//json请求数据
btn_json.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        //1创建一个请求队列
        RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);
        //2创建一个请求
        String url="http://api.m.mtime.cn/PageSubArea/TrailerList.api";
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(url, null, new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject jsonObject) {
                tv_volly_result.setText(jsonObject.toString());
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError volleyError) {
                tv_volly_result.setText("请求失败"+volleyError);
            }
        });
        //3将创建的请求放入队列中
        requestQueue.add(jsonObjectRequest);
    }
});