操作流程

1. 使用AndroidStudio创建一个空Android项目

2. 导入Unity的jar包（在Unity安装目录下搜索classes,随意复制一个到Android项目文件夹的libs目录下）

3. 添加脚本

   package com.company.baseet;
   
   import java.lang.reflect.Field;
   import java.lang.reflect.InvocationTargetException;
   import java.lang.reflect.Method;
   
   import android.app.Activity;
   import android.content.ComponentName;
   import android.content.Intent;
   import android.content.pm.PackageManager;
   import android.util.Log;
   
   public class Restart {
   
       private static final String TAG = "restart";
       private static Restart _instance;
       private Class<?> _unityPlayerClass;
       private Field _unityPlayerActivityField;
       private Method _unitySendMessageMethod;
       public Activity _activity;
       private String gameObject;
       public static Restart getInstanceInActivity() {
           return _instance;
       }
       //创建实例对象
       public static Restart getInstance(String gameObject) {
           if (_instance == null) {
               _instance = new Restart( gameObject);
           }
           return _instance;
       }
       //重启应用
       public void RestartGame ()
       {
           Log.i(TAG,"调用Android重启");
           PackageManager packageManager = _activity.getPackageManager();
           Intent intent = packageManager.getLaunchIntentForPackage(_activity.getPackageName());
           ComponentName componentName = intent.getComponent();
           Intent mainIntent = Intent.makeRestartActivityTask (componentName);
           _activity.startActivity(mainIntent);
           System.exit(0);
       }
       //获取Unity实例
       private Restart(String gameObject)
       {
           this.gameObject = gameObject;
   
           try {
               //这里使用的是导入的unity jar 包中脚本文件
               this._unityPlayerClass =  Class.forName("com.unity3d.player.UnityPlayer");
   
               this._unityPlayerActivityField = this._unityPlayerClass
                       .getField("currentActivity");
               this._unitySendMessageMethod = this._unityPlayerClass.getMethod(
                       "UnitySendMessage", new Class[] { String.class,
                               String.class, String.class });
   
           } catch (ClassNotFoundException e) {
               Log.i(TAG, "could not find UnityPlayer class: " + e.getMessage());
           } catch (NoSuchFieldException e) {
               Log.i(TAG,
                       "could not find currentActivity field: " + e.getMessage());
           } catch (NoSuchMethodException e) {
               Log.i(TAG, "could not find UnityPlayer class: " + e.getMessage());
           } catch (Exception e) {
               Log.i(TAG,
                       "unkown exception occurred locating getActivity(): "
                               + e.getMessage());
           }
           getActivity();
       }
       //获取Unity的Activity
       public Activity getActivity() {
           if(this._activity == null) {
               try {
                   this._activity = (Activity) this._unityPlayerActivityField.get(this._unityPlayerClass);
               } catch (IllegalArgumentException e) {
                   Log.i(TAG, "error getting currentActivity: " + e.getMessage());
               } catch (IllegalAccessException e) {
                   Log.i(TAG, "error getting currentActivity: " + e.getMessage());
               }
           }
   
           return this._activity;
       }
       //接受Unity发送的消息
       public void UnitySendMessage(String m, String p) {
   //         UnityPlayer.UnitySendMessage(gameObject, m, p);
   
           if (this._unitySendMessageMethod != null) {
               try {
   
                   this._unitySendMessageMethod.invoke(null, new Object[] {
                           gameObject, m, p });
               } catch (IllegalArgumentException e) {
                   Log.i(TAG,
                           "could not find UnitySendMessage method: "
                                   + e.getMessage());
               } catch (IllegalAccessException e) {
                   Log.i(TAG,
                           "could not find UnitySendMessage method: "
                                   + e.getMessage());
               } catch (InvocationTargetException e) {
                   Log.i(TAG,
                           "could not find UnitySendMessage method: "
                                   + e.getMessage());
               }
           } else {
               Log.i(TAG, "UnitySendMessage: " + gameObject + ", " + m + ", " + p);
           }
       }
   }
   

4. 打包jar，将jar文件复制到Unity项目中

5. Unity调用脚本

           public void ResartApp()
           {
               Log.Debug(" ResartApp");
   #if UNITY_ANDROID
               //获取导入的安卓包下的类
               AndroidJavaClass jc = new AndroidJavaClass("com.company.baseet.Restart");
               //通过类创建对象
               AndroidJavaObject jo = jc.CallStatic<AndroidJavaObject>("getInstance", "ResartApp");
               //调用对象重启方法
               jo.Call("RestartGame");
   #else
               EditorApplication.isPlaying = false;
   #endif
           }