文件上传功能

1.添加依赖

<!--文件上传-->
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.1</version>
</dependency>
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>1.3.1</version>
</dependency>

2.在springMVC.xml配置文件中添加文件上传解析器

<!--文件上传解析器-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <property name="maxUploadSize" value="10485760"></property>
    <property name="defaultEncoding" value="utf-8"></property>
</bean>

3.文件上传页面uploadpage.jsp的部分代码，前端用了bootstrap

<form action="saveImg?username=${username}" method="post" enctype="multipart/form-data">
    <h4><span>请选择头像：</span>
    <input type="file" name="pic" id="pic"/>
    </h4>
    <input type="submit" class="btn btn-primary" value="上传"/>
</form>

4.FileController文件

@RequestMapping("/saveImg")
public String saveImg(@RequestParam("pic")MultipartFile file, HttpServletRequest request, Model model) throws Exception {
    // 图片的路径，图片上传成功后，将路径保存到数据库
    String filePath = request.getSession().getServletContext().getRealPath("img");
    // 生成文件新的名字
    String newFileName = UUID.randomUUID() + ".jpg";
    // 封装上传文件位置的全路径
    File targetFile = new File(filePath, newFileName);
    if (!targetFile.exists()) {
        targetFile.mkdirs();
    }
    file.transferTo(targetFile);
    //获得此用户名
    String username = request.getParameter("username");
    //将文件路径存进数据库
    userService.upload(username,newFileName);
    model.addAttribute("newFileName",newFileName);
    return "/user_info";
}

5.图片显示页面user_info.jsp部分代码，用了bootstrap

<h4><span>头像：</span>
    <img alt="" src="img/${newFileName}" height="150" width="150" id="images"
         onerror="this.src='img/default.jpg'" class="img-rounded">
</h4>

οnerrοr="this.src=‘img/default.jpg’"表示的是当没有图片时显示默认图片default.jpg