【Java WEB】Nginx&Tomcat&HTTP协议

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Article directory

Nginx

Nginx is a server software
Its core function is that it can be combined with server hardware, so that the program can be published to the Nginx server, allowing more users to browse

Install

Upload compressed package: put nginx压缩包位置(press alt+p in CRT to enter sftp)
Unzip the compressed package:tar -zxvf 压缩包名
Enter the decompression directory:cd nginx解压目录
Install dependencies

yum -y install pcre pcre-devel

yum -y install zlib zlib-devel

yum -y install openssl openssl-devel
yum -y install gcc
Install nginx
./configure
make
make install(there will be an nginx directory under /usr/local/ after installation)
Enter the corresponding directory:cd /usr/local/nginx/sbin
Start nginx service: ./nginx
stop: ./nginx -s stop
restart:./nginx -s reload
Check the nginx service status:ps -ef | grep nginx
Test the nginx service: the browser opens the corresponding Linux server ip address

Finally, open the corresponding ip address in the browser and cannot access it. The solution:
the first step, configure the firewall for port 80: the firewall-cmd --zone=public --add-port=80/tcp --permanent
second step, restart the firewall service: systemctl restart firewalld.service
then re-visit your ip in the browser, it should be able to access .

Publish the project

exist/homeCreate a web directory under:mkdir web
Upload the project to this directory:put web项目压缩包
Unzip the project archive:unzip web程序压缩包
Edit the nginx configuration file: vim /home/nginx-1.18.0/conf/nginx.conf
find the curly bracket range of the server and modify the path of the location
Enter the corresponding directory:cd /usr/local/nginx/sbin
Shut down the nginx service:./nginx -s stop
Start the nginx service and load the configuration file:/usr/local/nginx/sbin/nginx -c/home/nginx-1.18.0/conf/nginx.conf
Test the website through your browser

Introduction to Enterprise Development

JavaEE Specification

JavaEE (Java Enterprise Edition): Java Enterprise Edition
It is an industry standard that is led by SUN and jointly developed by various manufacturers and is widely recognized.
JavaEE was called J2EE in the early days, but it did not continue to use its naming convention. The version of J2EE starts from 1.0 to the end of 1.4. The JavaEE version starts from the JavaEE 5 version, and the latest version is JavaEE 8.
The JavaEE specification is an umbrella term for many Java development techniques. These technical specifications are inherited from J2EE. A total of 13 technical specifications are included.
包括：JDBC, JNDI, EJB, RMI, IDL/CORBA, JSP, Servlet, XML, JMS, JTA, JTS, JavaMail, JAF。

WEB overview

Overview

WEB in the computer field representsThe internet。
Like the WWW we used before, it's an acronym for the three-word World Wide Web, called:World Wide Web
The emergence of network-related technologies is to allow us to live in a networked worldAccess to resources, where these resources are stored, we call itwebsite。
By entering the address (URL) of the website, we can access the resources provided in the website (without distinguishing between local area network and wide area network)

Resource classification

Static resources
The resources provided to people on the website are immutable, that is to say, different people or at different times, see the same content.

As developers, the HTML, CSS, and JavaScript we write are all static resources.
Dynamic resources
The resources displayed to people on the website are generated by programs, and different people see different content at different times or due to different identities.

As a website developer, the JSPs and Servlets we write are all dynamic resources.

system structure

In the previous study, all Java projects were developed. These projects are called projects or products in the enterprise. It's all about the system!

Infrastructure division

CS structure: (Client Server)Client + Serverway (installing different applications directly on the client)
BS structure: (Browser Server)browser + serverThe way

Technology selection division

Model1 model
Model2 model
MVC model
Three-tier architecture + MVC model

Deployment method division

Integrated structure
vertical split structure
Distributed structure
Microservice Architecture

Tomcat

server

A server is a type of computer that runs faster, has a higher load, and is more expensive than a normal computer.

The server provides computing or application services for other clients (such as PCs, smart devices, etc.) in the network.
The server has high-speed CPU computing power, long-term reliable operation, powerful I/O external data throughput and better scalability.

The server we are talking about here is actually a web server, or an application server. It is essentially a piece of software that, by combining with hardware, can help us publish applications and allow users to access our applications through clients.

Common application server

server nickname	illustrate
weblogic	Implements the JavaEE specification, heavyweight server, also known as JavaEE container
websphereAS	Implemented the JavaEE specification, heavyweight server
JBOSSAS	Implements the JavaEE specification, heavyweight server, free
Tomcat	It implements the jsp/servlet specification and is a lightweight server, open source and free

Tomcat

Tomcat is a core project in the Jakarta project group of the Apache Software Foundation, jointly developed by Apache, Sun and some other companies and individuals.

Thanks to Sun's participation and support, the latest Servlet and JSP specifications can always be reflected in Tomcat.
Because of its advanced technology, stable performance, and free, Tomcat is deeply loved by Java enthusiasts and has been recognized by some software developers. It has become a popular Web application server.
Tomcat official website: https://tomcat.apache.org/
Support required for each version of Tomcat

Download and install

Download: official website download
Installation: Just unzip it directly

directory composition

bin: some binary executables
conf: The path to save the configuration file
lib: jar package required by Tomcat during operation
logs: log file
temp: temporary file
webapps: The project publishing directory (a folder represents a web application) (ROOT represents the root project)
work: working directory

basic use

Startup
startup.bat: Start the executable file under Windows: Start the executable file
startup.shunder Linux

After startup, browser access: http://localhost:8080 to enter the welcome interface (Tomcat default port is 8080)
Stop
shutdown.bat: Close the executable file under Windows: Close the executable file
shutdown.shunder Linux
Deploy the project
Create a folder in the webapps directory
Put the resources in the folder
Start tomcat and enter the correct path

common problem

Startup problem
The startup window flashes by: jdk environment variables are not configured

java.net.BindException: Port 8080 is occupied
Console garbled problem solving
conf-logging.properties
modificationjava.util.logging.ConsoleHandler.encoding = UTF-8

Tomcat defaults to UTF-8, and the CMD command window defaults to GBK. Changing UTF-8 to GBK can solve the problem of garbled characters

IDEA integrates Tomcat

Click on Run -> Edit Configurations
点击Defaults -》 Tomcat Servlet -》 Local
Click Configure - "Tomcat Home -" to select the path where tomcat is located

Installation under Linux

Upload the compressed package to the /home path:put d:/apache-tomcat-9.0.58.tar.gz
Unzip the compressed package:tar -zxvf 压缩包名
Enter the bin directory:cd apache-tomcat-9.0.58/bin
Start the tomcat service:./startup.sh
Use browser test: browser open the corresponding Linux server ip address: 8080

Java WEB project

Create a new project model and select Java Enterprise
to determine the JDK version and Application Server version
右键Add Framework Support…
Check the Web Application option

Detailed project composition

src: store Java source code
web: store project-related resources (html, css, js, jsp, pictures, etc.)
WEB-INFO: Stores related configurations (web.xml, etc.)

IDEA publishes the project

Click on Run -> Edit Configurations
Click Tomcat Server -> Deployment
Application Context is the project access path, / represents the default path, there can only be one default path in multiple projects
Click Tomcat Server -> Server
settings associated browser
Two Update resources settings
Set JDK, port number
Start the Tomcat service
Validation results (browser)

Publish project via war package

Open the war package in the web path of the project:jar -cvf myweb.war .
Cut the prepared war package to the webapps path of tomcat
Start the tomcat service and automatically decompress the war package
Validation results

configuration file

Configure the default port number

main configuration fileserver.xml

<Connector>In the label, the port attribute represents the default port number of Tomcat (8080)
insert image description here

The default port number of the http protocol is 80, and the default port number of Tomcat is inconsistent with it, so
you need to add the port number every time you visit
the website. It is 80, so you don't need to add the port number when accessing the website

Configure virtual directory

Role: You can publish projects in any directory

editserver.xmlconfig file, find the <Host>tag
add the following
<Context path="/mytest" docBase="e:/test" />

path: The virtual directory name of the access resource (representing the access path in the browser address bar)
docBaserepresents the real path of the project that needs to be published

Configure virtual hosts

Role: You can specify the name of the access path

editserver.xmlconfig file, find the <Engine>tag
add the following

name: Virtual host name
appBase: The root path where the project is saved
unpackWARs: Whether to automatically decompress the war package
autoDeploy: Whether to automatically publish
Context: the same as the virtual directory

Modify the hosts file
to bind the IP address and the corresponding domain name
file path:c:\Windows\System32\drivers\etc

HTTP protocol

Overview

HTTP(Hyper Text Transfer Protocol)：Hypertext Transfer Protocol
HTTP protocol is based on TCP/IP protocol (secure)
Hypertext: more powerful than normal text (plus pictures, audio, etc.)
Transmission protocol: communication rules between client and server (handshake rules)

component

Request: The client initiates a request to the server
Response: The server sends a response to the client after receiving the client's request

In addition to manually initiated requests, JavaScript, CSS, images and other resources will automatically initiate requests

request for agreement

components of the request

Request line: Request method submission path (submission parameters) HTTP/version number

request header

name	illustrate
Accept	MIME types supported by client browsers
Accept-Encoding	The compression encoding format supported by the client browser. The most commonly used is gzip compression
Accept-Language	The languages supported by the client browser. Usually zh_CN or en_US, etc.
Referer	Tell the server where the current request is coming from
Content-Type	MIME types supported by the request body
Content-Length	the length of the request body
User-Agent	Browser related information
Connection	The status of the connection. Keep-Alive stay connected
If-Modified-Since	The last modification time of the client browser cache file
Cookie	Session management related, very important

Request blank line: normal newline, used to distinguish request header and request body
Request body: Only the POST submission method has a request body, which is used to display the submission parameters

way of request

GET

insert image description here

POST

insert image description here

Only the POST request method has a request body, and the GET request method does not have a request body
. The parameters submitted by get are in the request line, and the parameters submitted by post are in the request body.

protocol response

Components of a Response

Response Line: Request Mode HTTP/Version Number Status Code Status Description
Common Status Codes

status code	illustrate
200	everything is ok
302/307	Request redirection, two requests, address bar changes
304	The requested resource has not changed, use the cache
404	Requested resource not found
500	Server Error

response header

name	illustrate
Location	The address to request redirection, often used in conjunction with 302 and 307
Server	Server related information
Content-Type	MIME type of the response body
Content-Length	the length of the response body
Content-Disposition	Tell the client browser to open the response body as a download
Refresh	Timed refresh
Last-Modified	The last modification time of the server resource
Set-Cookie	Session management related, very important
Expires:-1	The cache time after the server resource is sent to the client browser
Catch-Control:no-catch	don't cache

Response blank line: a normal newline, used to distinguish the response header from the response body
Response body: Send the resource file to the client browser for parsing

Publish resource case

Publish static resources

Create a Java WEB project
Import the resources required by the static page into the web directory of the project

Modify the web.xml configuration file, modify the default home page

<!--在web.xml中加入-->
<welcome-file-list>
    <welcome-file>/路径/文件名.html</welcome-file>
</welcome-file-list>

Deploy the project to tomcat
Start the tomcat service
Open the browser to view the page

Introduction to Servlet

Servlet is a program running on the Java server side to receive and respond to requests from clients based on the HTTP protocol.
If you want to achieve the function of Servlet, you can achievejavax.servlet.Servletinterface or an implementation class that inherits it.
Core method: service(), any client request will go through this method.

Publish dynamic assets

Create a JavaWEB project
Import the resources required by the static page into the web directory of the project
Modify the web.xml configuration file, modify the default home page
Write a class under the src path of the project to implement the Servlet interface
Rewrite the service method and output a sentence

Modify the web.xml configuration file to configure servlet-related resources

<!--Servlet声明-->
<servlet>
    <servlet-name>自定义名称</servlet-name>
    <servlet-class>java全类名（包名.类名）</servlet-class>
</servlet>

<!--Servlet映射-->
<servlet-mapping>
    <servlet-name>和声明中的名称保持一致</servlet-name>
    <url-pattern>/访问路径(浏览器地址栏要输入的访问路径)</url-pattern>
</servlet-mapping>

Deploy the project to tomcat
Start the tomcat service
Open the browser test function

Implementation process

Access to the specified resource path through a browser
Find the corresponding name tag through url-pattern
Find the corresponding servlet declaration by name
Find the corresponding Java implementation class in the declaration
Execute the service method

Recommended reading: [Java WEB] Servlet & Annotation Development