springmvc文件下载实现

springmvc实现文件下载

使用springmvc实现文件下载有两种方式，都需要设置response的Content-Disposition为attachment;filename=test2.png

第一种可以直接向response的输出流中写入对应的文件流

第二种可以使用 ResponseEntity<byte[]>来向前端返回文件

一、使用response

@RestController
@RequestMapping("/download")
public class DownloadController {
<span class="hljs-meta">@RequestMapping</span>(<span class="hljs-string">"/d1"</span>)
<span class="hljs-function"><span class="hljs-keyword">public</span> ResultVo&lt;String&gt; <span class="hljs-title">downloadFile</span><span class="hljs-params">(HttpServletResponse response)</span></span>{

    String fileName=<span class="hljs-string">"test.png"</span>;
    <span class="hljs-keyword">try</span> {
        <span class="hljs-comment">//获取页面输出流</span>
        ServletOutputStream outputStream = response.getOutputStream();
        <span class="hljs-comment">//读取文件</span>
        <span class="hljs-keyword">byte</span>[] bytes = FileUtils.readFileToByteArray(<span class="hljs-keyword">new</span> File(<span class="hljs-string">"D:\my-study\test2.png"</span>));
        <span class="hljs-comment">//向输出流写文件</span>
        <span class="hljs-comment">//写之前设置响应流以附件的形式打开返回值,这样可以保证前边打开文件出错时异常可以返回给前台</span>
        response.setHeader(<span class="hljs-string">"Content-Disposition"</span>,<span class="hljs-string">"attachment;filename="</span>+fileName);
        outputStream.write(bytes);
        outputStream.flush();
        outputStream.close();
        <span class="hljs-keyword">return</span> ResultVoUtil.success(<span class="hljs-string">"success"</span>);
    } <span class="hljs-keyword">catch</span> (IOException e) {
        <span class="hljs-keyword">return</span> ResultVoUtil.error(e);
    }

}

}

推荐使用这种方式，这种方式可以以json形式给前台返回提示信息。

二、使用ResponseEntity

@Controller
@RequestMapping("/download2")
public class DownloadController2 {
<span class="hljs-keyword">private</span> <span class="hljs-keyword">final</span> <span class="hljs-keyword">static</span> Logger logger= LoggerFactory.getLogger(CategoryDataController.class);


<span class="hljs-meta">@GetMapping</span>(<span class="hljs-string">"/d2"</span>)
<span class="hljs-keyword">public</span> ResponseEntity&lt;<span class="hljs-keyword">byte</span>[]&gt; download2(){
    <span class="hljs-comment">//获取文件对象</span>
    <span class="hljs-keyword">try</span> {
        <span class="hljs-keyword">byte</span>[] bytes = FileUtils.readFileToByteArray(<span class="hljs-keyword">new</span> File(<span class="hljs-string">"D:\my-study\bill-admin\test2.png"</span>));
        HttpHeaders headers=<span class="hljs-keyword">new</span> HttpHeaders();
        headers.set(<span class="hljs-string">"Content-Disposition"</span>,<span class="hljs-string">"attachment;filename=test2.png"</span>);
        ResponseEntity&lt;<span class="hljs-keyword">byte</span>[]&gt; entity=<span class="hljs-keyword">new</span> ResponseEntity&lt;&gt;(bytes,headers,HttpStatus.OK);
        <span class="hljs-keyword">return</span> entity;
    } <span class="hljs-keyword">catch</span> (IOException e) {
        logger.error(<span class="hljs-string">"下载出错:"</span>,e);
        <span class="hljs-keyword">return</span> <span class="hljs-keyword">null</span>;
    }
}

}