request.getParameterMap值[Ljava.lang.String; cannot be cast to java.lang.String错误

When using request.getParameterMap() to get the data in the Map today, use
       Map map=hrequest.getParameterMap();
            Set key = map.keySet();
            for(Object aaa: key.toArray()){
            parakey = aaa.toString ();
            paravalue = (String)map.get(aaa);
            requestpath = requestpath+"?"+parakey+"="+paravalue;
            }

Cannot be cast to java.lang.String error, I checked the Internet and found out that get(key) returns String[], so use string array conversion to read, see the English interface documentation:
 

So you can create a tool class and convert it into a normal map:

[java] view plain copy

1. /** 
2.  * Get the parameter Map from the request and return a readable Map 
3.  *  
4.  * @param request 
5.  * @return 
6.  */  
7. @SuppressWarnings("unchecked")  
8. public static Map getParameterMap(HttpServletRequest request) {  
9.     // parameter Map  
10.     Map properties = request.getParameterMap();  
11.     // return value Map  
12.     Map returnMap = new HashMap();  
13.     Iterator entries = properties.entrySet().iterator();  
14.     Map.Entry entry;  
15.     String name = "";  
16.     String value = "";  
17.     while (entries.hasNext()) {  
18.         entry = (Map.Entry) entries.next();  
19.         name = (String) entry.getKey();  
20.         Object valueObj = entry.getValue();  
21.         if(null == valueObj){  
22.             value = "";  
23.         }else if(valueObj instanceof String[]){  
24.             String[] values = (String[])valueObj;  
25.             for(int i=0;i<values.length;i++){  
26.                 value = values[i] + ",";  
27.             }  
28.             value = value.substring(0, value.length()-1);  
29.         }else{  
30.             value = valueObj.toString();  
31.         }  
32.         returnMap.put(name, value);  
33.     }  
34.     return returnMap;  
35. }  

 

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