Example of Map of the returned value of request. getParameterMap in java

Request. the returned type of getParameterMap () is a Map-type object, that is, the corresponding relationship of key-value. However, note that the type of value is String [], not String.

It is easy to obtain the parameters submitted on the jsp page, but it can be used to convert the parameters and values in the request into a map. The following is a map structure formed by printing the obtained parameters and values: map (key, value []), that is, the key is a String type, and the value is a String type array.
For example:
The form request contains the multi-choice box checkbox or the parameter t1 = 1 & t1 = 2 & t2 = 3 in the request.
Map Structure:

The Code is as follows:	Copy code
Key = t1; value [0] = 1, value [1] = 2 Key = t2; value [0] = 3

If map. get ("t1") is used directly, the result is: Ljava. lang. String; value is only in the array format, which prevents the same parameter name.

Example

The Code is as follows:

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/** * Obtain the parameter Map from the request and return a readable Map. * * @ Param request * @ Return */ @ SuppressWarnings ("unchecked ") Public static Map getParameterMap (HttpServletRequest request ){ // Parameter Map Map properties = request. getParameterMap (); // Return value Map Map returnMap = new HashMap (); Iterator entries = properties. entrySet (). iterator (); Map. Entry entry; String name = ""; String value = ""; While (entries. hasNext ()){ Entry = (Map. Entry) entries. next (); Name = (String) entry. getKey (); Object valueObj = entry. getValue (); If (null = valueObj ){ Value = ""; } Else if (valueObj instanceof String []) { String [] values = (String []) valueObj; For (int I = 0; I <values. length; I ++ ){ Value = values [I] + ","; } Value = value. substring (0, value. length ()-1 ); } Else { Value = valueObj. toString (); } ReturnMap. put (name, value ); } Return returnMap; }