code: public String fillCode(File javaFile,StringBuilder bufferCode) throws IOException
  	{
  		String javaSource=FileUtils.readFileToString(javaFile, CharsetUtil.UTF_8);
  		javaSource=javaSource.replaceAll(BEGIN_FLAG_MATCH,BEGIN_FLAG);
  		javaSource=javaSource.replaceAll(END_FLAG_MATCH,END_FLAG);
  		String startFlag=BEGIN_FLAG;
  		String endFlag=END_FLAG;
  		int start=javaSource.indexOf(startFlag);
  		int end=javaSource.indexOf(endFlag);
  		if(start>0&& end>0)
  		{
  			String head=javaSource.substring(0, start+startFlag.length());
  			String til=javaSource.substring(end, javaSource.length());
  			javaSource=head+"\n"+bufferCode.toString()+"\n"+til;
  		}else
  		{
  			log.error("not found match:"+javaFile.getName());
  		}
  		return javaSource;
  	}
docs: 填充代码
  @param javaFile
  @param bufferCode
  @return
  @throws IOException