如何在Lower API中使用Volley Library

Question

我正在使用Volley Library开发一个android项目。 它是一个简单的登录项目。 用户必须输入他的手机号码才能查看他/她的详细信息。 该项目在API为23的仿真器上运行良好，但是当我在较低的API上运行该项目时，就会出现主要问题。 我的个人手机是Kitkat 4.4.4。 如果项目不在我的手机上运行。

这是我的MainActivity.java

public class MainActivity extends AppCompatActivity {

EditText et_mobile;
Button buttonFind;
String get_result_url = "http://myUrl.php";
AlertDialog.Builder builder;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    et_mobile = (EditText) findViewById(R.id.et_mobile);
    buttonFind = (Button) findViewById(R.id.b_find);

    builder = new AlertDialog.Builder(MainActivity.this);

    buttonFind.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (et_mobile.getText().toString().trim().length() == 10){
                Toast.makeText(MainActivity.this, "yay", Toast.LENGTH_SHORT).show();
                StringRequest stringRequest = new StringRequest(Request.Method.POST, get_result_url,

                        new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {
                                try {
                                    JSONArray jsonArray = new JSONArray(response);
                                    JSONObject jsonObject = jsonArray.getJSONObject(0); // since only one object is available
                                    String code = jsonObject.getString("code");
                                    if (code.equals("login_failed")){
                                        displayAlertMessage("Mobile Number Miss matched",jsonObject.getString("message"));


                                    }else{
                                        Intent intent = new Intent(MainActivity.this,UserDetails.class);
                                        Bundle bundle = new Bundle();
                                        bundle.putString("user_name",jsonObject.getString("user_name"));
                                        bundle.putString("user_address",jsonObject.getString("user_address"));
                                        bundle.putString("user_mobile",jsonObject.getString("user_mobile"));
                                        bundle.putString("user_notification",jsonObject.getString("user_notification"));
                                        bundle.putString("user_status",jsonObject.getString("user_status"));
                                        intent.putExtras(bundle);
                                        startActivity(intent);
                                    }

                                } catch (JSONException e) {
                                    e.printStackTrace();
                                }

                            }
                        },
                        new Response.ErrorListener() {
                            @Override
                            public void onErrorResponse(VolleyError error) {
                                Toast.makeText(MainActivity.this, "Error ...", Toast.LENGTH_SHORT).show();
                                error.printStackTrace();

                            }
                        }
                )
                {
                    @Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                        Map<String, String> params = new HashMap<String, String>();
                        params.put("user_mobile",et_mobile.getText().toString());
                        return params;
                    }
                };

                MySingleton.getInstance(MainActivity.this).addRequestQueue(stringRequest);
            }else {
                displayAlertMessage("Error ...","Input Valid Phone Number");
            }
        }
    });
}

public void displayAlertMessage (String title, String msg){
    builder.setTitle(title);
    builder.setMessage(msg);
    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });
    AlertDialog alertDialog = builder.create();
    alertDialog.show();
}
}

这是SingleTon类

public class MySingleton {

private static MySingleton mInstance;
private RequestQueue requestQueue;
private static Context mCtx;

private MySingleton(Context context){
    mCtx = context;
    requestQueue = getRequestQueue();
}

public RequestQueue getRequestQueue(){
    if (requestQueue == null){
        requestQueue = Volley.newRequestQueue(mCtx.getApplicationContext());
    }
    return requestQueue;
}

// this method will return instance of this class
public static synchronized MySingleton getInstance(Context context){

    if (mInstance == null){
        mInstance = new MySingleton(context);
    }
    return mInstance;
}

// this method will add requestQueue
public<T> void addRequestQueue (Request<T> request){
    requestQueue.add(request);
}
}

这是我可以看到输出的类

public class UserDetails extends AppCompatActivity {

TextView name, address, mobile, notification, status;

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

    name = (TextView) findViewById(R.id.tv_user_name);
    address = (TextView) findViewById(R.id.tv_user_address);
    mobile = (TextView) findViewById(R.id.tv_user_mobile);
    notification = (TextView) findViewById(R.id.tv_user_notification);
    status = (TextView) findViewById(R.id.tv_user_status);

    Bundle bundle = getIntent().getExtras();
    name.setText(bundle.getString("user_name"));
    address.setText(bundle.getString("user_address"));
    mobile.setText(bundle.getString("user_mobile"));
    notification.setText(bundle.getString("user_notification"));
    status.setText(bundle.getString("user_status"));
}

这是AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.dell103.VolleyProject">
    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        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>
        <activity android:name=".UserDetails"></activity>
    </application>
</manifest>

这是Build.gradle

defaultConfig {
    applicationId "com.example.dell103.DoctorPatientVolleyProject"
    minSdkVersion 15
    targetSdkVersion 23
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}


dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.4.0'
    compile 'com.mcxiaoke.volley:library:1.0.19'
}

这是LogCat中显示的错误

09-07 16:29:39.487 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err: com.android.volley.NoConnectionError: java.net.UnknownHostException: http://nirjan_munshi.netne.net/VolleyDemo/json_search_result.php
09-07 16:29:39.487 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.volley.toolbox.BasicNetwork.performRequest(BasicNetwork.java:158)
09-07 16:29:39.487 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.volley.NetworkDispatcher.run(NetworkDispatcher.java:114)
09-07 16:29:39.491 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err: Caused by: java.net.UnknownHostException: http://nirjan_munshi.netne.net/VolleyDemo/json_search_result.php
09-07 16:29:39.499 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:279)
09-07 16:29:39.499 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.okhttp.internal.http.HttpEngine.sendSocketRequest(HttpEngine.java:255)
09-07 16:29:39.500 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:206)
09-07 16:29:39.500 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:345)
09-07 16:29:39.500 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:89)
09-07 16:29:39.500 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:197)
09-07 16:29:39.501 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.volley.toolbox.HurlStack.addBodyIfExists(HurlStack.java:257)
09-07 16:29:39.501 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.volley.toolbox.HurlStack.setConnectionParametersForRequest(HurlStack.java:227)
09-07 16:29:39.503 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.volley.toolbox.HurlStack.performRequest(HurlStack.java:107)
09-07 16:29:39.504 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     at com.android.volley.toolbox.BasicNetwork.performRequest(BasicNetwork.java:97)
09-07 16:29:39.505 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/System.err:     ... 1 more
09-07 16:30:45.859 20509-20509/com.example.dell103.DoctorPatientVolleyProject W/IInputConnectionWrapper: showStatusIcon on inactive InputConnection

Answer 1

您的错误显然是由UnknownHostException引起的NoConnectionError

在您的Android浏览器中尝试http://nirjan_munshi.netne.net/VolleyDemo/json_search_result.php ，如果您收到404 ，则说明互联网连接是罪魁祸首 ！ （如果您在本地运行，如果不查找其他连接问题）