SpringMVC注解方式与文件上传

Posted 2021-11-30 yeyangtao

目录：

springmvc的注解方式

文件上传（上传图片，并显示）

一、注解

在类前面加上@Controller 表示该类是一个控制器
在方法handleRequest 前面加上 @RequestMapping("/index") 表示路径/index会映射到该方法上

将上一篇的博客改为注解方式：

SpringMVC的基础配置及视图定位

1、修改springmvc-servlet.xml

去掉映射相关的配置，因为已经使用注解方式了
增加
<context:component-scan base-package="controller" />
表示从包controller下扫描有@Controller注解的类

2、修改IndexController

@Controller
public class IndexController {
    @RequestMapping("/index")
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mav = new ModelAndView("index");
        mav.addObject("message", "Hello Spring MVC");
        return mav;
    }
}

也不需要实现Controller接口

 二、文件上传

1、配置web.xml使其允许访问jpg文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd http://xmlns.jcp.org/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.4">
  <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.jpg</url-pattern>
  </servlet-mapping>
</web-app>

2、配置springmvc-servlet.xml，开放对上传功能的支持

<?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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context         
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    
    <context:component-scan base-package="controller" />
    <bean id="irViewResolver"
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/page/" />
        <property name="suffix" value=".jsp" />
    </bean>
    
    
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"/>

</beans>

3、upload.jsp文件上传页面

<form action="uploadImage" method="post" enctype="multipart/form-data">
  选择图片:<input type="file" name="image" accept="image/*" /> <br>
  <input type="submit" value="上传">
</form>

4、准备UploadedImageFile封装MultipartFile类型的字段 image ，用于接受页面的注入

package pojo;

import org.springframework.web.multipart.MultipartFile;

public class UploadedImageFile {
    MultipartFile image;
 
    public MultipartFile getImage() {
        return image;
    }
 
    public void setImage(MultipartFile image) {
        this.image = image;
    }
 
}

注意：

这里的字段 image必须和上传页面upload.jsp中的image
<input type="file" name="image" accept="image/*" />
保持一致

5、UploadController 上传控制器

package controller;

import java.io.File;
import java.io.IOException;
 
import javax.servlet.http.HttpServletRequest;
 
import org.apache.commons.lang.xwork.RandomStringUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
 
import pojo.UploadedImageFile;
 
@Controller
public class UploadController {
 
    @RequestMapping("/uploadImage")
    public ModelAndView upload(HttpServletRequest request, UploadedImageFile file)
            throws IllegalStateException, IOException {
        //采用随机数来命名图片，防止上传文件名相同的文件会覆盖原文件
        String name = RandomStringUtils.randomAlphanumeric(10);
        String newFileName = name + ".jpg";
        //获取web目录下image目录来存放上传后的文件
        File newFile = new File(request.getServletContext().getRealPath("/image"), newFileName);
        newFile.getParentFile().mkdirs();
        //复制文件
        file.getImage().transferTo(newFile);
        //把生成的随机文件名传给视图，用来显示
        ModelAndView mav = new ModelAndView("showUploadedFile");
        mav.addObject("imageName", newFileName);
        return mav;
    }
}

6、显示图片showUploadedFile.jsp

注意是在page目录下新建jsp文件

<img src="image/${imageName}"/>