初步使用RecyclerView实现瀑布流

先看效果

关于RecyclerView，真的是很强大。

个人觉得主要方便的地方是

1.直接可以设置条目布局，通过setLayoutManager

　　

1. LinearLayoutManager:线性布局,横向或者纵向滑动列表
2. GridLayoutManager:表格布局
3. StaggeredGridLayoutManager:流式布局,例如瀑布流效果

2.可以直接设置分割线       addItemDecoration方法

3.直接设置添加删除item动画   setItemAnimator方法

4.对View的复用性好  （这个是别人总结的，我还没看源码）

5.对于分割线，和增删动画，github上开源的类很多

下面看看怎么用法

　　一 导入包，v7的recyclerview包

　　二 布局

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context="com.example.myrecyclerview.MainActivity" >

    <android.support.v7.widget.RecyclerView

        android:id="@+id/recyclerview_vertical"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

      />

</RelativeLayout>

item布局

<?xml version="1.0" encoding="utf-8"?>

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:background="#8A2BE2"

    android:layout_margin="3dp"

    android:layout_height="wrap_content" >

    <TextView

        android:id="@+id/id_num"

        android:layout_width="match_parent"

        android:layout_height="50dp"

        android:gravity="center"

        android:text="1" />

</FrameLayout>

三，创建Adapter

package com.example.myrecycleviewdemo;

import java.util.ArrayList;

import java.util.List;

import android.content.Context;

import android.support.v7.widget.RecyclerView;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.view.ViewGroup.LayoutParams;

import android.widget.TextView;

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>{

    Context mcontext;

    List<String> mlist;

    List<Integer> mheight;

    public MyAdapter(Context context, List<String> list) {

        mcontext=context;

        mlist=list;

        //随机高度集合

        mheight=new ArrayList<Integer>();

        for(int i=0;i<mlist.size();i++){

            mheight.add((int)(100+Math.random()*300));

        }

    }

    @Override

    public int getItemCount() {

        return mlist.size();

    }

    //找到布局中空间位置

    class MyViewHolder extends RecyclerView.ViewHolder{

        TextView tv;

        public MyViewHolder(View arg0) {

            super(arg0);

            tv=(TextView) arg0.findViewById(R.id.id_num);

        }

    }

    //绑定，渲染数据到view中

    @Override

    public void onBindViewHolder(MyViewHolder holder, int arg1) {

        LayoutParams lp=holder.tv.getLayoutParams();

        lp.height=mheight.get(arg1);

        holder.tv.setLayoutParams(lp);

        holder.tv.setText(mlist.get(arg1));

    }

    //先执行onCreateViewHolder

    @Override

    public MyViewHolder onCreateViewHolder(ViewGroup parent, int arg1) {

        MyViewHolder holder = new MyViewHolder(LayoutInflater.from(

               mcontext).inflate(R.layout.item, parent,

                false));

        return holder;

    }

    public void add(int pos) {

        mlist.add(pos, "insert");

        mheight.add((int)(100+Math.random()*300));

        notifyItemInserted(pos);

    }

    public void del(int pos) {

        mlist.remove(pos);

        notifyItemRemoved(pos);

    }

}

这里的Adapter需要继承RecyclerView.Adapter，需要实现3个方法：

- onCreateViewHolder()

- onBindViewHolder()

- getItemCount()

最后，MainActivity

package com.example.myrecycleviewdemo;

import java.util.ArrayList;

import java.util.List;

import android.app.Activity;

import android.os.Bundle;

import android.support.v7.widget.DefaultItemAnimator;

import android.support.v7.widget.RecyclerView;

import android.support.v7.widget.StaggeredGridLayoutManager;

import android.view.Menu;

import android.view.MenuItem;

public class MainActivity extends Activity {

    RecyclerView recyclerView;

    List<String> mlist;

    MyAdapter adapter;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        initData();

        initview();

    }

    private void initview() {

        recyclerView=(RecyclerView) findViewById(R.id.recyclerview_vertical);

        adapter=new MyAdapter(this,mlist);

        //设置动画

        recyclerView.setItemAnimator(new DefaultItemAnimator());

        //设置分割线

        //recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));

        //recyclerView.setLayoutManager(new LinearLayoutManager(this));

        //设置布局

         recyclerView.setLayoutManager(new StaggeredGridLayoutManager(4, StaggeredGridLayoutManager.VERTICAL));

        recyclerView.setAdapter(adapter);

    }

    private void initData() {

        mlist=new ArrayList<String>();

        for(int i=0;i<50;i++){

            mlist.add("number"+i);

        }

    }

    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.

        getMenuInflater().inflate(R.menu.main, menu);

        return true;

    }

    @Override

    public boolean onOptionsItemSelected(MenuItem item) {

        // Handle action bar item clicks here. The action bar will

        // automatically handle clicks on the Home/Up button, so long

        // as you specify a parent activity in AndroidManifest.xml.

        switch (item.getItemId())

        {

        case R.id.add:

            adapter.add(1);

            break;

        case R.id.del:

            adapter.del(1);

            break;

        }

        return true;

    }

}

更换布局，分割线,动画的方式很简单，直接通过方法让不同的类当参数。