[使用Android从URL获取JSON数据响应？

Question

我正在尝试从URL获取JSON响应。我已经尝试了下面的代码几次，但无法得到响应。请帮助我解决这个问题

我正在使用API​​级别29

这里我正在使用此URL来获取数据，URL-> https://api.androidhive.info/contacts/

我的代码：

public class MainActivity extends AppCompatActivity {

    private final static String URL = "https://api.androidhive.info/contacts/";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        RequestQueue queue = Volley.newRequestQueue(this);

        JsonArrayRequest arrayRequest = new JsonArrayRequest(
                Request.Method.GET, URL,null,new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                Log.d("Response : ", response.toString());
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                VolleyLog.d("Error : ", error.getMessage());
            }
        });
        queue.add(arrayRequest);
    }
}

AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.volleyparsing">

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Logcat的响应：

2020-05-03 22:19:49.600 11515-11515/? I/e.volleyparsin: Not late-enabling -Xcheck:jni (already on)
2020-05-03 22:19:49.749 11515-11515/? E/e.volleyparsin: Unknown bits set in runtime_flags: 0x8000
2020-05-03 22:19:53.066 11515-11515/com.example.volleyparsing D/Volley: [2] 2.onErrorResponse: Error :
2020-05-03 22:19:50.513 11515-11545/com.example.volleyparsing W/libc: Unable to set property "qemu.gles" to "1": connection failed; errno=13 (Permission denied)

Answer 1

您的响应是jsonObject而不是jsonArray。这样，您将获得解析错误。使用jsonObject：

RequestQueue queue = Volley.newRequestQueue(context);

    JsonObjectRequest objectRequest = new JsonObjectRequest(
            Request.Method.GET, URL, null, new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            JSONArray jsonArray = null;
            try {
                jsonArray = response.getJSONArray("contacts");
                Log.d("Response : ", jsonArray.toString());
            } catch (JSONException e) {
                e.printStackTrace();
            }

        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            VolleyLog.d("Error : ", error.getMessage());
        }
    });

    queue.add(objectRequest);   

Answer 2

在应用程序的清单文件上使用android：usesCleartextTraffic =“ true”。

  <application
    ...
    android:usesCleartextTraffic="true"
    ... >