<dependency>
    <groupId>io.esastack</groupId>
    <artifactId>httpclient-core</artifactId>
    <version>${esa-httpclient.version}</version>
</dependency>

final HttpClient client = HttpClient.ofDefault();

final HttpResponse response = client.post("http://127.0.0.1:8081/").body("Hello Server".getBytes()).execute().get();
// handle response here...

final HttpClient client = HttpClient.create().addInterceptor((request, next) -> {
    System.out.println("Interceptor");
    return next.proceed(request);
}).build();

final HttpClient client = HttpClient.create().addRequestFilter((request, ctx) -> {  // 仅处理Request
    System.out.println("Request Filter");
    return CompletableFuture.completedFuture(null);
}).addResponseFilter((request, response, ctx) -> {   // 仅处理Response
    System.out.println("Response Filter");
    return CompletableFuture.completedFuture(null);
}).addFilter(new DuplexFilter() {   // 同时处理Request和Response
    @Override
    public CompletableFuture<Void> doFilter(HttpRequest request, FilterContext ctx) {
        System.out.println("Request Filter(Duplex)");
        return CompletableFuture.completedFuture(null);
    }

    @Override
    public CompletableFuture<Void> doFilter(HttpRequest request, HttpResponse response, FilterContext ctx) {
        System.out.println("Response Filter(Duplex)");
        return CompletableFuture.completedFuture(null);
    }
}).build();

final HttpClient client = HttpClient.create().resolver(new HostResolver() {
    @Override
    public CompletableFuture<InetAddress> resolve(String inetHost) {
        // resolve inetHost
        return null;
    }
}).build();

public class FileHandler extends Handler {
    private static final String PATH = "xxxx";

    private RandomAccessFile file;

    @Override
    public void onStart() {
        String fileName = response().headers().get("fileName");
        try {
            file = new RandomAccessFile(new File(PATH, fileName), "rw");
        } catch (FileNotFoundException e) {
            // Handle execption
        }
    }

    @Override
    public void onData(Buffer content) {
        if (file != null) {
            byte[] data = new byte[content.readableBytes()];
            content.readBytes(data);
            try {
                file.write(data);
            } catch (IOException e) {
                // Handle exception
            }
        } else {
            throw new IllegalStateException("file is null");
        }
    }

    @Override
    public void onEnd() {
        IOUtils.closeQuietly(file);
    }

    @Override
    public void onError(Throwable cause) {
        IOUtils.closeQuietly(file);
    }
}

final HttpClient client = HttpClient.create()
        .readTimeout(5000).build();
final HttpRequestFacade request = client.get("http://127.0.0.1:8080/abc").handler(new FileHandler());

final CompletableFuture<HttpResponse> response =  request.execute();

response.whenComplete((rsp, th) -> System.out.println(rsp.status()));

// Wait until complete
System.in.read();

final HttpClient client = HttpClient.create().readTimeout(5000).build();

CompletableFuture<HttpResponse> response =  client.get("http://127.0.0.1:8080/abc")
        .handle((Handle h) -> {
            h.onData((Buffer buf) -> {
                System.out.println("Received response data: " + buf.readableBytes());
            })
             .onTrailer((HttpHeaders trailers) -> h.trailers().add(trailers))
             .onEnd((Void v) -> {
                 System.out.println("Response end");
             })
             .onError((Throwable t) -> System.out.println("Unexpected error: " + t.getMessage()));
        }).execute();

response.whenComplete((rsp, th) -> System.out.println(rsp.status()));

// Wait until complete
System.in.read();

final HttpClient client = HttpClient.ofDefault();

final SegmentRequest request = client.post("http://127.0.0.1:8080/").segment();

for (int i = 0; i < 100; i++) {
    // request.isWritable（）判断适用于较大内容的分块写
    if (request.isWritable()) {
        request.write("It's body".getBytes());
    } else {
        throw new IllegalStateException("Channel is unwritable");
    }
}

HttpResponse response = request.end("It's end".getBytes()).get();
System.out.println(response.status());
System.out.println(response.body().string(StandardCharsets.UTF_8));

final HttpClient client = HttpClient.ofDefault();
HttpResponse response = client.post("http://127.0.0.1:8080/abc")
        .body(new File("xxxxx"))
        .execute()
        .get();
System.out.println(response.status());

final HttpClient client = HttpClient.ofDefault();

File file = new File("xxxxx");
final MultipartRequest request = client.post("http://127.0.0.1:9997/file/upload")
        .multipart()
        .file("file", file)
        .attr("name", "Bob")
        .attr("address", "China");

HttpResponse response = request.execute().get();
System.out.println(response.status());
System.out.println(response.body().string(StandardCharsets.UTF_8));

final HttpClient client = HttpClient.create()
        .connectionPoolSize(512)
        .connectionPoolWaitingQueueLength(256)
        .readTimeout(6000)
        .connectTimeout(3000)
        .build();

final HttpClient client = HttpClient.create().channelPoolOptionsProvider(new ChannelPoolOptionsProvider() {
    @Override
    public ChannelPoolOptions get(SocketAddress key) {
        // customize options
	return null;
    }
}).build();

final HttpClient client = HttpClient.ofDefault();

ConnectionPoolMetricProvider connectionPoolMetricProvider = client.connectionPoolMetric();
ConnectionPoolMetric connectionPoolMetric = connectionPoolMetricProvider.get(InetSocketAddress.createUnresolved("127.0.0.1", 8080));

// 连接池配置
connectionPoolMetric.options();

// 等待获取连接的请求个数
connectionPoolMetric.pendingAcquireCount();

// 活跃连接个数
connectionPoolMetric.active();

// 等待获取连接队列最大值
connectionPoolMetric.maxPendingAcquires();

// 连接池最大值
connectionPoolMetric.maxSize();

IoThreadGroupMetric ioThreadGroupMetric = client.ioThreadsMetric();

for (IoThreadMetric ioThreadMetric : ioThreadGroupMetric.childExecutors()) {
    // 任务队列大小
    ioThreadMetric.pendingTasks();

    // 任务队列最大值
    ioThreadMetric.maxPendingTasks();

    // 线程状态
    ioThreadMetric.state();

    // 线程名称
    ioThreadMetric.name();
}