使用SpringMVC如何实现一个文件上传功能?很多新手对此不是很清楚,为了帮助大家解决这个难题,下面小编将为大家详细讲解,有这方面需求的人可以来学习下,希望你能有所收获。
说明:
文件上传的途径
文件上传主要有两种方式:
1.使用Apache Commons FileUpload元件。
2.利用Servlet3.0及其更高版本的内置支持。
客户端编程
1.为了上传文件,必须将HTML表格的enctype属性值设为multipart/form-data,像下面这样:
<form action="action" enctype="multipart/form-data" method="post">
Select a file<input type="file" name="fieldName"/>
<input type="submit" value="Upload"/>
</form>
2.在HTML5之前,如果要想上传多个文件,必须使用多个文件input元素。但是,在HTML5中,通过在input元素中引入多个multiple属性,使得多个文件的上传变得更加简单,下面均可使一个上传框支持多个文件上传。
<input type="file" name="fieldName" multiple/>
<input type="file" name="fieldName" multiple="multiple"/>
<input type="file" name="fieldName" multiple=""/>
MultipartFile接口
在SpringMVC中处理已经上传的文件十分简单,上传到SpringMVC应用程序中的文件会被包在一个MultipartFile对象中,你唯一要做的事情就是用类型为MultipartFile的属性编写一个Domain类。就像下面这样:
package domain;
import org.springframework.web.multipart.MultipartFile;
import java.io.Serializable;
import java.util.List;
public class Product implements Serializable {
//实现了这个接口,可以安全的将数据保存到HttpSession中
private long id;
private String name;
private String description;
private String price;
//在Domain类中加入MultipartFile类型的属性,用来保存上传的文件
private List<MultipartFile> images;
public List<MultipartFile> getImages() {
return images;
}
public void setImages(List<MultipartFile> images) {
this.images = images;
}
......多个get和set方法。
MultipartFile接口提供了以下方法:
Modifier and Type | Method and Description |
---|---|
byte[] | getBytes()Return the contents of the file as an array of bytes. |
String | getContentType()Return the content type of the file. |
InputStream | getInputStream()Return an InputStream to read the contents of the file from. |
String | getName()Return the name of the parameter in the multipart form. |
String | getOriginalFilename()Return the original filename in the client's filesystem. |
long | getSize()Return the size of the file in bytes. |
boolean | isEmpty()Return whether the uploaded file is empty, that is, either no file hasbeen chosen in the multipart form or the chosen file has no content. |
void | transferTo(File dest)Transfer the received file to the given destination file. |
实例:用CommonsFileUpLoad上传文件
导入Jar包及配置环境变量
编写视图
代码:
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Add Product Form</title>
</head>
<body>
<form:form action="product_save" method="post" commandName="product" enctype="multipart/form-data">
<fieldset>
<legend>Add a Product</legend>
<p>
<label for="name">ProductName</label>
<form:input type="text" id="name" name="name" tabindex="1" path="name"/>
</p>
<p>
<label for="description">ProductDescription</label>
<form:input type="text" id="description" name="description" tabindex="2" path="description"/>
</p>
<p>
<label for="price">ProductPrice</label>
<form:input type="text" id="price" name="price" tabindex="3" path="price"/>
</p>
<p>
<label for="image">ProductImage</label>
<input type="file" name="images[0]">
</p>
<p>
<input type="reset">
<input type="submit">
</p>
</fieldset>
</form:form>
</body>
</html>
说明:
首先为了上传文件,必须将HTML表格的enctype属性值设为multipart/form-data
其次,在HTML5之前,如果要想上传多个文件,必须要用到多个文件input元素。
但是在HTML5,通过在Input元素中引入过个multiple属性,使得多个文件上传变得更加简单。
<input type="file" name="fieldName" multiple/>
<input type="file" name="fieldName" multiple="multiple"/>
<input type="file" name="fieldName" multiple=""/>
图示:
编写控制器
package controller;
import domain.Product;
import Service.ProductService;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.util.List;
@Controller
public class ProductController {
private static final Log logger=LogFactory.getLog(ProductController.class);
@Autowired
private ProductService productService;
@RequestMapping(value = "/product_input")
public String inputProduct(Model model)
{
logger.info("inputProduct called");
model.addAttribute("product",new Product());
return "ProductForm";
}
@RequestMapping(value = "/product_save",method = RequestMethod.POST)
public String saveProduct(HttpServletRequest servletRequest, @ModelAttribute Product product,
BindingResult bindingResult,Model model)
{
List<MultipartFile> files= product.getImages();
System.out.println("文件数量是"+files.size());
if(null!=files&&files.size()>0)
{
for (MultipartFile file:files)
{
String fileName=file.getOriginalFilename(); //获得文件名称
File imagFile = new File(servletRequest.getServletContext().getRealPath("/image"),fileName);try {
file.transferTo(imagFile);//用于将文件写到服务器本地
} catch (IOException e) {
e.printStackTrace();
}
}
}
model.addAttribute("product",product);
return "ProductDetails";
}
@RequestMapping(value = "/product_view/{id}")
public String viewProduct(@PathVariable Long id,Model model)
{
Product product =productService.get(id);
model.addAttribute("product",product);
return "ProductDetails";
}
}
配置文件
你可以看到我们在SpringMVC的配置文件中配置了一个名为multipartResolver的Bean。
基于servlet的multipartresolver实现Apache Commons FileUpload 1.2或以上。
提供“maxuploadsize”、“maxinmemorysize”和“defaultencoding”设置bean的属性(继承commonsfileuploadsupport)
<?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:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
<context:component-scan base-package="controller"/>
<context:component-scan base-package="Service"/>
<!--
<mvc:annotation-driven>元素注册用于支持基于注解的控制器的请求处理方法的Bean对象。
详解:https://my.oschina.net/HeliosFly/blog/205343
-->
<mvc:annotation-driven></mvc:annotation-driven>
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/view/"/>
<property name="suffix" value=".jsp"/>
</bean>
<!--resources 元素指示SpringMVC那些静态资源需要单独处理-->
<mvc:resources mapping="/image/**" location="/image/"/>
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="2000000"/>
</bean>
</beans>
说明:
resources 元素指示SpringMVC那些静态资源需要单独处理,此处我们要单独处理的是image,如果不单独处理而是经过dispatcher的话,就会发生404错误.
实例:用Servlet3及其更高版本上传文件
说明:
有了Servlet3,就不需要Commons FileUpload 和Commons IO元件了.因为在Servlet3中内置了上传文件的特性.
幸运的是Domain类和Controller类基本不变,我们仅仅需要修改一下配置文件。
配置文件:
修改Web.xml
我们可以看到实在dispatcher的基础上添加了配置项:multipart-config
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
<multipart-config>
<max-file-size>20848820</max-file-size>
<!--上传内文件的最大容量-->
<max-request-size>418018841</max-request-size>
<!--表示多部分HTTP请求允许的最大容量-->
<file-size-threshold>1048576</file-size-threshold>
<!--超过这个容量将会被写到磁盘中-->
<location>/image/</location>
<!--要将已上传的文件保存到磁盘中的位置-->
</multipart-config>
</servlet>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!--Spring中文乱码拦截器-->
<filter>
<filter-name>setcharacter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>setcharacter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
SpringMVC配置文件添加多部分解析器
MultipartResolver接口的标准实现,基于Servlet 3.0部分API. To be added as "multipartResolver" bean to a Spring DispatcherServlet context, without any extra configuration at the bean level.
<bean id="MultipartResolver" class="org.springframework.web.multipart.support.StandardServletMultipartResolver"></bean>
实例:为多文件上传添加一个进度条
说明:
我们关注的是HTML5 input元素的change事件,当input元素的值发生改变时,他就会被触发。其次,我们还关注XMLHttpRequest对象中添加progress事件。XMLHttpRequest自然是AJAX的骨架。当异步使用XMLHttpRequest对象上传文件的时候就会持续地触发progress事件,直到上传进度完成或者取消。通过轻松监听progress事件,可以轻松地检测文件上传操作的进度。
编写Domain和Controller
1.Domain:UploadFile
package domain;
import org.springframework.web.multipart.MultipartFile;
import java.io.Serializable;
public class UploadFile implements Serializable {
private MultipartFile multipartFile;
public MultipartFile getMultipartFile() {
return multipartFile;
}
public void setMultipartFile(MultipartFile multipartFile) {
this.multipartFile = multipartFile;
}
}
2.Controller:Html5FileUploadController类
package controller;
import domain.UploadFile;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
@Controller
public class Html5FileUploadController {
private static final Log logger = LogFactory.getLog(Html5FileUploadController.class);
@RequestMapping("/html5")
public String inputProduct()
{
return "html5";
}
@RequestMapping("/file_upload")
public void saveFile(HttpServletRequest servletRequest, @ModelAttribute UploadFile file, BindingResult result)
{
MultipartFile multipartFile =file.getMultipartFile();
String filename =multipartFile.getOriginalFilename();
try {
File file1 = new File(servletRequest.getServletContext().getRealPath("/image"),filename);
multipartFile.transferTo(file1);
System.out.println("已经写人本地文件:"+file1.getName());
} catch (Exception e) {
e.printStackTrace();
}
}
}
编写HTML5页面
<%--
Created by IntelliJ IDEA.
User: zy
Date: 17-3-8
Time: 下午10:01
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<script>
var totalFileLength,totalUploaded,fileCount,filesUploaded;
function debug(s) { //输出调试信息
var debug = document.getElementById('debug');
if(debug)
{
debug.innerHTML =debug.innerHTML+'</br>'+s;
}
}
function onUploadComplete(e) { //当一个文件上传完成,紧接着开始调用下次upLoadNext();
totalUploaded+=document.getElementById('files').files[filesUploaded].size;
filesUploaded++;
debug('Complete'+filesUploaded+" of "+fileCount);
debug('totalUploaded:'+totalUploaded);
if(filesUploaded<fileCount)
{
upLoadNext();
}
}
function onUploadFailed() {
alert("Error uploading file");
}
function onUploadProgress(e) {//当进度发生改变时,改变进度条
if(e.lengthComputable)
{
var percentComplete =parseInt((e.loaded+totalUploaded)*100/totalFileLength);
var bar = document.getElementById("bar");
bar.style.width=percentComplete+"%";
bar.innerHTML =percentComplete+"% complete";
}
else
{
debug('unable to compute');
}
}
function upLoadNext() { //将XMLHttpRequest对象的progress事件添加到onLoadProgress并将load事件和error事件分别绑定到对应方法。
var xhr = new XMLHttpRequest();
var fd =new FormData();
var file =document.getElementById('files').files[filesUploaded];
fd.append("multipartFile",file);
xhr.upload.addEventListener("progress",onUploadProgress,false);
xhr.addEventListener("load",onUploadComplete,false);
xhr.addEventListener("error",onUploadFailed,false);
xhr.open("POST","file_upload");
debug('uploading'+file.name);
xhr.send(fd);
}
function onFileSelect(e) { //当选择的文件发生改变时,重新获取并打印现在所选的文件信息
var files =e.target.files;
var output=[];
fileCount =files.length;
totalFileLength =0;
for(var i=0;i<fileCount;i++)
{
var file =files[i];
output.push(file.name,'(',file.size,'bytes',')',file.lastModifiedDate.toLocaleDateString());
output.push("<br/>");
debug('add'+file.size);
totalFileLength+=file.size;
}
document.getElementById('selectedFiles').innerHTML = output.join('');
debug('totalFileLength:'+totalFileLength);
}
function startUpload() { //当用户点击提交以后开始执行
totalUploaded=filesUploaded=0;
upLoadNext();
}
window.onload=function () {
document.getElementById('files').addEventListener('change',onFileSelect,false);
document.getElementById('upLoadButton').addEventListener('click',startUpload,false);
}
</script>
</body>
<h2>Multipart File Uploads with Progress Bar</h2>
<div id="bar" >
</div>
<form>
<input type="file" id="files" multiple>
<br>
<output id="selectedFiles"></output>
<input id="upLoadButton" type="button" value="Upload">
</form>
<div id="debug" >
</div>
</html>
说明:
progressBar div用于展示上传进度,debug div用于显示调试信息。
执行脚本时,第一件事就是为4个变量分配空间:totalFileLength,totalUploaded,fileCount,filesUploaded;
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