Intent 跳转调用其余软件

Intent intent = new Intent(android.content.Intent.ACTION_VIEW);  
intent.addCategory("android.intent.category.DEFAULT");  	
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 
File file = new File("/sdcard/"+str);
Uri uri = Uri.fromFile(file); 
intent.setDataAndType(uri, "text/*" );
startActivity(intent);