不指定虚拟路径的前提下通过http访问pdf、图片等文件

　　

　　通常我们通过http访问图片或者pdf的时候都是将文件上传到指定文件夹下面，然后通过配置虚拟路径来访问指定的资源。

　　在不配置虚拟路径的情况下，我们通过获取到response的outpurstream，然后向该outputstream输出指定的文件也可以，用IOUtils工具类更是简单方便。

例如:

　　依赖的包:

　　　　

package cn.qlq.web;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.io.IOUtils;

/**
 * Servlet implementation class TestServlet
 */
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        FileInputStream in = null;
        ServletOutputStream outputStream = null;
        try {
            in = new FileInputStream(new File("C:\\Users\\Administrator\\Desktop\\测试文档\\Java开发-太原科技大学-软件工程-乔利强.pdf"));
            outputStream = response.getOutputStream();
            IOUtils.copyLarge(in, outputStream);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            IOUtils.closeQuietly(in);
            IOUtils.closeQuietly(outputStream);
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

测试:

补充:对于浏览器能解析的文件会解析，而对于浏览器不能解析的会下载，比如说docx等文件，如果想实现任何文件都下载，可以对response进行设置，如下:

            response.setContentType("application/force-download");
            response.setHeader("Content-Disposition", "attachment;fileName=" + path);