增加文件下载所需要的jar包。

pom.xml

			<artifactId>mail</artifactId>
			<version>1.4</version>
		</dependency>
		<dependency>
			<groupId>commons-io</groupId>
			<artifactId>commons-io</artifactId>
			<version>1.3.2</version>
		</dependency>
		<dependency>
			<groupId>commons-fileupload</groupId>
			<artifactId>commons-fileupload</artifactId>
			<version>1.3.2</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-log4j12</artifactId>
			<version>1.7.21</version>
		</dependency>
	</dependencies>
	<build>
		<plugins>