Spring MVC文件上傳和下載

時間 2019-12-14

標籤 spring mvc 文件上傳下載欄目 Spring 简体版

原文原文鏈接

在Spring MVC中有兩種實現上傳文件的辦法，第一種是Servlet3.0如下的版本經過commons-fileupload與commons-io完成的通用上傳，第二種是Servlet3.0以上的版本的Spring內置標準上傳，不需藉助第3方組件。通用上傳也兼容Servlet3.0以上的版本css

Servlet3.0如下的經過commons-fileupload上傳html

1.添加上傳依賴包java

一個是文件上傳的jar包，一個是其所依賴的IO包。這兩個jar包，均在Spring支持庫的org.apache.commons中web

2.index.jsp(文件上傳頁面)spring

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    <style type="text/css">
       form{
       background-color:pink;
         width:500px;
       }
    </style>
    <title>單個文件上傳</title>
  </head>
  
  <body>
    <form action="${pageContext.request.contextPath }/first.do" method="post" enctype="multipart/form-data">
    <h1>文件上傳</h1>
                 文件:<input type="file" name="uploadFile"/><br/>
       <input type="submit" value="上傳"/>
    </form>
  </body>
</html>

applicationContext.xmlapache

先在大配置中配置個包掃描器，後面的後續會引出spring-mvc

<?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:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx" 
    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 http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        ">
        
     <!-- 包掃描器 -->
     <context:component-scan base-package="cn.controller"></context:component-scan>
     
</beans>

書寫處理器服務器

package cn.controller;

import java.io.File;
import javax.servlet.http.HttpSession;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;

/**
 * 
 * @author 景佩佩
 *
 */
@Controller
public class MyController{
     //處理器方法
    @RequestMapping(value="/first.do")
    //springmvc類型
    /**
     *   將文件對象保存到文件(圖片)服務器上  Nugux
     *   
     * @param uploadFile  從頁面上過來的真實文件對象
     * @return
     * @throws Exception
     */ 
    public String doFirst(MultipartFile uploadFile,HttpSession session) throws Exception{
             //全部文件上傳
             //1.xxx：獲取文件名做爲保存到服務器的文件名稱 1.jpg
             String filename = uploadFile.getOriginalFilename();

             //2.前半部分路徑，目錄，將WebRoot下一個名稱爲images文件夾  轉換成絕對路徑
             String leftPath = session.getServletContext().getRealPath("/images");

              //3.進行路徑拼接=前半部分路徑+文件名稱
              File file=new File(leftPath,filename);
              //4.作保存
              uploadFile.transferTo(file);

            return "welcome.jsp";
    }
    
}

若是咱們如今啓動服務器，會報錯session

在applicationContext.xml配置文件上傳解析器mvc

<?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:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx" 
    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 http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        ">
     
        <!-- 配置包掃描器-->
       <context:component-scan base-package="cn.controller"></context:component-scan>
       
       <!-- 文件上傳解析器 -->
       <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"></bean>
       
       </beans>

可是啓動的話仍是會報錯，由於咱們沒有配置註解驅動

若是咱們沒有寫解析器的ID的話，就會報另外的錯

文件上傳大小設置

若是超過限制的大小的話會報以下的錯

沒有選擇要上傳的文件

若是沒有選擇要上傳的文件，能夠經過以下判斷代碼回到錯誤頁

限制上傳的文件

若是咱們上傳的文件中有亂碼的問題，咱們可使用如下兩種方式

<filter>
    <filter-name>characterEncoding</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>
    <init-param>
      <param-name>forceEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>characterEncoding</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping

多文件上傳

首先index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    <style type="text/css">
       form{
       background-color:pink;
         width:500px;
       }
    </style>
    <title></title>
  </head>
  
  <body>
    <form action="${pageContext.request.contextPath }/first.do" method="post" enctype="multipart/form-data">
    <h1>文件上傳</h1>
                 文件1:<input type="file" name="uploadFile"/><br/>
                     文件2:<input type="file" name="uploadFile"/><br/>
                         文件3:<input type="file" name="uploadFile"/><br/>
       <input type="submit" value="上傳"/>
    </form>
  </body>
</html>

2.applicationContext.xml配置文件

<?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:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx" 
    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 http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        ">
        
     <!-- 包掃描器 -->
     <context:component-scan base-package="cn.controller"></context:component-scan>
     
     <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
         <property name="maxUploadSize" value="50000000"></property>
         <property name="maxUploadSizePerFile" value="5000000"></property> 
          <property name="defaultEncoding" value="utf-8"></property> 
     </bean>
     <!--mvc註解驅動 包括：建立MultipartFile 實例 -->
     <mvc:annotation-driven/>
     </beans>

3.書寫處理器

package cn.controller;

import java.io.File;
import javax.servlet.http.HttpSession;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

/**
 * 
 * @author 景佩佩
 *
 */
@Controller
public class MyController{
     //處理器方法
    @RequestMapping(value="/first.do")
    //springmvc類型
    /**
     *   將文件對象保存到文件(圖片)服務器上  Nugux
     *   
     * @param uploadFile  從頁面上過來的真實文件對象
     * @return
     * @throws Exception
     */ 
    public String doFirst(@RequestParam MultipartFile[] uploadFile,HttpSession session) throws Exception{
        for (MultipartFile item : uploadFile) {
            if (item.getSize()>0) {
                
                //經過文件後綴名斷定只能讓用戶上傳 .jpg .gif .png
                //全部文件上傳
                //1.xxx：獲取文件名做爲保存到服務器的文件名稱 1.jpg
                String filename = item.getOriginalFilename();
                
                if (filename.endsWith("jpg")||filename.endsWith("gif")||filename.endsWith("png")) {
                    //2.前半部分路徑，目錄，將WebRoot下一個名稱爲images文件夾  轉換成絕對路徑
                    String leftPath = session.getServletContext().getRealPath("/images");

                    //3.進行路徑拼接=前半部分路徑+文件名稱
                    File file=new File(leftPath,filename);
                    item.transferTo(file);
    
                } 
            }else {
                return "error.jsp";
            }
        }
        
        return "welcome.jsp";
    }

}

提醒：在處理器方法中必定要對參數進行校對使用註解@RequestParam校訂參數

要否則會報以下錯誤

以後就能夠實現文件上傳

文件下載

index.jsp(咱們先給定資源路徑)

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    <style type="text/css">
       form{
       background-color:pink;
         width:500px;
       }
    </style>
    <title>單個文件上傳</title>
  </head>
  
  <body>
     <form action="${pageContext.request.contextPath }/download.do" method="post" enctype="multipart/form-data">
    <h1>文件下載</h1>
         <a href="${pageContext.request.contextPath }/download.do?1.jpg">下載</a>
    </form>
  </body>
</html>