Java 如何手写一段代码实现将java源码编译成字节码？ Java文件-》class文件

 JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

this.stdManager = compiler.getStandardFileManager(null, null, null);

/**
	 * Compile a Java source file in memory.
	 * 
	 * @param fileName
	 *            Java file name, e.g. "Test.java"
	 * @param source
	 *            The source code as String.
	 * @return The compiled results as Map that contains class name as key,
	 *         class binary as value.
	 * @throws IOException
	 *             If compile error.
	 */
	public Map<String, byte[]> compile(String fileName, String source) throws IOException {
		try (MemoryJavaFileManager manager = new MemoryJavaFileManager(stdManager)) {
			JavaFileObject javaFileObject = manager.makeStringSource(fileName, source);
			CompilationTask task = compiler.getTask(null, manager, null, null, null, Arrays.asList(javaFileObject));
			Boolean result = task.call();
			if (result == null || !result.booleanValue()) {
				throw new RuntimeException("Compilation failed.");
			}
			return manager.getClassBytes();
		}
	}