8 software engineering environment

Software engineering environment

Third party Library

Concept

️ After a programming language installs the development environment , Default will provide API. besides , A third party can also provide a code base （ We call it a third-party library , It's usually jar Format ）, We can provide through a third-party library API To use some existing functions , You don't need to do it yourself ;

jar File what ？

️ jar Files are third-party libraries , It's a compressed file , You can use the decompression software to open , It contains class file , That is, compiled , Can be found in JVM Bytecode running on ;

️ One Java When the program realizes some functions based on a third-party library , Change the third-party library to this Java Program dependent packages ;

Third party libraries are API Do you ？

️ API： namely application programming interface, Application program interface ;

️ A third-party library is one that provides API The warehouse of ;

How to use third-party libraries ？

️ stay Java in , Using third party libraries , Mainly reflected in the development Java Introduce dependencies when code （ Dependency is the resource or tool support used in development ）;

1、 stay cmd Third party libraries are used in

️ We try to use dependency to change the font printed by the code output to color ;

️ First write the following with a normal text editor Java Save the code locally ：

//import Introduce dependencies 
import org.fusesource.jansi.AnsiConsole;
import static org.fusesource.jansi.Ansi.Color.*;
import static org.fusesource.jansi.Ansi.ansi;

public class Main {
    
    public static void main(String[] args) {
    
        AnsiConsole.systemInstall();
        int lineNumber = 0;
        System.out.print( ansi().fg(MAGENTA).a(++lineNumber));
        System.out.println( ansi().fg(CYAN).a(" interviewer ：").fg(RED).a(" What programming languages do you know ？") );
        System.out.print( ansi().fg(MAGENTA).a(++lineNumber));
        System.out.println( ansi().fg(BLUE).a(" I ： ").fg(GREEN).a(" Master C、C++、Java、HTML、JavaScript Other languages , Spelling of words ") );
        System.out.print( ansi().fg(MAGENTA).a(++lineNumber));
        System.out.println( ansi().fg(CYAN).a(" interviewer ：").fg(RED).a(" Is this ？ What kind of system ？") );
        System.out.print( ansi().fg(MAGENTA).a(++lineNumber));
        System.out.println( ansi().fg(BLUE).a(" I ： ").fg(GREEN).a(" Master Windows、Mac、Linux System , Shutdown of ") );
        AnsiConsole.systemUninstall();
   }
}

️ Save the above code , Get into cmd Compile ;

️ There was an error compiling ;

️ Follow the prompt , Because the dependent package cannot be found , So something went wrong , At this time, we will introduce dependency packages ：

javac -cp "D:\CodeResource\Maven_repository\Repository\Maven\org\fusesource\jansi\jansi\2.3.3" Main.java

️ The operation results are as follows

️ Look at the prompt message, it seems that the coding format is wrong , Then enter the following code ：

java -cp "D:\CodeResource\Maven_repository\Repository\Maven\org\fusesource\jansi\jansi\2.3.3" -encoding utf-8 Main.java

️ After running Main.java Generate a in the directory Main.class file ;

️ Enter the following command again ：

java -cp ".;D:\CodeResource\Maven_repository\Repository\Maven\org\fusesource\jansi\jansi\2.3.3" Main
#.; Represents the current path 

️ The output is ：

Building tools

background

️ It can be seen from the above operation that , We just want to output color Fonts , The operation is so complicated , If you want to do something more fancy , That workload doesn't just take care of people emo ah ; So in order to make programming more convenient , Then there is the project construction tool ;

Common project building tools

️ about Java For projects , There are three kinds of construction tools that are used more ：

️ Ant： An older build tool , You need to make your own compilation path when building 、 Resource path, etc , Depending on the package, you still need to download it yourself , The current mainstream projects are no longer used ;

️ Maven： take “ Convention due to configuration ” Thought , Agree on the compilation path 、 Resource path, etc , Dependent packages can be downloaded from the network ,Maven Based mainly on XML File ; at present Java Most server-side projects use Maven To build ;

️ Gradle： and Maven The function is very similar , Just take based on Groovy Script language DSL Syntax to configure , Almost all Android development uses Gradle;

About maven

️ Maven Is a project building tool , To create a project, just follow Maven standard （ be called Maven project ）, You can use Maven Come on Conduct management ： compile , Packing, etc .

maven install

️ Download decompression , Download at ： edition 3.6.3;

️ After downloading, unzip it to any folder , After decompression, open the structure as follows ：

Configure environment variables

️ Right click ” This computer “, Click on ” attribute “, And open ” Advanced system setup “ Medium ” environment variable “, add to Maven environment variable ;

️ First define Maven Root path variables M2_HOME;

️ And then Path In the environment variables , add to Maven Tools bin The directory is the global command path ;

️ Check whether the installation configuration is successful ;

maven Introduce

Global dependency management

️ maven Dependent packages can be introduced into the project ;

️ When introducing dependent packages , Local preference maven Search in warehouse , It's not time to search , Then search in the remote warehouse ;

Local warehouse configuration

️ find maven In the root directory conf Catalog , find setting.xml file ;

️ Open with Notepad tool ;

️ Find the following code ：

️ Add the code in the red box to the position in the figure （ The path needs to be changed ）;

️ In this case, our local warehouse will be configured , In the future, put the downloaded dependent packages into this path ;

stay IDEA Middle configuration maven Local repository

️ open IDEA, Open up a project ;

️ Click on the file - Set up – New project settings - New project setup

️ Click on the building 、 perform 、 Deploy - Building tools -maven

️ Find... In the right interface maven The main path , Change to what you downloaded maven Storage path of tools ;

️ Of course, the user settings file and the local repository should also be rewritten , The user set the file path to the above modified setting.xml Path to file , The local warehouse path is the path of the local warehouse above ;

establish maven project

️ open IDEA, Click new project , choice maven（IDEA Different versions have different layouts ）;

️ Click next

️ The name and location can be set arbitrarily ;

️ Group ID： organization id、 Organization name , Generally use the company's domain name , Such as com.alibaba; At the same time, according to the specification , His writing java All under such a bag ;

️ workpiece ID： product id、 Product name , A project is a product , Therefore, the project name is generally used , More than one English - interval ;

️ edition ： Version number of the product , There may be multiple versions of this project available to others ;

️ After creation , Look at the directory structure on the left ;

️ main In the catalog Java The directory is used to store the Java Code ;

️ main In the catalog resources Directory is used to store configuration files for development ;

️ ​test In the catalog java The directory is used to store unit tests Java Code ;

️ The manual in test Create one in the directory resources Catalog , Used to store test resources ;

️ Try to create a Java Class and compile , Observe the change of directory structure on the left ;

️ stay src/main/resources Under the table of contents , Create a profile （ Any file will do , The following is the created test.xml file ）;

️ stay src/main/java Under the table of contents , Create an arbitrary class , To write main After the method runs , The compilation structure will be generated , Here's the picture ;

️ Catalog target Under the classes Catalog , Write for us Java Class to class The path where the file is stored ;

️ At the same time, the path also stores the xml file ;

maven Project configuration

️ Build on us maven In the project , There is one pom.xml file , This is maven The configuration file for the project ,maven The project construction tool is based on this configuration file to maven Project management ;

️ The xml file The format of is called ” Project object model “ The concept of （Project Object Model, abbreviation POM）, therefore Maven Name this file pom.xml;

️ stay IDEA Click to open the xml file ;

️ Find... In the code <maven.compiler.source> and <maven.compiler.target>, Change the numbers in both labels to 1.8,1.8 We use jdk Version of ;

️ find <dependencies> label , Change the content to the following code （ If there is no such label , Directly copy and paste the modified code into </project> above ）;

<dependencies>
    <dependency>
        <groupId>org.fusesource.jansi</groupId>
        <artifactId>jansi</artifactId>
        <version>2.3.3</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.49</version>
    </dependency>
</dependencies>

maven Life cycle of

️ stay IDEA In the rightmost sidebar , Click on maven, find Life cycle Catalog ;

️ clean： Used to delete target Catalog ;

️ compile： Compile development code and resource files ;

️ package： Package the whole project ;

️ deploy： Upload the project to the private server warehouse ;

The dependent resources of software runtime

Runtime environment

️ about Java Procedure ,JRE Is the necessary runtime environment ;

️ JDK yes Java The environment needed for program development ,JDK Contains JRE;

Program code

️ about Java Procedure ,class The file is the program code needed for the runtime ;

External resources

️ External resources include ： database 、 File resources, etc ;

Internal resources

️ about Java Procedure , Files to be used in the run time , except class The documents , All belong to internal resources ;

journal

️ In the production environment , If there are no log files , It's almost impossible to locate the problem with the program ;

️ JDK yes Java The environment needed for program development ,JDK Contains JRE;

Program code

️ about Java Procedure ,class The file is the program code needed for the runtime ;

External resources

️ External resources include ： database 、 File resources, etc ;

Internal resources

️ about Java Procedure , Files to be used in the run time , except class The documents , All belong to internal resources ;

journal

️ In the production environment , If there are no log files , It's almost impossible to locate the problem with the program ;