Android打造万能适配器--RecyclerView
16lz
2021-01-24
一、通常RecyclerView的Adapter写法
在使用RecyclerView之前我们还需要导入依赖库，在build.gradle中的dependencies下添加：
compile 'com.android.support:recyclerview-v7:24.2.1'通常情况下的RecyclerView的Adapter:
package com.gcy.universal_adapter_recyclerview.adapter;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 com.gcy.universal_adapter_recyclerview.Entity.Bean;import com.gcy.universal_adapter_recyclerview.R;import java.util.List;/** * Created by gcy71 on 2016/9/28. */public class MyAdapter extends RecyclerView.Adapter.MyViewHolder> { private Context mContext; private List mDatas; private LayoutInflater mInflater; public MyAdapter(Context context , List datas) { this.mContext = context; this.mDatas = datas; this.mInflater = LayoutInflater.from(mContext); } @Override public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { return new MyViewHolder(mInflater.inflate(R.layout.item_recyclerview, parent, false)); } @Override public void onBindViewHolder(MyViewHolder holder, int position) { holder.mTilte.setText(mDatas.get(position).getTitle()); holder.mInfo.setText(mDatas.get(position).getInfo()); holder.mTime.setText(mDatas.get(position).getTime()); } @Override public int getItemCount() { return mDatas.size(); } class MyViewHolder extends RecyclerView.ViewHolder{ TextView mTilte; TextView mInfo; TextView mTime; public MyViewHolder(View itemView) { super(itemView); mTilte = (TextView) itemView.findViewById(R.id.id_title); mInfo = (TextView) itemView.findViewById(R.id.id_info); mTime = (TextView) itemView.findViewById(R.id.id_time); } }} 观察发现，RecycleView已经强制我们使用ViewHolder，我们在这里仅仅只发现了getItemCount和onCreateViewHolder两个函数存在重复的代码
二、封装ViewHolder
- 同样我们需要一个SparseArray作为我们存放控件的容器，还需要一个itemView用来获取RecyclerView的Item包含的控件
- 用户需要在onBindViewHolder方法中对不同的空间实现数据绑定，所以我们需要一个抛出一个getView给用户获取控件
- 为了减少用户为控件设置值的代码，还可以添加一些辅助方法，例如本例中的setText2TextView，用户在使用的过程中可根据需要自行添加
BaseViewHolder.java
package com.gcy.universal_adapter_recyclerview.utils;import android.support.v7.widget.RecyclerView;import android.util.SparseArray;import android.view.View;import android.widget.TextView;/** * Created by gcy71 on 2016/9/28. */public class BaseViewHolder extends RecyclerView.ViewHolder { /*用于存储各类控件的容器*/ private SparseArray mViews; private View itemView; public BaseViewHolder(View itemView) { super(itemView); mViews = new SparseArray(); this.itemView = itemView; itemView.setTag(this); } //通过ViewID在容器中获取控件，若在容器中没有该控件就通过ID获取，然后存储到容器中 public T getView(int ViewID){ View view = mViews.get(ViewID); if(view == null){ view = itemView.findViewById(ViewID); mViews.put(ViewID , view); } return (T) view; } /** * 辅助方法，减少用户为控件设置值的代码 */ //返回值设置为BaseViewHolder类型是为了实现链式编程 public BaseViewHolder setText2TextView(int ViewID , String text){ ((TextView)getView(ViewID)).setText(text); return this; }} 三、封装Adapter
分析第一步里的MyAdapter可以看出在Adapter里我们至少需要一个Context和一个数据集还有Item的布局文件ID，和ListView的万能适配器类似，我们也定义一个为控件绑定数据的抽象方法，让用户自己实现。
MyBaseAdapter.java
package com.gcy.universal_adapter_recyclerview.utils;import android.content.Context;import android.support.v7.widget.RecyclerView;import android.view.LayoutInflater;import android.view.ViewGroup;import java.util.List;/** * Created by gcy71 on 2016/9/28. */public abstract class MyBaseAdapter extends RecyclerView.Adapter { private int LayoutID; private Context mContext; private List mDatas; public MyBaseAdapter(int layoutID, Context mContext , List datas) { this.LayoutID = layoutID; this.mContext = mContext; this.mDatas = datas; } @Override public BaseViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { BaseViewHolder holder = new BaseViewHolder(LayoutInflater.from(mContext).inflate(LayoutID, parent , false)); return holder; } @Override public void onBindViewHolder(BaseViewHolder holder, int position) { blindViewHolder(holder , mDatas.get(position)); } @Override public int getItemCount() { return mDatas.size(); } public abstract void blindViewHolder(BaseViewHolder holder , T t);} 四、工具类
RecyclerView并未给我们提供Item之间的分割线，所以需要我们自己定义分割线，这里我们直接引用网上的一个工具类DividerItemDecoration
package com.gcy.universal_adapter_recyclerview.utils;/* * Copyright (C) 2014 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * 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.view.View;/** * This class is from the v7 samples of the Android SDK. It's not by me! * * 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; protected 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); //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); } } @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); } }}五、测试
Bean.java（本例中所使用的实体类）
package com.gcy.universal_adapter_recyclerview.Entity;/** * Created by gcy71 on 2016/9/26. */public class Bean { private String title; private String info; private String time; public Bean(String title, String info, String time) { this.title = title; this.info = info; this.time = time; } public Bean() { } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getInfo() { return info; } public void setInfo(String info) { this.info = info; } public String getTime() { return time; } public void setTime(String time) { this.time = time; }}item_recyclerview.xml
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="wrap_content" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin"> <TextView android:id="@+id/id_title" android:layout_width="match_parent" android:layout_height="wrap_content" android:textSize="16sp" android:text="我是标题" android:textColor="#444"/> <TextView android:id="@+id/id_info" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@id/id_title" android:minLines="1" android:maxLines="2" android:text="Android打造万能的ListView和GridView适配器" android:textColor="#898989" android:textSize="16sp"/> <TextView android:id="@+id/id_time" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@id/id_info" android:minLines="1" android:maxLines="2" android:text="2016-09-26" android:textColor="#898989" android:textSize="12sp"/>RelativeLayout>activity_main.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/activity_main" 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" android:orientation="vertical"> <android.support.v7.widget.RecyclerView android:id="@+id/id_recyclerview" android:layout_width="match_parent" android:layout_height="wrap_content"> android.support.v7.widget.RecyclerView>LinearLayout>MainActivity.java
package com.gcy.universal_adapter_recyclerview;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import com.gcy.universal_adapter_recyclerview.Entity.Bean;import com.gcy.universal_adapter_recyclerview.utils.BaseViewHolder;import com.gcy.universal_adapter_recyclerview.utils.DividerItemDecoration;import com.gcy.universal_adapter_recyclerview.utils.MyBaseAdapter;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity { private List mDatas; private RecyclerView mRecyclerView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initData(); initRecyclerView(); } private void initRecyclerView() { mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview); mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)); //此处我们使用匿名内部类的方式来为mRecyclerView设置Adapter mRecyclerView.setAdapter(new MyBaseAdapter(R.layout.item_recyclerview , this , mDatas) { @Override public void blindViewHolder(BaseViewHolder holder, Bean bean) { holder.setText2TextView(R.id.id_title , bean.getTitle()) .setText2TextView(R.id.id_info , bean.getInfo()) .setText2TextView(R.id.id_time,bean.getTime()); } }); mRecyclerView.addItemDecoration(new DividerItemDecoration(this , DividerItemDecoration.VERTICAL_LIST)); } private void initData() { mDatas = new ArrayList(); for(int i=1 ; i<=10 ; i++){ mDatas.add(new Bean("我是标题 " + i, "Android打造ListView和GridView万能适配器" , "2016-09-28")); } }} 测试效果：
项目源码：
https://github.com/Sunrise7878/Universal_adapter/tree/master/universal_adapter_recyclerview
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