1. 先完成自定义手势的Activity

1.1 因为需要存储手势文件所以需要声明权限：

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> //读取SD卡权限
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> //写入SD卡权限

1.2 简单写一个布局文件，其中用到了GestureOverlayView，相当于一个绘制组件。其中有一个重要属性gestureStrokeType，值为single时表示只绘制一笔，若要多笔绘制值应该设为multiple：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:andro
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context=".addgesture.Main3Activity">
 <Button
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:onClick="recognition"
  android:text="识别手势" />
 <TextView
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:gravity="center"
  android:text="请绘制手势" />
 <android.gesture.GestureOverlayView
  android:
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:gestureStrokeType="multiple" //多笔绘制
  ></android.gesture.GestureOverlayView>
</LinearLayout>

1.3 这里自定义了AlertDialog的样式；

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:andro
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical">
 <LinearLayout
  android:layout_width="match_parent"
  android:layout_height="wrap_content">
  <TextView
   android:layout_width="wrap_content"
   android:layout_height="match_parent"
   android:gravity="center"
   android:text="请输入手势名称" />
  <EditText  //输入手势的名称
   android:
   android:layout_width="match_parent"
   android:layout_height="match_parent" />
 </LinearLayout>
 <ImageView  //展示绘制的手势
  android:
  android:layout_width="match_parent"
  android:layout_height="match_parent" />
</LinearLayout>

1.4 代码部分：

package com.example.mygesture.addgesture;
import android.Manifest;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.gesture.Gesture;
import android.gesture.GestureLibraries;
import android.gesture.GestureLibrary;
import android.gesture.GestureOverlayView;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
import com.example.mygesture.R;
import com.example.mygesture.recognitiongesture.Main4Activity;
public class Main3Activity extends AppCompatActivity {
 GestureOverlayView gov;   //定义绘制组件
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main3);
  if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
   ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);  
  }    //高版本需要动态申请权限
  init();
 }
 private void init() {
  gov = findViewById(R.id.activity_main3_gov);
//  gov.setGestureColor(Color.RED);  //设置绘制的颜色
  gov.setGestureStrokeWidth(4);  //设置画笔的宽度
  gov.addOnGesturePerformedListener(new GestureOverlayView.OnGesturePerformedListener() { //设置绘制完成监听
   @Override
   public void onGesturePerformed(GestureOverlayView overlay, final Gesture gesture) {
    View saveDialog = getLayoutInflater().inflate(R.layout.save_dialog, null); //获取AlertDialog的布局样式
    final EditText editText = saveDialog.findViewById(R.id.save_dialog_et);
    ImageView imageView = saveDialog.findViewById(R.id.save_dialog_iv);
    Bitmap bitmap = gesture.toBitmap(128, 128, 10, 0xFFFF0000);  //将手势转换为位图
    imageView.setImageBitmap(bitmap);   //用ImageView加载手势图片
    new AlertDialog.Builder(Main3Activity.this).setView(saveDialog).setPositiveButton("确定", new DialogInterface.OnClickListener() {
     @Override
     public void onClick(DialogInterface dialog, int which) {
      GestureLibrary gestureLibrary = GestureLibraries.fromFile("/mnt/sdcard/mygesture");//利用手势库获取存放手势文件的地址
      gestureLibrary.addGesture(editText.getText().toString(), gesture);  //向手势库中添加手势名称和手势
      gestureLibrary.save();    //保存手势库
      Toast.makeText(Main3Activity.this, "保存成功", Toast.LENGTH_SHORT).show();
     }
    }).setNegativeButton("取消", null)
      .show();
   }
  });
 }
 public void recognition(View view) {
  Intent intent = new Intent(this, Main4Activity.class);
  startActivity(intent);
 }
}