@Override
 public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
   for (TypeElement t : annotations) {
     for (Element e : roundEnv.getElementsAnnotatedWith(t)) {
       System.out.println(e + " " + t);
     }
   }
   return true;
 }
 // 循环处理每个需要处理的程序对象
 public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
   // 定义一个文件输出流,用于生成额外的文件
   PrintStream ps = null;
   try {
     // 遍历每个被@Persistent修饰的class文件
     for (Element t : roundEnv.getElementsAnnotatedWith(Persistent.class)) {
       // 获取正在处理的类名
       Name clazzName = t.getSimpleName();
       // 获取类定义前的@Persistent Annotation
       Persistent per = t.getAnnotation(Persistent.class);
       // 创建文件输出流
       ps = new PrintStream(new FileOutputStream(clazzName + ".hbm.xml"));
       // 执行输出
       ps.println("<?xml version=\"1.0\"?>");
       ps.println("<!DOCTYPE hibernate-mapping PUBLIC");
       ps.println("	\"-//Hibernate/Hibernate " + "Mapping DTD 3.0//EN\"");
       ps.println("	\"http://www.hibernate.org/dtd/" + "hibernate-mapping-3.0.dtd\">");
       ps.println("<hibernate-mapping>");
       ps.print("	<class name=\"" + t);
       // 输出per的table()的值
       ps.println("\" table=\"" + per.table() + "\">");
       for (Element f : t.getEnclosedElements()) {
         // 只处理成员变量上的Annotation
         if (f.getKind() == ElementKind.FIELD) // ①
         {
           // 获取成员变量定义前的@Id Annotation
           Id id = f.getAnnotation(Id.class); // ②
           // 当@Id Annotation存在时输出<id.../>元素
           if (id != null) {
             ps.println(
                 "		<id name=\""
                     + f.getSimpleName()
                     + "\" column=\""
                     + id.column()
                     + "\" type=\""
                     + id.type()
                     + "\">");
             ps.println("		<generator class=\"" + id.generator() + "\"/>");
             ps.println("		</id>");
           }
           // 获取成员变量定义前的@Property Annotation
           Property p = f.getAnnotation(Property.class); // ③
           // 当@Property Annotation存在时输出<property.../>元素
           if (p != null) {
             ps.println(
                 "		<property name=\""
                     + f.getSimpleName()
                     + "\" column=\""
                     + p.column()
                     + "\" type=\""
                     + p.type()
                     + "\"/>");
           }
         }
       }
       ps.println("	</class>");
       ps.println("</hibernate-mapping>");
     }
   } catch (Exception ex) {
     ex.printStackTrace();
   } finally {
     if (ps != null) {
       try {
         ps.close();
       } catch (Exception ex) {
         ex.printStackTrace();
       }
     }
   }
   return true;
 }