Spring MVC教學 » Spring MVC4使用Servlet3 MultiPartConfigElement檔案上傳範例

Spring MVC4使用Servlet3 MultiPartConfigElement檔案上傳範例

在這篇文章中，我們將使用Spring MultipartResolver 實現 StandardServletMultipartResolver在Servlet3環境中實現單點和多檔案上傳功能。Spring提供了內建的multipart支援來處理Web應用程式檔案上傳。

簡短的概述

在這篇文章中，我們將使用Servlet3.0以及javax.servlet.MultipartConfigElement，為了啟用 Servlet3.0環境和Spring 的Multipart支援，你需要做以下：

1.新增 StandardServletMultipartResolver Bean 在 Spring 組態。這是一個標準實現 MultipartResolver 介面，基於Servlet3.0 javax.servlet.http.Part API。

2. 啟用在Servlet3.0環境的多解析(MultiParsing)。要做到這一點，你有多種方案可供選擇。

  • 方案A. 對方案性 Servlet 註冊設定 javax.servlet.MultipartConfigElement。MultipartConfigElement是javax.servlet.annotation.MultipartConfig 的註釋值(如選擇C所述)的簡單Java類表示。 這篇文章將特別側重於這個選擇。
  • 方案B. 如果您使用基於XML的組態，可以在web.xml中在servlet組態宣告 multipart-configsection 部分，如下圖所示： 
        <servlet>
        <servlet-name>SpringDispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <multipart-config>
            <location>/tmp</location>
            <max-file-size>5242880</max-file-size><!--5MB-->
            <max-request-size>20971520</max-request-size><!--20MB-->
            <file-size-threshold>0</file-size-threshold>
        </multipart-config>
    </servlet>
  • 方案C. 可以建立一個自定義 Servlet 和 javax.servlet.annotation.MultipartConfig 標註其標註，如下圖所示： 
    @WebServlet(name = "fileUploadServlet", urlPatterns = {"/upload"})
@MultipartConfig(location=/tmp,
                 fileSizeThreshold=0,    
                 maxFileSize=5242880,       // 5 MB
                 maxRequestSize=20971520)   // 20 MB
public class FileUploadServlet extends HttpServlet {
  
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //handle file upload
    }
話雖這麼說，我們將專注於在這個例子中選擇。

完整的例子

使用以下技術：
  • Spring 4.2.0.RELEASE
  • validation-api 1.1.0.Final
  • Bootstrap v3.3.2
  • Maven 3
  • JDK 1.7
  • Tomcat 8.0.21
  • Eclipse JUNO Service Release 2

Let’s begin.

專案結構

在pom.xml宣告依賴關係 

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.yiibai.springmvc</groupId>
	<artifactId>Spring4MVCFileUploadMultipartFile</artifactId>
	<packaging>war</packaging>
	<version>1.0.0</version>
	<name>Spring4MVCFileUploadMultipartFile Maven Webapp</name>
	<url>http://maven.apache.org</url>

	<properties>
		<springframework.version>4.2.0.RELEASE</springframework.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>${springframework.version}</version>
		</dependency>

		<dependency>
			<groupId>javax.validation</groupId>
			<artifactId>validation-api</artifactId>
			<version>1.1.0.Final</version>
		</dependency>

		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>javax.servlet-api</artifactId>
			<version>3.1.0</version>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>jstl</artifactId>
			<version>1.2</version>
		</dependency>
	</dependencies>


	<build>
		<pluginManagement>
			<plugins>
				<plugin>
					<groupId>org.apache.maven.plugins</groupId>
					<artifactId>maven-war-plugin</artifactId>
					<version>2.4</version>
					<configuration>
						<warSourceDirectory>src/main/webapp</warSourceDirectory>
						<warName>Spring4MVCFileUploadMultipartFile</warName>
						<failOnMissingWebXml>false</failOnMissingWebXml>
					</configuration>
				</plugin>
			</plugins>
		</pluginManagement>

		<finalName>Spring4MVCFileUploadMultipartFile</finalName>
	</build>
</project>

MultiPartConfigElement的程式設計註冊

這個註冊提供一個組態，以設定像最大檔案大小，請求大小，位置和門限值。檔案上傳操作期間暫時儲存在磁碟上的特定屬性。 
package com.yiibai.springmvc.configuration;

import javax.servlet.MultipartConfigElement;
import javax.servlet.ServletRegistration;

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[] { "/" };
	}

	@Override
	protected void customizeRegistration(ServletRegistration.Dynamic registration) {
		registration.setMultipartConfig(getMultipartConfigElement());
	}

	private MultipartConfigElement getMultipartConfigElement() {
		MultipartConfigElement multipartConfigElement = new MultipartConfigElement(	LOCATION, MAX_FILE_SIZE, MAX_REQUEST_SIZE, FILE_SIZE_THRESHOLD);
		return multipartConfigElement;
	}

	private static final String LOCATION = "C:/temp/"; // Temporary location where files will be stored

	private static final long MAX_FILE_SIZE = 5242880; // 5MB : Max file size.
														// Beyond that size spring will throw exception.
	private static final long MAX_REQUEST_SIZE = 20971520; // 20MB : Total request size containing Multi part.
	
	private static final int FILE_SIZE_THRESHOLD = 0; // Size threshold after which files will be written to disk
}
請注意，我們如何才能註冊所需的 MultiPartConfigElement 到 DispatcherServlet 的重寫函式 customizeRegistration。

建立組態

組態StandardServletMultipartResolver Bean。這是一個標準實現MultipartResolver介面，基於Servlet3.0 javax.servlet.http.Part API。 

package com.yiibai.springmvc.configuration;

import org.springframework.context.MessageSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ResourceBundleMessageSource;
import org.springframework.web.multipart.support.StandardServletMultipartResolver;
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 {

	@Bean(name = "multipartResolver")
	public StandardServletMultipartResolver resolver() {
		return new StandardServletMultipartResolver();
	}

	@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);
	}

	@Bean
	public MessageSource messageSource() {
		ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
		messageSource.setBasename("messages");
		return messageSource;
	}

	@Override
	public void addResourceHandlers(ResourceHandlerRegistry registry) {
		registry.addResourceHandler("/static/**").addResourceLocations( "/static/");
	}

}
以XML格式組態類將是： 
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
 
    <context:component-scan base-package="com.yiibai.springmvc" />
    <mvc:annotation-driven />

    <bean id="multipartResolver" class="org.springframework.web.multipart.support.StandardServletMultipartResolver"/>

    <mvc:resources mapping="/static/**" location="/static/" />
    <mvc:default-servlet-handler />


    <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
        <property name="basename">
            <value>messages</value>
        </property>
    </bean>


    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix">
            <value>/WEB-INF/views/</value>
        </property>
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>
</beans>

建立模型類

Spring提供 org.springframework.web.multipart.MultipartFile， 這是一個 multipart 請求獲得上傳檔案的表示。 它提供了方便的方法，如getName()，getContentType()，GetBytes()，getInputStream()等。這讓我們處理更容易一點，同時檢索有關被上傳檔案的資訊。

讓我們寫一個包裝類，進一步簡化我們應用程式的使用。 
package com.yiibai.springmvc.model;

import org.springframework.web.multipart.MultipartFile;

public class FileBucket {

	MultipartFile file;
	
	public MultipartFile getFile() {
		return file;
	}

	public void setFile(MultipartFile file) {
		this.file = file;
	}
}
為了展示Multiple上傳的例子，讓我們再建立一個包裝類。 
package com.yiibai.springmvc.model;

import java.util.ArrayList;
import java.util.List;

public class MultiFileBucket {

	List<FileBucket> files = new ArrayList<FileBucket>();
	
	public MultiFileBucket(){
		files.add(new FileBucket());
		files.add(new FileBucket());
		files.add(new FileBucket());
	}
	
	public List<FileBucket> getFiles() {
		return files;
	}

	public void setFiles(List<FileBucket> files) {
		this.files = files;
	}
}
這個類可以處理多達3個檔案上傳。

建立控制器 

package com.yiibai.springmvc.controller;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.util.FileCopyUtils;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.multipart.MultipartFile;

import com.yiibai.springmvc.model.FileBucket;
import com.yiibai.springmvc.model.MultiFileBucket;
import com.yiibai.springmvc.util.FileValidator;
import com.yiibai.springmvc.util.MultiFileValidator;

@Controller
public class FileUploadController {

	private static String UPLOAD_LOCATION="C:/mytemp/";

	@Autowired
	FileValidator fileValidator;

	@Autowired
	MultiFileValidator multiFileValidator;

	@InitBinder("fileBucket")
	protected void initBinderFileBucket(WebDataBinder binder) {
		binder.setValidator(fileValidator);
	}

	@InitBinder("multiFileBucket")
	protected void initBinderMultiFileBucket(WebDataBinder binder) {
		binder.setValidator(multiFileValidator);
	}

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

	@RequestMapping(value = "/singleUpload", method = RequestMethod.GET)
	public String getSingleUploadPage(ModelMap model) {
		FileBucket fileModel = new FileBucket();
		model.addAttribute("fileBucket", fileModel);
		return "singleFileUploader";
	}

	@RequestMapping(value = "/singleUpload", method = RequestMethod.POST)
	public String singleFileUpload(@Valid FileBucket fileBucket,
			BindingResult result, ModelMap model) throws IOException {

		if (result.hasErrors()) {
			System.out.println("validation errors");
			return "singleFileUploader";
		} else {
			System.out.println("Fetching file");
			MultipartFile multipartFile = fileBucket.getFile();

			// Now do something with file...
			FileCopyUtils.copy(fileBucket.getFile().getBytes(), new File( UPLOAD_LOCATION + fileBucket.getFile().getOriginalFilename()));
			String fileName = multipartFile.getOriginalFilename();
			model.addAttribute("fileName", fileName);
			return "success";
		}
	}

	@RequestMapping(value = "/multiUpload", method = RequestMethod.GET)
	public String getMultiUploadPage(ModelMap model) {
		MultiFileBucket filesModel = new MultiFileBucket();
		model.addAttribute("multiFileBucket", filesModel);
		return "multiFileUploader";
	}

	@RequestMapping(value = "/multiUpload", method = RequestMethod.POST)
	public String multiFileUpload(@Valid MultiFileBucket multiFileBucket,
			BindingResult result, ModelMap model) throws IOException {

		if (result.hasErrors()) {
			System.out.println("validation errors in multi upload");
			return "multiFileUploader";
		} else {
			System.out.println("Fetching files");
			List<String> fileNames = new ArrayList<String>();
			// Now do something with file...
			for (FileBucket bucket : multiFileBucket.getFiles()) {
				FileCopyUtils.copy(bucket.getFile().getBytes(), new File(UPLOAD_LOCATION + bucket.getFile().getOriginalFilename()));
				fileNames.add(bucket.getFile().getOriginalFilename());
			}

			model.addAttribute("fileNames", fileNames);
			return "multiSuccess";
		}
	}

}
 

以上控制器是相當微不足道。它處理上傳檢視的GET和POST請求的檔案。當檔案從檔案選擇器，使用者選擇點選上傳，我們只是建立具有相同的名稱和位元組的內容作為原始檔案的新檔案，從原始複製檔案的位元組數。為此，我們正在使用Spring FileCopyUtils工具類流從源複製到目的地。在這個例子中，我們指定的目的地是 C:/mytemp 檔案夾，所有檔案將存在這個檔案夾中。

建立驗證類

我們使用的是一些驗證，以驗證使用者確實選擇了要上傳的檔案。它們如下所示。 
package com.yiibai.springmvc.util;

import org.springframework.stereotype.Component;
import org.springframework.validation.Errors;
import org.springframework.validation.Validator;

import com.yiibai.springmvc.model.FileBucket;

@Component
public class FileValidator implements Validator {
	
	public boolean supports(Class<?> clazz) {
		return FileBucket.class.isAssignableFrom(clazz);
	}

	public void validate(Object obj, Errors errors) {
		FileBucket file = (FileBucket) obj;
		
		if(file.getFile()!=null){
			if (file.getFile().getSize() == 0) {
				errors.rejectValue("file", "missing.file");
			}
		}
	}
}
package com.yiibai.springmvc.util;

import org.springframework.stereotype.Component;
import org.springframework.validation.Errors;
import org.springframework.validation.Validator;

import com.yiibai.springmvc.model.FileBucket;
import com.yiibai.springmvc.model.MultiFileBucket;

@Component
public class MultiFileValidator implements Validator {
	
	public boolean supports(Class<?> clazz) {
		return MultiFileBucket.class.isAssignableFrom(clazz);
	}

	public void validate(Object obj, Errors errors) {
		MultiFileBucket multiBucket = (MultiFileBucket) obj;
		
		int index=0;
		
		for(FileBucket file : multiBucket.getFiles()){
			if(file.getFile()!=null){
				if (file.getFile().getSize() == 0) {
					errors.rejectValue("files["+index+"].file", "missing.file");
				}
			}
			index++;
		}
		
	}
}

messages.properties 

missing.file= Please select a file.

建立檢視

singleFileUploader.jsp 

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<html>

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>Spring 4 MVC File Upload Example</title>
	<link href="<c:url value='/static/css/bootstrap.css' />"  rel="stylesheet" type="text/css"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet" type="text/css"></link>
</head>
<body> 

	<div class="form-container">
		<h1>Spring 4 MVC File Upload Example </h1>
		<form:form method="POST" modelAttribute="fileBucket" enctype="multipart/form-data" class="form-horizontal">
		
			<div class="row">
				<div class="form-group col-md-12">
					<label class="col-md-3 control-lable" for="file">Upload a file</label>
					<div class="col-md-7">
						<form:input type="file" path="file" id="file" class="form-control input-sm"/>
						<div class="has-error">
							<form:errors path="file" class="help-inline"/>
						</div>
					</div>
				</div>
			</div>
	
			<div class="row">
				<div class="form-actions floatRight">
					<input type="submit" value="Upload" class="btn btn-primary btn-sm">
				</div>
			</div>
		</form:form>
		<a href="<c:url value='/welcome' />">Home</a>
	</div>
</body>
</html>

success.jsp 

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>File Upload Success</title>
	<link href="<c:url value='/static/css/bootstrap.css' />" rel="stylesheet"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet"></link>
</head>
<body>
	<div class="success">
		File  <strong>${fileName}</strong> uploaded successfully.
		<br/><br/>
		<a href="<c:url value='/welcome' />">Home</a>	
	</div>
</body>
</html>

multiFileUploader.jsp 

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<html>

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>Spring 4 MVC File Multi Upload Example</title>
	<link href="<c:url value='/static/css/bootstrap.css' />"  rel="stylesheet" type="text/css"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet" type="text/css"></link>
</head>
<body> 

	<div class="form-container">
		<h1>Spring 4 MVC Multi File Upload Example </h1>
		<form:form method="POST" modelAttribute="multiFileBucket" enctype="multipart/form-data" class="form-horizontal">
		
			<c:forEach var="v" varStatus="vs" items="${multiFileBucket.files}">
				<form:input type="file" path="files[${vs.index}].file" id="files[${vs.index}].file" class="form-control input-sm"/>
				<div class="has-error">
					<form:errors path="files[${vs.index}].file" class="help-inline"/>
				</div>
			</c:forEach>
			<br/>
			<div class="row">
				<div class="form-actions floatRight">
					<input type="submit" value="Upload" class="btn btn-primary btn-sm">
				</div>
			</div>
		</form:form>
		
		<br/>
		<a href="<c:url value='/welcome' />">Home</a>
	</div>
</body>
</html>

multiSuccess.jsp 

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>File Upload Success</title>
	<link href="<c:url value='/static/css/bootstrap.css' />" rel="stylesheet"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet"></link>
</head>
<body>
	<div class="success">
			<c:forEach var="fileName" items="${fileNames}">
				File  <strong>${fileName}</strong> uploaded successfully<br/>
			</c:forEach>
			<br/>
		<a href="<c:url value='/welcome' />">Home</a>
	</div>
</body>
</html>

welcome.jsp 

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

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
	<title>Spring 4 MVC File Upload Example</title>
	<link href="<c:url value='/static/css/bootstrap.css' />"  rel="stylesheet"></link>
	<link href="<c:url value='/static/css/app.css' />" rel="stylesheet"></link>
</head>
<body>
	<div class="form-container">
		<h1>Welcome to FileUploader Example</h1>
		
		Click on below links to see FileUpload in action.<br/><br/>
		
		<a href="<c:url value='/singleUpload' />">Single File Upload</a>  OR  <a href="<c:url value='multiUpload' />">Multi File Upload</a>
	</div> 
</body>
</html>

構建，部署和執行應用程式

現在構建 war(前面的Eclipse教學)或通過Maven的命令列( mvn clean install).部署 war 到Servlet3.0容器。

開啟瀏覽器，瀏覽 http://localhost:8080/Spring4MVCFileUploadMultipart/

現在點選單個檔案上傳的連結。

點選上傳，而不是選擇一個檔案。它應該顯示驗證失敗訊息。

單擊選擇檔案。

應顯示檔案選擇器。選擇一個檔案。
點選上傳。開始上傳檔案。

您可以檢視上傳的檔案夾 [C:/mytemp] 對於上傳的檔案。 

現在回去，然後點選 multiupload 連結。

點選上傳沒有任何檔案的選擇，會收到驗證錯誤。

選擇要上傳的檔案。

點選上傳。所有選中的檔案都會被上傳。

最後，檢視儲存檔案夾 [C:/mytemp].

所有步驟完成，就講解到這裡，包教不包會！

程式碼下載：http://pan.baidu.com/s/1pK3gMXP