Android之RecyclerView

最新推荐文章于 2025-02-15 15:26:41 发布

Chase_Java

最新推荐文章于 2025-02-15 15:26:41 发布

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分类专栏： Android_Learning 文章标签： android sdk jar

本文链接：https://blog.youkuaiyun.com/Chase_Java/article/details/53293028

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RecyclerView有以下几点特性：
1.不关心Item是否显示在正确位置，如何显示。（所以我们可以水平垂直瀑布流）
2.不关心Item之间如何分隔。
3.不关心Item增加删除的动画效果。
4.仅仅关注如何收复和复用View。

使用RecyclerView需要添加v7中recycler的jar包支持。

一般情况下路径在sdk下的SDK\extras\android\support\v7\recyclerview\libs

AS中只需要在File — Project Structure 中对应module添加Dependence。

新建立一个Module：

这里的MainActivity继承了AppCompatActivity，这是高版本中的，其实ActionBarActivity也是可以的。

package com.chase.cn.recyclerview;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.LinearLayout;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private List<String> mDatas;
    private RecyclerSimpleAdapter mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initDatas();//初始化data

        initView();//初始化view
        mAdapter = new RecyclerSimpleAdapter(this,mDatas); //传入所建立的RecyclerSimplAdapter类数据
        mRecyclerView.setAdapter(mAdapter);

        LinearLayoutManager manager = new LinearLayoutManager(this, LinearLayout.VERTICAL,false);
        //上面的属性为(this,orientation,reverseLayout)上面使用垂直属性
        mRecyclerView.setLayoutManager(manager);
    }

    private void initView() {
        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
    }

    private void initDatas() {
        mDatas = new ArrayList<String>();
        for (int i = 'A'; i <= 'z'; i++) {
            mDatas.add(""+(char)i);
        }
    }
}

我们要自定义一个Adapter类，新建class：RecyclerSimpleAdapter.class

package com.chase.cn.recyclerview;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.List;

/**
 * Created by Chase on 2016/11/22.
 */
public class RecyclerSimpleAdapter extends RecyclerView.Adapter<MyViewHolder> {//填入下面建的内部类
    //第二步，实现方法

    private LayoutInflater mInflater; //声明inflater来inflate我们的布局
    //用来保存传进来的数据
    private Context mContext;
    private List<String> mDatas;

//第三步
    public RecyclerSimpleAdapter(Context context, List<String> datas){
        this.mContext = context;
        this.mDatas = datas;
        mInflater = LayoutInflater.from(context);
    }

    //第四步，创建ViewHolder
    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup arg0, int viewType) {
        View view = mInflater.inflate(R.layout.item_single_textview,arg0,false);
        MyViewHolder viewHolder = new MyViewHolder(view);
        return viewHolder; //reutrn这个ViewHloder
    }

    //第五步，绑定ViewHolder
    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        holder.tv.setText(mDatas.get(position)); //完成TextView的复制
    }

    @Override
    public int getItemCount() {
        return mDatas.size();
    }
}

//第一步，先建立这个内部类再实现方法
//viewHolder中会有当前item的所有空间
class MyViewHolder extends RecyclerView.ViewHolder{
    TextView tv;

    public MyViewHolder(View itemView) {
        super(itemView);

        tv = (TextView) itemView.findViewById(R.id.id_tv);
        //别的控件也可以在这里初始化
    }
}

上面用到的item布局文件为：item_single_textview.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="72dp"
    android:background="#44ff0000"
    >

    <TextView
        android:id="@+id/id_tv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center"/>
</FrameLayout>

更多更能如下。

因为上面运行以后，item之间贴在了一起。

要给item之间添加分隔，在MainActivity中继续添加：

mRecyclerView.addItemDecoration(new DividerItemDecoration(this,DividerItemDecoration.VERTICAL_LIST));

这里用到一个类，附上链接：
http://download.youkuaiyun.com/download/tobestrong_csdn/9348767

也附上代码如下，可以直接拿过来用：

package com.chase.cn.recyclerview;

/*
 * 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.
 */

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;

/**
 * This class is from the v7 samples of the Android SDK. It's not by me!
 * <p/>
 * See the license above for details.
 */
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; //item的间隔图片资源

    private int mOrientation; //方向：水平，垂直

    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)
    {
        Log.v("recyclerview - itemdecoration", "onDraw()");
         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);
            RecyclerView v = new RecyclerView(
                    parent.getContext());
            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);
        }
    }

    //提供绘制分割线的间隔
    @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);
        }
    }
}

如何自定义分隔线的图案呢？

以一个红绿蓝渐变的分割线为例：
新建xml文件：divider.xml 这是一个shape类型的。

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <size android:height="4dp" />
    <gradient
        android:centerColor="#ff00ff00"
        android:endColor="#ff0000ff"
        android:startColor="#ffff0000"
        android:type="linear"/>
</shape>

在values文件夹的style文件中加入一条，把我们上面的文件放进去。

<item name="android:listDivider">@drawable/divider</item>

如下：

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>

        <item name="android:listDivider">@drawable/divider</item>
    </style>

</resources>

在AS中，就可以运行了。

如果在eclipse中，要对应不同版本的values中，放在v14试试。

下面实现，listview，gridview，horizonalGridView，staggered（瀑布流）的切换。

添加一个菜单。如果没有，在res文件夹下建立menu文件夹。

建立menu.xml：

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:context="com.chase.cn.recyclerview.MainActivity"
    xmlns:tools="http://schemas.android.com/tools">
    <item
        android:id="@+id/action_listview"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="ListView"
        tools:ignore="AppCompatResource" />
    <item
        android:id="@+id/action_gridview"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="GridView"
        tools:ignore="AppCompatResource" />
    <item
        android:id="@+id/action_hor_gridview"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="Hor_GridView"
        tools:ignore="AppCompatResource" />
    <item
        android:id="@+id/action_staggered"
        android:orderInCategory="100"
        android:showAsAction="never"
        android:title="Staggered"
        tools:ignore="AppCompatResource" />
</menu>

在MainActivity中添加：

@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = new MenuInflater(this);
        inflater.inflate(R.menu.menu,menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        switch (id){
            case R.id.action_listview:
                mRecyclerView.setLayoutManager(new       LinearLayoutManager(this,
                        LinearLayout.VERTICAL,false));
                break;
            case R.id.action_gridview:
                mRecyclerView.setLayoutManager(new GridLayoutManager(this,3));//设置了3列
                break;
            case R.id.action_hor_gridview:
                mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager
                        (6,StaggeredGridLayoutManager.HORIZONTAL));//(列数，方向)
                break;
            case R.id.action_staggered:
                break;
        }

        return super.onOptionsItemSelected(item);
    }