字节码加载

gistfile1.java

参照网上其他童鞋的例子与介绍，修改了一下：
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Arrays;

import javax.tools.JavaCompiler;
import javax.tools.JavaCompiler.CompilationTask;
import javax.tools.JavaFileObject;
import javax.tools.SimpleJavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;

/**
 * 动态编译Java 源文件
 * 
 * @author shenshouer
 * 
 */
public class CompilerTest {

	public static void main(String[] args) throws Exception {
		String source = "public class Main { " + "public static void main(String[]args) {"
						+ "System.out.println(\"Hello World!\");" + "} " + "}";

		JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
		StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
		StringSourceJavaObject sourceObject = new CompilerTest.StringSourceJavaObject("Main",
						source);
		Iterable<? extends JavaFileObject> fileObjects = Arrays.asList(sourceObject);
		
		 // 获取编译类根路径，不然会报找不到类的错误
		String path = Class.class.getClass().getResource("/").getPath();
		Iterable< String> options = Arrays.asList("-d", path); 
		
		// 增加options参数
		// CompilationTask task = compiler.getTask(null, fileManager, null, null, null, fileObjects);
		CompilationTask task = compiler.getTask(null, fileManager, null, options, null, fileObjects);

		boolean result = task.call();

		if (result) {
			System.out.println("编译成功。");

			ClassLoader loader = CompilerTest.class.getClassLoader();
			try {
				Class<?> clazz = loader.loadClass("Main");
				Method method = clazz.getMethod("main", String[].class);
				// 修改调用参数，不然会报参数个数不对
				// Object value = method.invoke(null, new Object[] {});
				Object value = method.invoke(null, new Object[] {new String[]{}});
				System.out.println(value);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

	static class StringSourceJavaObject extends SimpleJavaFileObject {

		private String content = null;

		public StringSourceJavaObject(String name, String content) throws URISyntaxException {
			super(URI.create("string:///" + name.replace('.', '/') + Kind.SOURCE.extension),
							Kind.SOURCE);
			this.content = content;
		}

		public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {
			return content;
		}
	}
}