Spring文件下载

package com.smbea.demo.controller;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

/**
 * 文件下载
 * @author hapday
 * @date 2017年1月23日 @time上午10:58:04
 */
@Controller
@RequestMapping( value = "admin/file" )
public class FileDownloadController {
	protected static final Logger LOGGER = LoggerFactory.getLogger(FileDownloadController.class);

	@RequestMapping(value = "fileDownloadTest", method = { RequestMethod.GET, RequestMethod.POST })
	public void fileDownloadTest(HttpServletRequest request, HttpServletResponse response) {
		String fileName = "test.pdf";

		try {
			fileName = URLEncoder.encode("软件秘笈设计模式那点事.pdf", "UTF-8");
		} catch (UnsupportedEncodingException e1) {
			e1.printStackTrace();
		}

//		System.out.println(request.getServletContext().getMimeType(fileName));

		response.reset();
		response.setHeader("Content-Disposition", "attachment; filename=" + fileName);// 指定下载的文件名
		response.setContentType("application/octet-stream");
		response.setHeader("Pragma", "no-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		URL url = null;		// URL　地址

		try {
			url = new URL("http://www.smbea.com/pdf/软件秘笈设计模式那点事.pdf");
		} catch (MalformedURLException e) {
			LOGGER.error("无效的 PDF 文件。", e);
			e.printStackTrace();
		}

		try {
			HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();	// 打开 HTTP 连接
			httpURLConnection.setDoOutput(true);

			int responseCode = httpURLConnection.getResponseCode();
			System.out.println("responseCode = " + responseCode);

			if(500 == responseCode) {
				System.out.println("HttpURLConnection 内部错误！");

				return;
			}
			if(404 == responseCode) {
				System.out.println("文件未找到！");

				return;
			}

			if(200 != responseCode) {
				return ;
			} 

			InputStream inputStream = httpURLConnection.getInputStream();	// 获取 HTTP 连接中的输入流
			OutputStream outputStream = response.getOutputStream();

			BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
			BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(outputStream);

			int len = 2048;
    		　　　　  byte[] b = new byte[len];
    		　　　　　　　　while(-1 != (len = bufferedInputStream.read(b))) {
    		　　　　　　　bufferedOutputStream.write(b, 0, len);
    		　　　　 }  

			bufferedOutputStream.flush();
			bufferedOutputStream.close();
			bufferedInputStream.close();
			outputStream.close();
			inputStream.close();
			httpURLConnection.disconnect();
		} catch (IOException e) {
			LOGGER.error("文件下载 - 失败！", e);
			e.printStackTrace();
		}
	}
}