判断网络连接状态并自动界面跳转

/**
* 设置在onStart()方法里面，可以在界面每次获得焦点的时候都进行检测
*/

@Override
protected void onStart() {
ConnectivityManager manager = (ConnectivityManager) this
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = manager.getActiveNetworkInfo();
if (info != null && info.isConnected()) {
Toast.makeText(MainActivity.this, "网络连接连接", 0).show();
} else {
AlertDialog.Builder builder = new Builder(MainActivity.this);
builder.setTitle("开启网络服务");
builder.setMessage("网络没有连接，请到设置进行网络设置！");
builder.setPositiveButton("确定",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
if (android.os.Build.VERSION.SDK_INT > 10) {
// 3.0以上打开设置界面，也可以直接用ACTION_WIRELESS_SETTINGS打开到wifi界面
startActivity(new Intent(
android.provider.Settings.ACTION_SETTINGS));
} else {
startActivity(new Intent(
android.provider.Settings.ACTION_WIRELESS_SETTINGS));
}
dialog.cancel();
}
});

builder.setNegativeButton("取消",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
builder.show();
}
super.onStart();
}

需要注册的权限<p></p><p><span style="font-size: 18px;"> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/></span></p>