初识RecyclerView

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RecylerView是Android5.0时推出的ListView与GridView的升级版。

RecylerView的一些基本特性：

RecylerView的Item的显示格式，有LayoutManager设定。

RecylerView的Item间的分割。ItemDecoration

可以定义RecylerView的Item增加和删除的动画。

仅仅关注如何回收与复用View.

recyclerview的使用条件，可以在android-sdk-windows\extras\android\support\v7\recyclerview\libs下面找到

你所需的android-support-v7-recyclerview.jar；如果没有那你需要将Sdk跟新一下了。

一，实现ListView效果

布局文件：

<?xml version="1.0" encoding="utf-8"?><LinearLayout 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:padding="20dp"    android:orientation="vertical" >        <android.support.v7.widget.RecyclerView        android:id="@+id/rv_content"        android:layout_width="match_parent"        android:layout_height="match_parent"/></LinearLayout>

Item布局

<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:background="@drawable/item_selector"    android:layout_margin="3dp"    android:layout_height="72dp">        <TextView         android:id="@+id/tv_name"        android:layout_width="72dp"        android:layout_height="match_parent"        android:gravity="center"/>    </FrameLayout>

Adapter（适配器）文件：

package com.example.coolwf.adapter;import com.example.coolwf.R;import android.content.Context;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.RecyclerView.ViewHolder;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;import java.util.ArrayList;import java.util.List;public class SimpleAdapter extends RecyclerView.Adapter<MyViewHolder> {    private Context mContext;    private List<String> mDatas;    private LayoutInflater mLayoutInflater;    public interface OnItemClickListener {        public void onItemClick(View view, int pos);        public void onItemLongClick(View view, int pos);    }    private OnItemClickListener mOnItemClickListener;    public void setOnItemClickListener(OnItemClickListener mOnItemClickListener) {        this.mOnItemClickListener = mOnItemClickListener;    }    public SimpleAdapter(Context mContext, List<String> mDatas) {        this.mContext = mContext;        if (mDatas == null) {            this.mDatas = new ArrayList<String>();        } else {            this.mDatas = mDatas;        }        mLayoutInflater = LayoutInflater.from(mContext);    }    @Override    public int getItemCount() {        // TODO Auto-generated method stub        return mDatas.size();    }    /**     * 绑定ViewHolder     */    @Override    public void onBindViewHolder(final MyViewHolder viewHolder, final int pos) {        viewHolder.tv_name.setText(mDatas.get(pos));        //RecyclerView并没有封装好了的OnItemClick类的监听，所以需要自定义        if (mOnItemClickListener != null) {            viewHolder.itemView.setOnClickListener(new View.OnClickListener() {                                @Override                public void onClick(View view) {                    int index = viewHolder.getLayoutPosition();//pos在Item变动时，无法自动调节，出现误差                    mOnItemClickListener.onItemClick(view, index);                }            });                        viewHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {                                @Override                public boolean onLongClick(View view) {                    int index = viewHolder.getLayoutPosition();                    mOnItemClickListener.onItemLongClick(view, index);                    return false;                }            });                     }    }    /**     * 创建ViewHolder实例     */    @Override    public MyViewHolder onCreateViewHolder(ViewGroup arg0, int arg1) {        // 这个加载形式是必须的否则，会出现显示不全        View view = mLayoutInflater.inflate(R.layout.layout_item, arg0, false);        MyViewHolder myViewHolder = new MyViewHolder(view);        return myViewHolder;    }    /**     * 添加一个Item     *      * @param pos     */    public void addItem(int pos, String str) {        mDatas.add(pos, str);        notifyItemInserted(pos);//notifySetChange不会出现动画效果    }    /**     * 删除一个Item     *      * @param pos     */    public void deleteItem(int pos) {        mDatas.remove(pos);        notifyItemRemoved(pos);    }    /**     * 获取一个Item数据     *      * @param pos     * @return     */    public String getItem(int pos) {        return mDatas.get(pos);    }}class MyViewHolder extends ViewHolder {    TextView tv_name;    public MyViewHolder(View view) {        super(view);        tv_name = (TextView) view.findViewById(R.id.tv_name);    }}

设定Item的布局方式：

        // 设置适配器        mSimpleAdapter = new SimpleAdapter(mContext, mDatas);        mSimpleAdapter.setOnItemClickListener(new SimpleAdapter.OnItemClickListener() {            @Override            public void onItemLongClick(View view, int pos) {                Toast.makeText(mContext, "onLongClick pos->" + pos + " data:" + mSimpleAdapter.getItem(pos),                        Toast.LENGTH_LONG).show();            }            @Override            public void onItemClick(View view, int pos) {                Toast.makeText(mContext, "onClick pos->" + pos + " data:" + mSimpleAdapter.getItem(pos),                        Toast.LENGTH_LONG).show();            }        });        rv_content.setAdapter(mSimpleAdapter);        // 设置item布局        LinearLayoutManager mLinearLayoutManager = new LinearLayoutManager(mContext,                LinearLayoutManager.VERTICAL, false);        rv_content.setLayoutManager(mLinearLayoutManager);

如此ListView没有分割线，我们可以通过Item得margin属性来实现。

二，实现GridView布局

这里只需在上面的基础上做一个小修改，就可以了：

rv_content.setLayoutManager(new GridLayoutManager(mContext, 3));

三，实现横向的GridView布局

rv_content.setLayoutManager(new StaggeredGridLayoutManager(5,                        StaggeredGridLayoutManager.HORIZONTAL));

四，实现流式布局：

这个时候就需要重新定Adapter，即必须动态的定义Item的高度。

package com.example.coolwf.adapter;import com.example.coolwf.R;import android.content.Context;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.RecyclerView.ViewHolder;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.view.ViewGroup.LayoutParams;import java.util.ArrayList;import java.util.List;public class StaggeredAdapter extends RecyclerView.Adapter<StaggeredViewHolder> {    private Context mContext;    private List<String> mDatas;    private List<Integer> mHeights;    private LayoutInflater mLayoutInflater;    public StaggeredAdapter(Context mContext, List<String> mDatas) {        this.mContext = mContext;        if (mDatas == null) {            this.mDatas = new ArrayList<String>();        } else {            this.mDatas = mDatas;        }        mHeights = new ArrayList<Integer>();        for (int i = 0; i < mDatas.size(); i++) {            mHeights.add((int) (100+Math.random()*400));        }        mLayoutInflater = LayoutInflater.from(mContext);    }    @Override    public int getItemCount() {        // TODO Auto-generated method stub        return mDatas.size();    }    /**     * 绑定ViewHolder     */    @Override    public void onBindViewHolder(StaggeredViewHolder viewHolder, int pos) {        LayoutParams lp = viewHolder.itemView.getLayoutParams();//动态的设定Item的高度，加载图片时就可以动态的根据图片的大小设置高宽        lp.height = mHeights.get(pos);        viewHolder.itemView.setLayoutParams(lp);        viewHolder.tv_name.setText(mDatas.get(pos));    }    /**     * 创建ViewHolder实例     */    @Override    public StaggeredViewHolder onCreateViewHolder(ViewGroup arg0, int arg1) {        // 这个加载形式是必须的否则，会出现显示不全        View view = mLayoutInflater.inflate(R.layout.layout_item, arg0, false);        StaggeredViewHolder myViewHolder = new StaggeredViewHolder(view);        return myViewHolder;    }}

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