使用Maven创建Web应用程序项目
在本教程中，我们将演示如何使用 Maven 创建一个 Java Web 项目(Spring MVC)。
用到的技术/工具：
- Maven 3.3.3
- Eclipse 4.3
- JDK 8
- Spring 4.1.1.RELEASED
- Tomcat 7
- Logback 1.0.13
1. 从Maven模板创建Web项目
您可以通过使用Maven的maven-archetype-webapp模板来创建一个快速启动Java Web应用程序的项目。在终端(* UNIX或Mac)或命令提示符(Windows)中，导航至您想要创建项目的文件夹。
键入以下命令：
$ mvn archetype:generate -DgroupId=com.yiibai -DartifactId=CounterWebApp -DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false
具体示例 ：
C:\worksp>mvn archetype:generate -DgroupId=com.yiibai -DartifactId=CounterWebAp
p -DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] >>> maven-archetype-plugin:2.4:generate (default-cli) > generate-sources
@ standalone-pom >>>
[INFO]
[INFO] <<< maven-archetype-plugin:2.4:generate (default-cli) < generate-sources
@ standalone-pom <<<
[INFO]
[INFO] --- maven-archetype-plugin:2.4:generate (default-cli) @ standalone-pom --
-
[INFO] Generating project in Batch mode
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/archetypes/ma
ven-archetype-webapp/1.0/maven-archetype-webapp-1.0.jar
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/archetypes/mav
en-archetype-webapp/1.0/maven-archetype-webapp-1.0.jar (4 KB at 0.1 KB/sec)
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/archetypes/ma
ven-archetype-webapp/1.0/maven-archetype-webapp-1.0.pom
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/archetypes/mav
en-archetype-webapp/1.0/maven-archetype-webapp-1.0.pom (533 B at 0.1 KB/sec)
[INFO] -------------------------------------------------------------------------
---
[INFO] Using following parameters for creating project from Old (1.x) Archetype:
maven-archetype-webapp:1.0
[INFO] -------------------------------------------------------------------------
---
[INFO] Parameter: basedir, Value: C:\worksp
[INFO] Parameter: package, Value: com.yiibai
[INFO] Parameter: groupId, Value: com.yiibai
[INFO] Parameter: artifactId, Value: CounterWebApp
[INFO] Parameter: packageName, Value: com.yiibai
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] project created from Old (1.x) Archetype in dir: C:\worksp\CounterWebApp
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 10:30 min
[INFO] Finished at: 2015-10-28T20:31:03+08:00
[INFO] Final Memory: 16M/174M
[INFO] ------------------------------------------------------------------------
新的Web项目命名为 “CounterWebApp”，以及一些标准的 web 目录结构也会自动创建。
2. 项目目录布局
查看生成的项目结构布局：
.|____CounterWebApp
||____pom.xml
||____src
|||____main
||||____resources
||||____webapp
|||||____index.jsp
|||||____WEB-INF
||||||____web.xml
Maven 产生了一些文件夹，一个部署描述符 web.xml，pom.xml 和 index.jsp。
注意，
请查看官方Maven标准目录布局指南来了解更多。
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.yiibai</groupId>
<artifactId>CounterWebApp</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>CounterWebApp Maven Webapp</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>CounterWebApp</finalName>
</build>
</project>
web.xml – Servlet 2.3 已经比较旧, 建议升级到2.5
<!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>
index.jsp – 一个简单的 hello world html 页面文件
<html>
<body>
<div><div class="ads-in-post hide_if_width_less_800">
<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- 728x90 - After2ndH4 -->
<ins class="adsbygoogle hide_if_width_less_800"
data-ad-client="ca-pub-2836379775501347"
data-ad-slot="3642936086"
data-ad-region="mkyongregion"></ins>
<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>
</div></div><h2>Hello World!</h2>
</body>
</html>
3. Eclipse IDE 支持
要导入这个项目到Eclipse中，需要生成一些 Eclipse 项目的配置文件：
3.1、在终端，进入到 “CounterWebApp” 文件夹中，键入以下命令：
C:\worksp>cd CounterWebApp
C:\worksp\CounterWebApp>mvn eclipse:eclipse -Dwtpversion=2.0
[INFO] Scanning for projects...
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven -war-plugin/2.2/maven-war-plugin-2.2.pom
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven- war-plugin/2.2/maven-war-plugin-2.2.pom (7 KB at 2.5 KB/sec)
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven -war-plugin/2.2/maven-war-plugin-2.2.jar
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven- war-plugin/2.2/maven-war-plugin-2.2.jar (77 KB at 26.2 KB/sec)
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building CounterWebApp Maven Webapp 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] >>> maven-eclipse-plugin:2.10:eclipse (default-cli) > generate-resources
@ CounterWebApp >>>
[INFO]
[INFO] <<< maven-eclipse-plugin:2.10:eclipse (default-cli) < generate-resources
@ CounterWebApp <<<
[INFO]
[INFO] --- maven-eclipse-plugin:2.10:eclipse (default-cli) @ CounterWebApp ---
[INFO] Adding support for WTP version 2.0.
[INFO] Using Eclipse Workspace: null
[INFO] Adding default classpath container: org.eclipse.jdt.launching.JRE_CONTAINER
[INFO] Not writing settings - defaults suffice
[INFO] Wrote Eclipse project for "CounterWebApp" to C:\worksp\CounterWebApp.
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7.982 s
[INFO] Finished at: 2015-10-28T20:24:57+08:00
[INFO] Final Memory: 15M/146M
[INFO] ------------------------------------------------------------------------
注意，此选项 -Dwtpversion=2.0 告诉 Maven 将项目转换到 Eclipse 的 Web 项目(WAR)，而不是默认的Java项目(JAR)。为方便起见，以后我们会告诉你如何配置 pom.xml 中的这个 WTP 选项。
3.2 导入到 Eclipse IDE – File -> Import… -> General -> Existing Projects into workspace.
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图像说明: 在 Eclipse 中，如果看到项目顶部有地球图标，意味着这是一个 Web 项目。
4. 更新POM
在Maven中，Web项目的设置都通过这个单一的pom.xml文件配置。
- 添加项目依赖 - Spring, logback 和 JUnit
- 添加插件来配置项目
阅读注释清楚明了。
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.yiibai</groupId>
<artifactId>CounterWebApp</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>CounterWebApp Maven Webapp</name>
<url>http://maven.apache.org</url> <properties>
<jdk.version>1.7</jdk.version>
<spring.version>4.1.1.RELEASE</spring.version>
<jstl.version>1.2</jstl.version>
<junit.version>4.11</junit.version>
<logback.version>1.0.13</logback.version>
<jcl-over-slf4j.version>1.7.5</jcl-over-slf4j.version>
</properties>
<dependencies>
<!-- Unit Test -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
</dependency>
<!-- Spring Core -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
<exclusions>
<exclusion>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>${jcl-over-slf4j.version}</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>${logback.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- jstl -->
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>${jstl.version}</version>
</dependency>
</dependencies>
<build>
<finalName>CounterWebApp</finalName>
<plugins>
<!-- Eclipse project -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-eclipse-plugin</artifactId>
<version>2.9</version>
<configuration>
<!-- Always download and attach dependencies source code -->
<downloadSources>true</downloadSources>
<downloadJavadocs>false</downloadJavadocs>
<!-- Avoid type mvn eclipse:eclipse -Dwtpversion=2.0 -->
<wtpversion>2.0</wtpversion>
</configuration>
</plugin>
<!-- Set JDK Compiler Level -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>${jdk.version}</source>
<target>${jdk.version}</target>
</configuration>
</plugin>
<!-- For Maven Tomcat Plugin -->
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
<configuration>
<path>/CounterWebApp</path>
</configuration>
</plugin>
</plugins>
</build>
</project>
注意，为方便起见，声明 maven-eclipse-plugin，并配置wtpversion 来避免输入参数 -Dwtpversion=2.0。现在，每次使用 mvn eclipse:eclipse，Maven将这个项目导入转换为 Eclipse Web 项目。
#之前
mvn eclipse:eclipse --> Eclipse Java project (JAR)
mvn eclipse:eclipse -Dwtpversion=2.0 --> Eclipse Java web project (WAR)
#之后
mvn eclipse:eclipse --> Eclipse Java web project (WAR)
5. 更新源代码
在这一步中，在上一步配置完pom.xml后，重新执行 mvn eclipse:eclipse 这个命令，我们将创建Spring MVC的一些文件和logback日志框架的文件夹，最终的项目结构如下所示：
.
|____pom.xml
|____src
| |____main
| | |____java
| | | |____com
| | | | |____yiibai
| | | | | |____controller
| | | | | | |____BaseController.java
| | |____resources
| | | |____logback.xml
| | |____webapp
| | | |____WEB-INF
| | | | |____mvc-dispatcher-servlet.xml
| | | | |____pages
| | | | | |____index.jsp
| | | | |____web.xml
[图片上传失败...(image-597845-1546483238044)]
注意，如果它不存在，需要手动创建文件夹。
5.1 创建 Spring MVC 的控制器类。
/src/main/java/com/yiibai/controller/BaseController.java
package com.yiibai.controller;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
public class BaseController {
private static int counter = 0;
private static final String VIEW_INDEX = "index";
private final static org.slf4j.Logger logger = LoggerFactory.getLogger(BaseController.class);
@RequestMapping(value = "/", method = RequestMethod.GET)
public String welcome(ModelMap model) {
model.addAttribute("message", "Welcome");
model.addAttribute("counter", ++counter);
logger.debug("[welcome] counter : {}", counter);
// Spring uses InternalResourceViewResolver and return back index.jsp
return VIEW_INDEX;
}
@RequestMapping(value = "/{name}", method = RequestMethod.GET)
public String welcomeName(@PathVariable String name, ModelMap model) {
model.addAttribute("message", "Welcome " + name);
model.addAttribute("counter", ++counter);
logger.debug("[welcomeName] counter : {}", counter);
return VIEW_INDEX;
}
}
5.2 创建Spring配置文件。
/src/main/webapp/WEB-INF/mvc-dispatcher-servlet.xml
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="com.yiibai.controller" />
<bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix">
<value>/WEB-INF/pages/</value>
</property>
<property name="suffix">
<value>.jsp</value>
</property>
</bean>
</beans>
5.3 更新让现有的 web.xml 支持 Servlet 2.5(默认的Servlet2.3 太旧了)， 并且还通过 Spring 监听器 ContextLoaderListener 集成了Spring框架。
/src/main/webapp/WEB-INF/web.xml
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<display-name>Counter Web Application</display-name>
<servlet>
<servlet-name>mvc-dispatcher</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>mvc-dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value>
</context-param>
<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener
</listener-class>
</listener>
</web-app>
5.4 移动文件 index.jsp 到 WEB-INF/pages 目录下， 为了保护直接访问。并更新内容：
/src/main/webapp/WEB-INF/pages/index.jsp
5.5 在资源文件夹(resources)中创建 logback.xml 文件
/src/main/resources/logback.xml
<?xml version="1.0" encoding="UTF-8"?>
6. Eclipse + Tomcat
在第5步中创建所有文件以后，这里有一些方法可以用来部署和测试Web项目，我们这里推荐使用6.2中的方法。
6.1 要编译，测试和项目打包成一个WAR文件，输入：
mvn package
一个新的 WAR 文件将在 project/target/CounterWebApp.war产生，只需复制并部署到Tomcat 发布的目录。
6.2 如果想通过 Eclipse 服务器这个项目插件(Tomcat 或其它容器)调试，这里再输入：
mvn eclipse:eclipse
如果一切顺利，该项目的依赖将被装配附加到 Web部署项目。图片: 右键点击 project -> Properties -> Deployment Assembly
6.3 Maven 的 Tomcat 插件声明(加入到 pom.xml)：
pom.xml
<!-- For Maven Tomcat Plugin -->
键入以下命令(有时网络不通畅需要执行2-3次)：
mvn tomcat:run
tp://logback.qos.ch/codes.html#layoutInsteadOfEncoder for details
20:37:32,089 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Se
g level of logger [com.yiibai.controller] to DEBUG
20:37:32,089 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Se
g additivity of logger [com.yiibai.controller] to false
20:37:32,090 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction -
ching appender named [STDOUT] to Logger[com.yiibai.controller]
20:37:32,090 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction
tting level of ROOT logger to ERROR
20:37:32,090 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction -
ching appender named [STDOUT] to Logger[ROOT]
20:37:32,090 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationActi
End of configuration.
20:37:32,091 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@3bead5 Registering current configuration as safe fallback point
十月 28, 2015 20:37:32 下午 org.apache.catalina.core.ApplicationContext log
信息: Initializing Spring root WebApplicationContext
十月 28, 2015 20:37:33 下午 org.apache.catalina.core.ApplicationContext log
信息: Initializing Spring FrameworkServlet 'mvc-dispatcher'
十月 28, 2015 20:37:33 下午 org.apache.coyote.http11.Http11Protocol init
信息: Initializing Coyote HTTP/1.1 on http-8080
十月 28, 2015 20:37:33 下午 org.apache.coyote.http11.Http11Protocol start
信息: Starting Coyote HTTP/1.1 on http-8080
这将启动Tomcat，部署项目默认在端口8080。
出错：Maven项目下update maven后Eclipse报错：java.lang.ClassNotFoundException: ContextLoaderL
解决方案：
1.右键点击项目--选择Properties
选择Deployment Assembly,在右边点击Add按钮，在弹出的窗口中选择Java Build Path Entries
2.点击Next，选择Maven Dependencies
3.点击Finish，然后可以看到已经把Maven Dependencies添加到Web应用结构中了
操作完后，重新部署工程，不再报错了。然后我们再到.metadata.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\目录下，发现工程WEB-INF目录下自动生成了lib目录，并且所有的依赖jar包也都已经部署进来。问题因此解决。
