【SpringMVC---文件上传与下载】
SpringMVC文件上传
一、步骤
1、导包
<dependencies>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.4</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
</dependency>
</dependencies>
2、添加Spring配置
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--自动扫描包， 让指定包下的注解生效，由IOC容器统一管理-->
<context:component-scan base-package="com.darkerg.controller"/>
<!--让Spring MVC不处理静态资源 .css .js .html .mp3 .mp4-->
<mvc:default-servlet-handler />
<!--解决json 乱码配置-->
<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<bean class="org.springframework.http.converter.StringHttpMessageConverter">
<constructor-arg value="UTF-8"/>
</bean>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="objectMapper">
<bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
<property name="failOnEmptyBeans" value="false"/>
</bean>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
<!--支持mvc注解驱动
在spring中一般采用@RequestMapping注解完成映射关系， 要想使@RequestMapping注解生效，必须向上下文注册DefaultAnnotationHandlerMapping
和一个AnnotationMethodHandlerAdapter实例，这两个实例分别在类级别和方法级别处理， 而annotation-driven配置帮助我们自动完成上述两个实例的注入-->
<mvc:annotation-driven />
<!--处理器解析器-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
<!--前缀-->
<property name="prefix" value="/WEB-INF/jsp/"/>
<!--后缀-->
<property name="suffix" value=".jsp"/>
</bean>
<!--文件上传的配置-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!--请求的编码格式，必须和jsp的pageEncoding属性一致，以便正确的读取表单的内容，默认为ISO-8859-1 -->
<property name="defaultEncoding" value="utf-8"/>
<!--上传文件大小上限，单位为字节(10485760=10M)-->
<property name="maxUploadSize" value="104865760"/>
<property name="maxInMemorySize" value="40960"/>
</bean>
</beans>
3、web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
version="5.0">
<!--配置DispatcherServlet： 这个是SpringMVC的核心，请求分发器，前端控制器-->
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--DispatcherServlet要绑定spring的配置文件-->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc-servlet.xml</param-value>
</init-param>
<!--启动级别 1-->
<load-on-startup>1</load-on-startup>
</servlet>
<!--/: 只匹配所有的请求，不会去匹配jsp页面-->
<!--/*: 配所有的请求，包括jsp页面-->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<filter>
<filter-name>encoding</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>encoding</filter-name>
<url-pattern>/</url-pattern>
</filter-mapping>
</web-app>
4、前端jsp代码
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
<input type="file" name="file"/>
<input type="submit" value="upload">
</form>
</body>
</html>
二、方式一
package com.darkerg.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
@RestController
public class FileController {
//@RequestParam("file") 将name = file控件得到的文件封装成CommonsMultipartFile对象
//批量上传CommonsMultipartFile则为数组即可
@RequestMapping("/upload")
public String fileUpload(@RequestParam("file")CommonsMultipartFile file, HttpServletRequest request) throws IOException {
//获取文件名：file.getOriginalFilename();
String uploadFileName = file.getOriginalFilename();
//如果文件名为空，直接回到首页
if ("".equals(uploadFileName)){
return "redirect:/index.jsp";
}
System.out.println("上传文件名："+uploadFileName);
//上传路径保存设置
String path = request.getServletContext().getRealPath("/upload");
//如果路径不存在，创建一个
File realPath = new File(path);
if (!realPath.exists()){
realPath.mkdir();
}
System.out.println("上传文件保存地址："+realPath);
InputStream is = file.getInputStream();//文件输入流
FileOutputStream os = new FileOutputStream(new File(realPath, uploadFileName));//文件输出流
//读取写出
int len = 0;
byte[] buffer = new byte[1024];
while ((len=is.read(buffer))!=-1){
os.write(buffer,0,len);
os.flush();
}
os.close();
is.close();
return "redirect:/index.jsp";
}
}
效果：
三、方式二
/*
采用file.Transto来保存上传的文件
*/
@RequestMapping("upload2")
public String fileUpload2(@RequestParam("file") CommonsMultipartFile file,HttpServletRequest request) throws IOException {
//上传路径保存设置
String path = request.getServletContext().getRealPath("/upload");
//如果路径不存在，创建一个
File realPath = new File(path);
if (!realPath.exists()){
realPath.mkdir();
}
System.out.println("上传文件保存地址："+realPath);
//通过CommonsMultipartFile的方法直接写文件（注意这个时候)
file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));
return "redirect:/index.jsp";
}
修改一下前端的请求
四、文件下载
1、文件下载步骤：
- 设置response响应头
- 读取文件 -- InputStream
- 写出文件 -- OutputStream
- 执行操作
- 关闭流（先开后关)
2、代码实现
@RequestMapping("/download")
public String downloads(HttpServletResponse response,HttpServletRequest request) throws Exception{
//要下载图片的地址
String path = request.getServletContext().getRealPath("/upload");
String fileName = "1.jpg";
//1.设置response响应头
response.reset();//设置页面不缓存，清空buffer
response.setCharacterEncoding("UTF-8");//字符编码
response.setContentType("multipart/form-data");//二进制传输数据
//设置响应头
response.setHeader("Content-Disposition",
"attachment;fileName="+ URLEncoder.encode(fileName,"UTF-8"));
File file = new File(path, fileName);
//2、读取文件------输入流
FileInputStream input = new FileInputStream(file);
//3.写出文件----输出流
OutputStream out = response.getOutputStream();
byte[] buff = new byte[1024];
int index = 0;
//4。执行 写出操作
while ((index=input.read(buff))!=-1){
out.write(buff,0,index);
out.flush();
}
out.close();
input.close();
return null;
}
3、图片的保存位置
项目发布后的upload文件夹下
