Java web Spring 写一个文件下载的Controller

参考：https://stackoverflow.com/questions/1442893/implementing-a-simple-file-download-servlet，并做了好几处改进

import java.io.File;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;

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

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.bupt.nctc.service.impl.FileService;

/**
 * 文件的Controller类
 * @create 2018年1月18日
 */
@Controller
@RequestMapping("/file")
public class FileControllerUtils {
    //如：http://localhost:8080/file/download?name=E:/a.xls
    @ResponseBody
    @RequestMapping(value = "/download", method = RequestMethod.GET)  
    public Object download(@RequestParam(name="name", required=true) String name,
            HttpServletRequest request, HttpServletResponse response) {

        try {
            String filePath = name;// 如 E:/test.docx

            // You must tell the browser the file type you are going to send
            // for example application/pdf, text/plain, text/html, image/jpg
            String fileType = "text/plain";//纯文本
            response.setContentType(fileType);

            String fileName = "";
            int pos = 0;
            if( (pos = filePath.lastIndexOf("/")) > 0 ) {
                fileName = filePath.substring(pos + 1, filePath.length());//截取文件名字
            } else { fileName = filePath;} //没有父文件夹，如"1.txt"

            // Make sure to show the download dialog
            response.setHeader("Content-disposition","attachment; filename=" + fileName);

            // Assume file name is retrieved from database
            // For example D:\\file\\test.pdf
            File my_file = new File(filePath);
            System.out.println("要下载文件:" + my_file);
            if( !my_file.exists()){
                throw new Exception("文件不存在");
            }

            // This should send the file to browser
            OutputStream out = response.getOutputStream();
            FileInputStream in = new FileInputStream(my_file);
            byte[] buffer = new byte[4096];
            int length;
            while ((length = in.read(buffer)) > 0){
                out.write(buffer, 0, length);
            }
            in.close();
            out.flush();
            System.out.println("下载成功: " + name );
            return null;
        } catch (Exception e) {
            // TODO 自动生成的 catch 块
            e.printStackTrace();
            Map<String, String> map=new HashMap<String, String>();//返回成功、失败信息
            map.put("status", "false");
            map.put("reason", e.getMessage());
            return map;
        }
    }
}