springmvc template包下的文件是视图返回的吗

转载

索姆拉 2025-01-09 11:53:51

文章标签 java mvc例子下载 spring java ide 文章分类 机器学习人工智能

这篇文章将向您展示如何使用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。

本教程的主要亮点：

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。

完整实施例在下面讨论。

使用到以下技术：
Spring 4.2.0.RELEASE
Bootstrap v3.3.2
Maven 3
JDK 1.7
Tomcat 8.0.21
Eclipse JUNO Service Release 2

现在让我们开始

项目结构

springmvc template包下的文件是视图返回的吗_ide

在pom.xml中声明依赖关系

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
4.0.0
com.yiibai.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-war-plugin
2.4
src/main/webapp
Spring4MVCFileDownloadExample
false
Spring4MVCFileDownloadExample
创建控制器
package com.yiibai.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());
}
}

该控制器包括两个文件。一个文件是内部应用(内部资源)，和其他文件位于外部的应用程序的文件系统。您的项目一定要改变外部文件的路径。仅用于演示的目的，我们已在路径一个额外的路径变量(内部/外部)。我们正在使用Spring FileCopyUtils工具类流从源复制到目的地。

配置
package com.yiibai.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.yiibai.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
package com.yiibai.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[] { "/" };
}
}

添加视图

Spring 4 MVC File Download Example