Android ViewPager+Fragment lazy loading

16055539:

 

In most app development, the combination of viewpager and fragment is often used. Preloading will also be initialized when the next fragment is not displayed.

This leads to unnecessary time-consuming and resource-consuming when the amount of data is large; lazy loading is to initialize the currently visible fragment when the fragment is displayed, reducing time and resources;

 

Directly used as Fragment base class

package com.lazyloading.base;


import android.content.Context;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public abstract class BaseFragment extends Fragment {

    protected View mRootView;
    public Context mContext;
    protected boolean isVisible;
    private boolean isPrepared;
    private boolean isFirst = true;

    public BaseFragment() {
    }

    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        if (getUserVisibleHint()) {
            isVisible = true;
            lazyLoad();
        } else {
            isVisible = false;
            onInvisible();
        }
    }


    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mContext = getActivity();
        setHasOptionsMenu(true);
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        if (mRootView == null) {
            mRootView = initView();
        }
        return mRootView;
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        isPrepared = true;
        lazyLoad();
    }

    protected void lazyLoad() {
        if (!isPrepared || !isVisible || !isFirst) {
            return;
        }
        Log.d("TAG", getClass().getName() + "->initData()");
        initData();
        isFirst = false;
    }

    //do something
    protected void onInvisible() {


    }

    public abstract View initView();

    public abstract void initData();


}