android fragment懒加载

fragment基类

open abstract class BaseLazyLoadFragment : Fragment() {

    private var isFirstLoad = false

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view = initView(inflater, container) //让子类实现初始化视图
        return view
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        initEvent()
        isFirstLoad = true //视图创建完成，将变量置为true
        if (userVisibleHint) { //如果Fragment可见进行数据加载
            onLazyLoad()
            isFirstLoad = false
        }
    }

    override fun onDestroyView() {
        super.onDestroyView()
        isFirstLoad = false //视图销毁将变量置为false
    }

    override fun setUserVisibleHint(isVisibleToUser: Boolean) {
        super.setUserVisibleHint(isVisibleToUser)
        if (isFirstLoad && isVisibleToUser) { //视图变为可见并且是第一次加载
            onLazyLoad()
            isFirstLoad = false
        }
    }

    //数据加载接口，留给子类实现
    abstract fun onLazyLoad()

    //初始化视图接口，子类必须实现
    abstract fun initView(inflater: LayoutInflater?, container: ViewGroup?): View?

    //初始化事件接口，留给子类实现
    abstract fun initEvent()

    /**
     * 初始化View
     */
    protected open fun initView(){}

    /**
     * 初始化事件
     */
    protected open fun initListener(){}

    /**
     * 初始化Data
     */
    protected open fun initData(){}

}

实现fragment并继承基类

class ShopOrderFragment : BaseLazyLoadFragment() {

    var paramsOne:String? = null
    var paramsTwo:String? = null
    var shopOrderAdapter:ShopOrderAdapter? = null

    fun newInstance(paramsOne:String,paramsTwo:String): ShopOrderFragment{
        val args = Bundle()
        args.putString(MyParms.PARAMS,paramsOne)
        args.putString(MyParms.PARAMS_OTHER,paramsTwo)
        val fragment = ShopOrderFragment()
        fragment.arguments = args
        return fragment
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        if (arguments != null){
            paramsOne = arguments?.getString(MyParms.PARAMS)
            paramsTwo = arguments?.getString(MyParms.PARAMS_OTHER)
            Log.e("fragment",paramsOne ?: "")
        }
    }

    override fun initView(inflater: LayoutInflater?, container: ViewGroup?): View? {
        return inflater?.inflate(R.layout.fragment_shop_order_view,container,false)
    }

    override fun initEvent() {

    }

    override fun onLazyLoad() {
        Log.e("fragment","$paramsOne 加载数据")

        shopOrderAdapter = ShopOrderAdapter(this.activity!!)
        val lm = LinearLayoutManager(context)
        lm.orientation = LinearLayoutManager.VERTICAL
        with(rvList){
            layoutManager = lm
            adapter = shopOrderAdapter
        }
    }



}

activity加载

class ShopOrderActivity : BaseActivity(),View.OnClickListener {

    var fragmentList:ArrayList<Fragment>? = null
    var currentPosition = -1

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_shop_order_view)
        initView()
        initData()
        initListener()
    }

    override fun initView() {
        tvTitle.text = "店铺订单"
    }

    override fun initData() {
        currentPosition = intent.getIntExtra(MyParms.PARAMS,-1)

        fragmentList = arrayListOf()
        fragmentList?.add(ShopOrderFragment().newInstance("11","11"))
        fragmentList?.add(ShopOrderFragment().newInstance("22","22"))
        fragmentList?.add(ShopOrderFragment().newInstance("33","33"))
        fragmentList?.add(ShopOrderFragment().newInstance("44","44"))
        fragmentList?.add(ShopOrderFragment().newInstance("55","55"))
        fragmentList?.add(ShopOrderFragment().newInstance("66","66"))

        val tabStr = resources.getStringArray(R.array.shop_order_menu)
        tabLay.setViewPager(viewPager,tabStr,this,fragmentList)
        if (currentPosition >= 0)tabLay.currentTab = currentPosition
    }

    override fun initListener() {
        ivBack.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when(v?.id){
            R.id.ivBack ->{//返回
                finish()
            }
        }
    }

    override fun onDestroy() {
        super.onDestroy()
        if (fragmentList != null){
            fragmentList?.clear()
            fragmentList = null
        }
    }


}

使用的第三方插件

implementation 'com.flyco.tablayout:FlycoTabLayout_Lib:2.1.2@aar'