springmvc文件上传

1.加入jar包：

commons-fileupload-1.2.2.jar

commons-io-2.0.1.jar

lperson.java中加属性，实现get ,set方法

private String photoPath;

2.创建WebRoot/upload目录，存放上传的文件

<sf:form id="p" action="saveOrUpdate" 
    method="post" 
    modelAttribute="person" 
    enctype="multipart/form-data">

    <sf:hidden path="id"/> 
    name: <sf:input path="name"/><br>
    age: <sf:input path="age"/><br>
    photo: <input type="file" name="photo"/><br>

上面第9行文件上传框，不能和实体对象属性同名，类型不同

controller配置

12、文件上传功能实现 配置文件上传解析器
@RequestMapping(value={"/saveOrUpdate"},method=RequestMethod.POST)
public String saveOrUpdate(Person p,
        @RequestParam("photo") MultipartFile file,
        HttpServletRequest request
) throws IOException{
    if(!file.isEmpty()){
        ServletContext sc = request.getSession().getServletContext();
        String dir = sc.getRealPath(“/upload”);    //设定文件保存的目录
        
        String filename = file.getOriginalFilename();    //得到上传时的文件名
        FileUtils.writeByteArrayToFile(new File(dir,filename), file.getBytes());
        
        p.setPhotoPath(“/upload/”+filename);    //设置图片所在路径
        
        System.out.println("upload over. "+ filename);
    }    
    ps.saveOrUpdate(p);    
    return "redirect:/person/list.action";   //重定向
}

3.文件上传功能实现 spring-mvc.xml 配置文件上传解析器

    <!-- 文件上传解析器 id 必须为multipartResolver -->
    <bean id="multipartResolver" 
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value=“10485760"/>    
    </bean>

maxUploadSize以字节为单位：10485760 =10M   id名称必须这样写

映射资源目录
<mvc:resources location="/upload/" mapping="/upload/**"/>

随即文件名常用的三种方式：

文件上传功能（增强：防止文件重名覆盖）

fileName = UUID.randomUUID().toString() + extName;

fileName = System.nanoTime() + extName;

fileName = System.currentTimeMillis() + extName;

if(!file.isEmpty()){
    ServletContext sc = request.getSession().getServletContext();
    String dir = sc.getRealPath("/upload");
    String filename = file.getOriginalFilename();
    

    long _lTime = System.nanoTime();
    String _ext = filename.substring(filename.lastIndexOf("."));
    filename = _lTime + _ext;
    
    FileUtils.writeByteArrayToFile(new File(dir,filename), file.getBytes());
    
    p.setPhotoPath("/upload/"+filename);
    
    System.out.println("upload over. "+ filename);
}

图片显示 personList.jsp

 <td><img src="${pageContext.request.contextPath}${p.photoPath}">${p.photoPath}</td>