文件下载Servlet实现-优快云博客

本文链接：https://blog.youkuaiyun.com/lizhe10177/article/details/28876011

package com.solaw.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.ImageFormatException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageDecoder;

public class DownloadFile extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String storePath = new String(request.getParameter(
				"documentStorePath").getBytes("ISO-8859-1"), "utf-8").toString();
		String fileFullName = storePath.substring(storePath
				.lastIndexOf("/") + 1);
		String filePath = new String(request.getParameter("documentStorePath")
				.getBytes("ISO8859_1"), "utf-8").toString();
		
		response.setContentType("text/html");
		javax.servlet.ServletOutputStream out = response.getOutputStream();
		System.out.println("DownloadFile filepath:" + storePath);
		System.out.println("DownloadFile filename:" + fileFullName);
		java.io.File file = new java.io.File(filePath);
		if (!file.exists()) {
			System.out.println(file.getAbsolutePath() + " 文件不存在!");
			return;
		}
		// 读取文件流
		java.io.FileInputStream fileInputStream = new java.io.FileInputStream(
				file);
		// 下载文件
		// 设置响应头和下载保存的文件名
		if (fileFullName != null && fileFullName.length() > 0) {
			response.setContentType("application/x-msdownload");
			response.setHeader("Content-Disposition", "attachment; filename="
					+ new String(fileFullName.getBytes("utf-8"), "iso8859-1") + "");
			if (fileInputStream != null) {
				int filelen = fileInputStream.available();
				// 文件太大时内存不能一次读出,要循环
				byte a[] = new byte[filelen];
				fileInputStream.read(a);
				out.write(a);
			}
			fileInputStream.close();
			out.close();
		}
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<!DOCTYPE HTML PUBLIC -//W3C//DTD HTML 4.01 Transitional//EN>");
		out.println("<HTML>");
		out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println(" <BODY>");
		out.print(" This is ");
		out.print(this.getClass().getName());
		out.println(", using the POST method");
		out.println("your hobby is:"+request.getParameter("hobby"));
		out.println(" </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}
}

同时web.xml需要配置

	<servlet>
		<servlet-name>DownloadFile</servlet-name>
		<servlet-class>com.solaw.servlet.DownloadFile</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>DownloadFile</servlet-name>
		<url-pattern>/vip/downloadDocument</url-pattern>
	</servlet-mapping>

文件下载servlet