Maven依赖管理

Maven提供dependencyManagement 元素既能让子模块继承到父模块的依赖配置，又能保证自模块依赖的使用灵活性。（有选择的继承）

可在accout-parent 中加入：

 

Xml代码  

1. <project xmlnsxmlns="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/maven-v4_0_0.xsd">  
3.     <modelVersion>4.0.0</modelVersion>  
4.     <groupId>com.juvenxu.mvnbook.account</groupId>  
5.     <artifactId>account-parent</artifactId>  
6.     <version>1.0.0-SNAPSHOT</version>  
7.     <packaging>pom</packaging>  
8.     <name>Account Parent</name>  
9.     <properties>  
10.         <springframework.version>2.5.6</springframework.version>  
11.         <junit.version>4.7</junit.version>  
12.     </properties>  
13.     < dependencyManagement >  
14.         <dependencies>  
15.             <dependency>  
16.                 <groupId>org.springframework</groupId>  
17.                 <artifactId>spring-core</artifactId>  
18.                 <version>${springframework.version}</version>  
19.             </dependency>  
20.             <dependency>  
21.                 <groupId>org.springframework</groupId>  
22.                 <artifactId>spring-beans</artifactId>  
23.                 <version>${springframework.version}</version>  
24.             </dependency>  
25.             <dependency>  
26.                 <groupId>org.springframework</groupId>  
27.                 <artifactId>spring-context</artifactId>  
28.                 <version>${springframework.version}</version>  
29.             </dependency>  
30.             <dependency>  
31.                 <groupId>org.springframework</groupId>  
32.                 <artifactId>spring-context-support</artifactId>  
33.                 <version>${springframework.version}</version>  
34.             </dependency>  
35.             <dependency>  
36.                 <groupId>junit</groupId>  
37.                 <artifactId>junit</artifactId>  
38.                 <version>${junit.version}</version>  
39.                 <scope>test</scope>  
40.             </dependency>  
41.         </dependencies>  
42.     </ dependencyManagement >  
43. </project>  

 子模块继承代码如下：

 

Xml代码  

1. <project xmlnsxmlns="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/maven-v4_0_0.xsd">  
3.     <modelVersion>4.0.0</modelVersion>  
4.       
5.     < parent >  
6.         <groupId>com.juvenxu.mvnbook.account</groupId>  
7.         <artifactId> account-parent </artifactId>  
8.         <version>1.0.0-SNAPSHOT</version>  
9.     </ parent >  
10.       
11.     <artifactId>account-email</artifactId>  
12.     <name>Account Email</name>  
13.   
14.     <properties>  
15.         <javax.mail.version>1.4.1</javax.mail.version>  
16.         <greenmail.version>1.3.1b</greenmail.version>  
17.     </properties>  
18.   
19.     <dependencies>  
20.         <dependency>  
21.             <groupId>org.springframework</groupId>  
22.             <artifactId>spring-core</artifactId>                               
23.         </dependency>  
24.         <dependency>  
25.             <groupId>org.springframework</groupId>  
26.             <artifactId>spring-beans</artifactId>                                            
27.         </dependency>  
28.         <dependency>  
29.             <groupId>org.springframework</groupId>  
30.             <artifactId>spring-context</artifactId>                                         
31.         </dependency>  
32.         <dependency>  
33.             <groupId>org.springframework</groupId>  
34.             <artifactId>spring-context-support</artifactId>                                         
35.         </dependency>  
36.         <dependency>  
37.             <groupId>junit</groupId>  
38.             <artifactId>junit</artifactId>  
39.         </dependency>  
40.         <dependency>  
41.             <groupId>javax.mail</groupId>  
42.             <artifactId>mail</artifactId>  
43.             <version>${javax.mail.version}</version>  
44.         </dependency>                     
45.         <dependency>  
46.             <groupId>com.icegreen</groupId>  
47.             <artifactId>greenmail</artifactId>  
48.             <version>${greenmail.version}</version>  
49.             <scope>test</scope>  
50.         </dependency>  
51.     </dependencies>  
52.   
53.     <build>  
54.     </build>  
55.   
56. </project>  

   使用继承管理依赖 (dependencyManagement)带来的好处

1、代码量减少，不用多次重复声明 version等元素。

2、version受父管理，父变则子变，便于修改。

3、dependencyManagement一旦定义，可以复用。

例如想要在另外一个模块中使用如父模块中一样的  dependencyManagement 的设置。除了复制，还可以导入。如下：

Xml代码  

1. <dependencyManagement>  
2.     <dependencies>  
3.         <dependency>  
4.             <groupId>com.juvenxu.mvnbook.account</groupId>  
5.             <artifactId> account-parent </artifactId>  
6.             <version>1.0-SNAPSHOT</version>  
7.             <type>pom</type>  
8.             <scope>import</scope>  
9.         </dependency>  
10.     </dependencies>  
11. </dependencyManagement>