Doget and dopost

doGet And doPost

One 、 brief introduction

1、doGet
doGet Call to get server information , And put it back to the client as a corresponding . Through Web Browser or through HTML、JSP Direct access Servlet Of URL when , It's usually used Get call

2、doPost
It is used to transfer data from the client to the server , It can hide any data sent to the server .Post Suitable for sending large amounts of data .

Two 、 difference

1、 generation
get There are four ways to generate ：1） Directly in URL Enter... In the address field URL.2） Hyperlinks in web pages .3）form in method by get.4）form in method It's empty time , The default is get Submit .

post generation ：form in method The attribute is post.

2、 Data transmission mode
get The way ： The form data is stored in URL After the address . all get When the method is submitted HTTP There is no message body in .

post The way ： The form data is stored in HTTP The message body of the protocol is sent to the server in the form of entities .

3、 How the server obtains data
GET The way ： The server uses request.QueryString To get the value of a variable .

POST The way ： The server uses request.Form To get data .

4、 The amount of data transmitted
GET The way ： There is a limit on the amount and length of data , Generally not more than 2kb. Because it is parameter passing , And in the address bar , Therefore, the amount of data is limited .

POST The way ： Suitable for large-scale data transmission . Because it is transmitted in the form of entities .

5、 Security
GET The way ： Poor safety . Because the data is directly displayed in the address bar , The browser has a buffer , User information can be recorded . So low security .

POST The way ： High safety . because post When submitting data, we use HTTP post Mechanism , Is to place the fields and values in the form in HTTP HEADER Transfer to ACTION Referred to URL in , Users are invisible .

6、 On user refresh
GET The way ： There will be no hint 、

POST The way ： A prompt box will pop up , Ask the user whether to resubmit