Netty实战一 Netty实现文件的上传和下载，java程序员面试笔试宝典何昊pdf

import io.netty.bootstrap.ServerBootstrap;

import io.netty.channel.ChannelFuture;

import io.netty.channel.EventLoopGroup;

import io.netty.channel.nio.NioEventLoopGroup;

import io.netty.channel.socket.nio.NioServerSocketChannel;

import java.net.InetSocketAddress;

/**

• 作者：DarkKIng

• 创建日期：2019/12/17

• 类说明：文件下载服务端

*/

public class FileServer {

private final int port;

public FileServer(int port) {

this.port = port;

}

public static void main(String[] args) throws InterruptedException {

int port = 9999;

FileServer fileServer = new FileServer(port);

System.out.println(“服务器即将启动”);

fileServer.start();

System.out.println(“服务器关闭”);

}

public void start() throws InterruptedException {

final FileServerHandle serverHandler = new FileServerHandle();

/线程组/

EventLoopGroup group = new NioEventLoopGroup();

Pipeline pipeline = new Pipeline();

try {

/服务端启动必须/

ServerBootstrap b = new ServerBootstrap();

b.group(group)/将线程组传入/

.channel(NioServerSocketChannel.class)/指定使用NIO进行网络传输/

.localAddress(new InetSocketAddress(port))/指定服务器监听端口/

/*服务端每接收到一个连接请求，就会新启一个socket通信，也就是channel，

所以下面这段代码的作用就是为这个子channel增加handle*/

.childHandler(pipeline);

ChannelFuture f = b.bind().sync();/异步绑定到服务器，sync()会阻塞直到完成/

System.out.println("Netty server start,port is " + port);

f.channel().closeFuture().sync();/阻塞直到服务器的channel关闭/

} finally {

group.shutdownGracefully().sync();/优雅关闭线程组/

}

}

}

使用netty实现服文件服务器端。

3、Pipeline

import io.netty.channel.ChannelInitializer;

import io.netty.channel.ChannelPipeline;

import io.netty.channel.socket.SocketChannel;

import io.netty.handler.codec.http.HttpObjectAggregator;

import io.netty.handler.codec.http.HttpRequestDecoder;

import io.netty.handler.codec.http.HttpResponseEncoder;

import io.netty.util.concurrent.DefaultEventExecutorGroup;

import io.netty.util.concurrent.EventExecutorGroup;

/**

• 作者：DarkKIng

• 创建日期：2019/12/17

• 作用：职责链

*/

public class Pipeline extends ChannelInitializer {

private EventExecutorGroup businessEventExecutorGroup = new DefaultEventExecutorGroup(10);

@Override

protected void initChannel(SocketChannel ch) {

ChannelPipeline pipeline = ch.pipeline();

/**

• http服务器端对response编码

*/

pipeline.addLast(“encoder”, new HttpResponseEncoder());

/**

• http服务器端对request解码3.

*/

pipeline.addLast(“decoder”, new HttpRequestDecoder());

/**

• 合并请求

*/

pipeline.addLast(“aggregator”, new HttpObjectAggregator(655300000));

/**

• 正常业务逻辑处理

*/

pipeline.addLast(businessEventExecutorGroup, new FileServerHandle());

}

}

编写职责链，请求会从入栈以次从上到下经过编解码，请求和秉承HTTPObject，最后执行业务类FileServerHandle。

4、FileServerHandle

import io.netty.buffer.Unpooled;

import io.netty.channel.*;

import io.netty.channel.ChannelHandler.Sharable;

import io.netty.handler.codec.http.*;

import io.netty.handler.codec.http.multipart.*;

import io.netty.util.CharsetUtil;

import org.json.simple.JSONObject;

import java.io.*;

import java.net.URLEncoder;

import java.util.HashMap;

import java.util.Map;

import java.util.stream.Collectors;

/**

• 作者：DarkKIng

• 创建日期：2019/12/17

• 类说明：文件

《一线大厂Java面试题解析+后端开发学习笔记+最新架构讲解视频+实战项目源码讲义》

【docs.qq.com/doc/DSmxTbFJ1cmN1R2dB】 完整内容开源分享

下载handler

*/

@Sharable

public class FileServerHandle extends SimpleChannelInboundHandler {

/客户端读到数据以后，就会执行/

@Override

protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request)

throws Exception {

//打印请求url

System.out.println(request.uri());

//下载任务处理

if (request.uri().equals("/downFile")) {

responseExportFile(ctx, “D://model.txt”, “model.txt”);

}

//上传接口处理

if (request.uri().equals("/upLoadFile")) {

MultipartRequest MultipartBody = getMultipartBody(request);

Map<String, FileUpload> fileUploads = MultipartBody.getFileUploads();

//输出文件信息

for (String key : fileUploads.keySet()) {

//获取文件对象

FileUpload file = fileUploads.get(key);

System.out.println(“fileName is” + file.getFile().getPath());

//获取文件流

InputStream in = new FileInputStream(file.getFile());

BufferedReader bf = new BufferedReader(new InputStreamReader(in));

String content = bf.lines().collect(Collectors.joining("n"));

//打印文件

System.out.println(“content is n” + content);

}

//输出参数信息

JSONObject params = MultipartBody.getParams();

//输出文件信息

System.out.println(JSONObject.toJSONString(params));

}

}

/连接建立以后/

@Override

public void channelActive(ChannelHandlerContext ctx) throws Exception {

ctx.writeAndFlush(Unpooled.copiedBuffer(

“Hello Netty”, CharsetUtil.UTF_8));

}

@Override

public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)

throws Exception {

cause.printStackTrace();

ctx.close();

}

/**

• 返回下载内容

• @param ctx

• @author DarkKing 2019-12-17

*/

public static void responseExportFile(ChannelHandlerContext ctx, String path, String name) {

File file = new File(path);

try {

//随机读取文件

final RandomAccessFile raf = new RandomAccessFile(file, “r”);

long fileLength = raf.length();

//定义response对象

HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);

//设置请求头部

response.headers().set(HttpHeaderNames.CONTENT_LENGTH, fileLength);

response.headers().set(HttpHeaderNames.CONTENT_TYPE, “application/octet-stream; charset=UTF-8”);

response.headers().add(HttpHeaderNames.CONTENT_DISPOSITION,

“attachment; filename=”" + URLEncoder.encode(file.getName(), “UTF-8”) + “”;");

ctx.write(response);

//设置事件通知对象

ChannelFuture sendFileFuture = ctx

.write(new DefaultFileRegion(raf.getChannel(), 0, fileLength), ctx.newProgressivePromise());

sendFileFuture.addListener(new ChannelProgressiveFutureListener() {

//文件传输完成执行监听器

@Override

public void operationComplete(ChannelProgressiveFuture future)

throws Exception {

System.out.println(“file {} transfer complete.”);

}

//文件传输进度监听器

@Override

public void operationProgressed(ChannelProgressiveFuture future,

long progress, long total) throws Exception {

if (total < 0) {

System.out.println(“file {} transfer progress: {}”);

} else {

System.out.println(“file {} transfer progress: {}/{}”);

}

}

});

//刷新缓冲区数据，文件结束标志符

ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

}

/**

• 功能描述

• 解析文件上传

• @author DarkKing 2019/10/9 15:24

• @params [ctx, httpDecode]

*/

private static MultipartRequest getMultipartBody(FullHttpRequest request) {

try {

//创建HTTP对象工厂

HttpDataFactory factory = new DefaultHttpDataFactory(true);

//使用HTTP POST解码器

HttpPostRequestDecoder httpDecoder = new HttpPostRequestDecoder(factory, request);

httpDecoder.setDiscardThreshold(0);

if (httpDecoder != null) {

//获取HTTP请求对象

final HttpContent chunk = (HttpContent) request;

//加载对象到加吗器。

httpDecoder.offer(chunk);

if (chunk instanceof LastHttpContent) {

//自定义对象bean

MultipartRequest multipartRequest = new MultipartRequest();

//存放文件对象

Map<String, FileUpload> fileUploads = new HashMap<>();

//存放参数对象

JSONObject body = new JSONObject();

//通过迭代器获取HTTP的内容

java.util.List InterfaceHttpDataList = httpDecoder.getBodyHttpDatas();

for (InterfaceHttpData data : InterfaceHttpDataList) {

//如果数据类型为文件类型，则保存到fileUploads对象中

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