OkHttp post json数据，Java

需要印日maven依赖：

        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>5.0.0-alpha.10</version>
        </dependency>

private String post(OkHttpClient client, String url, String json) throws Exception {
        final MediaType JSON = MediaType.get("application/json; charset=utf-8");
        RequestBody body = RequestBody.create(json, JSON);
        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .build();

        final Call call = client.newCall(request);
        Response response = call.execute();
        return response.body().string();
    }

OkHttpClient需要以单例模式获取，最好不要每次请求都new一个新的。