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关于HTTP的介绍，参见HTTP协议介绍
Netty HTTP服务端开发：
public class HttpFileServer {
private static final String DEFAULT_URL = "/src/main/java/com/kim/";
private static String ip = "10.200.88.159";
static {
try {
//获取本地IP
ip = InetAddress.getLocalHost().getHostAddress();
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
public void run(final int port, final String url) throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch)
throws Exception {
//添加请求消息解码器，对HTTP 请求解码
ch.pipeline().addLast("http-decoder",
new HttpRequestDecoder());
//添加HttpObjectAggregator解码器，将多个消息转为单一的FullHttpRequest或者FullHttpResponse
//因为HTTP解码器会在每个HTTP消息中生成多个消息对象：
/*
1、HttpRequest/HttpResponse
2、HttpContent
3、LastHttpContent
*/
ch.pipeline().addLast("http-aggregator",
new HttpObjectAggregator(65536));
//添加响应编码器
ch.pipeline().addLast("http-encoder",
new HttpResponseEncoder());
//ChunkedWriteHandler支持异步传输大的码流（例如大的文件传输），不占用过多内存，防止内存溢出
ch.pipeline().addLast("http-chunked",
new ChunkedWriteHandler());
//添加文件服务器业务处理器
ch.pipeline().addLast("fileServerHandler",
new HttpFileServerHandler(url));
}
});
ChannelFuture future = b.bind(ip, port).sync();
System.out.println("HTTP文件目录服务器启动，网址是 : " + "http://" + ip + ":"
+ port + url);
future.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
int port = 8080;
if (args.length > 0) {
try {
port = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
e.printStackTrace();
}
}
String url = DEFAULT_URL;
if (args.length > 1) {
url = args[1];
}
new HttpFileServer().run(port, url);
}
}public class HttpFileServerHandler extends
SimpleChannelInboundHandler<FullHttpRequest> {
private final String url;
public HttpFileServerHandler(String url) {
this.url = url;
}
@Override
public void channelRead0(ChannelHandlerContext ctx,
FullHttpRequest request) throws Exception {
//解码失败，返回400，客户端请求错误
if (!request.decoderResult().isSuccess()) {
sendError(ctx, BAD_REQUEST);
return;
}
//只能接收GET请求
if (request.method() != GET) {
sendError(ctx, METHOD_NOT_ALLOWED);
return;
}
//获取和构造URI，返回资源定位符
final String uri = request.uri();
final String path = sanitizeUri(uri);
//如果路径不合法，返回403
if (path == null) {
sendError(ctx, FORBIDDEN);
return;
}
//如果文件不存在或者是隐藏文件，返回404
File file = new File(path);
if (file.isHidden() || !file.exists()) {
sendError(ctx, NOT_FOUND);
return;
}
//如果是目录，发送目录的链接给浏览器
if (file.isDirectory()) {
if (uri.endsWith("/")) {
sendListing(ctx, file);
} else {
sendRedirect(ctx, uri + '/');
}
return;
}
//如果不是个文件，返回403
if (!file.isFile()) {
sendError(ctx, 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, NOT_FOUND);
return;
}
long fileLength = randomAccessFile.length();
HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
//设置响应头参数
setContentLength(response, fileLength);
setContentTypeHeader(response, file);
if (isKeepAlive(request)) {
response.headers().set(CONNECTION, HttpHeaderValues.KEEP_ALIVE);
}
//将响应头写入channel
ctx.write(response);
ChannelFuture sendFileFuture;
//将文件写入channel
sendFileFuture = ctx.write(new ChunkedFile(randomAccessFile, 0,
fileLength, 8192), ctx.newProgressivePromise());
//添加文件发送的监听，监控下载进度和是否传输完成
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.");
}
});
//判断是否关闭channel
ChannelFuture lastContentFuture = ctx
.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
if (!isKeepAlive(request)) {
lastContentFuture.addListener(ChannelFutureListener.CLOSE);
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
throws Exception {
cause.printStackTrace();
if (ctx.channel().isActive()) {
sendError(ctx, INTERNAL_SERVER_ERROR);
}
}
private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");
private String sanitizeUri(String uri) {
try {
//对uri解码
uri = URLDecoder.decode(uri, "UTF-8");
} catch (UnsupportedEncodingException e) {
try {
uri = URLDecoder.decode(uri, "ISO-8859-1");
} catch (UnsupportedEncodingException e1) {
throw new Error();
}
}
//解码成功，对uri进行合法性判断
if (!uri.startsWith(url)) {
return null;
}
if (!uri.startsWith("/")) {
return null;
}
//将分隔符替换为操作系统文件路径分隔符
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;
}
//对文件路径拼接，当前运行程序所在的工程目录+uri的绝对路径
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(HTTP_1_1, OK);
response.headers().set(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);
//将目录列表响应给浏览器
response.content().writeBytes(buffer);
buffer.release();
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
private static void sendRedirect(ChannelHandlerContext ctx, String newUri) {
FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, FOUND);
response.headers().set(LOCATION, newUri);
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
private static void sendError(ChannelHandlerContext ctx,
HttpResponseStatus status) {
FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1,
status, Unpooled.copiedBuffer("Failure: " + status.toString()
+ "\r\n", CharsetUtil.UTF_8));
response.headers().set(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(CONTENT_TYPE,
mimeTypesMap.getContentType(file.getPath()));
}
}运行结果：
