Spring MVC文件上传示例教程 - 单个和多个文件

文件上传是任何Web应用程序中非常常见的任务。我们之前已经看过如何在Servlet和Struts2文件上传中上传文件。今天我们将学习Spring文件上传，特别是单个和多个文件的Spring MVC文件上传。

目录[ 隐藏 ]

1 Spring MVC文件上传
- 1.1 Apache Commons FileUpload的Maven依赖项
- 1.2 Spring文件上传表单视图
- 1.3 Spring MVC Multipart配置
- 1.4 Spring文件上传控制器类
2 Spring MVC文件上传示例

Spring MVC文件上传

Spring MVC框架通过集成Apache Commons FileUpload API为上传文件提供支持。上传文件的过程非常简单，需要简单的配置。我们将在STS中创建一个简单的Spring MVC项目，如下图所示。

大部分是由STS工具生成的样板代码，我们将重点关注利用Spring文件上传集成所需的更改。

Apache Commons FileUpload的Maven依赖项

首先，我们需要在我们的pom.xml文件中添加Apache Commons FileUpload依赖项，以便所需的jar文件是Web应用程序的一部分。下面是我的pom.xml文件中的依赖片段。


<!-- Apache Commons FileUpload -->
<dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3.1</version>
</dependency><!-- Apache Commons IO -->
<dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.4</version>
</dependency>

Spring文件上传表单视图

我们将创建两个JSP页面，以允许在spring Web应用程序中上传单个和多个文件。

upload.jsp查看代码：


<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
<title>Upload File Request Page</title>
</head>
<body><form method="POST" action="uploadFile" enctype="multipart/form-data">File to upload: <input type="file" name="file"><br /> Name: <input type="text" name="name"><br /> <br /> <input type="submit" value="Upload"> Press here to upload the file!</form>
</body>
</html>

uploadMultiple.jsp视图代码：


<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<html>
<head>
<title>Upload Multiple File Request Page</title>
</head>
<body><form method="POST" action="uploadMultipleFile" enctype="multipart/form-data">File1 to upload: <input type="file" name="file"><br /> Name1: <input type="text" name="name"><br /> <br /> File2 to upload: <input type="file" name="file"><br /> Name2: <input type="text" name="name"><br /> <br /><input type="submit" value="Upload"> Press here to upload the file!</form>
</body>
</html>

请注意，这些文件是简单的HTML文件，我没有使用任何JSP或Spring标签来避免复杂性。需要注意的重要一点是，表单enctype应该是multipart / form-data，以便Spring Web应用程序知道请求包含需要处理的文件数据。

另请注意，对于多个文件，输入字段中的表单字段“file”和“name”是相同的，因此数据将以数组的形式发送。我们将获取输入数组并解析文件数据并将其存储在给定的文件名中。

Spring MVC Multipart配置

要利用Apache Commons FileUpload来处理多部分请求，我们需要做的就是multipartResolver使用class as 配置bean org.springframework.web.multipart.commons.CommonsMultipartResolver。

我们的最终Spring配置文件如下所示。

servlet-context.xml代码：


<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsdhttp://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"><!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure --><!-- Enables the Spring MVC @Controller programming model --><annotation-driven /><!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory --><resources mapping="/**" location="/" /><!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory --><beans:beanclass="org.springframework.web.servlet.view.InternalResourceViewResolver"><beans:property name="prefix" value="/WEB-INF/views/" /><beans:property name="suffix" value=".jsp" /></beans:bean><beans:bean id="multipartResolver"class="org.springframework.web.multipart.commons.CommonsMultipartResolver"><!-- setting maximum upload size --><beans:property name="maxUploadSize" value="100000" /></beans:bean><context:component-scan base-package="com.journaldev.spring.controller" /></beans:beans>

请注意，我通过为multipartResolver bean 提供maxUploadSize属性值来设置最大上载大小限制。如果您将查看类的源代码，您将看到名为multipartResolver的MultipartResolver变量已定义并在下面的方法中初始化。DispatcherServlet


private void initMultipartResolver(ApplicationContext context){try{this.multipartResolver = ((MultipartResolver)context.getBean("multipartResolver", MultipartResolver.class));if (this.logger.isDebugEnabled()) {this.logger.debug("Using MultipartResolver [" + this.multipartResolver + "]");}}catch (NoSuchBeanDefinitionException ex){this.multipartResolver = null;if (this.logger.isDebugEnabled())this.logger.debug("Unable to locate MultipartResolver with name 'multipartResolver': no multipart request handling provided");}}

使用此配置，任何具有enctype作为multipart / form-data的请求将在传递给Controller类之前由multipartResolver处理。

Spring文件上传控制器类

控制器类代码非常简单，我们需要为uploadFile和uploadMultipleFile URI 定义处理程序方法。

FileUploadController.java代码：


package com.journaldev.spring.controller;import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;/*** Handles requests for the application file upload requests*/
@Controller
public class FileUploadController {private static final Logger logger = LoggerFactory.getLogger(FileUploadController.class);/*** Upload single file using Spring Controller*/@RequestMapping(value = "/uploadFile", method = RequestMethod.POST)public @ResponseBodyString uploadFileHandler(@RequestParam("name") String name,@RequestParam("file") MultipartFile file) {if (!file.isEmpty()) {try {byte[] bytes = file.getBytes();// Creating the directory to store fileString rootPath = System.getProperty("catalina.home");File dir = new File(rootPath + File.separator + "tmpFiles");if (!dir.exists())dir.mkdirs();// Create the file on serverFile serverFile = new File(dir.getAbsolutePath()+ File.separator + name);BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(serverFile));stream.write(bytes);stream.close();logger.info("Server File Location="+ serverFile.getAbsolutePath());return "You successfully uploaded file=" + name;} catch (Exception e) {return "You failed to upload " + name + " => " + e.getMessage();}} else {return "You failed to upload " + name+ " because the file was empty.";}}/*** Upload multiple file using Spring Controller*/@RequestMapping(value = "/uploadMultipleFile", method = RequestMethod.POST)public @ResponseBodyString uploadMultipleFileHandler(@RequestParam("name") String[] names,@RequestParam("file") MultipartFile[] files) {if (files.length != names.length)return "Mandatory information missing";String message = "";for (int i = 0; i < files.length; i++) {MultipartFile file = files[i];String name = names[i];try {byte[] bytes = file.getBytes();// Creating the directory to store fileString rootPath = System.getProperty("catalina.home");File dir = new File(rootPath + File.separator + "tmpFiles");if (!dir.exists())dir.mkdirs();// Create the file on serverFile serverFile = new File(dir.getAbsolutePath()+ File.separator + name);BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(serverFile));stream.write(bytes);stream.close();logger.info("Server File Location="+ serverFile.getAbsolutePath());message = message + "You successfully uploaded file=" + name+ "<br />";} catch (Exception e) {return "You failed to upload " + name + " => " + e.getMessage();}}return message;}
}

请注意Spring注释的使用，这些注释使我们的生活更轻松，代码看起来更具可读性。

uploadFileHandler方法用于处理单个文件上载方案，而uploadMultipleFileHandler方法用于处理多个文件上载方案。实际上，我们可以使用一种方法来处理这两种情况。

现在将应用程序导出为WAR文件并将其部署到Tomcat servlet容器中。

当我们运行我们的应用程序时，下面的图像向我们显示请求和响应。