Manually Set Map Value in Struts 2

you have to duplicate the format that Struts uses to receive the data. For example, to send a list of items (such as List<String> names;), you would format your URL to look like


&names=johnny&names=tim&names=bill


Maps are a little harder. To create a URL to send to a map, you can use the following format:


&variableName[key]=value


Say you have the following map:

Map<Integer, Integer> userIdOrderIdMap = new HashMap<Integer, Integer>();

To set the map from Struts 2, you’d use the following URL string:


&userIdOrderIdMap[0]=1&userIdOrderIdMap[10]=15

This is the equivalent of:


userIdOrderIdMap.put(0, 1);
userIdOrderIdMap.put(10, 15);


You will probably have to manually call encodeURIComponent() on the URL string to make sure the brackets and any other special characters are escaped properly, but you already knew that, right?

You can also use a dot notation (such as &variableName.key=value), but I find that a bit counterintuitive to the way KVC types are intended to be represented.