Java动态编译

import java.io.File;
import java.io.FileOutputStream;
import java.io.PrintWriter;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

/**
 * 动态编译Java代码
 */
public class DynamicCompileTest {
	public static void main(String[] args) {
		File file = null;
		String classname = null;
		try {
			String classDir = System.getProperty("user.dir");
			file = File.createTempFile("RunTime", ".java", new File(classDir));
			String filename = file.getName();
			classname = filename.substring(0, filename.lastIndexOf('.'));
			PrintWriter out = new PrintWriter(new FileOutputStream(file));
			// 代码
			String code = "public class " + classname + " {"
					+ "public void run() {"
					+ "System.out.println(\"DynamicCompile Success.\");" + "}}";
			out.println(code);
			out.flush();
			out.close();
			// 编译
			String[] arg = new String[] { "-d", classDir, filename };
			com.sun.tools.javac.Main.compile(arg);// JAVA_HOME/jdk/lib/tools.jar
			URL url = new URL("file:/" + classDir + File.separator);
			// 动态加载/执行
			URLClassLoader loader = new URLClassLoader(new URL[] { url });
			Class<?> clazz = loader.loadClass(classname);
			Object obj = clazz.newInstance();
			Method method = clazz.getMethod("run");
			method.invoke(obj);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (file != null) {
				file.delete();
				file = new File(classname + ".class");
				if (file != null)
					file.delete();
			}
		}
	}
}

 

代码参考了其它网站。