Creation of maven web project

1. Configuration of maven environment

First download the maven resource and visit the official website https://maven.apache.org/ Then click Download on the left and select the required resource in the File column.

Direct download link http://mirrors.hust.edu.cn/apache/maven/maven-3/3.5.3/binaries/apache-maven-3.5.3-bin.zip,

After the download is successful, decompress it directly, and then configure the environment.

Variable name: m2_home

Variable value: D:\study\apache-maven-3.5.3-bin\apache-maven-3.5.3 (you need to configure it according to the address you downloaded and decompressed)

Then add m2_home to the Path variable value: %m2_home%\bin;

Then enter mvn -v in the cmd command box to run the test, how to display maven related information is successfully configured.

Set the location of the resource download library: modify the path in the localRepository in the settings.xml file, for example <localRepository>D:\study\mven_jar_download</localRepository>

And put the settings.xml file in the D:\study\mven_jar_download file

Set the jdk version (settings.xml in the downloaded resource file): modify the profile tag to the jdk version you use (it doesn't matter if you don't modify it, but the default version number of the JRE System Library when you create the project is settings. Default 1.4 version in xml)

</activation>

The url in the mirrors tag can be set to a domestic mirror library or aliyun's mirror library

aliyun mirror library: http://maven.aliyun.com/nexus/content/groups/public/

If not set, it will be the default address http://my.repository.com/repo/path

2. Eclipse configuration (eclipse download address: https://www.eclipse.org/downloads/)

Click helo→install new software Click Add name and fill in maven location Fill in http://m2eclipse.sonatype.org/sites/m2e

Then click next and follow the prompts to complete the installation. (Official download of the latest version of eclipse comes with the maven plugin)

Start to configure the relevant settings of maven, click Window above eclipse, then select preferences→maven→installations, click Add, select the decompression address of maven, and click Finish.

Click User Settings. Under User Setting, select settings.xml in the resource package you want to download and click ok.

3. Create a maven web project

maven web project directory structure

src

main

java

resources

test

java

resources

Right-click new→other→then select Maven Project, click next→next→select org.apache.maven.archetypes maven-archetype-webapp 1.0 and then click next, fill in Group Id (company URL fill in backwards), Artifact Id (project name) , package (package name), click Finish.

Then complete the relevant documents

The general directory structure is as follows:

projectName

src/main/java

src/main/resources

src/test/java

src/test/resources

JRE System Library[JavaSE-1.8]

Maven Dependencies

Referenced Libraries

src

main

webapp

WEB-INF

web.xml

target

pom.xml

After just creating the project, index.jsp will have a red x number, that is because the corresponding jar package has not been introduced, and then add it in pom.xml

<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>${javax.servlet-api.version}</version>

<scope>provided</scope>
</dependency>

After the project is created, test whether the project can be started normally. There are two ways:

（1）jetty

add in pom.xml

<groupId>org.mortbay.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>8.1.16.v20140903</version>

<executions>
<execution>

<phase>package</phase>
<goals>
<goal>run</goal>
</goals>
</ execution>
</executions>

Then right-click on the project Run As and select Maven build..... Enter clean package in Goals to see if an error is reported in the console, then visit localhost:8080 for access, if the page displays Hello World! Congratulations, you have succeeded.

(2) tomcat (tomcat and jetty can only make one valid)

Configure in pom.xml

<groupId>org.apache.tomcat.maven</groupId>

<artifactId>tomcat7-maven-plugin</artifactId>

Then right-click on the project Run As and select Maven build..... Enter clean package in Goals to see if the console reports an error, then visit localhost:8080/projectName for access, if the page displays Hello World! Congratulations, you have succeeded.

If you encounter

[ERROR] /D:/study/project/bsdapp/src/main/java/com/mobisoft/meapbase/gateway/bi/ResDealer.java:[22,13] Unmappable character encoding GBK

Solution:

add in pom.xml file

</properties>

Just

4, maven common commands

mvn -v View maven version information

compile compile the project

test test

package packaging

clean delete target

install installs the jar package into the local repository

5. Maven's Dependency Scope, Dependency Transit, Dependency Conflict, Aggregation and Inheritance

maven dependency scope

(1) .complie default, all scopes
(2). provided compile and test
(3). runtime test and run
(4). test only test Junit
(5). system compile and test, poor portability
(6). import Import scope, only in utility dependencyManagement means importing dependencies from other poms

<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>

<scope>test</scope>
      </dependency>
       </dependencies>

mave dependency transfer

<dependency>
<groupId>com.hy</groupId>
<artifactId>a</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>

When executing the compile command, the dependent projects need to be packaged first (package a project first, that is, execute the package command, and install project a, that is, execute the install command)

Maven exclusion dependency (the hyue project depends on a, and a depends on b, but if this is the case, the hyue project depends on a and b, but b only wants to listen to a, so the exclusion of dependencies will work.)

<dependency>
<groupId>com.hy</groupId>
<artifactId>a</artifactId>
<version>0.0.1-SNAPSHOT</version>

<exclusions>
<exclusion>
<groupId>com.hu</groupId>
<artifactId>b</artifactId>
</exclusion>
</exclusions>
</dependency>

mave's principle of dependency conflict

Dependency conflict: the same build that depends on
different
versions

1. Short-circuit priority If AB depends on a different version of component X (jar), and A->B->C, for C that depends on AB, which version of the component will it depend on at this time? For example, in the following cases, it will be resolved first Second, C will inherit B's dependency version 2.0
A->B->CX-2.0(jar)
A->BX-1.0(jar)
needs to be installed in the local warehouse to take effect when A->BX-1.0(jar) is tested.
2. First declaration first priority
If the path lengths are the same, whoever declares in the pom first, who parses first (parse order from top to bottom),
A->B->X-1.0(jar)
A->C-> X-2.0 (jar)

Aggregation and inheritance in maven

polymerization

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<modules>
<module>../a</module>
<module>../spring-mvc-study</module>
</modules>

inherit

<dependencyManagement>
<dependencies>
<dependency>
<groupId> junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>

<scope>test</scope>
</dependency>
</dependencies>

</dependencyManagement>

Content in subclasses

<properties>
<javax.servlet-api.version>4.0.0</javax.servlet-api.version>
</properties>

<parent>
<groupId>com.hy</groupId>
<artifactId>hyue</artifactId>
<version>0.0.1-SNAPSHOT</version>
</ parent>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>

< /dependency>
</dependencies>

Creation of maven web project

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