Android 实现Activity后台运行

第一种方法

 Intentintent=newIntent(Intent.ACTION_MAIN);
 intent.addCategory(Intent.CATEGORY_HOME);
 intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
 startActivity(intent);

第二种方法

此方法其实不是主要是屏蔽Keycode_Back，让它不结束（finish()）Activity，直接显示HOME界面。

 PackageManagerpm=getPackageManager();
 ResolveInfohomeInfo=pm.resolveActivity(newIntent(Intent.ACTION_MAIN)
 .addCategory(Intent.CATEGORY_HOME),0);

 publicbooleanonKeyDown(intkeyCode,KeyEventevent){
 if(keyCode==KeyEvent.KEYCODE_BACK){
 ActivityInfoai=homeInfo.activityInfo;
 IntentstartIntent=newIntent(Intent.ACTION_MAIN);
 startIntent.addCategory(Intent.CATEGORY_LAUNCHER);
 startIntent.setComponent(newComponentName(ai.packageName,
 ai.name));
 startActivitySafely(startIntent);
 returntrue;
 }else
 returnsuper.onKeyDown(keyCode,event);
 }

 voidstartActivitySafely(Intentintent){
 intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
 try{
 startActivity(intent);
 }catch(ActivityNotFoundExceptione){
 Toast.makeText(this,R.string.unabletoopensoftware,
 Toast.LENGTH_SHORT).show();
 }catch(SecurityExceptione){
 Toast.makeText(this,R.string.unabletoopensoftware,
 Toast.LENGTH_SHORT).show();
 Log
 .e(
 TAG,
 "Launcherdoesnothavethepermissiontolaunch"
 +intent
 +".MakesuretocreateaMAINintent-filterforthecorrespondingactivity"
 +"orusetheexportedattributeforthisactivity.",
 e);
 }
 }