Spring MVC 4 文件下载实例（带源码）

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原文地址： http://websystique.com/springmvc/spring-mvc-4-file-download-example/

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本文将为你展示通过Spring MVC 4实现文件下载。

下载一个文件比较简单，主要包括下面几个步骤.

• 创建下载文件的InputStream（输入流）
• 找到下载文件类型的MIME type . – 可能是 application/pdf, text/html,application/xml,image/png, ..或者其他类型.
• 在response(HttpServletResponse)中设置  Content-Type 为上面的值. response.setContentType(mimeType);
• 设置Content length 文件长度. response.setContentLength(file.getLength());//字节长度
• 在响应中设置Content-Disposition HEADER  response.setHeader(“Content-Disposition”, “attachment; filename=” fileName); //With ‘attachement’ File will be downloaded as is. 可能会显示基于浏览器的 ‘文件另存为’对话框. response.setHeader(“Content-Disposition”, “inline; filename=” fileName);//With ‘inline’ browser will try to display content right into broswer for certain contents(imgages,PDF,text,..). 其他内容文件将直接被下载
• 拷贝 InputStream(输入流)的字节到 response的OutputStream（输出流） .
•  一旦拷贝完成，关闭输入输出流

下面是完整的例子

---

所用的技术或者软件：

• Spring 4.2.0.RELEASE
• Bootstrap v3.3.2
• Maven 3
• JDK 1.7
• Tomcat 8.0.21
• Eclipse JUNO Service Release 2

让我们开始吧

项目结构

 pom.xml文件声明依赖

代码语言：javascript复制

  4.0.0
  com.websystique.springmvc
  Spring4MVCFileDownloadExample
  war
  1.0.0
  Spring4MVCFileDownloadExample Maven Webapp
 
 
     
		4.2.0.RELEASE
	

	
		
			org.springframework
			spring-webmvc
			${springframework.version}
		

		
			javax.servlet
			javax.servlet-api
			3.1.0
		
		
			javax.servlet
			jstl
			1.2
		
	


	
		
			
				
					org.apache.maven.plugins
					maven-compiler-plugin
					3.2
					
						1.7
						1.7
					
				
				
					org.apache.maven.plugins
					maven-war-plugin
					2.4
					
						src/main/webapp
						Spring4MVCFileDownloadExample
						false
					
				
			
		

		Spring4MVCFileDownloadExample

创建控制器

代码语言：javascript复制

package com.websystique.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.ui.ModelMap;
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 FileDownloadController {
	
	private static final String INTERNAL_FILE="irregular-verbs-list.pdf";
	private static final String EXTERNAL_FILE_PATH="C:/mytemp/SpringMVCHibernateManyToManyCRUDExample.zip";
	

	@RequestMapping(value={"/","/welcome"}, method = RequestMethod.GET)
	public String getHomePage(ModelMap model) {
		return "welcome";
	}

	/*
	 * Download a file from 
	 *   - inside project, located in resources folder.
	 *   - outside project, located in File system somewhere. 
	 */
	@RequestMapping(value="/download/{type}", method = RequestMethod.GET)
	public void downloadFile(HttpServletResponse response, @PathVariable("type") String type) throws IOException {
	
		File file = null;
		
		if(type.equalsIgnoreCase("internal")){
			ClassLoader classloader = Thread.currentThread().getContextClassLoader();
			file = new File(classloader.getResource(INTERNAL_FILE).getFile());
		}else{
			file = new File(EXTERNAL_FILE_PATH);
		}
		
		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;
		}
		
		String mimeType= URLConnection.guessContentTypeFromName(file.getName());
		if(mimeType==null){
			System.out.println("mimetype is not detectable, will take default");
			mimeType = "application/octet-stream";
		}
		
		System.out.println("mimetype : " mimeType);
		
        response.setContentType(mimeType);
        
        /* "Content-Disposition : inline" will show viewable types [like images/text/pdf/anything viewable by browser] right on browser 
            while others(zip e.g) will be directly downloaded [may provide save as popup, based on your browser setting.]*/
        response.setHeader("Content-Disposition", String.format("inline; filename=""   file.getName()  """));

        
        /* "Content-Disposition : attachment" will be directly download, may provide save as popup, based on your browser setting*/
        //response.setHeader("Content-Disposition", String.format("attachment; filename="%s"", file.getName()));
        
        response.setContentLength((int)file.length());

		InputStream inputStream = new BufferedInputStream(new FileInputStream(file));

        //Copy bytes from source to destination(outputstream in this example), closes both streams.
        FileCopyUtils.copy(inputStream, response.getOutputStream());
	}

}

配置

代码语言：javascript复制

package com.websystique.springmvc.configuration;
 
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
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.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;
 
@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.websystique.springmvc")
public class HelloWorldConfiguration extends WebMvcConfigurerAdapter{
 
     
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setViewClass(JstlView.class);
        viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");
        registry.viewResolver(viewResolver);
    }
     
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("/static/");
    }
 
}

初始化

代码语言：javascript复制

package com.websystique.springmvc.configuration;
 
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
 
public class HelloWorldInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
  
 
    @Override
    protected Class[] getRootConfigClasses() {
        return new Class[] { HelloWorldConfiguration.class };
    }
   
    @Override
    protected Class[] getServletConfigClasses() {
        return null;
    }
   
    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }
  
 }

创建视图

代码语言：javascript复制

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

 

    
    Spring 4 MVC File Download Example
    
    


    
        Welcome to FileDownloader Example
         
        Click on below links to see FileDownload in action.


         
         
        Download This File (located inside project)  
        

        Download This File (located outside project, on file system)

构建发布和运行

在tomcat里面发布运行

浏览器输入  http://localhost:8080/Spring4MVCFileDownloadExample

点击第二个超链接 将下载外部（项目外）文件

点击第一个超链接. 内部（项目内部）文件 [一个 PDF] 将在浏览器中显示, 如果能在浏览器能够显示就会被显示在浏览器里面。

把Content-Disposition 从inline设置为 attachment.构建并重新发布 点第一个链接，PDF将被下载下来。

项目下载：http://websystique.com/?smd_process_download=1&download_id=1769

http c++ spring mvc servlet

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