Spring4 MVC文件下载实例(javaconfig)

展示如何使用Spring MVC4执行文件下载，我们将看到应用程序从文件系统内部以及外部文件下载文件。

下载文件是相当简单的，涉及以下步骤。

• 创建一个InputStream到文件用于下载。
• 查找MIME类型下载文件的内容。
  –可以是application/pdf, text/html,application/xml,image/png等等。
• 将内容类型与上述发现的MIME类型响应（HttpServletResponse）。
  response.setContentType(mimeType);
• 针对以上找到MIME类型设置内容长度。
  response.setContentLength(file.getLength());//length in bytes
• 为响应设置内容处理标头。
  response.setHeader(“Content-Disposition”, “attachment; filename=” + fileName); //随着“附件”文件将下载。可能会显示一个“另存为”基于浏览器的设置对话框。

  response.setHeader(“Content-Disposition”, “inline; filename=” + fileName);//通过“内联”浏览器将尝试显示内容到浏览器中（图片，PDF，文本，...）。对于其他内容类型，文件将直接下载。

• 从InputStream中复制字节响应到 OutputStream。
• 一旦复制完成后，关闭输入输出流。

内部文件下载：通过Thread.currentThread.getContextClassLoad()类来加载文件

//内部文件
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
file = new File(classLoader.getResource(INTERNAL_FILE).getFile());

　　

获取文件类型mimeTyp：URLConnection.guessContentTypeFromName(file.getName())

String  mimeType = URLConnection.guessContentTypeFromName(file.getName());
 response.setContentType(mimeType);

输出文件类型/文件下载路径：

　　

//文件类型
 response.setContentType(mimeType);
//文件地址
response.setHeader("Content-Disposition", String.format("inline; filename=\"" + file.getName() +"\""));
//文件大小
response.setContentLength((int)file.length());

　　

通过FileCopyUtils.copy（springmvc）复制文件流下载输出：

InputStream inputStream = new BufferedInputStream(new FileInputStream(file));
FileCopyUtils.copy(inputStream, response.getOutputStream());

　　

完整实施例在下面讨论。

pom.xml配置

 <properties>
  	<springVersion>4.3.5.RELEASE</springVersion>
   </properties>

  <dependencies>

     <!-- spring模块库 -->
    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-beans</artifactId>
    	<version>${springVersion}</version>
    </dependency>
    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-web</artifactId>
    	<version>${springVersion}</version>
    </dependency>
    <dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-webmvc</artifactId>
    	<version>${springVersion}</version>
    </dependency>
	<!-- https://mvnrepository.com/artifact/org.springframework/spring-tx -->
	<!-- transaction事务 -->
	<dependency>
	    <groupId>org.springframework</groupId>
	    <artifactId>spring-tx</artifactId>
	    <version>${springVersion}</version>
	</dependency>

     <!-- Servlet dependencies -->
    <!-- servlet(HttpServletRequest,HttpServletResponse) -->
	<dependency>
		<groupId>javax.servlet</groupId>
		<artifactId>javax.servlet-api</artifactId>
		<version>3.1.0</version>
	</dependency>

	<!-- https://mvnrepository.com/artifact/jstl/jstl -->
	<dependency>
	    <groupId>jstl</groupId>
	    <artifactId>jstl</artifactId>
	    <version>1.2</version>
	</dependency>

  </dependencies>

  <build>
    <finalName>gugua14</finalName>
    <pluginManagement>
    	<plugins>
    		<plugin>
    			<groupId>org.apache.maven.plugins</groupId>
    			<artifactId>maven-war-plugin</artifactId>
    			<version>2.6</version>
    			<configuration>
    				<warSourceDirectory>src/main/webapp</warSourceDirectory>
    				<warName>gugua14</warName>
    				<failOnMissingWebXml>false</failOnMissingWebXml>
    			</configuration>
    		</plugin>
    	</plugins>
    </pluginManagement>
  </build>
</project>

　　

HelloWorldConfiguration.java

package springmvc.configuration;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages="springmvc")
public class HelloWorldConfiguration  extends WebMvcConfigurerAdapter{

	@Override
	public void addResourceHandlers(ResourceHandlerRegistry registry) {
		// TODO Auto-generated method stub
		//super.addResourceHandlers(registry);

		//设置静态目录
		registry.addResourceHandler("/static/**").addResourceLocations("/static/");
	}

	@Override
	public void configureViewResolvers(ViewResolverRegistry registry) {
		// TODO Auto-generated method stub
		//super.configureViewResolvers(registry);
		InternalResourceViewResolver viewReslover = new InternalResourceViewResolver();
		viewReslover.setViewClass(JstlView.class);
		viewReslover.setPrefix("/WEB-INF/views/");
		viewReslover.setSuffix(".jsp");
		registry.viewResolver(viewReslover);
	}

}

　　

dispatcherServlet转发配置

package springmvc.configuration;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class HelloWorldIntializer extends AbstractAnnotationConfigDispatcherServletInitializer {

	@Override
	protected Class<?>[] getRootConfigClasses() {
		// TODO Auto-generated method stub
		return new Class[] {HelloWorldConfiguration.class};
	}

	@Override
	protected Class<?>[] getServletConfigClasses() {
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	protected String[] getServletMappings() {
		// TODO Auto-generated method stub
		return new String[] {"/"};
	}

}

　　

controller代码

package springmvc.controller;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLConnection;
import java.nio.charset.Charset;

import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;
import org.springframework.util.FileCopyUtils;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class HelloWorldController {

	private static final String FILE_1 = "APICloud-basic-2.2.1.zip";
	private static final String FILE_2 ="D:/download/APICloud-basic-2.2.1.zip";

	@RequestMapping(value="/down", method=RequestMethod.GET)
	public String index()
	{
		return "index";
	}

	@RequestMapping(value="/download/{type}", method=RequestMethod.GET)
	public void download(HttpServletResponse response, @PathVariable("type")  String type) throws IOException
	{
		File file = null;

		if( type.equalsIgnoreCase("internal") )
		{
			//内部地址
			ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
			file = new File( classLoader.getResource(FILE_1).getFile() );
		}else {
			//外部地址
			file = new File(FILE_2);
		}

		//文件是否存在
		if(!file.exists())
		{
			String errorMessage = "Sorry. The file you are looking for does not exist";
			System.out.println(errorMessage);
			OutputStream outputStream = response.getOutputStream();
			outputStream.write(errorMessage.getBytes(Charset.forName("UTF-8")));
			outputStream.close();
			return;

		}

		//获取文件类型，并输出文件类型
		String mimeType = URLConnection.guessContentTypeFromName(file.getName());
		if(mimeType == null)
		{
			System.out.println("mimeType is not detectable.");
			mimeType = "application/octet-stream";
		}
		System.out.println("mimeType:" + mimeType);

		//输出类型
		response.setContentType(mimeType);
		//mime协议:默认文件名
		response.setHeader("Content-Disposition", String.format("inline: filename=\""+file.getName()+"\""));
		//mime协议：以附件形式下载
		response.setHeader("Content-Disposition", String.format("attachment: filename=\"%s\"", file.getName()));
		//文件大小
		response.setContentLength((int) file.length());

		//读入文件,然后再输出
		InputStream inputStream = new BufferedInputStream(new  FileInputStream(file));
		//拷贝，下载
		FileCopyUtils.copy(inputStream, response.getOutputStream());

	}

}

　　

访问地址：http://localhost:8080/gugua14/down