android启动其他应用的一段代码

private void startAppByPackageName(String packageName){
PackageInfo pi = null;
try {
pi = getPackageManager().getPackageInfo(packageName, 0);
} catch (NameNotFoundException e) {
e.printStackTrace();
}

Intent resolveIntent = new Intent(Intent.ACTION_MAIN, null);
resolveIntent.addCategory(Intent.CATEGORY_LAUNCHER);
resolveIntent.setPackage(pi.packageName);

List<ResolveInfo> apps = getPackageManager().queryIntentActivities(resolveIntent, 0);

ResolveInfo ri = apps.iterator().next();
if (ri != null ) {
String packageName1 = ri.activityInfo.packageName;
String className = ri.activityInfo.name;

Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);

ComponentName cn = new ComponentName(packageName1, className);

intent.setComponent(cn);
startActivity(intent);
}

}