一、文件的上传
1、方式一
（1）基础配置：
pom.xml：导入依赖等：
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>pers.zhb</groupId> <artifactId>spring_file</artifactId> <version>1.0-SNAPSHOT</version> <!--依赖--> <dependencies> <!--spring--> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.2.5.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>4.2.4.RELEASE</version> </dependency> <!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload --> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3.3</version> </dependency> <!--servlet--> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> </dependency> </dependencies> <!--在bulid中配置resources，防止资源导出失败的问题--> <build> <resources> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> <resource> <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> </resources> </build> </project>
applicationContext.xml：对文件上传进行配置
<?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 http://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="pers.zhb.controller"></context:component-scan> <!--静态资源过滤，让Springmvc不处理静态资源，如css、js等--> <mvc:default-servlet-handler></mvc:default-servlet-handler> <!--使得注解生效--> <mvc:annotation-driven></mvc:annotation-driven> <!--视图解析器，前缀和后缀--> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"> <property name="prefix" value="/"></property> <property name="suffix" value=".jsp"></property> </bean> <!--文件上传--> <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <!--请求的编码格式，必须和jsp的pageEncoding属性的值保持一致，以便正确读取表单的内容，默认为ISO-8859-1--> <!--multipartResolver：以二进制形式传输数据--> <property name="defaultEncoding" value="utf-8"></property> <!--上传文件大小的上限--> <property name="maxUploadSize" value="10485760"></property> <property name="maxInMemorySize" value="40960"></property> </bean> </beans>
web.xml：配置前端控制器、处理乱码的过滤器：
<?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_4_0.xsd" version="4.0"> <!-- 前端控制器 --> <servlet> <servlet-name>springmvc</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <!--绑定springmvc的配置文件--> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </init-param> <load-on-startup>1</load-on-startup><!--启动服务器即创建--> </servlet> <servlet-mapping> <servlet-name>springmvc</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <filter> <filter-name>EncodingFilter</filter-name> <filter-class>pers.zhb.filter.EncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>utf-8</param-value> </init-param> </filter> <filter-mapping> <filter-name>EncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
过滤器：
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { servletRequest.setCharacterEncoding("utf-8"); servletResponse.setCharacterEncoding("utf-8"); filterChain.doFilter(servletRequest,servletResponse); }
(2)文件上传的核心代码：
页面：
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<form method="post" action="${pageContext.request.contextPath}/upload" enctype="multipart/form-data">
<input type="file" name="file">
<input type="submit" value="upload">
</form>
</body>
</html>
控制器：
@RequestMapping("upload")
//批量上传CommonsMultipartFile为数组即可
public String fileUpload(@RequestParam("file")CommonsMultipartFile file, HttpServletRequest request)throws IOException{
//获取文件名
String uploadFileName=file.getOriginalFilename();
//如果文件名为空直接回到首页
if("".equals(uploadFileName)){
return "redirect:/index.jsp";
}
System.out.println("上传的文件的文件名为："+uploadFileName);
//上传路径保存设置
String path=request.getSession().getServletContext().getRealPath("/upload");
//如果路径不存在，创建一个
File realPath =new File(path);
if(!realPath.exists()){
realPath.mkdir();
}
System.out.println("文件保存地址为："+realPath);
InputStream inputStream=file.getInputStream();//文件输入流
OutputStream outputStream=new FileOutputStream(new File(realPath,uploadFileName));//文件输出流，文件的保存地址和文件的文件名
//读取写入
int len=0;
byte[] buffer=new byte[1024];
while ((len= inputStream.read(buffer))!=-1){
outputStream.write(buffer,0,len);
outputStream.flush();
}
outputStream.close();
inputStream.close();
return "redirect:/index.jsp";
}
采用缓冲数组的方式读取文件可以加快文件处理的速度
（3）测试：
2、方式二
（1）控制器：
@RequestMapping("upload")
public String fileUpload(@RequestParam("file")CommonsMultipartFile file, HttpServletRequest request)throws IOException{
//上传路径保存设置
String path = request.getSession().getServletContext().getRealPath("upload");
File realPath=new File(path);
if(!realPath.exists()){
realPath.mkdir();
}
//上传文件地址
System.out.println("上传文件的保存地址为："+realPath);
//通过commosMultipartFile的方法直接写入文件
file.transferTo(new File(realPath+"/"+file.getOriginalFilename()));
return "redirect:/index.jsp";
}
二、文件的下载
（1）页面：
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>$Title$</title> </head> <body> <center> <h3> <a href="${pageContext.request.contextPath}/download">下载图片</a> </h3> </center> </form> </body> </html>
（2）控制器：
@RequestMapping("download")
public String download(HttpServletResponse response,HttpServletRequest request)throws Exception{
//要下载的文件的路径
String path=request.getSession().getServletContext().getRealPath("/upload");
String fileName="1.jpg";
//设置response响应头
response.reset();//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
response.setHeader("Content-Disposition","attachment;fileName="+ URLEncoder.encode(fileName,"utf-8"));
File file=new File(path,fileName);
InputStream inputStream=new FileInputStream(file);
OutputStream outputStream=response.getOutputStream();
byte[] buff=new byte[1024];
int index=0;
//执行写出操作
while((index=inputStream.read(buff))!=-1){
outputStream.write(buff,0,index);
outputStream.flush();
}
outputStream.close();
inputStream.close();
return null;
}
（3）测试：
下载后图片可以正常打开