Question: `getQueryString()` 

gives 

`cid=1&params=zDmrLGXJ1DboOuqBn2062Z%2BQmQ4w7ODNGAfZL4L8rpk%3D`.

and

`getParameter(PARAM_NAME)` 

gives 

```
zDmrLGXJ1DboOuqBn2062Z+QmQ4w7ODNGAfZL4L8rpk=

```

What happened with `%3D.` ?

I used `URLEncoder.encode(url, "UTF-8")` to create *params*.

Answer: 
`%3D` is the equal (=) sign you have at the end of the parameter string. It's the same with `%2B` which was replaced by its decoded value: plus (+) sign.
The `URLEncoder` coverts any [special characters](http://en.wikipedia.org/wiki/Percent-encoding) (@,=,+,etc.) so that it can be used as a url. `getParameter()` coverts the string back to what it was originally while `getQueryString()` returns the raw querystring.