使用OkHttp 3发送原始POST请求

dependencies {
    implementation 'com.squareup.okhttp3:okhttp:3.14.9'
}

OkHttpClient client = new OkHttpClient();

String json = "{\"key\":\"value\"}";
RequestBody requestBody = RequestBody.create(MediaType.parse("application/json"), json);

Request request = new Request.Builder()
        .url("http://example.com/api")
        .post(requestBody)
        .build();

client.newCall(request).enqueue(new Callback() {
    @Override
    public void onResponse(Call call, Response response) throws IOException {
        // 处理响应结果
        String responseData = response.body().string();
        // ...
    }

    @Override
    public void onFailure(Call call, IOException e) {
        // 处理请求失败
        e.printStackTrace();
    }
});