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2021-06-29 13:27
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Java怎么实现根据文件路径找到excel表格,从浏览器下载?

项目部署在服务器上,我做的一个生成excel表格保存在服务器文件路径中,java怎么实现根据服务器上的文件路径得到excel,下载到客户端浏览器上?

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  • 小P聊技术 2021-06-29 15:43
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    在实际应用中,经常会遇到上传Excel或者下载Excel的情况,比如导入数据、下载统计数据等等场景。针对这个问题,我写了个基于SpringMVC的简单上传下载示例,其中Excel的处理使用Apache的POI组件。

    主要依赖的包如下:

    <dependency> 
      <groupId>commons-io</groupId> 
      <artifactId>commons-io</artifactId> 
      <version>2.4</version> 
     </dependency> 
     <dependency> 
      <groupId>commons-fileupload</groupId> 
      <artifactId>commons-fileupload</artifactId> 
      <version>1.3.1</version> 
     </dependency> 
     <dependency> 
      <groupId>org.springframework</groupId> 
      <artifactId>spring-web</artifactId> 
      <version>4.0.0.RELEASE</version> 
     </dependency> 
     <dependency> 
      <groupId>org.springframework</groupId> 
      <artifactId>spring-webmvc</artifactId> 
      <version>4.0.0.RELEASE</version> 
     </dependency> 
     <dependency> 
      <groupId>org.apache.poi</groupId> 
      <artifactId>poi</artifactId> 
      <version>3.10.1</version> 
     </dependency> 
    

    相关处理类:

    (一)Controller类

    package com.research.spring.controller; 
     
    import java.io.IOException; 
    import java.util.ArrayList; 
    import java.util.HashMap; 
    import java.util.List; 
    import java.util.Map; 
     
    import org.apache.poi.hssf.usermodel.HSSFWorkbook; 
    import org.apache.poi.ss.usermodel.Row; 
    import org.apache.poi.ss.usermodel.Sheet; 
    import org.apache.poi.ss.usermodel.Workbook; 
    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; 
    import org.springframework.web.servlet.ModelAndView; 
     
    import com.research.spring.model.UserInfo; 
    import com.research.spring.view.ExcelView; 
     
    @Controller 
    @RequestMapping("/file") 
    public class FileController { 
     
     /** 
     * Excel文件上传处理 
     * @param file 
     * @return 
     */ 
     @RequestMapping("/upload") 
     public ModelAndView uploadExcel(@RequestParam("file") MultipartFile file){ 
     List<UserInfo> list = new ArrayList<UserInfo>(); 
      //这里只处理文件名包括“用户”的文件,模板使用下载模板 
     if( file.getOriginalFilename().contains("用户") ){ 
      try { 
      Workbook wb = new HSSFWorkbook(file.getInputStream()); 
      Sheet sheet = wb.getSheetAt(0); 
      for( int i = 1; i <= sheet.getLastRowNum(); i++ ){ 
       Row row = sheet.getRow(i); 
       UserInfo info = new UserInfo(); 
       info.setUserName(row.getCell(0).getStringCellValue()); 
       info.setPassword(row.getCell(1).getStringCellValue()); 
       list.add(info); 
      } 
      } catch (IOException e) { 
      e.printStackTrace(); 
      } 
     } 
     ModelAndView mav = new ModelAndView("content"); 
     mav.addObject("content",list.toString()); 
     return mav; 
     } 
     
     /** 
     * Excel文件下载处理 
     */ 
     @RequestMapping("/download") 
     public ModelAndView downloanExcel(){ 
     List<UserInfo> list = new ArrayList<UserInfo>(); 
     UserInfo userInfo = new UserInfo(); 
     userInfo.setPassword("0000"); 
     userInfo.setUserName("sdfas"); 
     list.add(userInfo); 
     list.add(userInfo); 
     list.add(userInfo); 
     list.add(userInfo); 
     Map<String,List<UserInfo>> map = new HashMap<String, List<UserInfo>>(); 
     map.put("infoList", list); 
     ExcelView ve = new ExcelView(); 
     return new ModelAndView(ve,map); 
     } 
    } 
    

    (二)实体类

    package com.research.spring.model; 
     
    public class UserInfo { 
     
     private String userName; 
     
     private String password; 
     
     public String getUserName() { 
     return userName; 
     } 
     
     public void setUserName(String userName) { 
     this.userName = userName; 
     } 
     
     public String getPassword() { 
     return password; 
     } 
     
     public void setPassword(String password) { 
     this.password = password; 
     } 
     
     @Override 
     public String toString() { 
     return "UserInfo [userName=" + userName + ", password=" + password 
      + "]"; 
     } 
    } 
    

    (三)View类

    这个类在下载时用到,在Spring渲染页面时使用自定义的View类进行Excel的相关处理。

    package com.research.spring.view; 
     
    import java.io.OutputStream; 
    import java.net.URLEncoder; 
    import java.util.List; 
    import java.util.Map; 
     
    import javax.servlet.http.HttpServletRequest; 
    import javax.servlet.http.HttpServletResponse; 
     
    import org.apache.poi.hssf.usermodel.HSSFWorkbook; 
    import org.apache.poi.ss.usermodel.Cell; 
    import org.apache.poi.ss.usermodel.Row; 
    import org.apache.poi.ss.usermodel.Sheet; 
    import org.springframework.web.servlet.view.document.AbstractExcelView; 
     
    import com.research.spring.model.UserInfo; 
     
    /** 
     * 下载Excel视图 
     * 
     * @author wdmcygah 
     * 
     */ 
    public class ExcelView extends AbstractExcelView { 
     
     @Override 
     protected void buildExcelDocument(Map<String, Object> model, 
      HSSFWorkbook workbook, HttpServletRequest request, 
      HttpServletResponse response) throws Exception { 
     @SuppressWarnings("unchecked") 
     List<UserInfo> list = (List<UserInfo>) model.get("infoList"); 
     if (list != null && list.size() != 0) { 
      int len = list.size(); 
      Sheet sheet = workbook.createSheet(); 
      // 第一行文字说明 
      Row row = sheet.createRow(0); 
      Cell cell = row.createCell(0, Cell.CELL_TYPE_STRING); 
      cell.setCellValue("用户名"); 
      cell = row.createCell(1, Cell.CELL_TYPE_STRING); 
      cell.setCellValue("密码"); 
     
      //下面是具体内容 
      for (int i = 0; i < len; i++) { 
      row = sheet.createRow(i + 1); 
      cell = row.createCell(0, Cell.CELL_TYPE_STRING); 
      cell.setCellValue(list.get(i).getUserName()); 
      cell = row.createCell(1, Cell.CELL_TYPE_STRING); 
      cell.setCellValue(list.get(i).getPassword()); 
      } 
     } 
     
     response.setContentType("application/vnd.ms-excel"); 
     response.setCharacterEncoding("utf-8"); 
     //这里对文件名进行编码,保证下载时汉字显示正常 
     String fileName = URLEncoder.encode("用户.xls", "utf-8"); 
     //Content-disposition属性设置成以附件方式进行下载 
     response.setHeader("Content-disposition", "attachment;filename=" 
      + fileName); 
     OutputStream os = response.getOutputStream(); 
     workbook.write(os); 
     os.flush(); 
     os.close(); 
     } 
    } 
    

    (四)主要配置文件

    上传文件时需要在配置文件中配置MultipartResolver类,配置后Spring会自动将文件传成MultipartFile对象,然后就可以进行相应的处理。示例看Controller类。

    <?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:p="http://www.springframework.org/schema/p" 
     xmlns:context="http://www.springframework.org/schema/context" 
     xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:util="http://www.springframework.org/schema/util" 
     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 
     http://www.springframework.org/schema/mvc 
     http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd 
     http://www.springframework.org/schema/util 
     http://www.springframework.org/schema/util/spring-util-3.0.xsd"> 
     
     <context:component-scan base-package="com.research" /> 
     
     <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> 
     <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" /> 
     <property name="prefix" value="/WEB-INF/" /> 
     <property name="suffix" value=".jsp" /> 
     </bean> 
     
     <!-- 上传文件解析器配置 --> 
     <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> 
     <property name="defaultEncoding" value="UTF-8"></property> 
     <!-- 上传文件的大小限制 ,单位是字节--> 
     <property name="maxUploadSize" value="5242880000000"></property> 
     <!-- 上传文件的临时路径,上传完成后会自动删除 --> 
     <property name="uploadTempDir" value="upload/temp"></property> 
     </bean> 
    </beans> 
    

    (五)测试页面

    <html> 
    <head>  
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
    </head> 
    <body> 
    <h3>测试下载Excel功能</h3> 
    <form action="file/download.htm" enctype="multipart/form-data" method="post"> 
     <input type="submit" value="下载Excel"></input> 
    </form> 
     
    <h3>测试上传Excel功能</h3> 
    <form action="file/upload.htm" enctype="multipart/form-data" method="post"> 
     <input type="file" name="file"></input> 
     <input type="submit" value="上传Excel"></input> 
    </form> 
    </body> 
    </html> 
    

    如果想看完整源码,可以到我的Github仓库查看。 其中,上传文件只处理符合下载模板的文件。若要处理其它文件需要自实现。代码测试通过无误。

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