Servlet 图片下载

package ResponseDemo;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;

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

public class DownloadTest extends HttpServlet
{
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException
	{
		//得到下载图片的绝对路径
		String path = this.getServletContext().getRealPath("/download/1.jpg");
		//截取得到文件名
		String filename = path.substring(path.lastIndexOf("\\")+1);
		//通知浏览器使用下载方式打开
		response.setHeader("content-disposition","attachment;filename="+filename);
		//如果需要下载的文件名为中文，则文件名需要URL编码,如下：
		//response.setHeader("content-disposition","attachment;filename="+URLEncoder.encode(filename,"UTF-8"));
		
		InputStream in = null;
		OutputStream out = null;
		try
		{
			in = new FileInputStream(path);
			int len = 0;
			byte[] buffer = new byte[1024];
			out = response.getOutputStream();
			while((len = in.read(buffer)) > 0)
			{
				out.write(buffer,0,len);
			}
		} finally
		{
			if(in != null)
			{
				try
				{
					in.close();
				} catch (Exception e)
				{
					e.printStackTrace();
				}
			}
			if(out != null)
			{
				try
				{
					out.close();
				} catch (Exception e)
				{
					e.printStackTrace();
				}
			}
		}
	}
	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException
	{
		doGet(request, response);
	}

}

下载资源放在download文件夹中。

运行后会出现如图所示：

web.xml中需要的相关配置信息：

<servlet>
    <servlet-name>DownloadTest</servlet-name>
    <servlet-class>ResponseDemo.DownloadTest</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>DownloadTest</servlet-name>
    <url-pattern>/servlet/DownloadTest</url-pattern>
</servlet-mapping>