Project Description
The project is not small, just meet it!
This blog project is a simple blog system based on the basic knowledge of JAVA web. The main functions include user login and basic operations of adding, deleting, checking and modifying articles.
Use technology
Maven: Manage dependent packaged projects
Mysql: Store business data
HTML: Make front-end login page
Servlet: Back- end service resources complete related business
Jackson: Complete the serialization and deserialization of Java objects and Json string data agreed upon between the front and back ends based on the Jackson framework
Tomcat: server for web project deployment
Filter: unified session management for all logins
Business realization
The article management operations of this system are all based on the premise of user login.
Implementation process
Ready to work
Design database tables
Since this system is relatively simple and only involves users and articles, only two tables are designed: user table and article table
Convention front and back json response format
The data carriers of the request and response of these interfaces such as articleAdd/articleUpdate/articleDelete/articleList are all in JSON format, so the front and back ends are agreed in advance, and the interaction between the two parties will be much easier.
Filter
Before the client's request is distributed by the server to the specific servlet service, it needs to be filtered (Filter linearly manages multiple filters), and the requests will be filtered one by one.
Configure the filter for user unified session management to match all request paths (/*)
- Each time an http request matches the filter path, the doFilter() of the filter will be executed first
- If it is executed later, it is to call filterChain.doFilter(request,response)
- Otherwise handle the response by yourself
Server resources
/login does not need to verify the Session, all others must be verified. If it fails, it returns 401, and the response content is customized
Front-end resources
/jsp/Verify session, if session is empty, redirect to login page
/js/,/static/,/view/ No verification required
Template technology
For repetitive things, let the interfaces handle them in a unified way, and leave the rest to subclasses to rewrite and implement themselves.
Here the parent class implements the doGet and doPost methods, and the subclass only needs to rewrite the process method according to its own business logic.
Realize code reuse.
Business Process
User is not logged in
Page information is realized through the above-mentioned filter unified session management! The access path here is "blog/", the filter judges that the user session is empty, and the access path does not start with "/jsp", it is known that the user has not logged in.
The user is not logged in, the judgment logic in the Filter:
enter the url, the user visits the login page, the
user enters the user information and clicks "login"
During the implementation of the login page, js was introduced into the HTML. When the user clicks to log in, the front end will initiate two js requests, the other one is an Ajax request. The "form submission" event is bound through Ajax. When the user submits and the login page is loaded, it will automatically carry the front-end data to initiate a request.
Ajax serializes the requested form data into json format, and executes the corresponding content according to the data analysis. The request service path of Ajax is "/login", and the server finds the corresponding servlet service to process the business according to the service path.
What happened after the user clicked submit?
When the user clicks submit, the server finds the LoginServlet service according to the request service path in the Ajax request, parses the user information here, and connects to the database through the JDBC operation to verify that the user information is correct.
If the user name and password match the database information, the front-end json response information is returned. In js, it is judged whether it is successful according to the json information, and success will jump to the user's article list interface, indicating that the user login is successful.
Successfully logged in!
From the user's point of view, I thought it was just a simple page jump. In fact, the front and back ends had multiple interactions. Otherwise, just the user clicks to log in, how can I get the user's personal article list?
Get a list of articles
front end
When the user clicks to log in, the front end initiates an articleList service request.
According to the json data of the back end response, the user's article list information is displayed.
The back-end
server receives the request and goes to the servlet service corresponding to "articleLis" to obtain user information from the session.
Connect to the database through JDBC to complete the query of the user's personal article list.
After the database operation is successful, the server will return json response information to the front end.
After the user logged in successfully, the background also quietly did one thing:
Kind of session! Save user information, which is equivalent to a pass!
Then you can add, delete, modify and check the articles under the user name!
Publish a new article
Click "Publish New Article" to open a new window, displaying the article details page for users to edit the content of the article.
Front end
When the user clicks "Publish a new article", the interface jumps to the article details page "jsp/articleDetail.jsp" and sets the type to add.
Details page request information
According to the type information, after the user clicks submit, a service request for articleAdd is initiated.
According to the json information returned by the server, determine whether the addition is successful, and feedback to the user.
The back-end
server obtains user information from the session under the corresponding service resources, obtains the complete request data from the request body through the input stream, and deserializes the json data into an article object. Enter ArticleDAO.insert(), and complete the article record insertion operation of the database through JDBC.
After the database record is successfully inserted, the server edits the response information according to the agreed json information format of the front and back ends, serializes it into json format, and returns it to the front end.
modify articles
Select the article that needs to be modified and click Modify, and a new window will open to jump to the article details page.
Only one article can be selected for modification, and the modification is bound to the button click event. After the click event is triggered, it will jump to jsp/articleDetail.jsp and add the setting type to "update".
The modification is based on the content of the original article, first request the "articleDetail" service resource.
After the user clicks submit, according to the type information, a post request is initiated to request the "articleUpdate" service resource.
According to the json information returned by the backend, determine whether the article has been updated successfully, and give feedback to the user. ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
The back-end
server first parses the article ID according to the received "articleDetail" service request, finds the article information in the database through JBDC, and returns it to the front-end to display the content information of the article.
After the user clicks submit, the server receives the request of the "articleUpdate" service, deserializes the request data in json format into an article class object, and then completes the update operation of the database record through JDBC. After the database is updated successfully, the json response information is returned to the front end to inform that it has been updated.
Delete article
The user selects the article that needs to be deleted, and clicks delete. A prompt box will pop up to ask the user whether to confirm the deletion.
After the front-end
user clicks to confirm, it initiates an articleDelete service resource request.
According to the back-end json response information, determine whether the deletion is successful. After the back end is successfully deleted, the front end can delete the article display.
The back-end
server finds the corresponding service resource "articleDelete", parses the request to obtain the article ID, and completes the deletion of the article record in the database through JDBC operations.
