request的Map数据的遍历
request得到的map的数据结构，<String,String[]>
Map<String, String[]> parameterMap = request.getParameterMap();
for(Map.Entry<String, String[]> entry:parameterMap.entrySet()){System.out.println(entry.getKey());
for(String str:entry.getValue()){
System.out.println(str);
}
}