Android TextView仿微信可折叠效果

import android.content.Context;import android.content.res.TypedArray;import android.util.AttributeSet;import android.view.LayoutInflater;import android.view.MotionEvent;import android.view.View;import android.view.ViewTreeObserver;import android.widget.LinearLayout;import android.widget.TextView;/** * 可折叠的textview */public class ExpandTextView extends LinearLayout {  public static final int DEFAULT_MAX_LINES = 3;  private TextView contentText;  private TextView textPlus;  private int showLines;  private ExpandStatusListener expandStatusListener;  private boolean isExpand;  public ExpandTextView(Context context) {    super(context);    initView();  }  public ExpandTextView(Context context, AttributeSet attrs) {    super(context, attrs);    initAttrs(attrs);    initView();  }  public ExpandTextView(Context context, AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    initAttrs(attrs);    initView();  }  private void initAttrs(AttributeSet attrs) {    TypedArray typedArray = getContext().getTheme().obtainStyledAttributes(attrs, R.styleable.ExpandTextView, 0, 0);    try {      showLines = typedArray.getInt(R.styleable.ExpandTextView_showLines, DEFAULT_MAX_LINES);    }finally {      typedArray.recycle();    }  }  private void initView() {    setOrientation(LinearLayout.VERTICAL);    LayoutInflater.from(getContext()).inflate(R.layout.layout_magic_text, this);    contentText = (TextView) findViewById(R.id.contentText);    if(showLines > 0){      contentText.setMaxLines(showLines);    }    textPlus = (TextView) findViewById(R.id.textPlus);    textPlus.setOnClickListener(new OnClickListener() {      @Override      public void onClick(View view) {        String textStr = textPlus.getText().toString().trim();        if("全文".equals(textStr)){          contentText.setMaxLines(Integer.MAX_VALUE);          textPlus.setText("收起");          setExpand(true);        }else{          contentText.setMaxLines(showLines);          textPlus.setText("全文");          setExpand(false);        }        //通知外部状态已变更        if(expandStatusListener != null){          expandStatusListener.statusChange(isExpand());        }      }    });  }  public void setText(final CharSequence content){    //在开始绘制contentText内容时，进行监听    contentText.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {      @Override      public boolean onPreDraw() {        // 避免重复监听        contentText.getViewTreeObserver().removeOnPreDrawListener(this);        //获取当前文本的行数        int linCount = contentText.getLineCount();        if(linCount > showLines){          if(isExpand){            contentText.setMaxLines(Integer.MAX_VALUE);            textPlus.setText("收起");          }else{            contentText.setMaxLines(showLines);            textPlus.setText("全文");          }          textPlus.setVisibility(View.VISIBLE);        }else{          textPlus.setVisibility(View.GONE);        }        return true;      }    });    contentText.setText(content);  }  public void setExpand(boolean isExpand){    this.isExpand = isExpand;  }  public boolean isExpand(){    return this.isExpand;  }  public void setExpandStatusListener(ExpandStatusListener listener){    this.expandStatusListener = listener;  }  public interface ExpandStatusListener{    void statusChange(boolean isExpand);  }  @Override  public boolean onTouchEvent(MotionEvent event) {    return textPlus.dispatchTouchEvent(event);  }}

<?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="match_parent"       android:orientation="vertical">  <TextView    android:id="@+id/contentText"    android:textSize="18sp"    android:textColor="#000000"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:text=""/>  <TextView    android:id="@+id/textPlus"    android:textSize="18sp"    android:textColor="#666666"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_marginTop="15dp"    android:text=""/></LinearLayout>

<declare-styleable name="ExpandTextView">    <attr name="showLines" format="integer"/></declare-styleable>

<mo.yumf.com.myviews.ExpandTextView    android:id="@+id/expandTextView"    android:layout_width="match_parent"    android:layout_height="wrap_content"    app:showLines="4"/>