maven打包的那些事

1. 关于 Maven 打 war 包

《使用 Eclipse 的 Maven 2 插件开发一个 JEE 项目》详细介绍了如何在 Eclipse 使用 Maven 新建一个 JEE 项目并对其进行断点跟踪调试，但是没有介绍如何对 JEE 项目打 war 包。其实很简单，你只需要把 pom.xml 中的 <packaging>jar</packaging> 换成 <packaging>war</packaging> 就可以使用 mvn package 命令对其打 war 包了，而不需要添加任何 maven 插件。只要你遵循了 maven 规范(比如照着《使用 Eclipse 的 Maven 2 插件开发一个 JEE 项目》所述做了)，那你打成的 war 包就肯定包含了第三方依赖包：


把这个 war 包丢进 tomcat 的 webapps 目录，重启 tomcat 即可完成了该项目的部署。你唯一需要注意的是，在重启 tomcat 之前把你的 war 重命名为 项目访问路径.war。比如作者打成的 war 包是为 swifton-1.0.0.war，对该项目定义的访问路径是 /swifton，那么我在重启 tomcat 之前需要将其重命名为 swifton.war。

2. 可执行程序打 jar 包

关于可执行程序(需要指定一个 main 类)打 jar 包就没这么方便了，我们需要考虑以下几个问题：

• 配置文件需要打进 jar 包；
• 需要指定 main 入口类；
• 所依赖的第三方库也要打进 jar 包；

只有同时满足以上三点，我们才可以直接使用 java -jar swiftonrsa-1.0.0.jar 命令成功执行该程序。
为了让讨论不那么抽象，我们在 Eclipse 下新建一个 maven 项目 swiftonrsa：


其中，com.defonds.RsaEncryptor 是入口 main 类，其源码如下：

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1. package com.defonds;  
2.   
3. import org.springframework.context.ApplicationContext;  
4. import org.springframework.context.support.ClassPathXmlApplicationContext;  
5.   
6. import com.defonds.service.LinkPayAntharService;  
7.   
8. public class RsaEncryptor {  
9.   
10.     public static void main(String[] args) {  
11.         ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");  
12.         LinkPayAntharService linkPayAntharService = (LinkPayAntharService) context.getBean("linkPayAntharService");  
13.         linkPayAntharService.dealWithYearData();  
14.     }  
15. }  

2.1 配置文件打包不需要额外关注

只要你项目所依赖的配置文件都按照 maven 规范放对位置(src/main/resources)，那么打好的 jar 包就会把它们一起打包：


但是这样打好的 jar 包既没有指定 main 入口类，也没有将依赖包打进来，我们运行它：


提示"swiftonrsa-1.0.0.jar中没有主清单属性"，我们查看打好 jar 包下 META-INF 目录中的 MANIFEST.MF，其内容如下：
Manifest-Version: 1.0
Built-By: Defonds
Build-Jdk: 1.7.0_67
Created-By: Apache Maven 3.2.3
Archiver-Version: Plexus Archiver
确实没有指出 main 入口类。

2.2 maven-assembly-plugin 插件

于是我们引入了 maven-assembly-plugin 插件，pom.xml 中加入如下代码：

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1. <build>  
2.     <plugins>  
3.         <plugin>  
4.             <artifactId>maven-assembly-plugin</artifactId>  
5.             <configuration>  
6.                 <appendAssemblyId>false</appendAssemblyId>  
7.                 <descriptorRefs>  
8.                     <descriptorRef>jar-with-dependencies</descriptorRef>  
9.                 </descriptorRefs>  
10.                 <archive>  
11.                     <manifest>  
12.                         <mainClass>com.defonds.RsaEncryptor</mainClass>  
13.                     </manifest>  
14.                 </archive>  
15.             </configuration>  
16.             <executions>  
17.                 <execution>  
18.                     <id>make-assembly</id>  
19.                     <phase>package</phase>  
20.                     <goals>  
21.                         <goal>assembly</goal>  
22.                     </goals>  
23.                 </execution>  
24.             </executions>  
25.         </plugin>  
26.     </plugins>  
27. </build>  

执行 mvn assembly:assembly，成功构建 swiftonrsa-1.0.0.jar，查看其打包目录，各种配置文件以及第三方依赖包也都有：


然后查看 META-INF 目录中的 MANIFEST.MF，内容如下：
Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven
Built-By: Defonds
Build-Jdk: 1.7.0_67
Main-Class: com.defonds.RsaEncryptor
怀着兴奋的心情执行之：


maven-assembly-plugin 插件没有给我们带来惊喜。错误信息如下：
Exception in thread "main" org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/context]
原来这是 assembly 插件的一个 bug：http://jira.codehaus.org/browse/MASSEMBLY-360，它在对第三方打包时，对于 META-INF 下的 spring.handlers，spring.schemas 等多个同名文件进行了覆盖，遗漏掉了一些版本的 xsd 本地映射。

2.3 maven-shade-plugin 插件

有破必有立。http://jira.codehaus.org/browse/MASSEMBLY-360 跟帖中有网友推荐了 maven-shade-plugin 插件。于是我们使用 maven-shade-plugin 将 maven-assembly-plugin 替代：

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1. <build>  
2.     <plugins>  
3.         <plugin>  
4.             <groupId>org.apache.maven.plugins</groupId>  
5.             <artifactId>maven-shade-plugin</artifactId>  
6.             <version>1.4</version>  
7.             <executions>  
8.                 <execution>  
9.                     <phase>package</phase>  
10.                     <goals>  
11.                         <goal>shade</goal>  
12.                     </goals>  
13.                     <configuration>  
14.                         <transformers>  
15.                             <transformer  
16.                                 implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">  
17.                                 <mainClass>com.defonds.RsaEncryptor</mainClass>  
18.                             </transformer>  
19.                             <transformer  
20.                                 implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
21.                                 <resource>META-INF/spring.handlers</resource>  
22.                             </transformer>  
23.                             <transformer  
24.                                 implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
25.                                 <resource>META-INF/spring.schemas</resource>  
26.                             </transformer>  
27.                         </transformers>  
28.                     </configuration>  
29.                 </execution>  
30.             </executions>  
31.         </plugin>  
32.     </plugins>  
33. </build>  

对于多个第三方包 META-INF 下的同名的 spring.handlers 文件它采取的态度是追加而不是覆盖。执行 maven clean package，成功构建 swiftonrsa-1.0.0.jar，查看其打包目录，各种配置文件以及第三方依赖包也都有，以及 META-INF 目录中的 MANIFEST.MF 的内容，基本如 maven-assembly-plugin 打包后的样子，执行之：


错误信息如下：
java.lang.SecurityException: Invalid signature file digest for Manifest main attributes
这是由于一些包重复引用，打包后的 META-INF 目录多出了一些 *.SF 等文件所致。
有破必有立。博客 http://zhentao-li.blogspot.com/2012/06/maven-shade-plugin-invalid-signature.html 给出了解决方案，pom.xml 添加：

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1. <configuration>  
2.   <filters>  
3.     <filter>  
4.       <artifact>*:*</artifact>  
5.       <excludes>  
6.         <exclude>META-INF/*.SF</exclude>  
7.         <exclude>META-INF/*.DSA</exclude>  
8.         <exclude>META-INF/*.RSA</exclude>  
9.       </excludes>  
10.     </filter>  
11.   </filters>  
12. </configuration>  

于是我们对 maven-shade-plugin 的配置变成这样：

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1. <build>  
2.     <plugins>  
3.         <plugin>  
4.             <groupId>org.apache.maven.plugins</groupId>  
5.             <artifactId>maven-shade-plugin</artifactId>  
6.             <version>1.4</version>  
7.             <executions>  
8.                 <execution>  
9.                     <phase>package</phase>  
10.                     <goals>  
11.                         <goal>shade</goal>  
12.                     </goals>  
13.                     <configuration>  
14.                         <filters>  
15.                             <filter>  
16.                                 <artifact>*:*</artifact>  
17.                                 <excludes>  
18.                                     <exclude>META-INF/*.SF</exclude>  
19.                                     <exclude>META-INF/*.DSA</exclude>  
20.                                     <exclude>META-INF/*.RSA</exclude>  
21.                                 </excludes>  
22.                             </filter>  
23.                         </filters>  
24.                         <transformers>  
25.                             <transformer  
26.                                 implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">  
27.                                 <mainClass>com.defonds.RsaEncryptor</mainClass>  
28.                             </transformer>  
29.                             <transformer  
30.                                 implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
31.                                 <resource>META-INF/spring.handlers</resource>  
32.                             </transformer>  
33.                             <transformer  
34.                                 implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
35.                                 <resource>META-INF/spring.schemas</resource>  
36.                             </transformer>  
37.                         </transformers>  
38.                     </configuration>  
39.                 </execution>  
40.             </executions>  
41.         </plugin>  
42.     </plugins>  
43. </build>  

再次执行 maven clean package，再次执行成功构建后的 swiftonrsa-1.0.0.jar：


最后两行是具体业务实现类 com.defonds.service.LinkPayAntharServiceImpl 成功执行打印出的 log 日志。

2.4 示例项目

本文示例项目 swiftonrsa 已上传至 CSDN 资源，有兴趣的朋友可以下载下来参考实验，下载地址：http://download.csdn.net/detail/defonds/8404739。
本文示例项目最终 pom.xml 如下：

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1. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
2.     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">  
3.     <modelVersion>4.0.0</modelVersion>  
4.   
5.     <groupId>settle</groupId>  
6.     <artifactId>swiftonrsa</artifactId>  
7.     <version>1.0.0</version>  
8.     <packaging>jar</packaging>  
9.   
10.     <name>swiftonrsa</name>  
11.     <url>http://maven.apache.org</url>  
12.   
13.     <properties>  
14.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  
15.     </properties>  
16.   
17.     <build>  
18.         <plugins>  
19.             <plugin>  
20.                 <groupId>org.apache.maven.plugins</groupId>  
21.                 <artifactId>maven-shade-plugin</artifactId>  
22.                 <version>1.4</version>  
23.                 <executions>  
24.                     <execution>  
25.                         <phase>package</phase>  
26.                         <goals>  
27.                             <goal>shade</goal>  
28.                         </goals>  
29.                         <configuration>  
30.                             <filters>  
31.                                 <filter>  
32.                                     <artifact>*:*</artifact>  
33.                                     <excludes>  
34.                                         <exclude>META-INF/*.SF</exclude>  
35.                                         <exclude>META-INF/*.DSA</exclude>  
36.                                         <exclude>META-INF/*.RSA</exclude>  
37.                                     </excludes>  
38.                                 </filter>  
39.                             </filters>  
40.                             <transformers>  
41.                                 <transformer  
42.                                     implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">  
43.                                     <mainClass>com.defonds.RsaEncryptor</mainClass>  
44.                                 </transformer>  
45.                                 <transformer  
46.                                     implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
47.                                     <resource>META-INF/spring.handlers</resource>  
48.                                 </transformer>  
49.                                 <transformer  
50.                                     implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">  
51.                                     <resource>META-INF/spring.schemas</resource>  
52.                                 </transformer>  
53.                             </transformers>  
54.                         </configuration>  
55.                     </execution>  
56.                 </executions>  
57.             </plugin>  
58.         </plugins>  
59.     </build>  
60.   
61.   
62.     <dependencies>  
63.   
64.         <!-- logs -->  
65.         <dependency>  
66.             <groupId>log4j</groupId>  
67.             <artifactId>log4j</artifactId>  
68.             <version>1.2.17</version>  
69.         </dependency>  
70.   
71.         <dependency>  
72.             <groupId>commons-logging</groupId>  
73.             <artifactId>commons-logging</artifactId>  
74.             <version>1.2</version>  
75.         </dependency>  
76.   
77.         <dependency>  
78.             <groupId>org.slf4j</groupId>  
79.             <artifactId>slf4j-api</artifactId>  
80.             <version>1.7.10</version>  
81.         </dependency>  
82.   
83.         <dependency>  
84.             <groupId>org.slf4j</groupId>  
85.             <artifactId>slf4j-log4j12</artifactId>  
86.             <version>1.7.10</version>  
87.         </dependency>  
88.   
89.         <!-- spring -->  
90.         <dependency>  
91.             <groupId>org.springframework</groupId>  
92.             <artifactId>spring-core</artifactId>  
93.             <version>3.2.3.RELEASE</version>  
94.         </dependency>  
95.   
96.         <dependency>  
97.             <groupId>org.springframework</groupId>  
98.             <artifactId>spring-orm</artifactId>  
99.             <version>3.2.3.RELEASE</version>  
100.         </dependency>  
101.   
102.         <dependency>  
103.             <groupId>org.springframework</groupId>  
104.             <artifactId>spring-context</artifactId>  
105.             <version>3.2.3.RELEASE</version>  
106.         </dependency>  
107.   
108.         <!-- ibatis -->  
109.         <dependency>  
110.             <groupId>org.apache.ibatis</groupId>  
111.             <artifactId>ibatis-sqlmap</artifactId>  
112.             <version>2.3.4.726</version>  
113.         </dependency>  
114.   
115.         <!-- connector -->  
116.         <dependency>  
117.             <groupId>mysql</groupId>  
118.             <artifactId>mysql-connector-java</artifactId>  
119.             <version>5.1.19</version>  
120.         </dependency>  
121.   
122.         <!-- dbcp -->  
123.         <dependency>  
124.             <groupId>commons-dbcp</groupId>  
125.             <artifactId>commons-dbcp</artifactId>  
126.             <version>1.4</version>  
127.         </dependency>  
128.   
129.         <dependency>  
130.             <groupId>commons-pool</groupId>  
131.             <artifactId>commons-pool</artifactId>  
132.             <version>1.6</version>  
133.         </dependency>  
134.   
135.         <!-- rsa encrypt -->  
136.         <dependency>  
137.             <groupId>org.bouncycastle</groupId>  
138.             <artifactId>bcprov-jdk15on</artifactId>  
139.             <version>1.51</version>  
140.         </dependency>  
141.   
142.         <!-- commons-codec -->  
143.         <dependency>  
144.             <groupId>commons-codec</groupId>  
145.             <artifactId>commons-codec</artifactId>  
146.             <version>1.6</version>  
147.         </dependency>  
148.   
149.     </dependencies>  
150. </project>