【java】— Spring Boot开发项目管理工具之Maven

引言：最近在着手Spring Boot开发，在安装项目管理工具Maven时，发现了很多坑，给大家分享一波，别踩坑。

1.下载Maven
官方地址：http://maven.apache.org/download.cgi

2.解压下来之后，找到这个xml文件，进行环境配置。


找到红色箭头的地方，在创建 meven项目时，由于导入的 jar包要在apache的官网上下载，速度极度的慢，而且在公网下还会报错，所以直接可以修改镜像文件，将地址改为阿里云的。

<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>nexus-aliyun</id>
<mirrorOf>*</mirrorOf>
<name>Nexus aliyun</name>
<url>http://maven.aliyun.com/nexus/content/groups/public</url>
</mirror>

</mirrors>

3.配置Path环境。

这里是你的解压路径！

添加环境变量！

终端输入mvn表示安装成功！

4.打开IDEA，进行配置Maven配置！
新建项目，选中Maven，选择Webapp开发！

项目名称必须是英文

依赖一定要选择自己下载的Maven镜像！！！

5.创建如下图的目录结构，进行代码编辑！

首先需要配置自己的pom.xml文件，这里面需要加载tomcat等一些插件，如果需要文件里面有飘红的地方，右下角会提示你 import… 点击安装就可以了！！！

<?xml version="1.0" encoding="UTF-8"?>

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.example</groupId>
  <artifactId>web-servlet-embedded</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>web-servlet-embedded Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
    <java.version>11</java.version>
    <tomcat.version>9.0.26</tomcat.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>

    <dependency>
      <groupId>org.apache.tomcat.embed</groupId>
      <artifactId>tomcat-embed-core</artifactId>
      <version>${tomcat.version}</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.apache.tomcat.embed</groupId>
      <artifactId>tomcat-embed-jasper</artifactId>
      <version>${tomcat.version}</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

  <build>
    <finalName>web-servlet-embedded</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

项目目录如下所示：

HelloServlet类

HelloServlet.java

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(urlPatterns = "/")
public class HelloServlet extends HttpServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html");
        String name = req.getParameter("name");
        if (name == null) {
            name = "shaonian";
        }
        PrintWriter pw = resp.getWriter();
        pw.write("<h1>He " + name + "!</h1>");
        pw.flush();
    }
}

主函数Main

import org.apache.catalina.Context;
import org.apache.catalina.WebResourceRoot;
import org.apache.catalina.startup.Tomcat;
import org.apache.catalina.webresources.DirResourceSet;
import org.apache.catalina.webresources.StandardRoot;

import java.io.File;

public class Main {
    public static void main(String[] args) throws Exception {
        // 启动Tomcat:
        Tomcat tomcat = new Tomcat();
        tomcat.setPort(Integer.getInteger("port", 8080));
        tomcat.getConnector();
        // 创建webapp:
        Context ctx = tomcat.addWebapp("", new File("src/main/webapp").getAbsolutePath());
        WebResourceRoot resources = new StandardRoot(ctx);
        resources.addPreResources(
                new DirResourceSet(resources, "/WEB-INF/classes", new File("target/classes").getAbsolutePath(), "/"));
        ctx.setResources(resources);
        tomcat.start();
        tomcat.getServer().await();
    }
}

Web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
</web-app>

6.打开http://localhost:8080/hi

到这里证明你的Maven已经安装成功了！！！