maven File encoding has not been set

原pom.xml配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>
    <groupId>com.my.helloworld</groupId>
    <artifactId>hello-world</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>Maven Hello World Project</name>
     <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.7</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

     <build>
        <plugins>
           <plugin>
             <artifactId>maven-compiler-plugin</artifactId>
             <version>2.3.2</version>
             <configuration>
               <source>1.7</source>
                <target>1.7</target>
                <encoding>UTF-8</encoding>
             </configuration>
           </plugin>
        </plugins>
      </build>

    </properties>
</project>

修改后的pom.xml配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>
    <groupId>com.my.helloworld</groupId>
    <artifactId>hello-world</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>Maven Hello World Project</name>
     <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.7</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

     <build>
        <plugins>
           <plugin>
             <artifactId>maven-compiler-plugin</artifactId>
             <version>2.3.2</version>
             <configuration>
               <source>1.7</source>
                <target>1.7</target>
                <encoding>UTF-8</encoding>
             </configuration>
           </plugin>
        </plugins>
      </build>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
</project>

增加了一个属性的设置。