安卓Fragment的切换

// 初始化默认显示的界面
		if (purchaserHomeFragment == null) {
			purchaserHomeFragment = new PurchaserHomeFragment();
			addFragment(purchaserHomeFragment);
			showFragment(purchaserHomeFragment);
		} else {
			showFragment(purchaserHomeFragment);
		}
		
// 购物车界面
			if (purchaserCarFragment == null) {
				purchaserCarFragment = new PurchaserCarFragment();
				// 判断当前界面是否隐藏，如果隐藏就进行添加显示，false表示显示，true表示当前界面隐藏
				if (!purchaserCarFragment.isHidden()) {
					addFragment(purchaserCarFragment);
					showFragment(purchaserCarFragment);
				}
			} else {
				if (purchaserCarFragment.isHidden()) {
					showFragment(purchaserCarFragment);
				}
			}
			

	/** 添加fragment **/
	public void addFragment(Fragment fragment) {
		FragmentTransaction ft = this.getSupportFragmentManager().beginTransaction();
		ft.add(R.id.fl_content, fragment);
		ft.commit();
	}

	/** 显示fragment **/
	public void showFragment(Fragment fragment) {
		FragmentTransaction ft = this.getSupportFragmentManager().beginTransaction();

		// 判断页面是否已经创建，如果已经创建，那么就隐藏掉
		if (purchaserHomeFragment != null) {
			ft.hide(purchaserHomeFragment);
		}
		if (purchaserTypeFragment != null) {
			ft.hide(purchaserTypeFragment);
		}
		if (purchaserOrderFragment != null) {
			ft.hide(purchaserOrderFragment);
		}
		if (purchaserCarFragment != null) {
			ft.hide(purchaserCarFragment);
		}

		ft.show(fragment);
		ft.commitAllowingStateLoss();
	}