RecyclerView的基本使用(二)

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生活本来就不容易啊,正是我们的不努力才会让生活变得更加无赖。

整个月没有写过博客,这几天趁着看项目代码有使用到ListView添加headView决定自己更新一下,使用RecyclerView来代替,记得之前就写过一篇关于ReCyclerView的基本使用(一),这次写个续集吧。但是我们在setHeadView()的时候并没有发现有这个方法,至于为什么呢我也不知道,但是各路大神已经优雅的为其添加HeadView和FootView了例如鸿洋大神,还有Loader的,还有很多很多,所以基本上不用写了,这篇笔记到此结束。嗯! 但是这笔记的意义不在此,只是想记录一下自己的参考过程,不,是思考过程。首先看看整个demo的预览图

阿拉蕾
#####基本思路 利用RecyclerView.Adapter中的getItemType()方法判断一下这是否为headView,footView,在onCreateViewHolder(ViewGroup parent, int viewType)方法中判断一下要给Viewholder的itemView是什么类型。就这样。下面直接看代码吧 #####基本实现 BaseRecyclerAdapter

/**
 * Created by AmatorLee on 2016/10/29.
 * 基类Adaper
 */

public abstract class BaseRecyclerAdapter<T> extends RecyclerView.Adapter<BaseRecyclerViewHolder>{


    private static final int ITEM_HEAD = 1000;
    private static final int ITEM_FOOT = 2000;
    private static final int ITEM_NOMAL = 3000;

    private View mHeadView;
    private View mFootView;
    private List<T> mDatas;
    private LayoutInflater mInflater;


    /**
     * 点击回调
     */
    private OnItemClickListener mListener;

    public void setListener(OnItemClickListener listener) {
        mListener = listener;
    }


    /**
     * 构造方法
     * @param context
     * @param mDatas
     */
    public BaseRecyclerAdapter(Context context, List<T> mDatas) {
        mInflater = LayoutInflater.from(context);
        this.mDatas = mDatas;
    }

    /**
     * headView
     * @param headView
     */
    public void addHeadView(View headView){
        this.mHeadView = headView;
        notifyItemInserted(0);
    }
    public View getHeadView(){
        if (mHeadView != null){
            return mHeadView;
        }
        return null;
    }

    /**
     * FootView
     * @param footView
     */
    public void addFootView(View footView){
        this.mFootView = footView;
        notifyItemInserted(getItemCount() - 1);
    }
    public View getFootView(){
        if (mFootView != null){
            return mFootView;
        }
        return null;
    }

    @Override
    public BaseRecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (mHeadView != null && viewType == ITEM_HEAD){
            //如果为headView则itemView为headView
            return new BaseRecyclerViewHolder(mHeadView);
        }else if (mFootView != null && viewType == ITEM_FOOT){
            //如果为footView则itemView为footView
            return new BaseRecyclerViewHolder(mFootView);
        }
        //否则自己解析
       return new BaseRecyclerViewHolder(mInflater.inflate(getLayoutID(),parent,false));
    }

    /*此方法为解析自己的view提供一个layoutId*/
    public abstract int getLayoutID();

    @Override
    public void onBindViewHolder(BaseRecyclerViewHolder holder, final int position) {
        /*判断是否有headView,如果0被占用则position-1*/
        final int pos = getLayoutPos(holder);

        if (getItemViewType(position) == ITEM_HEAD)return;/*交予自己处理headView*/
        if (getItemViewType(position) == ITEM_FOOT)return;/*处理footView*/
        /*点击监听*/
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mListener != null){
                    mListener.onItemClick(v,pos);
                }
            }
        });
        /*自己处理数据的方法*/
        onBindData(holder,pos);
    }
    /*判断是否有headView,如果0被占用则position-1*/
    private int getLayoutPos(BaseRecyclerViewHolder holder){
        return mHeadView == null?holder.getLayoutPosition():holder.getLayoutPosition() - 1;
    }

    /*自己处理数据的方法*/
    public abstract void onBindData(BaseRecyclerViewHolder holder, int position);

    @Override
    public int getItemCount() {
        if (mHeadView == null && mFootView != null){
            //如果footView则count+1
            return mDatas.size() + 1;
        }else if (mHeadView != null && mFootView == null){
            //如果有headView则+1
            return mDatas.size()+ 1;
        }else if(mFootView != null && mHeadView != null){
            //假如都有则+2
            return mDatas.size() + 2;
        }
        /*否则不处理*/
        return mDatas.size();
    }

    /***
     * 此方法判断itemType的类型
     * @param position
     * @return
     */
    @Override
    public int getItemViewType(int position) {
        if (mHeadView == null && mFootView == null)return ITEM_NOMAL;
        if (position == 0 && mHeadView != null) return ITEM_HEAD;
        if (position == getItemCount() -1) return ITEM_FOOT;
        return ITEM_NOMAL;

    }

    /**
     *回调监听 
     */
    public interface OnItemClickListener{
        void onItemClick(View v, int pos);
    }
}```
**BaseViewHolder**

/**

  • Created by AmatorLee on 2016/10/29.
  • 基类Viewholder */

public class BaseRecyclerViewHolder extends RecyclerView.ViewHolder{

private SparseArray<View> mViews;/*传说中装在view性能好的容器,key为int型,value为View*/
public View itemView;

/**
 * 构造方法
 * @param itemView
 */
public BaseRecyclerViewHolder(View itemView) {
    super(itemView);
    mViews = new SparseArray<>();
    this.itemView = itemView;
}

/**
 * 利用SpaseArray和泛型省略多次findViewbyid()
 * @param viewId id
 * @param <T> 类型
 * @return
 */
public <T extends View>T getView(int viewId){
    View view = mViews.get(viewId);
    if (view == null){
        view = itemView.findViewById(viewId);
        mViews.put(viewId,view);
    }
    return (T) view;
}

/**
 * 给外部调用的设置文本的方法
 * @param viewId
 * @param msg
 */
public void setText(int viewId,String msg){
    TextView textView = getView(viewId);
    textView.setText(msg);
}

/**
 * 给外部调用的设置图片资源的方法
 * @param viewID
 * @param resID
 */
public void setImgRes(int viewID,int resID){
    ImageView imageView = getView(viewID);
    imageView.setImageResource(resID);
}

}```

  • 这里定义了一个BaseRecyclerAdapter And BaseViewHolder用以处理是否添加headView,代码注释比较清楚。 #####基本使用 使用起来也是十分简单,我们新建一个自己的TestAdapter扩展自BaseRecyclerAdapter,需要实现其两个抽象方法:
 @Override
    public int getLayoutID() {
        return R.layout.recycler_test;/*提供需要解析的layoutID*/
    }
    @Override
    public void onBindData(BaseRecyclerViewHolder holder, int position) {
        //处理数据
        holder.setText(R.id.recycler_textView,mDatas.get(position));
    }```
**TestAdapter**

/**

  • Created by AmatorLee on 2016/10/29.

  • 目的Adapter,处理自己的相关逻辑 */ public class TestAdapter extends BaseRecyclerAdapter {

    private List mDatas; private LayoutInflater mInflater;

    public TestAdapter(Context context, List mDatas) { super(context, mDatas); mInflater = LayoutInflater.from(context); this.mDatas = mDatas; }

    @Override public int getLayoutID() { return R.layout.recycler_test; }

    @Override public void onBindData(BaseRecyclerViewHolder holder, int position) { holder.setText(R.id.recycler_textView,mDatas.get(position)); } }``` Activity

public class HFActivity extends AppCompatActivity {
    private List<String> mDatas = new ArrayList<>();

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

        for (int i = 0; i < 30; i++) {
            mDatas.add("这是第" + i + "item");
        }
        RecyclerView recycler_hf = (RecyclerView) findViewById(R.id.recycler_hf);
        recycler_hf.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));
        TestAdapter adapter = new TestAdapter(this, mDatas);
        recycler_hf.addItemDecoration(new ItemDecoration(this,LinearLayoutManager.VERTICAL));
        View view = getLayoutInflater().inflate(R.layout.layout_headview, null);
        adapter.addFootView(view);
        adapter.addHeadView(view);
        recycler_hf.setAdapter(adapter);
        adapter.setListener(new BaseRecyclerAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(View v, int pos) {
                Toast.makeText(HFActivity.this,pos + "onClick",Toast.LENGTH_SHORT).show();
            }
        });
    }
}```

**效果演示**

![demo.gif](http://upload-images.jianshu.io/upload_images/2605454-9532a34e5740fc37.gif?imageMogr2/auto-orient/strip)
最近觉得要多使用github了,所以把自己写的一些demo放在github上面吧
[github地址](https://github.com/AmatorLee/RDemo/tree/master)

---
**总结**
RecyclerView已经在逐步取代listView了,但是相对来说listview使用起来更加方便,虽然目前很多大神已经将RecyclerView封装得完美,但是我不是啊,虽然可以用,但是我更加希望在使用之前可以先学习一遍。
#####如果你觉得本文有所错漏,麻烦留言指出,交流学习共同进步