练习记录0821--RecyclerView实现网络图片瀑布流

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RecyclerView简介：

RecyclerView是一个像listview和GridView合体的View，功能比较强大，使用起来还比较简单。
想具体学习RecyclerView的话可以到鸿洋大佬的博客中学习
Android RecyclerView 使用完全解析体验艺术般的控件

RecyclerView中提供了几个方法可以设置View的效果，以下几条总结言简意赅：
你想要控制其显示的方式，请通过布局管理器LayoutManager
你想要控制Item间的间隔（可绘制），请通过ItemDecoration
你想要控制Item增删的动画，请通过ItemAnimator
你想要控制点击、长按事件，请自己写

正题：实现网络图片瀑布流

这里写图片描述
图1图片瀑布流效果展示

图2标题栏隐藏及下拉刷新

此练习设计大体思路：
数据为gank.io的福利接口，地址为http://gank.io/api/data/%E7%A6%8F%E5%88%A9/10/1
①将资源URL用Volley进行请求返回资源Json字段
②通过FastJson将Json中的资源解析出来
③添加RecyclerView控件，并将LayoutManager设置为StaggeredGridLayoutManager（交错网格布局）
④给RecyclerView添加Adapter，在Adapter中将资源填入每一个Item中利用Glide显示图片
activity_main.xml
在布局中添加控件，RecyclerView是我们的主角，其他的控件是做下拉刷新及标题栏隐藏的见图2，可忽略。

<?xml version="1.0" encoding="utf-8"?><android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:id="@+id/main_content"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:fitsSystemWindows="true">    <android.support.design.widget.AppBarLayout        android:layout_width="match_parent"        android:layout_height="wrap_content">        <android.support.v7.widget.Toolbar            android:id="@+id/toolbar_main"            android:layout_width="match_parent"            android:layout_height="?attr/actionBarSize"            app:layout_scrollFlags="scroll">        </android.support.v7.widget.Toolbar>    </android.support.design.widget.AppBarLayout>    <android.support.v4.widget.SwipeRefreshLayout        android:id="@+id/swipeRefreshLayout"        android:layout_width="match_parent"        android:layout_height="match_parent"        app:layout_behavior="@string/appbar_scrolling_view_behavior">        <android.support.v7.widget.RecyclerView            android:id="@+id/recyclerview_main"            android:layout_width="match_parent"            android:layout_height="match_parent"/>    </android.support.v4.widget.SwipeRefreshLayout></android.support.design.widget.CoordinatorLayout>

MainActivity：
在Activity中设置RecyclerView的布局管理及添加适配器

package com.example.user.recyclerview_imagedemo;import android.support.v4.widget.SwipeRefreshLayout;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.StaggeredGridLayoutManager;import android.util.Log;import android.view.View;public class MainActivity extends AppCompatActivity {    private final String url = "http://gank.io/api/data/%E7%A6%8F%E5%88%A9/10/1";    private RecyclerView recyclerView;    private SwipeRefreshLayout swipeRefreshlayout;    private RecyclerAdapter myAdapter;    private StaggeredGridLayoutManager myLayoutManager;    private int lastVisibleItem;    private int page = 1;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initViews();        initListener();        initDatas();    }    private void initViews() {        recyclerView = (RecyclerView) findViewById(R.id.recyclerview_main);        //设置RecyclerView的视图布局        myLayoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);        recyclerView.setLayoutManager(myLayoutManager);        swipeRefreshlayout = (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayout);        swipeRefreshlayout.setColorSchemeResources(R.color.colorAccent, R.color.colorPrimary, R.color.colorRefresh);    }    private void initListener() {        swipeRefreshlayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {            @Override            public void onRefresh() {                //do something you like                swipeRefreshlayout.setRefreshing(false);            }        });        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {            @Override            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {                super.onScrollStateChanged(recyclerView, newState);                if (newState == recyclerView.SCROLL_STATE_IDLE && lastVisibleItem + 2 >= myAdapter.getItemCount()) {                    setImage("http://gank.io/api/data/%E7%A6%8F%E5%88%A9/10/" + (++page));                }            }            @Override            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {                super.onScrolled(recyclerView, dx, dy);                int[] positions = myLayoutManager.findLastVisibleItemPositions(null);                lastVisibleItem = Math.max(positions[0], positions[1]);            }        });    }    private void initDatas() {        setImage(url);    }    private void setImage(String url) {        VolleyUtil volleyutil = new VolleyUtil(this, url,                new VolleyUtil.VolleyCallBack() {                    @Override                    public void onSuccess(String result) {                        if (myAdapter == null) {                            myAdapter = new RecyclerAdapter(getApplicationContext(), result);                            myAdapter.setonRecyclerItemClickListener(new RecyclerAdapter.onRecyclerItemClickListener() {                                @Override                                public void onItemClick(View view, int pos) {                                    Log.e("78978979", "onItemClick: " + pos);                                }                            });                            recyclerView.setAdapter(myAdapter);                        } else {                            myAdapter.addItem(result);                        }                    }                });    }}

RecyclerAdapter
RecyclerView适配器，在适配器中先进行了JSON字段的解析，然后在onBindViewHolder中通过Glide加载图片。

package com.example.user.recyclerview_imagedemo;import android.content.Context;import android.support.v7.app.AlertDialog;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.RecyclerView.ViewHolder;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import com.alibaba.fastjson.JSON;import com.bumptech.glide.Glide;import java.util.ArrayList;import java.util.List;/** * @author LiXinyu * @date 2017/8/16 15:38. */public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.MyViewHolder> {    private Context mContext;    private String mJson;    private List<ImageBean.Result> mDatas;    private List<Integer> mHeight;    private List<String> urls;    private onRecyclerItemClickListener listener;    public RecyclerAdapter(Context context, String datas) {        mContext = context;        mJson = datas;        initdata();    }    private void initdata() {        ImageBean imageBean = JSON.parseObject(mJson, ImageBean.class);        mDatas = imageBean.getResults();        mHeight=new ArrayList<>();        urls=new ArrayList<>();    }//  初始化view视图，将item视图添加到RecyclerView中    @Override    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        View view = LayoutInflater.from(mContext).inflate(R.layout.recycler_image, null);        MyViewHolder myViewHolder = new MyViewHolder(view);        return myViewHolder;    }//  添加数据到View中    @Override    public void onBindViewHolder(final MyViewHolder holder, final int position) {        String url;        url = mDatas.get(position).getUrl();        if (mHeight.size()<=mDatas.size()){            mHeight.add((int)(400+Math.random()*300));            urls.add(url);        }        ViewGroup.LayoutParams layoutParams = holder.imageView.getLayoutParams();        layoutParams.height = mHeight.get(position);        holder.imageView.setLayoutParams(layoutParams);        Glide.with(mContext).load(url).into(holder.imageView);        if(listener!=null){            holder.imageView.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View v) {                    listener.onItemClick(v,position);                }            });        }    }    @Override    public int getItemCount() {        return mDatas.size();    }    public void addItem(String str){        List<ImageBean.Result> result;        ImageBean imageBean = JSON.parseObject(str, ImageBean.class);        result= imageBean.getResults();        mDatas.addAll(result);        notifyDataSetChanged();    }    public interface onRecyclerItemClickListener{        void onItemClick(View view,int pos);    }    public void setonRecyclerItemClickListener(onRecyclerItemClickListener listener){        this.listener=listener;    }    class MyViewHolder extends RecyclerView.ViewHolder {        ImageView imageView;        public MyViewHolder(View itemView) {            super(itemView);            imageView = (ImageView) itemView.findViewById(R.id.image_recycler);        }    }}

关于Volley及Json就不贴出来了没什么特殊的，Volley中写了一个onResponse的回调监听解决了数据的传输问题。

代码地址

https://github.com/Lixinyu00/RecyclerView_ImageDemo

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