Java 下载文件

public @ResponseBody void exportExcel(HttpServletRequest request, HttpServletResponse response, KhxxCxVO vo) throws IOException{
        File csvFile = createCSVFile(request,vo);//获取要下载的文件

        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;

        response.setHeader("Content-disposition", "attachment; filename=" + URLEncoder.encode(csvFile.getName(), "UTF-8"));

        response.setHeader("Content-Length", String.valueOf(csvFile.length()));

        bis = new BufferedInputStream(new FileInputStream(csvFile));
        bos = new BufferedOutputStream(response.getOutputStream());
        byte[] buff = new byte[2048];
        while (true) {
          int bytesRead;
          if (-1 == (bytesRead = bis.read(buff, 0, buff.length))) break;
          bos.write(buff, 0, bytesRead);
        }
        bis.close();
        bos.close();
    }

经常遇到选择多个文件进行批量下载的情况，可以先将选择的所有的文件生成一个zip文件，然后再下载，该zip文件，即可实现批量下载，但是在打包过程 中，常常也会出现下载过来的zip文件中里面有乱码的文件名，通过使用ant.jar中的org.apache.tools.zip里的 ZipOutPutStream为实现编码的设置。
代码如下：

ant包引用

<dependency>
  <groupId>ant</groupId>
  <artifactId>ant</artifactId>
  <version>1.6.5</version>
</dependency>  

压缩下载的action代码

    package demo.action;  

    import java.io.BufferedInputStream;
    import java.io.BufferedOutputStream;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.net.URLEncoder;  

    import javax.servlet.http.HttpServletResponse;  

    import org.apache.log4j.Logger;
    import org.apache.struts2.ServletActionContext;
    import org.apache.tools.zip.ZipEntry;
    import org.apache.tools.zip.ZipOutputStream;  

    import com.opensymphony.xwork2.ActionSupport;  

    /**
     * 批量下载文件：
     *   使用ant.jar包中的org.apache.tools.zip.*完成压缩，
     * java原生也有java.util.zip.*但是测试了下无法搞定压缩
     * 文件内文件名的中文问题
     * @author yangcong
     *
     */
    public class BatchDownloadAction extends ActionSupport {  

        private Logger Log = Logger.getLogger(BatchDownloadAction.class);
        private static final String FilePath = "D:\\";  

        private static final long serialVersionUID = -8694640030455344419L;  

        public String execute() {
            //生成的ZIP文件名为Demo.zip
            String tmpFileName = "Demo.zip";
            byte[] buffer = new byte[1024];
            String strZipPath = FilePath + tmpFileName;
            try {
                ZipOutputStream out = new ZipOutputStream(new FileOutputStream(
                        strZipPath));
                // 需要同时下载的两个文件result.txt ，source.txt
                File[] file1 = { new File(FilePath+"test1.txt"),
                        new File(FilePath+"测试2.docx") };
                for (int i = 0; i < file1.length; i++) {
                    FileInputStream fis = new FileInputStream(file1[i]);
                    out.putNextEntry(new ZipEntry(file1[i].getName()));
                    //设置压缩文件内的字符编码，不然会变成乱码
                    out.setEncoding("GBK");
                    int len;
                    // 读入需要下载的文件的内容，打包到zip文件
                    while ((len = fis.read(buffer)) > 0) {
                        out.write(buffer, 0, len);
                    }
                    out.closeEntry();
                    fis.close();
                }
                out.close();
                this.downFile(getResponse(), tmpFileName);
            } catch (Exception e) {
                Log.error("文件下载出错", e);
            }
            return null;
        }  

        /**
         * 获取Response
         * @return
         */
        private HttpServletResponse getResponse() {
            return ServletActionContext.getResponse();
        }  

        /**
         * 文件下载
         * @param response
         * @param str
         */
        private void downFile(HttpServletResponse response, String str) {
            try {
                String path = FilePath + str;
                File file = new File(path);
                if (file.exists()) {
                    InputStream ins = new FileInputStream(path);
                    BufferedInputStream bins = new BufferedInputStream(ins);// 放到缓冲流里面
                    OutputStream outs = response.getOutputStream();// 获取文件输出IO流
                    BufferedOutputStream bouts = new BufferedOutputStream(outs);
                    response.setContentType("application/x-download");// 设置response内容的类型
                    response.setHeader(
                            "Content-disposition",
                            "attachment;filename="
                                    + URLEncoder.encode(str, "UTF-8"));// 设置头部信息
                    int bytesRead = 0;
                    byte[] buffer = new byte[8192];
                    // 开始向网络传输文件流
                    while ((bytesRead = bins.read(buffer, 0, 8192)) != -1) {
                        bouts.write(buffer, 0, bytesRead);
                    }
                    bouts.flush();// 这里一定要调用flush()方法
                    ins.close();
                    bins.close();
                    outs.close();
                    bouts.close();
                } else {
                    response.sendRedirect("../error.jsp");
                }
            } catch (IOException e) {
                Log.error("文件下载出错", e);
            }
        }
    }  

经过在windows环境下测试通过，使用struts2

• ant-1.6.5.jar (1009.8 KB)