MockServer是OKHttp中的一个子模块，如其名，用来模拟服务器的，用于测试。

compile 'com.squareup.okhttp3:okhttp:3.9.0'
compile 'com.squareup.okhttp3:mockwebserver:3.9.0'

具体的版本号，请查看OKHttp在GitHub上的网址

示例：

示例：

package com.fpliu.newton.websocket;

import okhttp3.*;
import okhttp3.mockwebserver.MockResponse;
import okhttp3.mockwebserver.MockWebServer;
import okio.ByteString;

import java.io.IOException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public final class WebSocketTest {

    public static void main(String[] args) {
        //模拟服务器端：
        ExecutorService writeExecutor = Executors.newSingleThreadExecutor();

        MockWebServer mockWebServer = new MockWebServer();
        mockWebServer.enqueue(new MockResponse().withWebSocketUpgrade(new WebSocketListener() {

            @Override
            public void onOpen(final WebSocket webSocket, Response response) {
                //打印一些内容
                System.out.println("server onOpen");
                System.out.println("server request header:" + response.request().headers());
                System.out.println("server response header:" + response.headers());
                System.out.println("server response:" + response);
            }

            @Override
            public void onMessage(WebSocket webSocket, String text) {
                super.onMessage(webSocket, text);
            }

            @Override
            public void onMessage(WebSocket webSocket, ByteString bytes) {
                super.onMessage(webSocket, bytes);
                String string = bytes.toString();
                System.out.println("onMessage() message = " + string);
                //当收到客户端的command 1时回复replay command 1
                if ("command 1".equals(string)) {
                    writeExecutor.execute(new Runnable() {
                        @Override
                        public void run() {
                            try {
                                webSocket.send(RequestBody.create(WebSocket.TEXT, "replay command 1"));
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    });
                } else if ("command 2".equals(string)) {
                    //当收到客户端的command 2时，发送ping帧
                    writeExecutor.execute(new Runnable() {
                        @Override
                        public void run() {
                            webSocket.send(ByteString.of("ping from server...".getBytes()));
                        }
                    });
                }
            }

            @Override
            public void onClosing(WebSocket webSocket, int code, String reason) {
                super.onClosing(webSocket, code, reason);
                System.out.println("onClosing()" + "code = " + code + ", reason = " + reason);
            }

            @Override
            public void onClosed(WebSocket webSocket, int code, String reason) {
                super.onClosed(webSocket, code, reason);
                System.out.println("onClosed()" + "code = " + code + ", reason = " + reason);
            }

            @Override
            public void onFailure(WebSocket webSocket, Throwable throwable, Response response) {
                super.onFailure(webSocket, throwable, response);
                //出现异常会进入此回调
                System.out.println("onFailure()");
                System.out.println("throwable:" + throwable);
                System.out.println("response:" + response);
            }
        }));

        //模拟客户端：
        String hostName = mockWebServer.getHostName();
        int port = mockWebServer.getPort();
        System.out.println("hostName:" + hostName + ", port:" + port);

        OkHttpClient client = new OkHttpClient.Builder().build();
        //构造request对象
        Request request = new Request.Builder().url("ws://" + hostName + ":" + port + "/").build();
        //new 一个websocket调用对象并建立连接
        client.newWebSocket(request, new WebSocketListener() {

            @Override
            public void onOpen(final WebSocket webSocket, Response response) {
                //打印一些内容
                System.out.println("client onOpen");
                System.out.println("client request header:" + response.request().headers());
                System.out.println("client response header:" + response.headers());
                System.out.println("client response:" + response);
                //注意下面都是write线程回写给客户端
                //建立连接成功后，发生command 1给服务器端
                writeExecutor.execute(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            webSocket.send(RequestBody.create(WebSocket.TEXT, "command 1"));
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                });
            }

            @Override
            public void onMessage(WebSocket webSocket, String text) {
                super.onMessage(webSocket, text);
            }

            @Override
            public void onMessage(WebSocket webSocket, ByteString bytes) {
                super.onMessage(webSocket, bytes);
            }

            @Override
            public void onClosing(WebSocket webSocket, int code, String reason) {
                super.onClosing(webSocket, code, reason);
            }

            @Override
            public void onClosed(WebSocket webSocket, int code, String reason) {
                super.onClosed(webSocket, code, reason);
            }

            @Override
            public void onFailure(WebSocket webSocket, Throwable t, Response response) {
                super.onFailure(webSocket, t, response);
            }
        });
    }
}