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Outline
netty Version: 4.1.45
Use netty build a simple file server, using the HTTP protocol to provide services.
If the file does not exist, it returns a 403 response code. If the folder to display hyperlinks, if the file download support.
Server encoding
/**
* netty http 文件下载 服务器
*/
public class MyHttpFileBrowserServer {
int port;
public MyHttpFileBrowserServer(int port) {
this.port = port;
}
public void start() throws Exception {
ServerBootstrap bootstrap = new ServerBootstrap();
EventLoopGroup boss = new NioEventLoopGroup();
EventLoopGroup work = new NioEventLoopGroup();
try {
bootstrap.group(boss, work)
.handler(new LoggingHandler(LogLevel.DEBUG))
.channel(NioServerSocketChannel.class)
.childHandler(new HttpBrowserServerInitializer());
ChannelFuture f = bootstrap.bind(new InetSocketAddress(port)).sync();
System.out.println("http server started . port : " + port);
f.channel().closeFuture().sync();
}catch (Exception e){
e.printStackTrace();
}finally {
boss.shutdownGracefully();
work.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
MyHttpFileBrowserServer server = new MyHttpFileBrowserServer(8080);// 8081为启动端口
server.start();
}
}
class HttpBrowserServerInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel channel) throws Exception {
ChannelPipeline pipeline = channel.pipeline();
pipeline.addLast(new HttpServerCodec())// http 编解器
// http 消息聚合器 512*1024为接收的最大contentlength
.addLast("httpAggregator", new HttpObjectAggregator(512 * 1024))
// 支持异步发送大的码流(大的文件传输),但不占用过多的内存，防止java内存溢出
.addLast("http-chunked", new ChunkedWriteHandler())
.addLast(new HttpBrowserRequestHandler());// 请求处理器
}
}
Note that channelpipeline in HttpObjectAggregator and ChunkedWriteHandler.
- HttpObjectAggregator: HTTP message for the polymerization, a plurality of converted message and a single FullHttpRequest FullHttpResponse. Because HttpServerCodec decoder will produce each of a plurality of objects in an HTTP message: HttpRequest, HttpResponse, HttpContent, LastHttpContent.
- ChunkedWriteHandler: support asynchronous send large streams (large file transfers), but do not take up too much memory, prevent memory overflow java.
File Server service code
HttpBrowserRequestHandler is the core business logic code. For checking the correctness of the request, traversing a list of files in a read-only and read a file, sent to the client in a streaming manner.
Here are just examples of code, function is not perfect.
class HttpBrowserRequestHandler extends SimpleChannelInboundHandler<FullHttpRequest> {
@Override
public void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
// 解码失败 400
if (!request.getDecoderResult().isSuccess()) {
sendError(ctx, HttpResponseStatus.BAD_REQUEST);
return;
}
// 只支持get方法
if (request.getMethod() != HttpMethod.GET) {
sendError(ctx, HttpResponseStatus.METHOD_NOT_ALLOWED);
return;
}
//
final String uri = request.getUri();
// 处理Uri地址
final String path = sanitizeUri(uri);
if (path == null) {
sendError(ctx, HttpResponseStatus.FORBIDDEN);
return;
}
File file = new File(path);
// 如果文件不存在，或不可访问
if (file.isHidden() || !file.exists()) {
sendError(ctx, HttpResponseStatus.NOT_FOUND);
return;
}
// 如果请求是文件夹
if (file.isDirectory()) {
// 请求以 '/'结尾，列出该文件夹下的所有内容
if (uri.endsWith("/")) {
sendListing(ctx, file);
} else {
// 否则自动补全'/' 然后再重定向访问
sendRedirect(ctx, uri + '/');
}
return;
}
if (!file.isFile()) {
sendError(ctx, HttpResponseStatus.FORBIDDEN);
return;
}
RandomAccessFile randomAccessFile = null;
try {
randomAccessFile = new RandomAccessFile(file, "r");// 以只读的方式打开文件
} catch (FileNotFoundException fnfe) {
sendError(ctx, HttpResponseStatus.NOT_FOUND);
return;
}
long fileLength = randomAccessFile.length();
// 创建一个默认的Http响应
HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
// 设置响应文件大小
HttpUtil.setContentLength(response, fileLength);
// 设置 content Type
setContentTypeHeader(response, file);
// 设置 keep alive
if (HttpUtil.isKeepAlive(request)) {
response.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
}
ctx.write(response);
//通过Netty的ChunkedFile对象直接将文件写入发送到缓冲区中
ChannelFuture sendFileFuture = ctx.write(new ChunkedFile(randomAccessFile, 0, fileLength, 8192), ctx.newProgressivePromise());
sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
@Override
public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) {
if (total < 0) { // total unknown
System.err.println("Transfer progress: " + progress);
} else {
System.err.println("Transfer progress: " + progress + " / " + total);
}
}
@Override
public void operationComplete(ChannelProgressiveFuture future) throws Exception {
System.out.println("Transfer complete.");
}
});
ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
//如果不支持keep-Alive，服务器端主动关闭请求
if (!HttpUtil.isKeepAlive(request)) {
lastContentFuture.addListener(ChannelFutureListener.CLOSE);
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
if (ctx.channel().isActive()) {
sendError(ctx, HttpResponseStatus.INTERNAL_SERVER_ERROR);
}
}
private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");
/**
* 格式化uri并且获取路径
*
* @param uri
* @return
*/
private String sanitizeUri(String uri) {
try {
uri = URLDecoder.decode(uri, "UTF-8");
} catch (UnsupportedEncodingException e) {
try {
uri = URLDecoder.decode(uri, "ISO-8859-1");
} catch (UnsupportedEncodingException e1) {
throw new Error();
}
}
if (!uri.startsWith("/")) {
return null;
}
uri = uri.replace('/', File.separatorChar);
if (uri.contains(File.separator + '.') || uri.contains('.' + File.separator) || uri.startsWith(".")
|| uri.endsWith(".") || INSECURE_URI.matcher(uri).matches()) {
return null;
}
return System.getProperty("user.dir") + File.separator + uri;
}
private static final Pattern ALLOWED_FILE_NAME = Pattern.compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");
private static void sendListing(ChannelHandlerContext ctx, File dir) {
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html; charset=UTF-8");
StringBuilder buf = new StringBuilder();
String dirPath = dir.getPath();
buf.append("<!DOCTYPE html>\r\n");
buf.append("<html><head><title>");
buf.append(dirPath);
buf.append(" 目录：");
buf.append("</title></head><body>\r\n");
buf.append("<h3>");
buf.append(dirPath).append(" 目录：");
buf.append("</h3>\r\n");
buf.append("<ul>");
buf.append("<li>链接：<a href=\"../\">..</a></li>\r\n");
for (File f : dir.listFiles()) {
if (f.isHidden() || !f.canRead()) {
continue;
}
String name = f.getName();
if (!ALLOWED_FILE_NAME.matcher(name).matches()) {
continue;
}
buf.append("<li>链接：<a href=\"");
buf.append(name);
buf.append("\">");
buf.append(name);
buf.append("</a></li>\r\n");
}
buf.append("</ul></body></html>\r\n");
ByteBuf buffer = Unpooled.copiedBuffer(buf, CharsetUtil.UTF_8);
response.content().writeBytes(buffer);
buffer.release();
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
private static void sendRedirect(ChannelHandlerContext ctx, String newUri) {
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.FOUND);
response.headers().set(HttpHeaderNames.LOCATION, newUri);
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
private static void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, status,
Unpooled.copiedBuffer("Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8));
response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain; charset=UTF-8");
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
private static void setContentTypeHeader(HttpResponse response, File file) {
MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();
response.headers().set(HttpHeaderNames.CONTENT_TYPE, mimeTypesMap.getContentType(file.getPath()));
}
}
Run HTTPserver server.
Browser to http: // localhost: 8080 /
Visit: http: // localhost: 8080 / reactor3-helloworld /. For files that can be downloaded directly to the local.
Enter an invalid URL, it returns a 403 error.
Note: If you are java11 version, you need to add activationdependencies. See: java11: NoClassDefFoundError: javax / Activation / MimetypesFileTypeMap
Note: For more related articles visit netty bloggers Column: netty column
