URLEncoder. Encode and urldecoder Decode processing URL

URLEncoder.encode (str,"UTF-8");

URLDecoder.decode(str,"UTF-8");

URLEncoder.encode and URLDecoder.decode Handle url Special parameters of

In the use of url Of queryString When passing parameters , Because the value of the parameter , By DES Encrypted , And the result of encryption is Base64 Encoding string of , Be similar to ：

za4T8MHB/6mhmYgXB7IntyyOUL7Cl++0jv5rFxAIFVji8GDrcf+k8g==

obviously It contains Special characters ： / + = wait , If you go straight through url To pass this parameter ：

url = "xxxxx?param=" + "za4T8MHB/6mhmYgXB7IntyyOUL7Cl++0jv5rFxAIFVji8GDrcf+k8g==";

Then get at the server param It will become a value similar to the following ：

"za4T8MHB/6mhmYgXB7IntyyOUL7Cl  0jv5rFxAIFVji8GDrcf k8g=="

We see Three + No. 1 disappeared .

And the reason is ： If url When the parameter value contains special characters , Need to use url code .

url = "xxxxx?param=" + URLEncoder.encode("xxx", "utf-8");

Then when the server obtains ：

String param = URLDecoder.decode(param, "utf-8");

In this way, the correct value can be obtained ："za4T8MHB/6mhmYgXB7IntyyOUL7Cl++0jv5rFxAIFVji8GDrcf+k8g=="

Actually js There are functions with similar functions in ：

See ：js Three encoding functions in ：escape,encodeURI,encodeURIComponent

matters needing attention ：

URLEncoder should be the way to go. You only need to keep in mind to encode only the individual query string parameter name and/or value, not the entire URL, for sure not the query string parameter separator character & nor the parameter name-value separator character =

String q = "random word  Close up 500 bank $";
String url = "http://example.com/query?q=" + URLEncoder.encode(q, "UTF-8");

URLEncoder must only code Parameters Or the value of the parameter , Cannot encode the whole url, Nor can we do it together param=value Encoding . It should be ： param=URLEncode(value, "utf-8")

perhaps URLEncode(param, "utf-8")=URLEncode(value, "utf-8")

because url Medium & and = They are used as parameters between as well as Separator between parameter and value . If we code together , You can't distinguish them .

Further reference documentation ：

https://www.talisman.org/~erlkonig/misc/lunatech%5Ewhat-every-webdev-must-know-about-url-encoding/