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 = (HttpURLConnection) 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);
String 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");
FileInputStream 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();
}
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。
