<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:more="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:id="@+id/activity_main"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context="com.example.my.textviewdemotest.MainActivity">

 <TextView
 android:id="@+id/textView1"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:textColor="@android:color/black"
 android:textSize="18sp">
 </TextView>

 <RelativeLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content">

 <TextView
 android:id="@+id/expand_text"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="更多"
 android:textSize="18sp"
 android:visibility="gone"/>

 <ImageView
 android:id="@+id/expand_view1"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_alignParentRight="true"
 android:paddingBottom="5dip"
 android:paddingLeft="5dip"
 android:paddingRight="5dip"
 android:paddingTop="5dip"
 android:src="@drawable/ic_expand_more_red_700_24dp"
 android:visibility="gone"
 />
 </RelativeLayout>
 <!-- 第二種方法 -->
 <com.example.my.textviewdemotest.TextMoreTextView
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:ellipsize="end"
 more:maxLine="2"
 more:text="@string/text"
 more:textColor="@android:color/black"
 more:textSize="18dip">
 </com.example.my.textviewdemotest.TextMoreTextView>
</LinearLayout>

package com.example.my.textviewdemotest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.view.animation.Transformation;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

 TextView text1;
 ImageView mImageView1;
 TextView expandText;
 //TextMoreTextView text2;

 boolean isExpand;//是否已展開的狀態(tài)
 private int maxDescripLine = 3; //TextView默認(rèn)最大展示行數(shù)
 private int deltaValue;//默認(rèn)高度，即前邊由maxLine確定的高度
 private int startValue;//起始高度
 private int durationMillis = 350;//動(dòng)畫持續(xù)時(shí)間

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 text1 = (TextView) findViewById(R.id.textView1);
 // text2= (TextMoreTextView) findViewById(R.id.text_textView);
 expandText = (TextView) findViewById(R.id.expand_text);

 mImageView1 = (ImageView) findViewById(R.id.expand_view1);
 mImageView1.setOnClickListener(this);

 text1.setText(getText(R.string.text));
 //第二種可以在這里直接設(shè)置文字
 // text2.setText(getText(R.string.text));
 //這里大家可以根據(jù)實(shí)際情況來設(shè)置文字的高度，做個(gè)判斷（可能會(huì)文字只有一行，也會(huì)占據(jù)maxDescripLine行）
 text1.setHeight(text1.getLineHeight() * maxDescripLine);
 text1.post(new Runnable() {
 @Override
 public void run() {
 mImageView1.setVisibility(text1.getLineCount() > maxDescripLine ? View.VISIBLE : View.GONE);
 expandText.setVisibility(text1.getLineCount() > maxDescripLine ? View.VISIBLE : View.GONE);
 }
 });
 }

 @Override
 public void onClick(View v) {
 switch (v.getId()) {
 case R.id.expand_view1:
 zheDie(text1, mImageView1);
 break;
 }

 }

 private void zheDie(final TextView text, ImageView imageView) {
 isExpand = !isExpand;
 text.clearAnimation();
 startValue = text.getHeight();
 if (isExpand) {
 /**
 * 折疊動(dòng)畫
 * 從實(shí)際高度縮回起始高度
 */
 deltaValue = text.getLineHeight() * text.getLineCount() - startValue;
 RotateAnimation animation = new RotateAnimation(0, 180, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 imageView.startAnimation(animation);
 expandText.setText("收起");
 } else {
 /**
 * 展開動(dòng)畫
 * 從起始高度增長(zhǎng)至實(shí)際高度
 */
 deltaValue = text.getLineHeight() * maxDescripLine - startValue;
 RotateAnimation animation = new RotateAnimation(180, 0, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 imageView.startAnimation(animation);
 expandText.setText("更多");
 }
 Animation animation = new Animation() {
 protected void applyTransformation(float interpolatedTime, Transformation t) { //根據(jù)ImageView旋轉(zhuǎn)動(dòng)畫的百分比來顯示textview高度，達(dá)到動(dòng)畫效果
 text.setHeight((int) (startValue + deltaValue * interpolatedTime));
 }
 };
 animation.setDuration(durationMillis);
 text.startAnimation(animation);
 }
}

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="MoreTextStyle">
 <attr name="textSize" format="dimension"/>
 <attr name="textColor" format="color"/>
 <attr name="maxLine" format="integer" />
 <attr name="text" format="string" />
 </declare-styleable>
</resources>

package com.example.my.textviewdemotest;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewTreeObserver;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.view.animation.Transformation;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class TextMoreTextView extends LinearLayout {
 protected TextView contentView;
 protected ImageView expandView;

 protected int textColor;
 protected float textSize;
 protected int maxLine;
 protected String text;

 public int defaultTextColor = Color.BLACK;//默認(rèn)文字顏色
 public int defaultTextSize = 12; //默認(rèn)文字大小
 public int defaultLine = 3; //默認(rèn)行數(shù)

 public TextMoreTextView(Context context, AttributeSet attrs) {
 super(context, attrs);
 initalize();
 initWithAttrs(context, attrs);
 // bindListener();
 }

 protected void initWithAttrs(Context context, AttributeSet attrs) {
 TypedArray a = context.obtainStyledAttributes(attrs,
 R.styleable.MoreTextStyle);
 int textColor = a.getColor(R.styleable.MoreTextStyle_textColor,
 defaultTextColor);
 textSize = a.getDimensionPixelSize(R.styleable.MoreTextStyle_textSize, defaultTextSize);
 maxLine = a.getInt(R.styleable.MoreTextStyle_maxLine, defaultLine);
 text = a.getString(R.styleable.MoreTextStyle_text);
 bindTextView(textColor, textSize, maxLine, text);
 a.recycle();
 }

 protected void initalize() {
 setOrientation(VERTICAL);
 setGravity(Gravity.RIGHT);
 contentView = new TextView(getContext());
 addView(contentView, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
 expandView = new ImageView(getContext());
 int padding = dip2px(getContext(), 5);
 expandView.setPadding(padding, padding, padding, padding);
 expandView.setImageResource(R.drawable.ic_expand_more_red_700_24dp);
 LayoutParams llp = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
 addView(expandView, llp);
 }

 protected void bindTextView(int color, float size, final int line, String text) {
 contentView.setTextColor(color);
 contentView.setTextSize(TypedValue.COMPLEX_UNIT_PX, size);
 contentView.setText(text);
 ViewTreeObserver observer = contentView.getViewTreeObserver();
 observer.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
 //判斷寫在這個(gè)方法里面能拿到contentView.getLineCount()，否則返回時(shí)0；
 @Override
 public void onGlobalLayout() {
 ViewTreeObserver obs = contentView.getViewTreeObserver();
 obs.removeGlobalOnLayoutListener(this);
 if (contentView.getLineCount() < line) {
 contentView.setHeight(contentView.getLineHeight() * contentView.getLineCount());
 } else {
 contentView.setHeight(contentView.getLineHeight() * line);
 bindListener();//只有在行數(shù)大于設(shè)定行數(shù)才會(huì)執(zhí)行這個(gè)方法，做了調(diào)整否則會(huì)有bug。
 }
 //Log.e("aaa", "bindTextView111: " + contentView.getLineCount());//返回0，為什么
 }
 });

 post(new Runnable() {
 @Override
 public void run() {
 expandView.setVisibility(contentView.getLineCount() > line ? View.VISIBLE : View.GONE);
 //Log.e("aaa", "run: "+contentView.getLineCount() );
 }
 });
 }

 protected void bindListener() {
 setOnClickListener(new OnClickListener() {
 boolean isExpand;

 @Override
 public void onClick(View v) {
 isExpand = !isExpand;
 contentView.clearAnimation();
 final int deltaValue;
 final int startValue = contentView.getHeight();
 int durationMillis = 350;
 if (isExpand) {
 deltaValue = contentView.getLineHeight() * contentView.getLineCount() - startValue;
 RotateAnimation animation = new RotateAnimation(0, 180, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 expandView.startAnimation(animation);
 } else {
 deltaValue = contentView.getLineHeight() * maxLine - startValue;
 RotateAnimation animation = new RotateAnimation(180, 0, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
 animation.setDuration(durationMillis);
 animation.setFillAfter(true);
 expandView.startAnimation(animation);
 }
 Animation animation = new Animation() {
 protected void applyTransformation(float interpolatedTime, Transformation t) {
 contentView.setHeight((int) (startValue + deltaValue * interpolatedTime));
 }

 };
 animation.setDuration(durationMillis);
 contentView.startAnimation(animation);
 }
 });
 }

 public TextView getTextView() {
 return contentView;
 }

 public void setText(CharSequence charSequence) {
 contentView.setText(charSequence);
 }

 public static int dip2px(Context context, float dipValue) {
 final float scale = context.getResources().getDisplayMetrics().density;
 return (int) (dipValue * scale + 0.5f);
 }
}