了
			IPackageFragment packageFragment = packageFragmentRoot.createPackageFragment("com.aptech.plugin", true, null);

		// //////////////////////////////////建立Java檔案////////////////////////
			String javaCode = "package com.aptech.plugin;public class HelloWorld{public static void main(String[] args){System.out.println(\"中華人民共和國\");}}";
			packageFragment.createCompilationUnit("HelloWorld.java", javaCode, true, new NullProgressMonitor());

		} catch (JavaModelException e) {
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}


	public void setActivePart(IAction action, IWorkbenchPart targetPart) {
	}


	public void selectionChanged(IAction action, ISelection selection) {
	}

}