【Android】使用ConnectivityManager與NetworkInfo實現判斷當前網路環境是否可用

iteye_20954發表於2011-12-09
Android
public class

ConnectivityManager

extendsObject
java.lang.Object
↳ android.net.ConnectivityManager

這個類用來查詢當前網路狀態，通知網路狀態變化。

Class that answers queries about the state of network connectivity. It also notifies applications when network connectivity changes. Get an instance of this class by callingContext.getSystemService(Context.CONNECTIVITY_SERVICE).

The primary responsibilities of this class are to:

  1. Monitor network connections (Wi-Fi, GPRS, UMTS, etc.)
  2. Send broadcast intents when network connectivity changes
  3. Attempt to "fail over" to another network when connectivity to a network is lost
  4. Provide an API that allows applications to query the coarse-grained or fine-grained state of the available networks.
  5. 監視網路連線（WIFI，GPRS，UMTS等）
  6. 當網路變化時發出broadcast.
  7. 當目前的網路丟失的時候嘗試轉移到另一個網路
  8. 提供API來允許AP查詢當前可用網路的精確度
<nobr><a href="http://developer.android.com/reference/android/net/NetworkInfo.html" style="color:rgb(0,102,153); text-decoration:none">NetworkInfo</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#getActiveNetworkInfo()" style="color:rgb(0,102,153); text-decoration:none">getActiveNetworkInfo</a></span>()</nobr>
<nobr><a href="http://developer.android.com/reference/android/net/NetworkInfo.html" style="color:rgb(0,102,153); text-decoration:none">NetworkInfo[]</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#getAllNetworkInfo()" style="color:rgb(0,102,153); text-decoration:none">getAllNetworkInfo</a></span>()</nobr>
<nobr>boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#getBackgroundDataSetting()" style="color:rgb(0,102,153); text-decoration:none">getBackgroundDataSetting</a></span>()</nobr>
This method is deprecated. As ofICE_CREAM_SANDWICH, availability of background data depends on several combined factors, and this method will always returntrue. Instead, when background data is unavailable,getActiveNetworkInfo()will now appear disconnected.
<nobr><a href="http://developer.android.com/reference/android/net/NetworkInfo.html" style="color:rgb(0,102,153); text-decoration:none">NetworkInfo</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#getNetworkInfo(int)" style="color:rgb(0,102,153); text-decoration:none">getNetworkInfo</a></span>(int networkType)</nobr>
<nobr>int</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#getNetworkPreference()" style="color:rgb(0,102,153); text-decoration:none">getNetworkPreference</a></span>()</nobr>
<nobr>static boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#isNetworkTypeValid(int)" style="color:rgb(0,102,153); text-decoration:none">isNetworkTypeValid</a></span>(int networkType)</nobr>
<nobr>boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#requestRouteToHost(int,%20int)" style="color:rgb(0,102,153); text-decoration:none">requestRouteToHost</a></span>(int networkType, int hostAddress)</nobr>
Ensure that a network route exists to deliver traffic to the specified host via the specified network interface.
<nobr>void</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#setNetworkPreference(int)" style="color:rgb(0,102,153); text-decoration:none">setNetworkPreference</a></span>(int preference)</nobr>
<nobr>int</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#startUsingNetworkFeature(int,%20java.lang.String)" style="color:rgb(0,102,153); text-decoration:none">startUsingNetworkFeature</a></span>(int networkType,<a href="http://developer.android.com/reference/java/lang/String.html" style="color:rgb(0,102,153); text-decoration:none">String</a>feature)</nobr>
Tells the underlying networking system that the caller wants to begin using the named feature.
<nobr>int</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/ConnectivityManager.html#stopUsingNetworkFeature(int,%20java.lang.String)" style="color:rgb(0,102,153); text-decoration:none">stopUsingNetworkFeature</a></span>(int networkType,<a href="http://developer.android.com/reference/java/lang/String.html" style="color:rgb(0,102,153); text-decoration:none">String</a>feature)</nobr>
Tells the underlying networking system that the caller is finished using the named feature.

public class

NetworkInfo

extendsObject
implementsParcelable
java.lang.Object
↳ android.net.NetworkInfo

Describes the status of a network interface of a given type (currently either Mobile or Wifi).

描述目前網路的狀態（）

Detailed state Coarse-grained state
IDLE DISCONNECTED
SCANNING CONNECTING
CONNECTING CONNECTING
AUTHENTICATING CONNECTING
CONNECTED
DISCONNECTING DISCONNECTING
DISCONNECTED DISCONNECTED
UNAVAILABLE DISCONNECTED
FAILED DISCONNECTED

Public Methods
<nobr><a href="http://developer.android.com/reference/android/net/NetworkInfo.DetailedState.html" style="color:rgb(0,102,153); text-decoration:none">NetworkInfo.DetailedState</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getDetailedState()" style="color:rgb(0,102,153); text-decoration:none">getDetailedState</a></span>()</nobr>
Reports the current fine-grained state of the network.
<nobr><a href="http://developer.android.com/reference/java/lang/String.html" style="color:rgb(0,102,153); text-decoration:none">String</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getExtraInfo()" style="color:rgb(0,102,153); text-decoration:none">getExtraInfo</a></span>()</nobr>
Report the extra information about the network state, if any was provided by the lower networking layers., if one is available.
<nobr><a href="http://developer.android.com/reference/java/lang/String.html" style="color:rgb(0,102,153); text-decoration:none">String</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getReason()" style="color:rgb(0,102,153); text-decoration:none">getReason</a></span>()</nobr>
Report the reason an attempt to establish connectivity failed, if one is available.
<nobr><a href="http://developer.android.com/reference/android/net/NetworkInfo.State.html" style="color:rgb(0,102,153); text-decoration:none">NetworkInfo.State</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getState()" style="color:rgb(0,102,153); text-decoration:none">getState</a></span>()</nobr>
Reports the current coarse-grained state of the network.
<nobr>int</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getSubtype()" style="color:rgb(0,102,153); text-decoration:none">getSubtype</a></span>()</nobr>
Return a network-type-specific integer describing the subtype of the network.
<nobr><a href="http://developer.android.com/reference/java/lang/String.html" style="color:rgb(0,102,153); text-decoration:none">String</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getSubtypeName()" style="color:rgb(0,102,153); text-decoration:none">getSubtypeName</a></span>()</nobr>
Return a human-readable name describing the subtype of the network.
<nobr>int</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getType()" style="color:rgb(0,102,153); text-decoration:none">getType</a></span>()</nobr>
Reports the type of network (currently mobile or Wi-Fi) to which the info in this object pertains.
<nobr><a href="http://developer.android.com/reference/java/lang/String.html" style="color:rgb(0,102,153); text-decoration:none">String</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#getTypeName()" style="color:rgb(0,102,153); text-decoration:none">getTypeName</a></span>()</nobr>
Return a human-readable name describe the type of the network, for example "WIFI" or "MOBILE".
<nobr>boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#isAvailable()" style="color:rgb(0,102,153); text-decoration:none">isAvailable</a></span>()</nobr>
Indicates whether network connectivity is possible.
<nobr>boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#isConnected()" style="color:rgb(0,102,153); text-decoration:none">isConnected</a></span>()</nobr>
Indicates whether network connectivity exists and it is possible to establish connections and pass data.
<nobr>boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#isConnectedOrConnecting()" style="color:rgb(0,102,153); text-decoration:none">isConnectedOrConnecting</a></span>()</nobr>
Indicates whether network connectivity exists or is in the process of being established.
<nobr>boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#isFailover()" style="color:rgb(0,102,153); text-decoration:none">isFailover</a></span>()</nobr>
Indicates whether the current attempt to connect to the network resulted from the ConnectivityManager trying to fail over to this network following a disconnect from another network.
<nobr>boolean</nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#isRoaming()" style="color:rgb(0,102,153); text-decoration:none">isRoaming</a></span>()</nobr>
Indicates whether the device is currently roaming on this network.
<nobr><a href="http://developer.android.com/reference/java/lang/String.html" style="color:rgb(0,102,153); text-decoration:none">String</a></nobr> <nobr><span class="sympad" style="margin-right:2px"><a href="http://developer.android.com/reference/android/net/NetworkInfo.html#toString()" style="color:rgb(0,102,153); text-decoration:none">toString</a></span>()</nobr>
Returns a string containing a concise, human-readable description of this object.

一個用上面兩個類實現的查詢當前網路狀態是否可用的工具類：

public static boolean isNetworkAvailable(Context context) { ConnectivityManager mConnMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo mWifi = mConnMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI); NetworkInfo mMobile = mConnMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE); boolean flag = false; if((mWifi != null) && ((mWifi.isAvailable()) || (mMobile.isAvailable()))) { if((mWifi.isConnected()) || (mMobile.isConnected())) { flag = true; } } return flag; }
上面這個類實現了單獨查詢WiFi與Mobile的行動網路是否可用，可以看到就是使用了ConnectivityManager與NetworkInfo提供的介面實現的功能！
public static boolean isConnectionAvailable(Context cotext) { boolean isConnectionFail = true; ConnectivityManager connectivityManager = (ConnectivityManager)cotext.getSystemService(Context.CONNECTIVITY_SERVICE); if (connectivityManager != null) { NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo(); if (activeNetworkInfo == null || !activeNetworkInfo.isConnected()) { isConnectionFail = true; } else { isConnectionFail = false; } } else { Log.e(TAG, "Can't get connectivitManager"); } return isConnectionFail; }








isConnectionAvailable則實現了所有網路是否可用的判斷，程式不關心當前使用的是何種網路，只需關係是否連線上網際網路既可，第一個工具類在某些時候會需要使用到，比如只在WiFi情況下才進行下載的操作，等等。





謝謝！



















            




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