引用：http://blog.csdn.net/vrix/article/details/6851557

//启动媒体库

Intent i = new Intent();

ComponentName comp = new ComponentName("com.android.camera","com.android.camera.GalleryPicker");

i.setComponent(comp);

i.setAction("android.intent.action.VIEW");

startActivity(i);

//启动相机

Intent mIntent = new Intent();

ComponentName comp = new ComponentName("com.android.camera","com.android.camera.Camera");

mIntent.setComponent(comp);

mIntent.setAction("android.intent.action.VIEW");

startActivity(mIntent);

//启动htmlviewer,并打开指定的一个文件 注意TXT不能是ANSI的，否则会乱码

Intent intent = new Intent();

ComponentName cn = new ComponentName("com.android.htmlviewer", "com.android.htmlviewer.HTMLViewerActivity");

intent.setComponent(cn);

Uri uri = Uri.fromFile(new File("/sdcard/demo.txt"));

intent.setDataAndType(uri, "text/plain");

startActivity(intent)