Java-Beans rufen Instanzen über die API der Karte auf

//将student的信息拼成字符串，格式：stuname|stuage|stuclass
protected String getLine(Student student) {
           StringBuilder sb = new StringBuilder();
           BeanMap map = new BeanMap(student );
           appStr(sb, map, "stuname");
           appStr(sb, map, "stuage");
           appStr(sb, map, "stuclass");
           return sb.toString();
     }
 
//将teacher的信息拼成字符串，格式：tname|tage|tclass
protected String getLine(Teacher teacher) {
           StringBuilder sb = new StringBuilder();
           BeanMap map = new BeanMap(teacher);
           appStr(sb, map, "tname");
           appStr(sb, map, "tage");
           appStr(sb, map, "tclass");
           return sb.toString();
     }
     
 
//拼字符串公用方法，将不同的对象，比如studengt和teacher的信息通过map传到方法里
protected void appStr(StringBuilder sb, Map<String, Object> map,
                String str) {
           Object value = map.get(str);
           sb.append(newValue).append("|");
     }