Android仿微信朋友圈全文、收起功能的实例代码

package com.wildma.wildmaexpandfoldtext;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import java.util.ArrayList;import java.util.List;/** * Author   wildma * DATE    2017/8/3 * Des    ${TODO} */public class MainActivity extends AppCompatActivity {  private RecyclerView mRecyclerView;  List<ExpandFoldTextBean> mList = new ArrayList<>();  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    initData();    ExpandFoldTextAdapter adapter = new ExpandFoldTextAdapter(mList, this);    mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);    mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));    mRecyclerView.setAdapter(adapter);  }  /**   * 初始化数据   */  private void initData() {    String longContent = "-->游泳、快走、慢跑、骑自行车，及一切有氧运动都能锻炼心脏。有氧运动好处多：能锻炼心肺、增强循环系统功能、燃烧脂肪、加大肺活量、降低血压，甚至能预防糖尿病，减少心脏病的发生。美国运动医学院建议，想知道有氧运动强度是否合适，可在运动后测试心率，以达到最高心率的60%―90%为宜。如果想通过有氧运动来减肥，可以选择低度到中度的运动强度，同时延长运动时间，这种方法消耗的热量更多。运动频率每周3―5次，每次20―60分钟。想要锻炼肌肉，可以练举重、做体操以及其他重复伸、屈肌肉的运动。肌肉锻炼可以燃烧热量、增强骨密度、减少受伤，尤其是关节受伤的几率，还能预防骨质疏松。 在做举重运动前，先测一下，如果连续举8次你最多能举多重的东西，就从这个重量开始练习。当你可以连续12次举起这个重量时，试试增加5%的重量。注意每次练习时，要连续举8―12次，这样可以达到肌肉最大耐力的70%―80%，锻炼效果较好。每周2―3次，但要避免连续两天锻炼同一组肌肉群， 以便让肌肉有充分的恢复时间。";    String shortContent = "-->健身是一种体育项目，如各种徒手健美操、韵律操、形体操以及各种自抗力动作。";    for (int i = 0; i < 20; i++) {      ExpandFoldTextBean bean = new ExpandFoldTextBean();      if (i % 2 == 0) {        bean.setContent(i + shortContent);        bean.setId(i);      } else {        bean.setContent(i + longContent);        bean.setId(i);      }      mList.add(bean);    }  }}

package com.wildma.wildmaexpandfoldtext;import android.app.Activity;import android.support.v7.widget.RecyclerView;import android.util.SparseArray;import android.view.View;import android.view.ViewGroup;import android.view.ViewTreeObserver;import android.widget.TextView;import java.util.List;/** * Author   wildma * DATE    2017/8/3 * Des    ${展开折叠文本适配器} */public class ExpandFoldTextAdapter extends RecyclerView.Adapter<ExpandFoldTextAdapter.MyViewHolder> {  private Activity mContent;  private final int MAX_LINE_COUNT = 3;//最大显示行数  private final int STATE_UNKNOW = -1;//未知状态  private final int STATE_NOT_OVERFLOW = 1;//文本行数小于最大可显示行数  private final int STATE_COLLAPSED = 2;//折叠状态  private final int STATE_EXPANDED = 3;//展开状态  /**   * 注意：保存文本状态集合的key一定要是唯一的，如果用position。   * 如果使用position作为key，则删除、增加条目的时候会出现显示错乱   */  private SparseArray<Integer> mTextStateList;//保存文本状态集合  List<ExpandFoldTextBean> mList;  public ExpandFoldTextAdapter(List<ExpandFoldTextBean> list, Activity context) {    mContent = context;    this.mList = list;    mTextStateList = new SparseArray<>();  }  @Override  public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {    return new MyViewHolder(mContent.getLayoutInflater().inflate(R.layout.item_expand_fold_text, parent, false));  }  @Override  public void onBindViewHolder(final MyViewHolder holder, final int position) {    int state = mTextStateList.get(mList.get(position).getId(), STATE_UNKNOW);    //第一次初始化，未知状态    if (state == STATE_UNKNOW) {      holder.content.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {        @Override        public boolean onPreDraw() {          //这个回掉会调用多次，获取完行数后记得注销监听          holder.content.getViewTreeObserver().removeOnPreDrawListener(this);          //holder.content.getViewTreeObserver().addOnPreDrawListener(null);          //如果内容显示的行数大于最大显示行数          if (holder.content.getLineCount() > MAX_LINE_COUNT) {            holder.content.setMaxLines(MAX_LINE_COUNT);//设置最大显示行数            holder.expandOrFold.setVisibility(View.VISIBLE);//显示“全文”            holder.expandOrFold.setText("全文");            mTextStateList.put(mList.get(position).getId(), STATE_COLLAPSED);//保存状态          } else {            holder.expandOrFold.setVisibility(View.GONE);            mTextStateList.put(mList.get(position).getId(), STATE_NOT_OVERFLOW);          }          return true;        }      });      holder.content.setMaxLines(Integer.MAX_VALUE);//设置文本的最大行数，为整数的最大数值      holder.content.setText(mList.get(position).getContent());    } else {      //如果之前已经初始化过了，则使用保存的状态。      switch (state) {        case STATE_NOT_OVERFLOW:          holder.expandOrFold.setVisibility(View.GONE);          break;        case STATE_COLLAPSED:          holder.content.setMaxLines(MAX_LINE_COUNT);          holder.expandOrFold.setVisibility(View.VISIBLE);          holder.expandOrFold.setText("全文");          break;        case STATE_EXPANDED:          holder.content.setMaxLines(Integer.MAX_VALUE);          holder.expandOrFold.setVisibility(View.VISIBLE);          holder.expandOrFold.setText("收起");          break;      }      holder.content.setText(mList.get(position).getContent());    }    //全文和收起的点击事件    holder.expandOrFold.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View v) {        int state = mTextStateList.get(mList.get(position).getId(), STATE_UNKNOW);        if (state == STATE_COLLAPSED) {          holder.content.setMaxLines(Integer.MAX_VALUE);          holder.expandOrFold.setText("收起");          mTextStateList.put(mList.get(position).getId(), STATE_EXPANDED);        } else if (state == STATE_EXPANDED) {          holder.content.setMaxLines(MAX_LINE_COUNT);          holder.expandOrFold.setText("全文");          mTextStateList.put(mList.get(position).getId(), STATE_COLLAPSED);        }      }    });    //删除点击事件    holder.delete.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View view) {        mList.remove(position);        notifyDataSetChanged();      }    });  }  @Override  public int getItemCount() {    return mList.size();  }  public class MyViewHolder extends RecyclerView.ViewHolder {    public TextView nickname;    public TextView content;    public TextView delete;    public TextView expandOrFold;    public MyViewHolder(View itemView) {      super(itemView);      nickname = (TextView) itemView.findViewById(R.id.tv_nickname);      content = (TextView) itemView.findViewById(R.id.tv_content);      delete = (TextView) itemView.findViewById(R.id.tv_delete);      expandOrFold = (TextView) itemView.findViewById(R.id.tv_expand_or_fold);    }  }}

package com.wildma.wildmaexpandfoldtext;/** * Author   wildma * DATE    2017/8/3 * Des    ${TODO} */public class ExpandFoldTextBean {  private String content;//内容  private int id;//该条数据的id  public String getContent() {    return content;  }  public void setContent(String content) {    this.content = content;  }  public int getId() {    return id;  }  public void setId(int id) {    this.id = id;  }}

<?xml version="1.0" encoding="utf-8"?><RelativeLayout  android:id="@+id/activity_main"  xmlns:android="http://schemas.android.com/apk/res/android"  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.support.v7.widget.RecyclerView    android:id="@+id/recyclerview"    android:layout_width="match_parent"    android:layout_height="match_parent">  </android.support.v7.widget.RecyclerView></RelativeLayout>

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"       android:layout_width="match_parent"       android:layout_height="wrap_content"       android:orientation="vertical"       android:paddingBottom="@dimen/activity_vertical_margin"       android:paddingLeft="@dimen/activity_horizontal_margin"       android:paddingRight="@dimen/activity_horizontal_margin"       android:paddingTop="@dimen/activity_vertical_margin">  <LinearLayout    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_gravity="center_vertical"    android:orientation="horizontal">    <ImageView      android:layout_width="40dp"      android:layout_height="40dp"      android:layout_marginRight="16dp"      android:gravity="center"      android:scaleType="centerCrop"      android:src="@mipmap/ic_launcher"/>    <RelativeLayout      android:layout_width="match_parent"      android:layout_height="wrap_content">      <TextView        android:id="@+id/tv_nickname"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="wildma"        android:textColor="@android:color/black"        android:textSize="14sp"/>      <TextView        android:id="@+id/tv_delete"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentRight="true"        android:layout_marginLeft="12dp"        android:paddingLeft="5dp"        android:paddingRight="5dp"        android:text="删除"        android:textColor="@android:color/holo_red_dark"        android:textSize="14sp"/>    </RelativeLayout>  </LinearLayout>  <LinearLayout    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_marginLeft="56dp"    android:orientation="vertical"    android:paddingBottom="8dp">    <TextView      android:id="@+id/tv_content"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:layout_marginBottom="8dp"      android:alpha="0.85"      android:ellipsize="end"      android:text="内容"      android:textColor="@android:color/black"      android:textSize="14sp"/>    <TextView      android:id="@+id/tv_expand_or_fold"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:text="全文"      android:textColor="@color/colorPrimaryDark"      android:textSize="14sp"/>  </LinearLayout>  <View    android:layout_width="match_parent"    android:layout_height="0.5dp"    android:background="@android:color/black"/></LinearLayout>