java动态编译加载类问题

Question

今天看到这个http://www.infoq.com/cn/articles/cf-java-byte-code
想试一试，但是编译通过之后的，想执行结果那，总是不成功。现在将代码贴上，望大神指点!
[code="java"]
package com.deep.byteOpera;

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;

public class CompilerTest {
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;
      }
   }

   public static void main(String[] args) throws Exception {      

       String className = "MainTest";
       String methodName = "main";

      String source = "public class "+className+" { public static String "+methodName+" () { System.out.println(\"Hello World!\"); return \"haha\";} }";
      JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

      //动态编译
      StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
      StringSourceJavaObject sourceObject = new CompilerTest.StringSourceJavaObject(className, source);
      Iterable<? extends JavaFileObject> fileObjects = Arrays.asList(sourceObject);
      CompilationTask task = compiler.getTask(null, fileManager, null, null, null, fileObjects);
      boolean result = task.call();

      System.out.println(result);

      if (result) {
          //编译成功，进行加载执行

// ClassLoader loader = fileManager.getClass().getClassLoader();
// ClassLoader loader = fileObjects.getClass().getClassLoader();
// ClassLoader loader = task.getClass().getClassLoader();
// ClassLoader loader = compiler.getClass().getClassLoader();
ClassLoader loader = CompilerTest.class.getClassLoader();
// ClassLoader loader = ToolProvider.getSystemToolClassLoader();
try {

Class<?> clazz = loader.loadClass(className);
Method method = clazz.getMethod(methodName, new Class<?>[] {});
Object value = method.invoke(null, new Object[] {});
System.out.println(value);
} catch (Exception e) {
e.printStackTrace();
}

}
}
}

[/code]

Answer 1

其实编译后会生成一个class文件，关键是文件的路径有问题，所以就找不到了

加上编译选项，指定目录
[code="java"] Iterable options = Arrays.asList("-d", "bin",
"-sourcepath", "src");
CompilationTask task = compiler.getTask(null, null, diagnostics,
options, null, compilationUnits);[/code]
我项目的源代码文件在“src”目录下，生产的class文件在“bin”目录下，你依据自己情况修改。