編輯:關於Android編程
RecyclerView是Google在android-supportv7包中推出的一個新的控件,該控件的主要作用是用於替代ListView、GridView,相比較於這兩種控件RecyclerView有以下有點:
RecyclerView內部封裝了ViewHolder,更加方便Item的復用 提供了一種插拔式的體驗,高度解耦,異常靈活,增加控件的擴展性。效果如下:
實現代碼如下:<喎?/kf/ware/vc/" target="_blank" class="keylink">vcD4NCjxwcmUgY2xhc3M9"brush:java;">
package com.example.zhangke.recyclerviewdemo;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private ArrayList
同ListView一樣,RecyclerView現實數據需要通過Adapter實現,Google已給我們提供了RecyclerView.Adapter的內部抽象類,所以必須通過繼承該類實現一個Adapter。繼承該類需要復寫三個方法:
public int getItemCount():獲得item數目 public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType):創建一個ViewHolder public void onBindViewHolder(final RecyclerViewHolder holder, int position):綁定Viewholder即對Item進行具體操作注意:由於Adapter會在內部封裝一個ViewHolder,所以我們還要自定義一個ViewHolder。
對於RecyviewView,系統並沒有提供item點擊事件,所以在自定義Adapter時,通常會自己定義Item的點擊事件的接口以實現item點擊。
具體代碼如下:
package com.example.zhangke.recyclerviewdemo;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.text.Layout;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
/**
* Created by zhangke on 16/6/15.
*/
public class RecyclerViewAdapter extends RecyclerView.Adapter {
private Context mContext;
private ArrayList mDatas;
private OnItemClickListener mOnItemClickListener;
private OnLongItemClickListener mOnLongItemClickListener;
public RecyclerViewAdapter(Context context, ArrayList datas) {
this.mContext = context;
this.mDatas = datas;
}
@Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerViewHolder holder = new RecyclerViewHolder(View.inflate(mContext, R.layout.item, null));
return holder;
}
@Override
public void onBindViewHolder(final RecyclerViewHolder holder, int position) {
holder.mTextView.setText(mDatas.get(position));
if (mOnItemClickListener != null) {
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int layoutPosition = holder.getLayoutPosition();
mOnItemClickListener.onItemClick(v, layoutPosition);
}
});
}
if (mOnLongItemClickListener != null) {
holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
int layoutPosition = holder.getLayoutPosition();
mOnLongItemClickListener.onLongItemClick(v, layoutPosition);
return true;
}
});
}
}
@Override
public int getItemCount() {
return mDatas.size();
}
/**
* viewholder
*/
class RecyclerViewHolder extends RecyclerView.ViewHolder {
private TextView mTextView;
public RecyclerViewHolder(View itemView) {
super(itemView);
mTextView = (TextView) itemView.findViewById(R.id.textview);
}
}
/**
* 添加
* @param position
* @param item
*/
public void addItem(int position, String item){
mDatas.add(position, item+position);
notifyItemInserted(position);
}
/**
* 刪除
* @param position
*/
public void removeItem(int position){
mDatas.remove(position);
notifyItemRemoved(position);
}
/**
* item點擊事件
*/
public interface OnItemClickListener {
/**
* item點擊事件
*
* @param view
* @param position
*/
void onItemClick(View view, int position);
}
public interface OnLongItemClickListener {
/**
* item長按點擊事件
*
* @param view
* @param position
*/
void onLongItemClick(View view, int position);
}
public void setOnItemClickListener(OnItemClickListener listener) {
this.mOnItemClickListener = listener;
}
public void setOnLongItemClickListener(OnLongItemClickListener listener) {
this.mOnLongItemClickListener = listener;
}
}
在之前已經提到,RecyclerView有addItemDecoration()的方法,該方法的作用是為RecyclerView添加item分割線,為此我們不難想象RecyclerView默認是沒有分割線的。但是google官方並沒有提供具體ItemDecoration的方法,僅僅是定義了一個ItemDecoration的抽象類,所以要想實現分割線效果,必須要自己實現一個ItemDecoration。
ItemDecoration抽象方法介紹:
public void onDraw(Canvas c, RecyclerView parent, State state):繪制分割線 public void onDrawOver(Canvas c, RecyclerView parent, State state):繪制分割線,該方法後於onDraw,一般實現一個即可 public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state):用於計算item分割線的偏移量以下是通過ItemDecoration實現ListView和GridView的分割線:
package com.example.zhangke.recyclerviewdemo; import android.annotation.TargetApi; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.os.Build; import android.support.v4.view.ViewCompat; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.View; import android.view.ViewGroup; /** * item分割線 * <p/> * Created by zhangke on 16/6/15. */ public class DividerItemDecoration extends RecyclerView.ItemDecoration { /** * 分割線 */ private static int[] ATTRS = new int[]{android.R.attr.listDivider}; /** * 水平分割線 */ public static final int HORIZONTAL = LinearLayoutManager.HORIZONTAL; /** * 垂直分割線 */ public static final int VERTICAL = LinearLayoutManager.VERTICAL; /** * 上下文 */ private Context mContext; /** * 分割線 */ private Drawable mDivider; private int mOrientation; /** * @param context 上下文 * @param orientation 分割線方向 */ @TargetApi(Build.VERSION_CODES.LOLLIPOP) public DividerItemDecoration(Context context, int orientation) { this.mContext = context; // TypedArray typedArray = mContext.obtainStyledAttributes(ATTRS); // mDivider = typedArray.getDrawable(0); // typedArray.recycle(); mDivider = context.getDrawable(R.drawable.divider_view); setOrientation(orientation); } /** * 設置分割線方向 * * @param orientation */ private void setOrientation(int orientation) { if (orientation != HORIZONTAL && orientation != VERTICAL) { throw new IllegalArgumentException("參數異常"); } this.mOrientation = orientation; } @Override public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) { if (mOrientation == HORIZONTAL) { drawHorizontal(c, parent, state); } else { drawVertical(c, parent, state); } super.onDraw(c, parent, state); } /** * 繪制垂直方向分割線 * * @param c * @param parent * @param state */ private void drawVertical(Canvas c, RecyclerView parent, RecyclerView.State state) { int left = parent.getPaddingLeft(); int right = parent.getWidth() - parent.getPaddingRight(); int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { View childView = parent.getChildAt(i); RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) childView.getLayoutParams(); int top = childView.getBottom() + layoutParams.bottomMargin + Math.round(ViewCompat.getTranslationY(childView)); int bottom = top + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } /** * 繪制水平方向分割線 * * @param c * @param parent * @param state */ private void drawHorizontal(Canvas c, RecyclerView parent, RecyclerView.State state) { int top = parent.getPaddingTop(); int bottom = parent.getHeight() - parent.getPaddingBottom(); int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { View childView = parent.getChildAt(i); RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) childView.getLayoutParams(); int left = childView.getRight() + layoutParams.rightMargin + Math.round(ViewCompat.getTranslationX(childView)); int right = left + mDivider.getIntrinsicWidth(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } /** * 設置分割線寬偏移量: * 通過RecyclerView源碼可知:getItemOffset方法會在measureChild方法中調用,我們通過給方法的參數outRect * 設置left、top、right、bottom,設置的值會被增加到childView的padding值中。 * * @param outRect * @param view * @param parent * @param state */ @Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { if (mOrientation == HORIZONTAL) { outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } else { outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } } }
package com.example.zhangke.recyclerviewdemo; import android.annotation.TargetApi; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.os.Build; import android.support.v4.view.ViewCompat; import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.util.Log; import android.view.View; import android.view.ViewGroup; /** * item分割線 * <p/> * Created by zhangke on 16/6/15. */ public class DividerGridItemDecoration extends RecyclerView.ItemDecoration { /** * 分割線 */ private static int[] ATTRS = new int[]{android.R.attr.listDivider}; /** * 水平分割線 */ public static final int HORIZONTAL = LinearLayoutManager.HORIZONTAL; /** * 垂直分割線 */ public static final int VERTICAL = LinearLayoutManager.VERTICAL; /** * 上下文 */ private Context mContext; /** * 分割線 */ private Drawable mDivider; private int mOrientation; private int spanCount; /** * @param context 上下文 * @param orientation 分割線方向 */ @TargetApi(Build.VERSION_CODES.LOLLIPOP) public DividerGridItemDecoration(Context context, int orientation) { this.mContext = context; // TypedArray typedArray = mContext.obtainStyledAttributes(ATTRS); // mDivider = typedArray.getDrawable(0); // typedArray.recycle(); mDivider = context.getDrawable(R.drawable.divider_view); setOrientation(orientation); } /** * 設置分割線方向 * * @param orientation */ private void setOrientation(int orientation) { if (orientation != HORIZONTAL && orientation != VERTICAL) { throw new IllegalArgumentException("參數異常"); } this.mOrientation = orientation; } @Override public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) { drawHorizontal(c, parent, state); drawVertical(c, parent, state); } /** * 繪制垂直方向分割線 * * @param c * @param parent * @param state */ private void drawVertical(Canvas c, RecyclerView parent, RecyclerView.State state) { int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { View child = parent.getChildAt(i); RecyclerView.LayoutParams params = (GridLayoutManager.LayoutParams) child.getLayoutParams(); int left = child.getLeft() - params.leftMargin; int right = child.getRight()+ params.rightMargin; int top = child.getBottom() + params.bottomMargin; int bottom = top + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } /** * 繪制水平方向分割線 * * @param c * @param parent * @param state */ private void drawHorizontal(Canvas c, RecyclerView parent, RecyclerView.State state) { int childCount = parent.getChildCount(); for (int i = 0; i < childCount; i++) { View child = parent.getChildAt(i); RecyclerView.LayoutParams params = (GridLayoutManager.LayoutParams) child.getLayoutParams(); int left = child.getRight() + params.rightMargin; int right = left + mDivider.getIntrinsicWidth(); int top = child.getTop() - params.topMargin; int bottom = child.getBottom() + params.bottomMargin; mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } /** * 設置分割線寬偏移量: * 通過RecyclerView源碼可知:getItemOffset方法會在measureChild方法中調用,我們通過給方法的參數outRect * 設置left、top、right、bottom,設置的值會被增加到childView的padding值中。 */ @Override public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) { if (isLastColum(itemPosition, parent)) { //最後一列 outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } else if (isLastRow(itemPosition, parent)) { //最後一行 outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } else { outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight()); } } /** * 是否是最後一行 * * @param itemPosition * @param parent * @return */ private boolean isLastRow(int itemPosition, RecyclerView parent) { int spanCount = getSpanCount(parent); RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { int childCount = parent.getAdapter().getItemCount(); int lastRowCount = childCount % spanCount; if (lastRowCount == 0) { return false; } else if(itemPosition >= (childCount - lastRowCount)){ return true; } } return false; } /* * 是否是最後一列 */ private boolean isLastColum(int itemPosition, RecyclerView parent) { RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { int spanCount = getSpanCount(parent); if ((itemPosition + 1) % spanCount == 0) { return true; } } return false; } private int getSpanCount(RecyclerView parent) { RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { GridLayoutManager lm = (GridLayoutManager) layoutManager; int spanCount = lm.getSpanCount(); return spanCount; } return 0; } }
效果圖如下:
代碼如下:
package com.example.zhangke.recyclerviewdemo;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
private ArrayList mDatas;
private RecyclerViewAdapter mAdapter;
private StaggeredGridLayoutAdapter mStagAdapter;
private RecyclerView.ItemDecoration mItemDecoration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.recycleview);
initData();
//垂直listview
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
//設置分割線
mItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
mRecyclerView.addItemDecoration(mItemDecoration);
// 設置增刪動畫
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
mAdapter = new RecyclerViewAdapter(this, mDatas);
//設置點擊事件
mAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {
@Override
public void onItemClick(View view, int position) {
Toast.makeText(MainActivity.this, "onItemClick " + position, Toast.LENGTH_SHORT).show();
}
});
mAdapter.setOnLongItemClickListener(new RecyclerViewAdapter.OnLongItemClickListener() {
@Override
public void onLongItemClick(View view, int position) {
Toast.makeText(MainActivity.this, "onLongItemClick " + position, Toast.LENGTH_SHORT).show();
}
});
//設置Adapter
mRecyclerView.setAdapter(mAdapter);
}
/**
* 初始化數據
*/
private void initData() {
mDatas = new ArrayList();
for (int i = 0; i < 100; i++) {
mDatas.add("item " + i);
}
}
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (mItemDecoration != null) {
mRecyclerView.removeItemDecoration(mItemDecoration);
}
switch (item.getItemId()) {
case R.id.add:
mAdapter.addItem(1, "item" + 1);
break;
case R.id.remove:
mAdapter.removeItem(1);
break;
case R.id.showVertical:
//垂直listview
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
mRecyclerView.addItemDecoration(mItemDecoration);
mAdapter = new RecyclerViewAdapter(this, mDatas);
mAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {
@Override
public void onItemClick(View view, int position) {
Toast.makeText(MainActivity.this, "onItemClick " + position, Toast.LENGTH_SHORT).show();
}
});
mAdapter.setOnLongItemClickListener(new RecyclerViewAdapter.OnLongItemClickListener() {
@Override
public void onLongItemClick(View view, int position) {
Toast.makeText(MainActivity.this, "onLongItemClick " + position, Toast.LENGTH_SHORT).show();
}
});
mRecyclerView.setAdapter(mAdapter);
break;
case R.id.showHorizontal:
//水平listview
mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
mItemDecoration = new DividerItemDecoration(this, DividerItemDecoration.HORIZONTAL);
mRecyclerView.addItemDecoration(mItemDecoration);
mAdapter = new RecyclerViewAdapter(this, mDatas);
mRecyclerView.setAdapter(mAdapter);
break;
case R.id.showGridHorizontal:
// 水平gridview
mRecyclerView.setLayoutManager(new GridLayoutManager(this, 4, LinearLayoutManager.HORIZONTAL, false));
mItemDecoration = new DividerGridItemDecoration(this, DividerGridItemDecoration.HORIZONTAL);
mRecyclerView.addItemDecoration(mItemDecoration);
mAdapter = new RecyclerViewAdapter(this, mDatas);
mRecyclerView.setAdapter(mAdapter);
break;
case R.id.showGridVertical:
// 垂直gridview
mRecyclerView.setLayoutManager(new GridLayoutManager(this, 4));
mItemDecoration = new DividerGridItemDecoration(this, DividerGridItemDecoration.VERTICAL);
mRecyclerView.addItemDecoration(mItemDecoration);
mAdapter = new RecyclerViewAdapter(this, mDatas);
mRecyclerView.setAdapter(mAdapter);
break;
case R.id.showStaggle:
// 瀑布流
mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(3, LinearLayoutManager.VERTICAL));
mStagAdapter = new StaggeredGridLayoutAdapter(this, mDatas);
mRecyclerView.setAdapter(mStagAdapter);
break;
}
return true;
}
}
在自定義控件這個學習系列裡,首先寫篇文章記錄一下View的繪制流程,壓壓驚:-P。也為以後的自定義控件實踐打個基礎。雖然講解View工作流程的文章很多,其中不乏很多精品文
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