在这篇文章中,我们将使用Spring MultipartResolver 实现 StandardServletMultipartResolver在Servlet3环境中实现单点和多文件上传功能。Spring提供了内置的multipart支持来处理Web应用程序文件上传。
简短的概述
在这篇文章中,我们将使用Servlet3.0以及javax.servlet.MultipartConfigElement,为了激活 Servlet3.0环境和Spring 的Multipart支持,你需要做以下:
1.添加 StandardServletMultipartResolver Bean 在 Spring 配置。这是一个标准实现 MultipartResolver 接口,基于Servlet3.0 javax.servlet.http.Part API。
2. 启用在Servlet3.0环境的多解析(MultiParsing)。要做到这一点,你有多种方案可供选择。
- 方案A. 对方案性 Servlet 注册设置 javax.servlet.MultipartConfigElement。MultipartConfigElement是javax.servlet.annotation.MultipartConfig 的注释值(如选择C所述)的简单Java类表示。 这篇文章将特别侧重于这个选择。
- 方案B. 如果您使用基于XML的配置,可以在web.xml中在servlet配置声明 multipart-configsection 部分,如下图所示:
<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. 可以创建一个自定义 Servlet 和 javax.servlet.annotation.MultipartConfig 标注其标注,如下图所示:
@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 }
话虽这么说,我们将专注于在这个例子中选择。
完整的例子
使用以下技术:
- 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.
项目结构
在pom.xml声明依赖关系
<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的编程注册
这个注册提供一个配置,以设置像最大文件大小,请求大小,位置和门限值。文件上传操作期间暂时存储在磁盘上的特定属性。
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 }
请注意,我们如何才能注册所需的 MultiPartConfigElement 到 DispatcherServlet 的重写函数 customizeRegistration。
创建配置
配置StandardServletMultipartResolver Bean。这是一个标准实现MultipartResolver接口,基于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格式配置类将是:
<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>
创建模型类
Spring提供 org.springframework.web.multipart.MultipartFile, 这是一个 multipart 请求获得上传文件的表示。 它提供了方便的方法,如getName(),getContentType(),GetBytes(),getInputStream()等。这让我们处理更容易一点,同时检索有关被上传文件的信息。
让我们写一个包装类,进一步简化我们应用程序的使用。
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; } }
为了展示Multiple上传的例子,让我们再创建一个包装类。
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; } }
这个类可以处理多达3个文件上传。
创建控制器
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"; } } }
以上控制器是相当微不足道。它处理上传视图的GET和POST请求的文件。当文件从文件选择器,用户选择点击上传,我们只是创建具有相同的名称和字节的内容作为原始文件的新文件,从原始复制文件的字节数。为此,我们正在使用Spring FileCopyUtils工具类流从源复制到目的地。在这个例子中,我们指定的目的地是 C:/mytemp 文件夹,所有文件将存在这个文件夹中。
创建验证类
我们使用的是一些验证,以验证用户确实选择了要上传的文件。它们如下所示。
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.
创建视图
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>
构建,部署和运行应用程序
现在构建 war(前面的Eclipse教程)或通过Maven的命令行( mvn clean install).部署 war 到Servlet3.0容器。
打开浏览器,浏览 http://localhost:8080/Spring4MVCFileUploadMultipart/
现在点击单个文件上传的链接。
点击上传,而不是选择一个文件。它应该显示验证失败消息。
单击选择文件。
应显示文件选择器。选择一个文件。
点击上传。开始上传文件。
您可以查看上传的文件夹 [C:/mytemp] 对于上传的文件。
现在回去,然后点击 multiupload 链接。
点击上传没有任何文件的选择,会收到验证错误。
选择要上传的文件。
点击上传。所有选中的文件都会被上传。
最后,查看存储文件夹 [C:/mytemp].
原文地址:https://www.cnblogs.com/borter/p/9519828.html