Android 实现当下最流行的吸顶效果

2019-12-12 03:13:43

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开始逐渐领略到ItemDecoration的美~

今天让我使用 ItemDecoration 来完成 可推动的悬浮导航栏的效果，最终实现的效果如下图：

具体实现步骤如下：

根据我前面的文章所讲的RecyclerView的基本使用，我们先来完成基本的recyclerView：

第一步：布局里写一个RecyclerView

第二步：实例化

recyclerView = (RecyclerView) findViewById(R.id.recyclerView);

第三步：获取所需的数据 (这里我们来个真实点的情景，去联网请求数据)

/** * 联网请求所需的url */  public String url=http://api.meituan.com/mmdb/movie/v2/list/rt/order/coming.json?ci=1&limit=12&token=&__vhost=api.maoyan.com&utm_campaign=AmovieBmovieCD-1&movieBundleVersion=6801&utm_source=xiaomi&utm_medium=android&utm_term=6.8.0&utm_content=868030022327462&net=255&dModel=MI%205&uuid=0894DE03C76F6045D55977B6D4E32B7F3C6AAB02F9CEA042987B380EC5687C43&lat=40.100673&lng=116.378619&__skck=6a375bce8c66a0dc293860dfa83833ef&__skts=1463704714271&__skua=7e01cf8dd30a179800a7a93979b430b2&__skno=1a0b4a9b-44ec-42fc-b110-ead68bcc2824&__skcy=sXcDKbGi20CGXQPPZvhCU3%2FkzdE%3D;

//联网获取数据  getDataFromNet();

/** * 使用okhttpUtils进行联网请求数据 */  private void getDataFromNet() {  OkHttpUtils.  get()  .url(url)  .build()  .execute(new StringCallback() {   @Override   public void onError(okhttp3.Call call, Exception e, int id) {   Log.e("TAG", "联网失败" + e.getMessage());   }    @Override   public void onResponse(String response, int id) {   Log.e("TAG", "联网成功==" + response);    //联网成功后使用fastjson解析   processData(response);   }  });  }

/** * 使用fastjson进行解析 * * @param json */  private void processData(String json) {  //这里使用GsonFormat生成对应的bean类  JSONObject jsonObject = parseObject(json);   String data = jsonObject.getString("data");  JSONObject dataObj = JSON.parseObject(data);   String coming = dataObj.getString("coming");  List<WaitMVBean.DataBean.ComingBean> comingslist = parseArray(coming, WaitMVBean.DataBean.ComingBean.class);   //测试是否解析数据成功 // String strTest = comingslist.get(0).getCat(); // Log.e("TAG", strTest + "222");   //解析数据成功,设置适配器-->   }  }

第四步：解析数据成功后，创建并设置适配器,并传递相关数据

//解析数据成功,设置适配器  MyRecyclerAdapter adapter = new MyRecyclerAdapter( mContext,comingslist);  recyclerView.setAdapter(adapter);

适配器：

public class MyRecyclerAdapter extends RecyclerView.Adapter {  private final List<WaitMVBean.DataBean.ComingBean> comingslist;  private final Context mContext;  private final LayoutInflater mLayoutInflater;  public MyRecyclerAdapter(Context mContext, List<WaitMVBean.DataBean.ComingBean> comingslist) {  this.mContext = mContext;  this.comingslist = comingslist;  mLayoutInflater = LayoutInflater.from(mContext);  }  @Override  public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {  return new MyViewHolder(mLayoutInflater.inflate(R.layout.date_item, null));  }  @Override  public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {  MyViewHolder myholder = (MyViewHolder) holder;  myholder.setData(position);  }  @Override  public int getItemCount() {  return comingslist.size();  }  class MyViewHolder extends RecyclerView.ViewHolder {  private TextView mv_name;  private TextView mv_dec;  private TextView mv_date;  private ImageView imageView;  public MyViewHolder(View itemView) {  super(itemView);  mv_name = (TextView) itemView.findViewById(R.id.mv_name);  mv_dec = (TextView) itemView.findViewById(R.id.mv_dec);  mv_date = (TextView) itemView.findViewById(R.id.mv_date);  imageView = (ImageView) itemView.findViewById(R.id.image);  }  public void setData(int position) {  WaitMVBean.DataBean.ComingBean coming = comingslist.get(position);  String name = coming.getNm();  mv_name.setText(name);  String date = coming.getShowInfo();  mv_date.setText(date);  String dec = coming.getScm();  mv_dec.setText(dec);  //注：当你发下图片无法打开是，做个字符串替换即可  String imagUrl = coming.getImg();  String newImagUrl = imagUrl.replaceAll("w.h", "50.80");   //使用Glide加载图片  Glide.with(mContext)   .load(newImagUrl)   .into(imageView);  }  } }

item的布局：

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:background="#ffffff"  android:gravity="center_vertical"  android:orientation="horizontal">  <ImageView  android:id="@+id/image"  android:layout_width="70dp"  android:layout_height="110dp"  android:layout_marginBottom="5dp"  android:layout_marginLeft="10dp"  android:layout_marginRight="8dp"  android:layout_marginTop="5dp" />  <LinearLayout  android:layout_width="0dp"  android:layout_height="wrap_content"  android:layout_marginLeft="6dp"  android:layout_weight="1"  android:orientation="vertical">  <TextView  android:id="@+id/mv_name"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text="神奇物在哪"  android:textColor="#000000"  android:textSize="15sp" />  <LinearLayout  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:orientation="horizontal">  <TextView  android:layout_width="wrap_content" android:layout_height="wrap_content"  android:text="观众"  android:textColor="#55000000"  android:textSize="14sp" />  <TextView  android:id="@+id/tv_people"  android:layout_width="wrap_content" android:layout_height="wrap_content"  android:text="9.0 "  android:textColor="#FFCE42"  android:textSize="18sp" />  <TextView  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text=" | 专业"  android:textColor="#55000000"  android:textSize="14sp" />  <TextView  android:id="@+id/tv_professional"  android:layout_width="wrap_content" android:layout_height="wrap_content"  android:text="6.7"  android:textColor="#FFCE42"  android:textSize="18sp" />  </LinearLayout>  <TextView  android:id="@+id/mv_dec"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:layout_marginTop="8dp"  android:text="神奇物城，法超能"  android:textColor="#99000000"  android:textSize="11sp" />  <TextView  android:id="@+id/mv_date"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:layout_marginTop="10dp"  android:text="今天165家影院放映2088场"  android:textColor="#99000000"  android:textSize="11sp" />  </LinearLayout> </LinearLayout>

第五步：一定不能忘！！！

recycleView不仅要设置适配器还要设置布局管理者,否则图片不显示

GridLayoutManager manager = new GridLayoutManager(this, 1);  recyclerView.setLayoutManager(manager);

此时RecyclerView简单的完成效果如下：

下面开始做可推动的悬浮导航栏：

第一步：首先我们来写一个类，它起标记的作用，来放每一个item的对应的悬浮栏的字符串

public class NameBean {  String name;  public String getName() {  return name;  }  public void setName(String name) {  this.name = name;  } }

第二步：自定义一个SectionDecoration 类继承 RecyclerView的ItemDecoration

public class SectionDecoration extends RecyclerView.ItemDecoration {  private static final String TAG = "SectionDecoration";  private List<NameBean> dataList;  private DecorationCallback callback;  private TextPaint textPaint;  private Paint paint;  private int topGap;  private int alignBottom;  private Paint.FontMetrics fontMetrics;  public SectionDecoration(List<NameBean> dataList, Context context, DecorationCallback decorationCallback) {  Resources res = context.getResources();  this.dataList = dataList;  this.callback = decorationCallback;  //设置悬浮栏的画笔---paint  paint = new Paint();  paint.setColor(res.getColor(R.color.colorGray));  //设置悬浮栏中文本的画笔  textPaint = new TextPaint();  textPaint.setAntiAlias(true);  textPaint.setTextSize(DensityUtil.dip2px(context, 14));  textPaint.setColor(Color.DKGRAY);  textPaint.setTextAlign(Paint.Align.LEFT);  fontMetrics = new Paint.FontMetrics();  //决定悬浮栏的高度等  topGap = res.getDimensionPixelSize(R.dimen.sectioned_top);  //决定文本的显示位置等  alignBottom = res.getDimensionPixelSize(R.dimen.sectioned_alignBottom);  }  @Override  public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {  super.getItemOffsets(outRect, view, parent, state);  int pos = parent.getChildAdapterPosition(view);  Log.i(TAG, "getItemOffsets：" + pos);  String groupId = callback.getGroupId(pos);  if (groupId.equals("-1")) return;  //只有是同一组的第一个才显示悬浮栏  if (pos == 0 || isFirstInGroup(pos)) {  outRect.top = topGap;  if (dataList.get(pos).getName() == "") {  outRect.top = 0;  }  } else {  outRect.top = 0;  }  }  @Override  public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {  super.onDraw(c, parent, state);  int left = parent.getPaddingLeft();  int right = parent.getWidth() - parent.getPaddingRight();  int childCount = parent.getChildCount();  for (int i = 0; i < childCount; i++) {  View view = parent.getChildAt(i);  int position = parent.getChildAdapterPosition(view);  String groupId = callback.getGroupId(position);  if (groupId.equals("-1")) return;  String textLine = callback.getGroupFirstLine(position).toUpperCase();  if (textLine == "") {  float top = view.getTop();  float bottom = view.getTop();  c.drawRect(left, top, right, bottom, paint);  return;  } else {  if (position == 0 || isFirstInGroup(position)) {   float top = view.getTop() - topGap;   float bottom = view.getTop();   //绘制悬浮栏   c.drawRect(left, top - topGap, right, bottom, paint);   //绘制文本   c.drawText(textLine, left, bottom, textPaint);  }  }  }  }  @Override  public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {  super.onDrawOver(c, parent, state);  int itemCount = state.getItemCount();  int childCount = parent.getChildCount();  int left = parent.getPaddingLeft();  int right = parent.getWidth() - parent.getPaddingRight();  float lineHeight = textPaint.getTextSize() + fontMetrics.descent;  String preGroupId = "";  String groupId = "-1";  for (int i = 0; i < childCount; i++) {  View view = parent.getChildAt(i);  int position = parent.getChildAdapterPosition(view);  preGroupId = groupId;  groupId = callback.getGroupId(position);  if (groupId.equals("-1") || groupId.equals(preGroupId)) continue;  String textLine = callback.getGroupFirstLine(position).toUpperCase();  if (TextUtils.isEmpty(textLine)) continue;  int viewBottom = view.getBottom();  float textY = Math.max(topGap, view.getTop());  //下一个和当前不一样移动当前  if (position + 1 < itemCount) {  String nextGroupId = callback.getGroupId(position + 1);  //组内最后一个view进入了header  if (nextGroupId != groupId && viewBottom < textY) {   textY = viewBottom;  }  }  //textY - topGap决定了悬浮栏绘制的高度和位置  c.drawRect(left, textY - topGap, right, textY, paint);  //left+2*alignBottom 决定了文本往左偏移的多少（加-->向左移）  //textY-alignBottom 决定了文本往右偏移的多少 (减-->向上移)  c.drawText(textLine, left + 2 * alignBottom, textY - alignBottom, textPaint);  }  }  /** * 判断是不是组中的第一个位置 * * @param pos * @return */  private boolean isFirstInGroup(int pos) {  if (pos == 0) {  return true;  } else {  // 因为是根据 字符串内容的相同与否 来判断是不是同意组的，所以此处的标记id 要是String类型  // 如果你只是做联系人列表，悬浮框里显示的只是一个字母，则标记id直接用 int 类型就行了  String prevGroupId = callback.getGroupId(pos - 1);  String groupId = callback.getGroupId(pos);  //判断前一个字符串 与 当前字符串 是否相同  if (prevGroupId.equals(groupId)) {  return false;  } else {  return true;  }  }  }  //定义一个借口方便外界的调用  interface DecorationCallback {  String getGroupId(int position);  String getGroupFirstLine(int position);  } }

第三步：在向list集合中先把每一个item的起“标记”作用的字符串都加进去

setPullAction(comingslist);

private void setPullAction(List<WaitMVBean.DataBean.ComingBean> comingslist) {  dataList = new ArrayList<>();  for (int i = 0; i < comingslist.size(); i++) {  NameBean nameBean = new NameBean();  String name0 = comingslist.get(i).getComingTitle();  nameBean.setName(name0);  dataList.add(nameBean);  }  }

第四步：在setAdapter() 前，为RecyclerView添加ItemDecoration:

recyclerView.addItemDecoration(new SectionDecoration(dataList,mContext, new SectionDecoration.DecorationCallback() {  //返回标记id (即每一项对应的标志性的字符串)  @Override  public String getGroupId(int position) {   if(dataList.get(position).getName()!=null) {   return dataList.get(position).getName();   }   return "-1";  }   //获取同组中的第一个内容  @Override  public String getGroupFirstLine(int position) {   if(dataList.get(position).getName()!=null) {   return dataList.get(position).getName();   }   return "";  }  }));

这样就完成了~

再看一眼最终效果感受一下：