java中一个简单的下载示例

首先在tomcat服务器下的webapps的download项目下建一个doc文件夹,再建个test.doc.防止控指针异常

DownLoad.java代码

package com.down;

import java.io.IOException;
import java.io.InputStream;

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;

@WebServlet(
        name="download",
        urlPatterns={"/test"}
        )
public class DownLoad extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        doGet(req, resp);
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("application/msword");
        response.addHeader("Content-disposition","attachment;filename=test.doc");
        InputStream in=getServletContext().getResourceAsStream("/doc/test.doc");
        ServletOutputStream os=response.getOutputStream();
        byte[] bytes=new byte[1024];
        int len=-1;
        while((len=in.read(bytes))!=-1){
            os.write(bytes,0,len);
        }
        in.close();
        os.close();
    }
}

运行结果: