第3章：Maven使用入門/3.2 編寫源代碼

• 編寫源代碼

1. 安裝Maven約定，源代碼要存放在src/java/main，所以依次創建三個目錄
2. 按照POM中的<groupId>com.wys.myapp</groupId>和<artifactId>HelloWord</artifactId>創建目錄：com\wys\myapp\helloWorld，這個目錄是約定存在本項目的Java源代碼的，所以最後的目錄是：
3. 創建HelloWorld.java源代碼文件：

   
   package com.wys.myapp.mypackage

public class HelloWorld{
public String SayHello(){
return "hello world";
}

public static void main(String[] args) {
    System.out.println(new HelloWorld().SayHello());
}

}

4. 切換到項目的根目錄，也就是POM.xml文件所在目錄
[c:\~]$ cd D:\MavenTest\HelloWord

    5. 執行情況和編譯目錄
[D:\MavenTest\HelloWord]$ mvn clean compile
[INFO] Scanning for projects...
[INFO]                                                                        
[INFO] ------------------------------------------------------------------------
[INFO] Building My first Maven project 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ HelloWord ---
[INFO] Deleting D:\MavenTest\HelloWord\target
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ HelloWord ---
[WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory D:\MavenTest\HelloWord\src\main\resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ HelloWord ---
[INFO] Changes detected - recompiling the module!
[WARNING] File encoding has not been set, using platform encoding GBK, i.e. build is platform dependent!
[INFO] Compiling 1 source file to D:\MavenTest\HelloWord\target\classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.277 s
[INFO] Finished at: 2018-08-02T13:35:47+08:00
[INFO] Final Memory: 13M/108M
[INFO] ------------------------------------------------------------------------

    6. 完成後Maven自動新建target目錄存在class文件![](http://i2.51cto.com/images/blog/201812/16/f042f37a911d32a6a15b434d2c12de35.png?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_90,type_ZmFuZ3poZW5naGVpdGk=)
    7. 在POM.xml下新增加依賴：junit（單元測試jar包）和新的控件

        1. 新的依賴
<dependencies>
         <dependency>
                   <groupId>junit</groupId>
                   <artifactId>junit</artifactId>
                   <version>4.11</version>
                   <scope>test</scope>
         </dependency>
  </dependencies>

        2. 新的插件
<build>
         <plugins>
                   <plugin>
                            <groupId>org.apache.maven.plugins</groupId>
                            <artifactId>maven-compiler-plugin</artifactId>
                            <configuration>
                            <source>1.5</source>
                            <targer>1.5</targer>
                            </configuration>
                   </plugin>
         </plugins>
  </build>