Android上的Unity程序，程序左侧是ugui制作的listview，右边由UniWebview2占据剩余空间。正常情况下没有任何问题。一旦该程序进入后台，再转回前台，发现listview的空间全是黑色，也就是listview看起来消失了。
这个问题的解决方式是：
让webview能hide和show，在进入后台的时候hide，进前台的时候show。
因为Unity有OnApplicationPause，所以我们利用在这个地方动手。
OnApplicationPause的参数是true的时候，我们知道程序会进入后台了，所以调用webview的hide().
OnApplicationPause的参数是false的时候，我们知道程序会进入前台了，所以调用webview的show().
问题解决。
Orbit Camera在观察物体，比如模型观察器中使用，这种camera总是以一个模型为目标，观察点围绕该目标，实现：
1、相机远近操控
2、相机水平旋转操控
3、相机垂直方向抬高、压低
总之，这种相机模型还是非常常用的。下面是代码：
using UnityEngine;
using System.Collections;
public class OrbitCamera : MonoBehaviour
{
public Transform target;
public float distance = 5.0f;
public float xSpeed = 120.0f;
public float ySpeed = 120.0f;
public float yMinLimit = -20f;
public float yMaxLimit = 80f;
public float distanceMin = .5f;
public float distanceMax = 15f;
public float mouseTranslateSpeed = 20;
float x = 0.0f;
float y = 0.0f;
void Start()
{
Vector3 angles = transform.eulerAngles;
x = angles.y;
y = angles.x;
Quaternion rotation = Quaternion.Euler(y, x, 0);
RaycastHit hit;
if (Physics.Linecast(target.position, transform.position, out hit))
{
distance -= hit.distance;
}
Vector3 negDistance = new Vector3(0.0f, 0.0f, -distance);
Vector3 position = rotation * negDistance + target.position;
transform.position = position;
}
void LateUpdate()
{
distance = Mathf.Clamp(distance - Input.GetAxis("Mouse ScrollWheel") * mouseTranslateSpeed, distanceMin, distanceMax);
if (Input.GetMouseButton(0) && target)
{
x += Input.GetAxis("Mouse X") * xSpeed * distance * 0.02f;
y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;
y = ClampAngle(y, yMinLimit, yMaxLimit);
}
Quaternion rotation = Quaternion.Euler(y, x, 0);
transform.rotation = rotation;
RaycastHit hit;
if (Physics.Linecast(target.position, transform.position, out hit))
{
distance -= hit.distance;
}
Vector3 negDistance = new Vector3(0.0f, 0.0f, -distance);
Vector3 position = rotation * negDistance + target.position;
transform.position = position;
}
public static float ClampAngle(float angle, float min, float max)
{
while(angle < -360f)
angle += 360F;
while(angle > 360f)
angle -= 360f;
return Mathf.Clamp(angle, min, max);
}
}
在Unity面板上出现的参数说明：
1、Target：相机观察目标
2、X Speed：鼠标水平移动控制相机旋转的速度，一般不用太大，个位数即可。
3、Y Speed：鼠标上下控制相机仰角的速度，100左右
4、Y Min （Max）Limit：鼠标仰角的最小最大值，-90到90
5、Distance Min：相机离开目标中心的最小距离
6、Distance Max： 相机离开目标中心的最大距离
7、Mouse Translate Speed：鼠标拉近拉远时的速度
写了个蓝牙的server，可以直接编译成aar，供unity使用。技术上利用了service和java反射，因此无需在Unity中注入和改动任何东西。
代码在github，这里。
编译出的aar直接放Unity工程的Assets目录下的任何地方即可开始使用。
Unity代码开启和关闭蓝牙服务器：
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class NewBehaviourScript : MonoBehaviour {
AndroidJavaClass blueToothServer;
void Awake() {
AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
AndroidJavaObject unityContext = currentActivity.Call<AndroidJavaObject>("getApplicationContext");
blueToothServer = new AndroidJavaClass ("com.huashi.bluetuth.BlueTuthServer");
blueToothServer.CallStatic ("init", unityContext);
}
void Start () {
GameObject.Find ("Canvas/Start").GetComponent<Button> ().onClick.AddListener (onStartClick);
GameObject.Find ("Canvas/Stop").GetComponent<Button> ().onClick.AddListener (onStopClick);
}
void onStartClick() {
blueToothServer.CallStatic ("startServer");
}
void onStopClick () {
blueToothServer.CallStatic ("stopServer");
}
}
Unity代码接收服务器消息：
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Text;
public class JavaMessageReceiver : MonoBehaviour {
public void ReceiveJavaMessage(string msg) {
Debug.Log ("Receive msg.");
byte[] bytes = Encoding.ASCII.GetBytes (msg);
if (bytes.Length != 0) {
switch (bytes [0]) {
case 1:
Debug.Log ("CLIENT_CONNECTED");
string real = msg.Substring (1);
Debug.Log ("Content is: " + real);
break;
case 2:
Debug.Log ("RECEIVE_CLIENT_DATA");
for (int i = 1; i < bytes.Length; ++i) {
Debug.Log ("index = " + i + ":" + bytes[i]);
}
break;
case 3:
Debug.Log ("REMOTE_SHUTDOWN");
string realll = msg.Substring (1);
Debug.Log ("Content is: " + realll);
break;
default:
Debug.Log ("Received from java, tag = " + bytes[0]);
break;
}
}
}
}
上面的这个代码必须挂在一个名字为JavaMessageReceiver的GameObject上。
Unity侧：
AAR文件可以放在assets目录的任何地方
AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");AndroidJavaObject unityContext = currentActivity.Call<AndroidJavaObject>("getApplicationContext");
这三步能拿到大多数aar需要的context，activity
AndroidJavaClass.CallStatic(methodName, parameter0, parameter1, pameter2);
使用最上面的方法得到Android Class后，内部的static方法，用这个方法调用。多个参数依次排列在方法名字后面即可（官方文档没有例子，使用了数组形式，没测过）
AndroidJavaClass.Call(methodName, parameter0, parameter1, pameter2);
调用实例的方法。
Java侧：
com.unity3d.player包中，有类
UnityPlayer，提供方法UnitySendMessage(GameObjectName, MethodName, parameter)
该类的反编译结果可以在这里看到。截取方法的定义如下：
public static native void UnitySendMessage(String var0, String var1, String var2);
写插件的过程中，如果不想让java侧代码一定跟Unity3d绑定，那么可以使用java的反射来取得上面的方法。
Class playerClass = Class.forName("com.unity3d.player.UnityPlayer");
Log.d("MyTag", playerClass.toString());
Method sendMessageMethod = playerClass.getMethod("UnitySendMessage", String.class, String.class, String.class);
Log.d("MyTag", sendMessageMethod.getName() + ", " + sendMessageMethod.toString());
string path;
void Start () {
path = "/storage/emulated/0/Android/data/test.apk";
Debug.Log (path);
GameObject.Find ("Canvas/Button").GetComponent<Button> ().onClick.AddListener (OnClick);
}
// Update is called once per frame
void OnClick () {
installApp (path);
}
public bool installApp(string apkPath)
{
try
{
AndroidJavaClass intentObj = new AndroidJavaClass("android.content.Intent");
string ACTION_VIEW = intentObj.GetStatic<string>("ACTION_VIEW");
int FLAG_ACTIVITY_NEW_TASK = intentObj.GetStatic<int>("FLAG_ACTIVITY_NEW_TASK");
AndroidJavaObject intent = new AndroidJavaObject("android.content.Intent", ACTION_VIEW);
AndroidJavaObject fileObj = new AndroidJavaObject("java.io.File", apkPath);
AndroidJavaClass uriObj = new AndroidJavaClass("android.net.Uri");
AndroidJavaObject uri = uriObj.CallStatic<AndroidJavaObject>("fromFile", fileObj);
intent.Call<AndroidJavaObject>("setDataAndType", uri, "application/vnd.android.package-archive");
intent.Call<AndroidJavaObject>("addFlags", FLAG_ACTIVITY_NEW_TASK);
intent.Call<AndroidJavaObject>("setClassName", "com.android.packageinstaller", "com.android.packageinstaller.PackageInstallerActivity");
AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
currentActivity.Call("startActivity", intent);
GameObject.Find("TextDebug").GetComponent<Text>().text = "Success";
return true;
}
catch (System.Exception e)
{
GameObject.Find("TextDebug").GetComponent<Text>().text = "Error: " + e.Message;
return false;
}
}
方法installApp能通过android安装指定路径下的apk。跑起来后，如果apk存在，会弹出对话框，让用户确认安装；安装完毕，会弹出对话框让用户选择“完成”还是“打开”。
API 24以上：
//For API 24 and above
private bool installApp(string apkPath)
{
bool success = true;
GameObject.Find("TextDebug").GetComponent<Text>().text = "Installing App";
try
{
//Get Activity then Context
AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
AndroidJavaObject unityContext = currentActivity.Call<AndroidJavaObject>("getApplicationContext");
//Get the package Name
string packageName = unityContext.Call<string>("getPackageName");
string authority = packageName + ".fileprovider";
AndroidJavaClass intentObj = new AndroidJavaClass("android.content.Intent");
string ACTION_VIEW = intentObj.GetStatic<string>("ACTION_VIEW");
AndroidJavaObject intent = new AndroidJavaObject("android.content.Intent", ACTION_VIEW);
int FLAG_ACTIVITY_NEW_TASK = intentObj.GetStatic<int>("FLAG_ACTIVITY_NEW_TASK");
int FLAG_GRANT_READ_URI_PERMISSION = intentObj.GetStatic<int>("FLAG_GRANT_READ_URI_PERMISSION");
//File fileObj = new File(String pathname);
AndroidJavaObject fileObj = new AndroidJavaObject("java.io.File", apkPath);
//FileProvider object that will be used to call it static function
AndroidJavaClass fileProvider = new AndroidJavaClass("android.support.v4.content.FileProvider");
//getUriForFile(Context context, String authority, File file)
AndroidJavaObject uri = fileProvider.CallStatic<AndroidJavaObject>("getUriForFile", unityContext, authority, fileObj);
intent.Call<AndroidJavaObject>("setDataAndType", uri, "application/vnd.android.package-archive");
intent.Call<AndroidJavaObject>("addFlags", FLAG_ACTIVITY_NEW_TASK);
intent.Call<AndroidJavaObject>("addFlags", FLAG_GRANT_READ_URI_PERMISSION);
currentActivity.Call("startActivity", intent);
GameObject.Find("TextDebug").GetComponent<Text>().text = "Success";
}
catch (System.Exception e)
{
GameObject.Find("TextDebug").GetComponent<Text>().text = "Error: " + e.Message;
success = false;
}
return success;
}