Spring Mvc下实现以文件流方式下载文件的方法示例

Spring Mvc下实现以文件流方式下载文件的方法示例

项目中需要对一个点击事件进行下载操作，同时通过点击事件，已经可以从jsp页面获取到需要访问的URL和下载的文件名（数据库获取，jsp页面显示）。点击事件JS如下：

function downloadFile(filePath,fileName){

fileName = fileName.substr(0,fileName.lastIndexOf("."));

$.ajax({

async : false,

cache:false,

type: 'get',

dataType : "json",

url: RootPath() + "/checkDownload",//请求的action路径

data:{url:filePath},

error: function () {//请求失败处理函数

alert("下载失败");

},

success:function(json) { //请求成功后处理函数。

var code = json.code;

if(code) {

window.location.href = RootPath()+"/todownload?url="+filePath+"&name="+fileName;

}else {

layer.alert(fileName+' 文件不存在');

}

}

});

}

该ajax调用后台（checkDownload）方法，首先判断从该url能否获得指定下载的文件，如果获取不到，方法返回参数code=0，页面弹出“...文件不存在”。

@RequestMapping("/checkDownload")

@ResponseBody

public Result checkDownload(String url,HttpServletResponse response) {

Result result = Result.createSuccessResult();

HttpURLConnection conn = null;

try {

URL path = new URL(url);

conn = (HttpURLConneCuGsIXsNction) path.openConnection();

conn.setRequestMethod("GET");

conn.setConnectTimeout(5 * 1000);

conn.getInputStream();// 通过输入流获取数据

} catch (IOException ex) {

result.setCode(0);

ex.printStackTrace();

}finally {

if(conn != null) {

conn.disconnect();

}

}

return result;

}

如果checkDownload方法中能够正确获得资源，方法返回参数code=1，ajax成功执行：window.location.href = RootPath()+"/todownload?url="+filePath+"&name="+fileName;   调用（todownload)方法，传入url和name，执行文件下载。

@RequestMapping("/todownload")

@ResponseBody

public void download(String url, String name, HttpServletResponse response) {

HttpURLConnection conn = null;

try {

File file = new File(url);

// 取得文件的后缀名。

String ext = file.getName().substring(file.getName().lastIndexOf(".") + 1).toLowerCase();

StringBuffer buffername = new StringBuffer(name);

Strihttp://ng filename = buffername.append(".").append(ext).toString();

URL path = new URL(url);

conn = (HttpURLConnection) path.openConnection();

conn.setRequestMethod("GET");

conn.setConnectTimeout(5 * 1000);

InputStream fis = conn.getInputStream();// 通过输入流获取数据

byte[] buffer = readInputStream(fis);

if (null != buffer && buffer.length > 0) {

// 清空response

response.reset();

// 设置response的Header

response.addHeader("Content-Disposition","attachment;filename="+ new String((filename).getBytes("GBK"),"ISO8859_1"));

response.addHeader("Content-Length", "" + buffer.length);

OutputStream toClient = response.getOutputStream();

response.setContentType("application/octet-stream");

toClient.write(buffer);

toClient.flush();

toClient.close();

}

} catch (IOException ex) {

ex.printStackTrace();

}finally {

if(conn != null) {

conn.disconnect();

}

}

}

/**

* 从输入流中获取数据

* @param inStream 输入流

* @return

* @throws Exception

*/

private byte[] readInputStream(InputStream fis) throws IOException {

ByteArrayOutputStream outStream = new ByteArrayOutputStream();

byte[] buffer = new byte[1024];

int len = 0;

while( (len=fis.read(buffer)) != -1 ){

outStream.write(buffer, 0, len);

}

fis.close();

return outStream.toByteArray();

}

PS：Spring MVC 文件流形式下载(返回)视频文件

import io.swagger.annotations.Api;

import io.swagger.annotations.ApiOperation;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletResponse;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.net.URLEncoder;

/**

* 文件流形式下载视频

* @author Front Ng

* @date 2019-05-23 09:25

**/

@Controller

@RequestMapping(value = "/download")

@Api(value = "下载", tags = "下载")

public class DownloadController {

@ApiOperation(value = "下载视频")

@RequestMapping(method = RequestMethod.GET)

public void download(HttpServletResponse response) throws IOException {

File file = new File("/Users/front/Downloads/123.mp4");

FileInCuGsIXsNputStream inputStream = new FileInputStream(file);

byte[] data = new byte[(int) file.length()];

int length = inputStream.read(data);

inputStream.close();

String fileName = URLEncoder.encode("文件流形式视频.mp4", "UTF-8");

response.setContentType("application/octet-stream;charset=UTF-8");

response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");

response.addHeader("Content-Length", "" + data.length);

OutputStream stream = response.getOutputStream();

stream.write(data);

stream.flush();

stream.close();

}

}

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