Jetty + Servlet 实现文件下载

Jetty非常适合做嵌入式web开发，正如Jetty的口号"Don’t deploy your application in Jetty, deploy Jetty in your application!"。

这个简单的例子是使用Jetty提供文件下载：

首先pom.xml配置文件如下

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.luangeng</groupId>
  <artifactId>jettydownload</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>jettydownload</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <jetty.version>8.1.9.v20130131</jetty.version>
  </properties>

  <dependencies>
    <!-- jetty -->
    <dependency>
      <groupId>org.eclipse.jetty.aggregate</groupId>
      <artifactId>jetty-webapp</artifactId>
      <version>${jetty.version}</version>
    </dependency>
    <dependency>
      <groupId>org.eclipse.jetty</groupId>
      <artifactId>jetty-jsp</artifactId>
      <version>${jetty.version}</version>
    </dependency>

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>
View Code

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main方法启动Jetty：

package com.luangeng;

import org.eclipse.jetty.server.Connector;
import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.DefaultHandler;
import org.eclipse.jetty.server.handler.HandlerCollection;
import org.eclipse.jetty.server.nio.SelectChannelConnector;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.webapp.WebAppContext;

public class App 
{
    public static void main( String[] args ) throws Exception {

        Server server = new Server();
        server.setStopAtShutdown(true);
        SelectChannelConnector connector = new SelectChannelConnector();
        connector.setPort(8080);
        connector.setReuseAddress(true);
        server.setConnectors(new Connector[] { connector });
        ServletContextHandler context = new ServletContextHandler();
        context.setContextPath("/lg");
        context.addServlet(DownLoadServlet.class, "/download");
        context.addServlet(TestServlet.class, "/test/*");
        HandlerCollection handlers = new HandlerCollection();
        handlers.setHandlers(new Handler[] { context, new DefaultHandler() });
        server.setHandler(handlers);

        server.start();
        server.join();

    }
}

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提供简单的测试 TestServlet.java

package com.luangeng;

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.PrintWriter;

/**
 * Created by LG.
 */
public class TestServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {


            response.setContentType("text/html");
            PrintWriter out = response.getWriter();
            out.println("<HTML>");
            out.println("<HEAD><TITLE>test</TITLE></HEAD>");
            out.println("<BODY>");
            out.println("GET method");
            out.println("</BODY>");
            out.println("</HTML>");
            out.flush();
            out.close();

    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<HTML>");
        out.println("<HEAD><TITLE>test</TITLE></HEAD>");
        out.println("<BODY>");
        out.println("POST method");
        out.println("</BODY>");
        out.println("</HTML>");
        out.flush();
        out.close();
    }



}

---

完成下载功能的Servlet：

DownloadServlet.java

package com.luangeng;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;

/**
 * Created by LG.
 */
public class DownLoadServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) {

        //PrintWriter pw = null;
        FileInputStream in = null;
        OutputStream outs = null;

        //String path = request.getParameter("filepath");
        String path = "/Users/LG/test.txt";
        //path = new String(fileName.getBytes("iso8859-1"),"UTF-8");

        try {
            File file = new File(path);
            if(!file.exists())
            {
                response.setStatus(404);
                //pw.println("file not found!");
                //request.getRequestDispatcher("/err.jsp").forward(request, response);
                return;
            }
            response.setContentType("text/html");
            String realname = path.substring(path.indexOf("/")+1);
            response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(realname, "UTF-8"));
            in = new FileInputStream(path);
            outs = response.getOutputStream();
            byte buffer[] = new byte[1024];
            int len = 0;
            while ((len = in.read(buffer)) > 0) {
                outs.write(buffer, 0, len);
            }

            System.out.println(response.getStatus());
        }
        catch(Exception e)
        {
            //pw.println(e.getMessage());
            response.setStatus(300);
            //log
        }
        finally {
            response.setStatus(200);
            try {
                if(outs != null) {
                    outs.flush();
                    outs.close();
                }
                if(in != null) {
                    in.close();
                }

            } catch (IOException e) {
            }
//            if(pw!=null) {
//                pw.flush();
//                pw.close();
//            }
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

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浏览器访问网址 http://localhost:8080/lg/download 即可看到下载

 

end

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原文地址：https://www.cnblogs.com/luangeng/p/6079604.html