Android網絡連接服務

Android網絡連接服務允許我們檢查設備的網絡連接信息。愛掏網 - it200.com在執行基于互聯網服務的任務（如從服務器獲取數據或向服務器寫入數據）時，檢查設備的互聯網連接非常重要。愛掏網 - it200.com

使用Android網絡連接服務，我們還可以確定Android設備的網絡類型。愛掏網 - it200.com它可以是以下類型之一： TYPE_WIFI（wifi），TYPE_MOBILE（移動網絡） ， TYPE_BLUETOOTH（藍牙） 等等。愛掏網 - it200.com

讓我們創建一個簡單的示例，以檢查設備的網絡連接及其類型。愛掏網 - it200.com

要訪問設備的網絡連接功能，我們需要在AndroidMenifest.xml文件中提供網絡訪問權限。愛掏網 - it200.com

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

在layout的activity_main.xml文件中添加以下代碼。愛掏網 - it200.com要訪問設備的網絡狀態，不需要使用layout文件。愛掏網 - it200.com在這里，我們只使用activity_main.xml文件來存儲網絡類型的狀態。愛掏網 - it200.com

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="example.javatpoint.com.networkconnectivityservice.MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="16dp"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:contentDescription="networkstate"
        android:text="Network state ?"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.183" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:text="Check Connection Type"
        android:layout_marginTop="392dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

創建一個名為NetworkState.java的java類。愛掏網 - it200.com此類包含一個getConnectivityStatus()方法，根據當前網絡連接返回常量整數值。愛掏網 - it200.com

代碼 context.getSystemService(Context.CONNECTIVITY_SERVICE) 用于返回 ConnectivityManager 類的實例，以訪問網絡屬性。愛掏網 - it200.com

NetworkState.java

package example.javatpoint.com.networkconnectivityservice;


import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class NetworkState {
    public static int TYPE_NOT_CONNECTED = 0;
    public static int TYPE_WIFI = 1;
    public static int TYPE_MOBILE = 2;

    public static int getConnectivityStatus(Context context) {
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        if (null != activeNetwork) {
            if(activeNetwork.getType() == ConnectivityManager.TYPE_WIFI)
                return TYPE_WIFI;

            if(activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE)
                return TYPE_MOBILE;
        }
        return TYPE_NOT_CONNECTED;
    }

    public static String getConnectivityStatusString(Context context) {
        int conn = NetworkState.getConnectivityStatus(context);
        String status = null;
        if (conn == NetworkState.TYPE_WIFI) {
            status = "Wifi enabled";
        } else if (conn == NetworkState.TYPE_MOBILE) {
            status = "Mobile data enabled";
        } else if (conn == NetworkState.TYPE_NOT_CONNECTED) {
            status = "Not connected to Internet";
        }
        return status;
    }
}

創建一個接收器類，取名為 NetworkReceiver.java 并繼承 BroadcastReciever 類。愛掏網 - it200.com這個類處理設備網絡狀態發生的變化。愛掏網 - it200.com當設備的網絡狀態變化時，BroadcastReciever 類的 onReceive() 方法被調用。愛掏網 - it200.com

NetworkReceiver.java

package example.javatpoint.com.networkconnectivityservice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;


public class NetworkReceiver extends BroadcastReceiver {
    static String  status =null;
    @Override
    public void onReceive(Context context, Intent intent) {
        status = NetworkState.getConnectivityStatusString(context);
        Toast.makeText(context, status, Toast.LENGTH_LONG).show();
        if(status == "Wifi enabled"){
            //your code when wifi enable
        }
        else if(status=="Mobile data enabled"){
            //your code when TYPE_MOBILE network enable
        }
        else if(status=="Not connected to Internet"){
            //your code when no network connected
        }
    }
}

在 MainActivity.java 類中，通過點擊按鈕，在TextView中顯示設備的網絡狀態。愛掏網 - it200.com

MainActivity.java

package example.javatpoint.com.networkconnectivityservice;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    Button button;
    TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = findViewById(R.id.button);
        textView = findViewById(R.id.textView);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                NetworkReceiver receiver = new NetworkReceiver() ;
                String networkStatus = receiver.status;
                textView.setText("connection type: "+networkStatus);
                Toast.makeText(getApplicationContext(), networkStatus, Toast.LENGTH_LONG).show();
            }
        });
    }
}

在 AndroidMenifest.xml 文件中，添加網絡訪問權限和接收器類，用于處理BroadcastReceiver類中發生的更改。愛掏網 - it200.com

AndroidMenifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="example.javatpoint.com.networkconnectivityservice">
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <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>
        <receiver
            android:name=".NetworkReceiver"
            android:enabled="true">
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
                <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
            </intent-filter>
        </receiver>
    </application>

</manifest>

輸出