第十一章节-上传文件

在Spring MVC中处理文件上传有两种方法：

（1）使用Common FileUp元件。

（2）使用Servlet 3.0和更高版本对文件上传的支持。

一、客户端编程

为了上传文件，要将html表格的enctype设置为multipart/form-data，表格中还要有一个类型为file的input元素，它会显示成一个按钮，点击时会打开一个选择文件的对话框。

如下：

<form action="action" enctype="multipart/form-data" method="post>
    选择文件<input type="file" name="filedName"/ multiple>
    <input type="submit" value="Upload"/>
</form>

在html5之前，如果要上传多个文件，就要写多个input，有了html5,只用在input中加入multiple属性。

二、MultipartFile接口

已经上传到Spring MVC的文件会包在一个MutlipartFile对象中，我们唯一要做的就是使用类型为MultipartFile的属性写一个domain类。

接下来讲解怎么得到控制器中已经上传的文件。

三、用Common FileUpload上传文件

这里要用到两个jar文件：

commons-fileupload.jar 

common-io.jar

此外还要在springmvc-servlet.xml文件中定义 multipartResolver bean 

<bean id="multipartResolver"     class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
    <property name="mxcUploadSize" value="2000000"/>
</bean>

四、用common FileUpload的例子

工程目录 

Product文件

public class Product implements Serializable{
	
	private String name ;
	private String description ;
	private Float price ;
	private List<MultipartFile> images ;
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	public Float getPrice() {
		return price;
	}
	public void setPrice(Float price) {
		this.price = price;
	}
	public List<MultipartFile> getImages() {
		return images;
	}
	public void setImages(List<MultipartFile> images) {
		this.images = images;
	}
	
	
}

ProductController文件

@Controller
public class ProductController {
	private static final Log logger = LogFactory.getLog(ProductController.class) ;
	
	@RequestMapping(value ="/product_input")
	public String inputProduct(Model model){
		model.addAttribute("product" , new Product()) ; //什么意思 
		return "ProductForm" ;
	}
	/**
	 * ModelAttribute:将product添加到model中
	 */
	@RequestMapping(value="/product_save")
	public String saveProduct(HttpServletRequest request ,@ModelAttribute Product product,
			BindingResult bindingResult, Model model){
		List<MultipartFile> files = product.getImages() ;
		
		List<String> fileNames = new ArrayList<String>() ;
		
		if (null!= files && files.size()>0){
			for (MultipartFile multipartFile : files){
				String fileName = multipartFile.getOriginalFilename() ;
				fileNames.add(fileName) ;
				// 这里得到的不是WebRoot下面的image文件夹，而是在tomcat里面的app11b里面的image文件夹
				File imageFile = new File(request.getServletContext().getRealPath("/image"), fileName) ;
				logger.info("imageFile:"+imageFile);
				try {
					multipartFile.transferTo(imageFile );
					logger.info("save file");
				} catch (Exception e) {
					logger.info("save file failed");
					e.printStackTrace();
				}
			}
		}
		//save product 
		model.addAttribute("product" , product) ;
		return "ProductDetails";
	}
}　　

springmvc-config.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xmlns:p="http://www.springframework.org/schema/p"
	xmlns:mvc="http://www.springframework.org/schema/mvc" 
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-4.1.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd     
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

	<context:component-scan base-package="app11a.controller" />
	
	<mvc:annotation-driven/>
	<mvc:resources mapping="/css/**" location="/css/" />
	<mvc:resources mapping="/*.html" location="/" />
    <mvc:resources mapping="/image/**" location="/image/" />

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

    <bean id="multipartResolver"
            class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="2000000"/>
    </bean>

</beans>　　

web.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 
		xmlns="http://java.sun.com/xml/ns/javaee"
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
	    <init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>/WEB-INF/config/springmvc-config.xml</param-value>
		</init-param>
        <load-on-startup>1</load-on-startup>    
	</servlet>

    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

ProductForm.jsp

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML>
<html>
<head>
<title>Add Product Form</title>
<style type="text/css">@import url("<c:url value="/css/main.css"/>");</style>
</head>
<body>

<div id="global">
<form:form commandName="product" action="product_save" method="post" enctype="multipart/form-data">
    <fieldset>
        <legend>Add a product</legend>
        <p>
            <label for="name">Product Name: </label>
            <form:input id="name" path="name" cssErrorClass="error"/>
            <form:errors path="name" cssClass="error"/>
        </p>
        <p>
            <label for="description">Description: </label>
            <form:input id="description" path="description"/>
        </p>
        <p>
            <label for="price">Price: </label>
            <form:input id="price" path="price" cssErrorClass="error"/>
        </p>
        <p>
            <label for="image">Product Image: </label>
            <input type="file" name="images[0]"/>
        </p>
        <p id="buttons">
            <input id="reset" type="reset" tabindex="4">
            <input id="submit" type="submit" tabindex="5" 
                value="Add Product">
        </p>
    </fieldset>
</form:form>
</div>
</body>
</html>

ProductDetails.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML>
<html>
<head>
<title>Save Product</title>
<style type="text/css">@import url("<c:url value="/css/main.css"/>");</style>
</head>
<body>
<div id="global">
    <h4>The product has been saved.</h4>
    <p>
        <h5>Details:</h5>
        Product Name: ${product.name}<br/>
        Description: ${product.description}<br/>
        Price: $${product.price}
        <p>Following files are uploaded successfully.</p>
        <ol>
        <c:forEach items="${product.images}" var="image">
            <li>${image.originalFilename}
            <img width="100" src="<c:url value="/image/"/>
            ${image.originalFilename}"/>
            </li>
        </c:forEach>
        </ol>
    </p>
</div>
</body>
</html>