Servlet:利用Response实现文件下载
一、自己添加一个图片/文件在resources中,并找到其绝对路径写在类中
二、创建FIleServlet类
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
public class FileServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.要获取下载文件的路径
String realPath = "C:\\代码\\javaweb-servlet\\response\\target\\classes\\1.png";
System.out.println("下载文件的路径:"+realPath);
//2.下载的文件名是什么?
String filename = realPath.substring(realPath.lastIndexOf("\\") + 1);
//3.设置想办法让浏览器能够支持下载我们需要的东西
resp.setHeader("Content-Disposition","attachment;filename="+filename);
//4.获取下载文件的输入流
FileInputStream in = new FileInputStream(realPath);
//5.创建缓冲区
int len=0;
byte[] buffer = new byte[1024];
//6.获取OutputStream对象
ServletOutputStream out = resp.getOutputStream();
//7.将FileOutputStream流写入到buffer缓冲区,使用OutputStream将缓冲区中的数据输出到客户端
while((len=in.read(buffer))>0) {
out.write(buffer,0,len);
}
in.close();
out.close();
}
三、在web.xml中注册servlet
<web-app>
<display-name>Archetype Created Web Application</display-name>
<servlet>
<servlet-name>filedown</servlet-name>
<servlet-class>com.huang.servlet.FileServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>filedown</servlet-name>
<url-pattern>/down</url-pattern>
</servlet-mapping>
</web-app>
四、配置Tomcat并运行
五、自动跳转到浏览器显示下载
有些浏览器会自动下载,有些浏览器会出现下载界面