JAVA下载文件工具类 原创

JAVA下载文件工具类

复制收展Javapackage com.nstc.iface.handler;
import com.nstc.smartform.core.ContextUtils;
import com.nstc.smartform.core.RequestContext;
import javax.servlet.http.HttpServletResponse;
import java.io.*;

/**
 * <p>
 * Title: 下载文件工具类
 * </p>
 *
 * <p>
 * Description: 下载文件工具类
 * </p>
 *
 * <p>
 * Company:
 * </p>
 *
 * @author luolei
 *
 * @since：2021-12-24
 *
 */
public class DownloadFileUtils {

    /**
     * 下载附件 返回文件
     * @param requestContext
     * @throws Exception
     */
    public static void download(RequestContext requestContext) throws Exception {
        HttpServletResponse response=(HttpServletResponse) ContextUtils.getHttpContext().getResponse();
        String id = requestContext.getParameter("fileId");
        /**根据id取得文件的名字和路径**/
        /**附件路径**/
        String fileName = "";
        /**附件名称**/
        String fatTitel = "";
        if (!"".equals(fileName) && !"".equals(fatTitel)) {
            InputStream inputStream = null;
            OutputStream outputStream = null;
            try {
                File file = new File(fileName);
                if (!file.exists()) {
                    throw new RuntimeException("资料文件“" + fileName + "”不存在！");
                }
                response.reset();
                response.setContentType("application/x-msdownload");
                response.setHeader("Content-disposition", "attachment; filename=" + java.net.URLEncoder.encode(fatTitel, "UTF-8").replace('+', ' '));
                response.setHeader("Content_Length", String.valueOf(file.length()));
                inputStream = new FileInputStream(file);
                outputStream = response.getOutputStream();
                byte[] buff = new byte[2048];
                int bytesRead = 0;
                while ((bytesRead = inputStream.read(buff, 0, buff.length)) > 0) {
                    outputStream.write(buff, 0, bytesRead);
                }
                outputStream.flush();
            } catch (Exception e) {
                e.printStackTrace();
                throw new RuntimeException(e.getMessage());
            } finally {
                if (inputStream != null)
                    try {
                        inputStream.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                        /**
                         * throw new RuntimeException(e.getMessage());从finally块返回，中断，抛出等等会抑制在try或catch块中抛出的任何未处理的Throwable的传播。
                         */
                    }
                if (outputStream != null){
                    try {
                        outputStream.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                        /**
                         * throw new RuntimeException(e.getMessage());
                         */
                    }
                }
            }
        }
    }

}
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