目錄
一、Netty應用場景
講了一些Netty的組件,來聊一聊大家最關心的事情吧,他能夠做什麼?畢竟,我們學習就是拿來用的嘛。我可以簡單的概括一下,凡是牽扯到網絡相關的,都可以使用Neety去實現!
- 構建高性能、低時延的各種 Java 中間件,例如 MQ、分佈式服務框架、ESB 消息總線等,Netty 主要作爲基礎通信框架提供高性能、低時延的通信服務;
- 公有或者私有協議棧的基礎通信框架,例如可以基於 Netty 構建異步、高性能的 WebSocket 協議棧;
- 各領域應用,例如大數據、遊戲等,Netty 作爲高性能的通信框架用於內部各模塊的數據分發、傳輸和彙總等,實現模塊之間高性能通信。
接下來的幾篇,會圍繞Netty實現相關功能進行展開。
二、Netty實現文件的上傳和下載
1、MultipartRequest
import io.netty.handler.codec.http.multipart.FileUpload;
import org.json.simple.JSONObject;
import java.util.Map;
/**
* <p>請求對象</p>
*
* @author DarkKing
*/
public class MultipartRequest {
private Map<String, FileUpload> fileUploads;
private JSONObject params;
public Map<String, FileUpload> getFileUploads() {
return fileUploads;
}
public void setFileUploads(Map<String, FileUpload> fileUploads) {
this.fileUploads = fileUploads;
}
public JSONObject getParams() {
return params;
}
public void setParams(JSONObject params) {
this.params = params;
}
}
定義了一個http封裝的對象。保存對應的傳參數。
2、FileServer
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
* 創建日期:2019/12/17
* 類說明:文件下載服務端
*/
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("服務器即將啓動");
fileServer.start();
System.out.println("服務器關閉");
}
public void start() throws InterruptedException {
final FileServerHandle serverHandler = new FileServerHandle();
/*線程組*/
EventLoopGroup group = new NioEventLoopGroup();
Pipeline pipeline = new Pipeline();
try {
/*服務端啓動必須*/
ServerBootstrap b = new ServerBootstrap();
b.group(group)/*將線程組傳入*/
.channel(NioServerSocketChannel.class)/*指定使用NIO進行網絡傳輸*/
.localAddress(new InetSocketAddress(port))/*指定服務器監聽端口*/
/*服務端每接收到一個連接請求,就會新啓一個socket通信,也就是channel,
所以下面這段代碼的作用就是爲這個子channel增加handle*/
.childHandler(pipeline);
ChannelFuture f = b.bind().sync();/*異步綁定到服務器,sync()會阻塞直到完成*/
System.out.println("Netty server start,port is " + port);
f.channel().closeFuture().sync();/*阻塞直到服務器的channel關閉*/
} finally {
group.shutdownGracefully().sync();/*優雅關閉線程組*/
}
}
}
使用netty實現服文件服務器端。
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
* 創建日期:2019/12/17
* 作用:職責鏈
*/
public class Pipeline extends ChannelInitializer<SocketChannel> {
private EventExecutorGroup businessEventExecutorGroup = new DefaultEventExecutorGroup(10);
@Override
protected void initChannel(SocketChannel ch) {
ChannelPipeline pipeline = ch.pipeline();
/**
* http服務器端對response編碼
*/
pipeline.addLast("encoder", new HttpResponseEncoder());
/**
* http服務器端對request解碼3.
*/
pipeline.addLast("decoder", new HttpRequestDecoder());
/**
* 合併請求
*/
pipeline.addLast("aggregator", new HttpObjectAggregator(655300000));
/**
* 正常業務邏輯處理
*/
pipeline.addLast(businessEventExecutorGroup, new FileServerHandle());
}
}
編寫職責鏈,請求會從入棧以次從上到下經過編解碼,請求和秉承HTTPObject,最後執行業務類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
* 創建日期:2019/12/17
* 類說明:文件下載handler
*/
@Sharable
public class FileServerHandle extends SimpleChannelInboundHandler<FullHttpRequest> {
/*客戶端讀到數據以後,就會執行*/
@Override
protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request)
throws Exception {
//打印請求url
System.out.println(request.uri());
//下載任務處理
if (request.uri().equals("/downFile")) {
responseExportFile(ctx, "D://model.txt", "model.txt");
}
//上傳接口處理
if (request.uri().equals("/upLoadFile")) {
MultipartRequest MultipartBody = getMultipartBody(request);
Map<String, FileUpload> fileUploads = MultipartBody.getFileUploads();
//輸出文件信息
for (String key : fileUploads.keySet()) {
//獲取文件對象
FileUpload file = fileUploads.get(key);
System.out.println("fileName is" + file.getFile().getPath());
//獲取文件流
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);
}
//輸出參數信息
JSONObject params = MultipartBody.getParams();
//輸出文件信息
System.out.println(JSONObject.toJSONString(params));
}
}
/*連接建立以後*/
@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();
}
/**
* <p>
* 返回下載內容
* </p>
*
* @param ctx
* @author DarkKing 2019-12-17
*/
public static void responseExportFile(ChannelHandlerContext ctx, String path, String name) {
File file = new File(path);
try {
//隨機讀取文件
final RandomAccessFile raf = new RandomAccessFile(file, "r");
long fileLength = raf.length();
//定義response對象
HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
//設置請求頭部
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);
//設置事件通知對象
ChannelFuture sendFileFuture = ctx
.write(new DefaultFileRegion(raf.getChannel(), 0, fileLength), ctx.newProgressivePromise());
sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
//文件傳輸完成執行監聽器
@Override
public void operationComplete(ChannelProgressiveFuture future)
throws Exception {
System.out.println("file {} transfer complete.");
}
//文件傳輸進度監聽器
@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: {}/{}");
}
}
});
//刷新緩衝區數據,文件結束標誌符
ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 功能描述
* <p>解析文件上傳</p>
*
* @author DarkKing 2019/10/9 15:24
* @params [ctx, httpDecode]
*/
private static MultipartRequest getMultipartBody(FullHttpRequest request) {
try {
//創建HTTP對象工廠
HttpDataFactory factory = new DefaultHttpDataFactory(true);
//使用HTTP POST解碼器
HttpPostRequestDecoder httpDecoder = new HttpPostRequestDecoder(factory, request);
httpDecoder.setDiscardThreshold(0);
if (httpDecoder != null) {
//獲取HTTP請求對象
final HttpContent chunk = (HttpContent) request;
//加載對象到加嗎器。
httpDecoder.offer(chunk);
if (chunk instanceof LastHttpContent) {
//自定義對象bean
MultipartRequest multipartRequest = new MultipartRequest();
//存放文件對象
Map<String, FileUpload> fileUploads = new HashMap<>();
//存放參數對象
JSONObject body = new JSONObject();
//通過迭代器獲取HTTP的內容
java.util.List<InterfaceHttpData> InterfaceHttpDataList = httpDecoder.getBodyHttpDatas();
for (InterfaceHttpData data : InterfaceHttpDataList) {
//如果數據類型爲文件類型,則保存到fileUploads對象中
if (data != null && InterfaceHttpData.HttpDataType.FileUpload.equals(data.getHttpDataType())) {
FileUpload fileUpload = (FileUpload) data;
fileUploads.put(data.getName(), fileUpload);
}
//如果數據類型爲參數類型,則保存到body對象中
if (data.getHttpDataType() == InterfaceHttpData.HttpDataType.Attribute) {
Attribute attribute = (Attribute) data;
body.put(attribute.getName(), attribute.getValue());
}
}
//存放文件信息
multipartRequest.setFileUploads(fileUploads);
//存放參數信息
multipartRequest.setParams(body);
return multipartRequest;
}
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
業務執行類,實現了文件上傳和下載的接口。當請求爲downFile則下載文件,請求爲upLoadFile則爲上傳文件
三、程序演示
1、下載演示
啓動服務器端
瀏覽器執行下載文件,正確的下載到文件test.txt
2、上傳演示
使用apipost或者postman執行文件上傳操作
文件上傳成功併成功讀取文件內容
本博文主要演示瞭如何不使用spring或者tomcat當做服務器,使用netty實現自己的文件上傳和下載服務。並根據請求來實現對應的api接口操作。當然,如果想使用netty像spring那樣簡單並規範化的封裝自己的api,那麼就要考自己去封裝實現了。有興趣的朋友可以自己嘗試下