SpringMVC 通过commons-fileupload实现文件上传功能

<?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">
 <!--注册dispatcherservlet-->
 <servlet>
  <servlet-name>springmvc</servlet-name>
  <servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>
  <init-param>
   <param-name>contextconfiglocation</param-name>
   <param-value>classpath:applicationcontext.xml</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
 </servlet>
 <servlet-mapping>
  <servlet-name>springmvc</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>
</web-app>

<?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">

 <!--配置自动扫描controller包-->
 <context:component-scan base-package="com.pro.controller"/>
 <!--配置静态资源过滤-->
 <mvc:default-servlet-handler/>
 <!--配置注解驱动-->
 <mvc:annotation-driven/>

 <!--配置视图解析器-->
 <bean id="internalresourceviewresolver" class="org.springframework.web.servlet.view.internalresourceviewresolver">
  <!--前缀-->
  <property name="prefix" value="/web-inf/jsp/"/>
  <!--后缀-->
  <property name="suffix" value=".jsp"/>
 </bean>

 <!--springmvc文件上传配置-->
 <bean id="multipartresolver" class="org.springframework.web.multipart.commons.commonsmultipartresolver">
  <!--设置请求的编码格式, 必须和pageencoding的属性一致, 以便正确读取表单的值, 默认为iso-8859-1-->
  <property name="defaultencoding" value="utf-8"/>
  <!--上传文件的大小限制, 单位为字节 (10485760 = 10m)-->
  <property name="maxuploadsize" value="10485760"/>
  <property name="maxinmemorysize" value="40960"/>
 </bean>
</beans>

package com.pro.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 javax.servlet.http.httpservletresponse;
import java.io.*;
import java.net.urlencoder;
import java.util.hashmap;
import java.util.map;

@restcontroller
public class filecontroller {
  /*
   * 采用file.transferto 来保存上传的文件
   */
  @requestmapping("/upload2")
  public map fileupload2(@requestparam("file") commonsmultipartfile file, httpservletrequest request) throws ioexception {

    //上传路径保存设置
    string path = request.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()));

    map<object, object> hashmap = new hashmap<>();
    hashmap.put("code", 0);
    hashmap.put("msg", "上传成功");

    return hashmap;
  }
}

package com.pro.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 javax.servlet.http.httpservletresponse;
import java.io.*;
import java.net.urlencoder;
import java.util.hashmap;
import java.util.map;

@restcontroller
public class filecontroller {

  // @requestparam("file") 将 name=file 控件得到的文件封装成 commonsmultipartfile 对象
  // 批量上传把 commonsmultipartfile 改为数组即可
  @requestmapping("/upload")
  public string upload(@requestparam("file") commonsmultipartfile file, httpservletrequest request) throws ioexception {
    // 获取文件名称
    string uploadfilename = file.getoriginalfilename();

    // 如果文件名为空, 直接返回首页
    if ("".equals(uploadfilename)) {
      return "file upload error";
    }

    system.out.println("上传文件名 --> " + uploadfilename);


    // 设置文件的保存位置
    string path = request.getservletcontext().getrealpath("/upload");
    // 判断路径是否存在
    file realpath = new file(path);
    if (!realpath.exists()) {
      // 如果不存在就创建
      realpath.mkdir();
    }

    system.out.println("文件保存路径 --> " + realpath);

    // 获取文件输入流
    inputstream is = file.getinputstream();
    // 获取文件输出流
    fileoutputstream os = new fileoutputstream(new file(realpath, uploadfilename));

    // 缓冲区读写文件
    byte[] buffer = new byte[1024];
    int len;
    while ((len = is.read(buffer)) != -1) {
      os.write(buffer, 0, len);
      os.flush();
    }

    // 关闭流
    os.close();
    is.close();

    return "file upload success";
  }
}

<%@ page contenttype="text/html;charset=utf-8" language="java" %>
<html>
 <head>
  <title>$title$</title>
 </head>
 <body>
  <form enctype="multipart/form-data" action="${pagecontext.request.contextpath}/upload2" method="post">
   <input type="file" name="file">
   <input type="submit" value="上传实现一">
  </form>
  
  
  <form enctype="multipart/form-data" action="${pagecontext.request.contextpath}/upload" method="post">
   <input type="file" name="file">
   <input type="submit" value="上传实现二">
  </form>
 </body>
</html>

<!--导入依赖-->
<dependencies>
  <!--单元测试-->
  <dependency>
    <groupid>junit</groupid>
    <artifactid>junit</artifactid>
    <version>4.13</version>
  </dependency>
  <!--spring-->
  <dependency>
    <groupid>org.springframework</groupid>
    <artifactid>spring-webmvc</artifactid>
    <version>5.2.0.release</version>
  </dependency>
  <!--文件上传-->
  <dependency>
    <groupid>commons-fileupload</groupid>
    <artifactid>commons-fileupload</artifactid>
    <version>1.3.3</version>
  </dependency>
  <!--servlet-api导入高版本的-->
  <dependency>
    <groupid>javax.servlet</groupid>
    <artifactid>javax.servlet-api</artifactid>
    <version>4.0.1</version>
  </dependency>
  <!--jsp-->
  <dependency>
    <groupid>javax.servlet.jsp</groupid>
    <artifactid>jsp-api</artifactid>
    <version>2.2</version>
  </dependency>
  <!--jstl表达式-->
  <dependency>
    <groupid>javax.servlet</groupid>
    <artifactid>jstl</artifactid>
    <version>1.2</version>
  </dependency>
</dependencies>