JSP & servlet Study Notes (1) Basic Web Development Theory

Before actual development, it is necessary to understand some basic theories of web development.
1. url, urn, Uri
URL: Uniform Resource Locator
URN: Uniform Resource Name
Uri: Uniform Resource Identifier
URL: describes how to obtain Internet Resources in text format.
Format: <protocol >:< specific protocol section>
The protocols include FTP, HTTP, mailto, and file.

2. Http features
1) Request \ Response Model
2) stateless communication protocol

3. GET request
Obtain the specified resource from the server. When sending a GET request, you must notify the server of the requested resource URL and some header information.
The request parameter follows a question mark (?) after the URL (?), Then, the Server Request Name and request parameter value are in pairs with the equal sign (=). If there are multiple requests, connect them with the & character.

4. POST request
When a request is sent, the post information is sent to the server. For a large amount of or complex information, it is basically sent using post.

5. Get and post options
1) The length of request parameters that can be sent by GET requests is limited. It is not applicable to a large amount of data. post should be used in this case;
2) the parameters of the GET request will appear in the address bar. The sensitivity and security should be considered when using the GET request;
3) The request parameters of the post request do not appear in the address bar, so they cannot be added to the browser's bookmarks;
4) using post can prevent the browser from retrieving data from catch (get can also be implemented through timestamps );
5) The GET request retrieves resources from the server without changing the data or status on the server. the post request will send data to the server for the query operation of the corresponding database, may affect the data or status on the server.

6. Web Container Definition
1) specific level: A write program responsible for parsing, conversion, and other operations;
2) abstraction layer: the HTTP server running servlet \ jsp can run on the Web container as long as it is written as servlet \ JSP and complies with the Web Container Standard Specifications.

7. javase, javaee, and javame relationships
Javase is an essential standard version for beginners of Java and can meet the needs of standard desktop applications;
Javaee is a comprehensive solution to the problems that enterprises may encounter in various fields;
Javame is a solution for micro-devices, mobile phones, and PDAs.

Reference: JSP & servlet Study Notes Lin Xinliang Tsinghua University Press