1. Agile development and continuous integration (CI)
1. What is agile development
Agile development takes the evolution of user needs as the core and adopts an iterative and step-by-step approach to software development. In agile development, the software project is divided into multiple sub-projects in the early stages of construction, and the results of each sub-project are tested and have the characteristics of being visible, integrable, and runnable. In other words, a large project is divided into multiple small projects that are interrelated but can also be run independently and are completed separately. During this process, the software is always in a usable state.
2. What is continuous integration (CI)
Because the development department maintains multiple versions at the same time, the release and testing of multiple versions requires a lot of manpower, so a professional continuous integration tool is needed to manage continuous repetitive work.
// 1. Party A makes a request
// Feasibility Analysis
// Requirements -> Development -> Test
//bug ZenTao
// bug level high
2. Continuous Integration Tool (CI)
1.Jenkins and Hudson
Jenkins is a continuous integration (CI) tool. It can continuously compile and run your code; run unit tests (UT) or integration tests; send running results to email or display them as reports.
Jenkins originated from Hudson. Hudson continues to move forward on the road of commercial software, while Jenkins is branched from hudson as open source software. Therefore, the current Jenkins and Hudson are very similar, but with their respective development, there have been some differences.
2. Technology combination
Jenkins can integrate GitHub or Subversion. Husband can also integrate GitHub or Subversion. Since the two are the same source of tool software, the operation and guiding ideology are close.
3. Comparison of deployment projects
Comparison of JavaEE project deployment methods
Manual deployment
git ->checkout-> war ->deployment
Automated deployment
The specific embodiment of “automation”: after submitting new code to the repository, it is automatically deployed on the application server, and users or testers immediately use the latest application.
Building the above-mentioned continuous integration environment can automate the entire construction and deployment process, reducing the workload to a great extent. It will not cause any additional burden on programmers’ daily development – after they submit the code, the latest version will be running on the server immediately – everything happens invisibly.
3. Install Jenkins
1. Installation prerequisites
Configure tomcat and jdk11 on the virtual machine (jdk8 is not recommended here because jdk8 is not suitable for jenkins, so jdk11 is recommended)
1.1 jdk11 download and configuration
First install jdk. After successful installation, you will go to the default location for file download. Remember the path to set the environment variable. After the setting is completed, make the configuration file take effect. Finally, enter java -version to check whether the configuration is successful.
①Install jdk
Command: yum install -y java-11-openjdk-headless-11.0.13.0.8-1.el7_9.x86_64 java-11-openjdk-11.0.13.0.8-1.el7_9.x86_64 java-11-openjdk-devel- 11.0.13.0.8-1.el7_9.x86_64
The above picture appears and the installation is successful.
The default installation location for files is: /usr/lib/jvm
②Set environment variables
Command: vim /etc/profile
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-11.0.13.0.8-1.el7_9.x86_64
export JRE_HOME=/usr/lib/jvm/java-11-openjdk-11.0.13.0.8-1.el7_9.x86_64
export CLASSPATH=.:$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
OS: The previous jdk1.8 can be uninstalled directly, and there will be no need to write it again~
③Make the configuration file effective
Command: source /etc/profile
④Enter java -version to check whether the configuration is successful
1.2 tomcat installation and startup
1.2 tomcat installation and startupFirst download the compressed package, put it into the specified directory and decompress it. After decompressing, enter the bin directory to start tomcat, and then start the browser to check whether tomcat is started.
①Download
Official website: http://tomcat.apache.org/, select the download version
②Put it into the specified directory to decompress it.
I used the Xftp software to import it directly.
Decompression command: tar -axvf compressed package
③Enter the bin directory and start tomcat
Command: sh startup.sh
④Start the browser to see if tomcat is started
Path: virtual machine IP/8080
2. Install jenkins
1. Download jekins.war
https://www.jenkins.io/download/
https://get.jenkins.io/war-stable/2.222.4/
2. Start jenkins
Place the war in the webapps under tomcat, restart tomcat, and access the ip address: port number/jenkins
①Put the war package into webapps under tomcat
②Restart tomcat
③Access IP address: port number/jenkins
When the picture above appears, it’s a small step towards success.
3. Enter jenkins
Find the password from the server, then install the plugin, create a user, configure the instance, and then you can start using it 
②Install plug-in
Failure occurs when installing the plug-in. You can change the default access address of Jenkins and install it again.
Change the default access address of jenkins
Command: vim /root/.jenkins/hudson.model.UpdateCenter.xml
Change https://updates.jenkins.io/update-center.json in the url
Change to https://mirrors.tuna.tsinghua.edu.cn/jenkins/updates/update-center.json
It is the mirror address of Tsinghua University in China.
Or change it to http://updates.jenkins.io/update-center.json, that is, remove the s in https.
Then restart the tomcat service
③Create user
④Instance configuration
⑤Installation successful
⑥Enter and use
Since then, I have successfully entered Jenkins~