<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"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"tools:context="com.figo.study.activity.TextActivity"><TextViewandroid:id="@+id/txt_msg"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_above="@+id/et_msg"android:text="@string/hello_world"android:textColor="#ffffff" /><EditTextandroid:id="@+id/et_msg"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_alignParentBottom="true"android:layout_alignParentLeft="true"android:layout_alignParentStart="true"android:layout_marginBottom="141dp" /></RelativeLayout>

package com.figo.study.activity;import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextPaint;
import android.text.TextWatcher;
import android.util.Log;
import android.widget.EditText;
import android.widget.TextView;
import com.figo.study.R;
import com.figo.study.utils.CommonUtil;
import java.util.ArrayList;/*** 控制在3行，自动调整textSize*/
public class TextActivity extends Activity {TextView mTxt;EditText mEt;int mDefaultTextSize = 50;int lineCount = 0;int lastTextLength = 0;boolean isMinus = false;int maxTextSize = 50;int minTextSize = 6;ArrayList<PositionTextSize> arrayListPts = new ArrayList<>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_text);initView();}private void initView() {mTxt = (TextView) findViewById(R.id.txt_msg);mTxt.setMaxWidth(600);mTxt.setTextSize(mDefaultTextSize);mEt = (EditText) findViewById(R.id.et_msg);mEt.addTextChangedListener(new TextWatcher() {@Overridepublic void beforeTextChanged(CharSequence s, int start, int count, int after) {}@Overridepublic void onTextChanged(CharSequence s, int start, int before, int count) {}@Overridepublic void afterTextChanged(Editable s) {mTxt.setText(s.toString());resizeTextSize(mTxt);}});}private void resizeTextSize(final TextView textView) {textView.post(new Runnable() {@Overridepublic void run() {TextPaint textPaint = textView.getPaint();float currentTextSize = CommonUtil.px2sp(TextActivity.this, textPaint.getTextSize());float newTextSize = currentTextSize;lineCount = textView.getLineCount();int currentTextLength = textView.getText().length();if (currentTextLength > lastTextLength) {isMinus = false;} else {//说明是在减isMinus = true;}lastTextLength = currentTextLength;if (lineCount > 3) {if (currentTextSize > minTextSize) {newTextSize = currentTextSize - 10;}PositionTextSize pts = new PositionTextSize();pts.textSize = currentTextSize;pts.position = currentTextLength;arrayListPts.add(pts);}if (isMinus) {newTextSize = findPositionTextSize(currentTextLength);}if ((newTextSize != currentTextSize) && newTextSize > 0) {textView.setTextSize(newTextSize);}Log.i("TextActivity", "getLineCount:" + lineCount);Log.i("TextActivity", "textSize：" + currentTextSize);Log.i("TextActivity", "textLength：" + currentTextLength);Log.i("TextActivity", "ArraryTextSize：" + arrayToString(arrayListPts));}});}private String arrayToString(ArrayList<PositionTextSize> arrPts) {StringBuffer buffer = new StringBuffer();for (PositionTextSize pts : arrPts) {buffer.append("position:" + pts.position);buffer.append(",textSize:" + pts.textSize + "|");}return buffer.toString();}private float findPositionTextSize(int position) {float textSize = 0;PositionTextSize result = null;int size = arrayListPts.size();for (int p = size - 1; p >= 0; p--) {if (arrayListPts.get(p).position > position) {result = arrayListPts.get(p);textSize = result.textSize;arrayListPts.remove(result);//删除重新训练
            }}return textSize;}public class PositionTextSize {int position;float textSize;}
}