1. Maven concept
Many times when we are developing a project, we need to import the required jar packages into the project, which can not avoid the conflict between the jar packages we download and the wrong version. maven solves this problem very well.
2.Maven installation and configuration
Download address: http://maven.apache.org/download.cgi
two point one Download and unzip
2.2 configuring Maven environment variables
This computer properties advanced system settings environment variables NEW
The variable value refers to your Maven decompression path
Path
2.3 check whether Maven is installed successfully
win+R opens the DOS window and enters mvn -version
There will be a situation where maven is successfully installed, but the following still shows that cmd is not an internal or external command or a runnable program. Here, it can be solved by adding% SystemRoot%\system32 to the environment variable path
3. Change Maven local warehouse location and Maven download path
First of all, maven will download the required dependencies from the central warehouse according to the dependencies you write. After all, the warehouse is abroad, so it is natural that the download is unsuccessful and the download speed is very slow. Therefore, we need to download the jar package from the image source
3.1 find the settings.xml configuration file in conf under maven
<?xml version="1.0" encoding="UTF-8"?>
<!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License athttp://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. -->
<!--| This is the configuration file for Maven. It can be specified at two levels:|| 1. User Level. This settings.xml file provides configuration for a single user,| and is normally provided in ${user.home}/.m2/settings.xml.|| NOTE: This location can be overridden with the CLI option:|| -s /path/to/user/settings.xml|| 2. Global Level. This settings.xml file provides configuration for all Maven| users on a machine (assuming they're all using the same Maven| installation). It's normally provided in| ${maven.conf}/settings.xml.|| NOTE: This location can be overridden with the CLI option:|| -gs /path/to/global/settings.xml|| The sections in this sample file are intended to give you a running start at| getting the most out of your Maven installation. Where appropriate, the default| values (values used when the setting is not specified) are provided.||-->
-<settings xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/SETTINGS/1.0.0">
<!-- localRepository| The path to the local repository maven will use to store artifacts.|| Default: ${user.home}/.m2/repository<localRepository>/path/to/local/repo</localRepository> -->
<localRepository>E:/maven_jar</localRepository>
<!-- interactiveMode| This will determine whether maven prompts you when it needs input. If set to false,| maven will use a sensible default value, perhaps based on some other setting, for| the parameter in question.|| Default: true<interactiveMode>true</interactiveMode> -->
<!-- offline| Determines whether maven should attempt to connect to the network when executing a build.| This will have an effect on artifact downloads, artifact deployment, and others.|| Default: false<offline>false</offline> -->
<!-- pluginGroups| This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e.| when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers| "org.apache.maven.plugins" and "org.codehaus.mojo" if these are not already contained in the list.|-->
-<pluginGroups>
<!-- pluginGroup| Specifies a further group identifier to use for plugin lookup.<pluginGroup>com.your.plugins</pluginGroup> -->
</pluginGroups>
<!-- proxies| This is a list of proxies which can be used on this machine to connect to the network.| Unless otherwise specified (by system property or command-line switch), the first proxy| specification in this list marked as active will be used.|-->
-<proxies>
<!-- proxy| Specification for one proxy, to be used in connecting to the network.|<proxy><id>optional</id><active>true</active><protocol>http</protocol><username>proxyuser</username><password>proxypass</password><host>proxy.host.net</host><port>80</port><nonProxyHosts>local.net|some.host.com</nonProxyHosts></proxy> -->
</proxies>
<!-- servers| This is a list of authentication profiles, keyed by the server-id used within the system.| Authentication profiles can be used whenever maven must make a connection to a remote server.|-->
-<servers>
<!-- server| Specifies the authentication information to use when connecting to a particular server, identified by| a unique name within the system (referred to by the 'id' attribute below).|| NOTE: You should either specify username/password OR privateKey/passphrase, since these pairings are| used together.|<server><id>deploymentRepo</id><username>repouser</username><password>repopwd</password></server> -->
<!-- Another sample, using keys to authenticate.<server><id>siteServer</id><privateKey>/path/to/private/key</privateKey><passphrase>optional; leave empty if not used.</passphrase></server> -->
</servers>
<!-- mirrors| This is a list of mirrors to be used in downloading artifacts from remote repositories.|| It works like this: a POM may declare a repository to use in resolving certain artifacts.| However, this repository may have problems with heavy traffic at times, so people have mirrored| it to several places.|| That repository definition will have a unique id, so we can create a mirror reference for that| repository, to be used as an alternate download site. The mirror site will be the preferred| server for that repository.|-->
-<mirrors>
<!-- mirror| Specifies a repository mirror site to use instead of a given repository. The repository that| this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used| for inheritance and direct lookup purposes, and must be unique across the set of mirrors.|<mirror><id>mirrorId</id><mirrorOf>repositoryId</mirrorOf><name>Human Readable Name for this Mirror.</name><url>http://my.repository.com/repo/path</url></mirror> -->
-<mirror>
<id>alimaven</id>
<mirrorOf>central</mirrorOf>
<name>aliyun maven</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
</mirror>
</mirrors>Local warehouse settings
The local warehouse address is defined by itself
<localRepository>E:/maven_jar</localRepository>
This is the download address of alicloud image warehouse. Put it in the < mirrors > tab
<mirror> <id>alimaven</id> <mirrorOf>central</mirrorOf> <name>aliyun maven</name> <url>http://maven.aliyun.com/nexus/content/groups/public/</url> </mirror>
4. Create Maven project and use Java
4.1 creating Maven project
When creating maven, ensure good network quality. When creating Maven for the first time, you need to download the jar package and wait
group id: Organization id, which is generally the reverse of the company domain name
artifact id: project name
Version: version
Package: java package name
4.2Maven local warehouse setup installation path
Add Mavena installation path
Local warehouse configuration
4.3jdk configuration
4.4 eclipse needs to change the following configuration to create maven project
4.5 modifying web.xml
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<display-name>Archetype Created Web Application</display-name>
</web-app>
5 Tomcat run output statement
Note: maven project does not have Tomcat dependency by default;
Therefore, you need to import Tomcat related dependencies, or servlet related dependencies, into maven;
5.1 importing jar package dependencies in pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.wyy</groupId> <artifactId>Maven_wyy</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>Maven_wyy Maven Webapp</name> <url>http://maven.apache.org</url> <dependencies> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency> </dependencies> <build> <finalName>Maven_wyy</finalName> </build> </project>
Verify that the jar package was successfully imported
5.2 testing
package com.wyy.demo;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/demo")
public class Demo extends HttpServlet{
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("maven Ha ha ha!!!");
}
}
