Android入门程序(ListView包括一个网络状态显示)

为了能够让我们的应用得到网络状态需要在application外部增加权限

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.hello.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

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

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

<!-- Network State Permissions -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

下面我们在MainActivity中增加ListView，并增加ClickListener

public class MainActivity extends Activity {

private ListView listView;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

listView = new ListView(this);
listView.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, getData()));

listView.setOnItemClickListener(new OnItemClickListener(){

@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
ListView listView = (ListView)parent;
String item = (String) listView.getItemAtPosition(position);
if (item.equals("SystemInfo"))
{
Intent ii=new Intent();
/* 可以向SystemInfo Activity传递数据,这里没有用到 */
ii.putExtra("myKey", "value");
ii.setClass(MainActivity.this, SystemInfo.class);
startActivity(ii);
}
}

});

setContentView(listView);
}

private List<String> getData(){

List<String> data = new ArrayList<String>();
data.add("SystemInfo");
data.add("测试数据2");
data.add("测试数据3");
data.add("测试数据4");

return data;
}
}

进入SystemInfo Activity

public class SystemInfo extends Activity {

/* 保存网络状态 */
private String network_state;

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

/* 获取网络状态 */
ConnectionDetector cd = new ConnectionDetector(getApplicationContext());
Boolean isInternetPresent;
isInternetPresent = cd.isConnectingToInternet();
if (isInternetPresent) {
network_state = "connecting";
} else {
network_state = "disconnect";
}
/* 根据res/layout/activity_main.xml中的内容设置TextView内容 */
((TextView)findViewById(R.id.network_state)).setText(network_state);
}
}

获取网络状态部分

/* ConnectionDetector.java */
public class ConnectionDetector {

private Context _context;

public ConnectionDetector(Context context){
this._context = context;
}

public boolean isConnectingToInternet(){
ConnectivityManager connectivity = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity != null)
{
NetworkInfo[] info = connectivity.getAllNetworkInfo();
if (info != null)
for (int i = 0; i < info.length; i++)
if (info[i].getState() == NetworkInfo.State.CONNECTED)
{
return true;
}

}
return false;
}
}

源码:http://pan.baidu.com/share/link?shareid=437617&uk=218977851