Servlet下载文件

import org.apache.commons.io.IOUtils;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * @author Prannt
 * @throws Exception
 * @param req
 * @param resp
 */
public class Download extends HttpServlet {
     
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
     
        //读取要下载的文件内容(通过servletContext对象可以读取)
        ServletContext servletContext = getServletContext();
        InputStream resourceAsStream = servletContext.getResourceAsStream("/file/aaa.docx");
        //获取要下载的文件类型
        String mimeType = servletContext.getMimeType("/file/aaa.docx");
        System.out.println("下载的文件类型为:" + mimeType);
        resp.setContentType(mimeType);
        //获取响应的输出流
        OutputStream outputStream = resp.getOutputStream();
        //把下载的文件内容回传给客户端
        //读取输入流中所有数据,复制给输出流,再输出给客户端
        IOUtils.copy(resourceAsStream,outputStream);//copy复制的意思是resourceAsStream和outputStream完全一样
        //还要告诉客户端收到的数据是用于下载使用,而非在网页上显示出来(还是使用响应头)
        resp.setHeader("Content-Disposition","attachment;filename=检讨书.docx");
    }
}

    <servlet>
        <servlet-name>Downloadservlet-name>
        <servlet-class>ProjectTest.Downloadservlet-class>
    servlet>
    <servlet-mapping>
        <servlet-name>Downloadservlet-name>
        <url-pattern>/downloadurl-pattern>
    servlet-mapping>

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