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解析怎么通過Spring MVC實(shí)現(xiàn)文件上傳和下載的功能

猿友 2021-07-22 09:57:52 瀏覽數(shù) (1922)
反饋

相信各位對(duì)文件上傳和下載這兩個(gè)功能不陌生,但是它們是具體怎么實(shí)現(xiàn)的呢?接下來,我將通過簡單的介紹和具體的代碼實(shí)例來和大家分享一下怎么通過SpringMVC來實(shí)現(xiàn)文件的上傳和下載的功能。

文件上傳

2021412142437829

1、導(dǎo)入主要依賴

<!--文件上傳-->
<dependency>
 <groupId>commons-fileupload</groupId>
 <artifactId>commons-fileupload</artifactId>
 <version>1.3.3</version>
</dependency>
<!--servlet-api導(dǎo)入高版本的-->
<dependency>
 <groupId>javax.servlet</groupId>
 <artifactId>javax.servlet-api</artifactId>
 <version>4.0.1</version>
</dependency>

2、配置bean:multipartResolver(注:此bena的id必須為:multipartResolver , 否則上傳文件會(huì)報(bào)400的錯(cuò)誤?。?/p>

<!--文件上傳配置-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
 <!-- 請(qǐng)求的編碼格式,必須和jSP的pageEncoding屬性一致,以便正確讀取表單的內(nèi)容,
 默認(rèn)為ISO-8859-1 -->
 <property name="defaultEncoding" value="utf-8"/>
 <!-- 上傳文件大小上限,單位為字節(jié)(10485760=10M) -->
 <property name="maxUploadSize" value="10485760"/>
 <property name="maxInMemorySize" value="40960"/>
</bean>

3、index.jsp

4、Controller

@RestController
public class FileController {
    //@RequestParam("file") 將name=file控件得到的文件封裝成 CommonsMultipartFile 對(duì)象

    //批量上傳 CommonsMultipartFile 則為數(shù)組即可
    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        //獲取文件名 : file.getOriginalFilename();
        String uploadFileName = file.getOriginalFilename();
        //如果文件名為空,直接回到首頁!
        if ("".equals(uploadFileName)) {
            return "redirect:/index.jsp";
        }
        System.out.println("上傳文件名 : " + uploadFileName);
        //上傳路徑保存設(shè)置
        String path = request.getServletContext().getRealPath("/upload");
        //如果路徑不存在,創(chuàng)建一個(gè)
        File realPath = new File(path);
        if (!realPath.exists()) {
            realPath.mkdir();
        }
        System.out.println("上傳文件保存地址:" + realPath);
        InputStream is = file.getInputStream(); //文件輸入流
        OutputStream os = new FileOutputStream(new File(realPath, uploadFileName)); //文件輸出流
        //讀取寫出
        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";
    }

    /*
     * 采用file.Transto 來保存上傳的文件
     */
    @RequestMapping("/upload2")
    public String fileUpload2(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {
        //上傳路徑保存設(shè)置
        String path = request.getServletContext().getRealPath("/upload");
        File realPath = new File(path);
        if (!realPath.exists()) {
            realPath.mkdir();
        }
        System.out.println("上傳文件保存地址:" + realPath);
        //通過CommonsMultipartFile的方法直接寫文件(注意這個(gè)時(shí)候)
        file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));
        return "redirect:/index.jsp";
    }
}

文件下載

index.jsp

Controller

@RequestMapping(value = "/download")
public String downloads(HttpServletResponse response, HttpServletRequest request) throws Exception {
    //要下載的圖片地址
    String path = request.getServletContext().getRealPath("/upload");
    String fileName = "基礎(chǔ)語法.jpg";

    //1、設(shè)置response 響應(yīng)頭
    response.reset(); //設(shè)置頁面不緩存,清空buffer
    response.setCharacterEncoding("UTF-8"); //字符編碼
    response.setContentType("multipart/form-data"); //二進(jìn)制傳輸數(shù)據(jù)
    //設(shè)置響應(yīng)頭
    response.setHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode(fileName, "UTF-8"));
    File file = new File(path, fileName);
    //2、 讀取文件--輸入流
    InputStream input = new FileInputStream(file);
    //3、 寫出文件--輸出流
    OutputStream out = response.getOutputStream();
    byte[] buff = new byte[1024];
    int index = 0;
    //4、執(zhí)行 寫出操作
    while ((index = input.read(buff)) != -1) {
        out.write(buff, 0, index);
        out.flush();
    }
    out.close();
    input.close();
    return null;
}

2021412142619161

到此本篇關(guān)于怎么通過 Spring MVC 來實(shí)現(xiàn)文件的上傳和下載的功能的全部內(nèi)容就介紹到此結(jié)束了,想要了解更過相關(guān) Spring MVC 的其他內(nèi)容,可以搜索相關(guān)內(nèi)容的文章。希望本篇文章能對(duì)大家的學(xué)習(xí)有所幫助,也希望大家多多支持W3Cschool


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