IDEA创建Maven Web项目

概述

以IDEA2020.3.1+Tomcat9.0+Maven3.6.3+jdk1.8+web4.0演示，单项目

Maven Mac下安装和IDEA配置见 https://www.cnblogs.com/shenleg/p/14218613.html

新建项目

IDEA补目录

直接选择

更改Web4.0版本

早期的web工程中并不支持@WebServlet注解配置，甚至不支持El表达式（在web 3.0版本之后才支持）

一定要将matadata-complete属性显式改为"false"这样创建的web工程才是web-4.0

<?xml version="1.0" encoding="UTF-8"?>
<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_4_0.xsd"
         version="4.0"
         metadata-complete="false">
</web-app>

修改创建模版

手动修改默认模版，默认为1.4版本

位置在：%maven_repository%\org\apache\maven\archetypes\maven-archetype-webapp\1.4

更改Pom文件

防止资源导入错误

<build>
  <!-- 防止资源导入错误 -->
  <resources> 
    <resource> 
      <directory>src/main/resources</directory> 
      <includes> 
        <include>**/*.properties</include> 
        <include>**/*.xml</include> 
      </includes> 
      <filtering>true</filtering> 
    </resource> 
    <resource> 
      <directory>src/main/java</directory> 
      <includes> 
        <include>**/*.properties</include> 
        <include>**/*.xml</include> 
      </includes> 
      <filtering>true</filtering> 
    </resource> 
  </resources>
</build>

引入Servlet API

<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>4.0.1</version>
  <scope>provided</scope>
</dependency>

引入后可以右键新建Servlet文件了

引入Servlet JSP

<!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
<dependency>
    <groupId>javax.servlet.jsp</groupId>
    <artifactId>javax.servlet.jsp-api</artifactId>
    <version>2.3.3</version>
    <scope>provided</scope>
</dependency>

引入JSTL API

部分Tomcat需要引入jstl的包，否则会报错：JSTL解析错误

<!-- https://mvnrepository.com/artifact/javax.servlet.jsp.jstl/jstl-api -->
<dependency>
    <groupId>javax.servlet.jsp.jstl</groupId>
    <artifactId>jstl-api</artifactId>
    <version>1.2</version>
</dependency>

JSTL依赖包含了jsp-api和servlet-pai：

太低servlet-api不支持@WebServlet注解

引入Strand

<!-- https://mvnrepository.com/artifact/org.apache.taglibs/taglibs-standard-impl -->
<dependency>
    <groupId>org.apache.taglibs</groupId>
    <artifactId>taglibs-standard-impl</artifactId>
    <version>1.2.5</version>
</dependency>

引入MySQL驱动包

mysql 5.7 用8.0版本的驱动可以，5.1版本也可以，MySQL 5.5, 5.6, 5.7, and 8.0（都兼容，大胆用了）

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.22</version>
</dependency>

引入后记得手动更新一下Maven

指定Maven JDK编译版本

pom中修改

局部修改

<build>  
   <plugins>  
       <plugin>  
           <groupId>org.apache.maven.plugins</groupId>  
              <artifactId>maven-compiler-plugin</artifactId>  
              <version>3.1</version>  
              <configuration>  
                  <source>1.8</source>  
                  <target>1.8</target>  
              </configuration>  
        </plugin>  
    </plugins>  
 </build>

Maven修改

全局修改，在maven配置文件settings.xml中设置

<profile>    
  <id>jdk-1.8</id>    
  <activation>    
    <activeByDefault>true</activeByDefault>    
    <jdk>1.8</jdk>    
  </activation>    
  <properties>    
    <maven.compiler.source>1.8</maven.compiler.source>    
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
  </properties>
</profile>