android v7兼容包RecyclerView的使用（一）

什么是RecyclerView？个人理解，它是一个在数据量大的时候，为了显示在界面上提供的灵活高效处理的控件。可以替代listview，gallery，gridview等控件。

如何使用？本篇文章只是热热身，不会过多介绍细节。

首先需要导入\sdk\extras\android\support\v7\recyclerview\libs\android-support-v7-recyclerview.jar包，如果sdk目录下没有该文件，则adt版本可能太低，建议升级或者从网上下载该库。

RecyclerView的使用准备多谢几篇，所以这篇只是入门。

国际惯例，先看效果图，此程序实现微信的会话记录界面。

分析一下，该界面的每一项都是由四个组件构成，即图标，标题，描述，时间。所以，开始编写实体类。

package cn.edu.zafu.recyclerviewdemo;

/**
 * 实体类
 * @author lizhangqu
 *
 * 2015-3-10
 */
public class Item {
    //图标，简单起见存在本地drawable目录
    private int img;
    //标题
    private String title;
    //描述
    private String description;
    //时间
    private String time;

    //getter 和 setter
    public int getImg() {
        return img;
    }

    public void setImg(int img) {
        this.img = img;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }

    @Override
    public String toString() {
        return "Item [img=" + img + ", title=" + title + ", description="
                + description + ", time=" + time + "]";
    }

}

编写完实体类后，开始对每一项的布局进行编写，使用相对布局

<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="wrap_content"
    android:paddingBottom="10dp"
    android:paddingLeft="15dp"
    android:paddingRight="15dp"
    android:paddingTop="10dp" >

    <ImageView
        android:id="@+id/img"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true"
        android:background="@drawable/icon" />

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="5dp"
        android:layout_toRightOf="@id/img"
        android:text="微信支付"
        android:textColor="#000"
        android:textSize="16sp" />

    <TextView
        android:id="@+id/time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_marginTop="5dp"
        android:text="晚上20:09"
        android:textColor="#777"
        android:textSize="12sp" />

    <TextView
        android:id="@+id/description"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/title"
        android:layout_below="@id/title"
        android:layout_marginTop="5dp"
        android:text="微信支付：支付成功通知" />

</RelativeLayout>

编写适配器，并编写接口处理点击事件

package cn.edu.zafu.recyclerviewdemo;

import java.util.List;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import cn.edu.zafu.recyclerviewdemo.RecyclerAdapter.ItemViewHolder;

public class RecyclerAdapter extends RecyclerView.Adapter<ItemViewHolder> {
    private List<Item> items;
    //点击监听事件
    interface OnRecyclerViewItemClickListener{
        void onClick(View view,int position);
    };
    private OnRecyclerViewItemClickListener listener;
    //设置监听器
    public void setListener(OnRecyclerViewItemClickListener listener) {
        this.listener = listener;
    }
    //构造函数，将数据赋值给成员变量
    public RecyclerAdapter(List<Item> items) {
        this.items = items;
    }
    //获得数据大小
    @Override
    public int getItemCount() {
        return items.size();
    }

    @Override
    public ItemViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        //将布局进行绑定
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(
                R.layout.item, viewGroup, false);
        return new ItemViewHolder(view);
    }
    //绑定数据
    @Override
    public void onBindViewHolder(final ItemViewHolder viewHolder,final int position) {
        Item item = items.get(position);
        viewHolder.img.setImageResource(item.getImg());
        viewHolder.title.setText(item.getTitle());
        viewHolder.description.setText(item.getDescription());
        viewHolder.time.setText(item.getTime());

        viewHolder.itemView.setOnClickListener(new OnClickListener() {
            //如果监听器非空，则回调
            @Override
            public void onClick(View v) {
                if (listener!=null) {
                    listener.onClick(viewHolder.itemView, position);
                }

            }
        });
    }
    //ViewHolder，用于缓存，提高效率
    public final static class ItemViewHolder extends RecyclerView.ViewHolder {
        //每一项的四个控件
        ImageView img;
        TextView title;
        TextView description;
        TextView time;

        public ItemViewHolder(View itemView) {
            super(itemView);
            img = (ImageView) itemView.findViewById(R.id.img);
            title = (TextView) itemView.findViewById(R.id.title);
            description = (TextView) itemView.findViewById(R.id.description);
            time = (TextView) itemView.findViewById(R.id.time);
        }
    }
}

在Activity中使用，为recyclerview设置适配器，数据改变时的动画，

package cn.edu.zafu.recyclerviewdemo;

import java.util.ArrayList;

import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Toast;
import cn.edu.zafu.recyclerviewdemo.RecyclerAdapter.OnRecyclerViewItemClickListener;

public class MainActivity extends Activity {
    private RecyclerView recyclerView;
    private ArrayList<Item> items = new ArrayList<Item>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);initDatas();
        setContentView(R.layout.activity_main);
        initDatas();//初始化数据
        initViews();//初始化recyclerview
    }
    private void initViews() {

        recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        //新建适配器
        RecyclerAdapter adapter = new RecyclerAdapter(items);
        //设置监听器
        adapter.setListener(new OnRecyclerViewItemClickListener() {

            @Override
            public void onClick(View view, int position) {
                Toast.makeText(getApplicationContext(), items.get(position).getTitle(), Toast.LENGTH_LONG).show();
            }
        });
        //设置适配器
        recyclerView.setAdapter(adapter);
        //默认动画效果
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        //设置布局管理器，第三个参数为是否逆向布局
        recyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));
        //设置每一项的装饰，这里给它加入分隔线
        recyclerView.addItemDecoration(new RecyclerView.ItemDecoration() {
            Paint paint = new Paint();
            @Override
            public void onDraw(Canvas c, RecyclerView parent,
                    RecyclerView.State state) {
                super.onDraw(c, parent, state);
            }
            @Override
            public void onDrawOver(Canvas c, RecyclerView parent,
                    RecyclerView.State state) {
                super.onDrawOver(c, parent, state);
                paint.setColor(Color.LTGRAY);
                for (int i = 0, size = parent.getChildCount(); i < size; i++) {
                    View child = parent.getChildAt(i);
                    c.drawLine(child.getLeft(), child.getBottom(),
                            child.getRight(), child.getBottom(), paint);
                }
            }

        });
        //可以提高效率
        recyclerView.setHasFixedSize(true);
    }
    private void initDatas() {
        Item item = new Item();
        item.setImg(R.drawable.icon);
        item.setTitle("微信支付");
        item.setDescription("微信支付：支付成功通知");
        item.setTime("晚上20:35");
        items.add(item);

        item = new Item();
        item.setImg(R.drawable.icon);
        item.setTitle("微信支付");
        item.setDescription("微信支付：支付成功通知");
        item.setTime("晚上20:35");
        items.add(item);

        item = new Item();
        item.setImg(R.drawable.icon);
        item.setTitle("微信支付");
        item.setDescription("微信支付：支付成功通知");
        item.setTime("晚上20:35");
        items.add(item);

        item = new Item();
        item.setImg(R.drawable.icon);
        item.setTitle("微信支付");
        item.setDescription("微信支付：支付成功通知");
        item.setTime("晚上20:35");
        items.add(item);

        item = new Item();
        item.setImg(R.drawable.icon);
        item.setTitle("微信支付");
        item.setDescription("微信支付：支付成功通知");
        item.setTime("晚上20:35");
        items.add(item);

        item = new Item();
        item.setImg(R.drawable.icon);
        item.setTitle("微信支付");
        item.setDescription("微信支付：支付成功通知");
        item.setTime("晚上20:35");
        items.add(item);

        item = new Item();
        item.setImg(R.drawable.icon);
        item.setTitle("微信支付");
        item.setDescription("微信支付：支付成功通知");
        item.setTime("晚上20:35");
        items.add(item);
    }
}

ItemDecoration也可以使用现成的，但是我没有在android源码里找打它，反而是在github上找到的它，这里贴出源码，其作用就是增加分隔线，支持水平和竖直状态，而我的代码只是简单处理了竖直状态下的分隔线

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{
            android.R.attr.listDivider
    };

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;

    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    private Drawable mDivider;

    private int mOrientation;

    public DividerItemDecoration(Context context, int orientation) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }

    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}

布局文件

<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.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

整个使用过程还是相当简单的，这只是这个控件的使用的开始，而它的作用远远不止这些。更多的内容在之后的博文中详细写。

源码下载
http://download.csdn.net/detail/sbsujjbcy/8489667