Uri uri = Uri.parse("market://details?id="+getPackageName());  
Intent intent = new Intent(Intent.ACTION_VIEW,uri);  
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);  
startActivity(intent);

intent.setAction(Intent.ACTION_SEND);  
iIntent.setType("text/*");  
intent.putExtra(Intent.EXTRA_TEXT, "内容");