[移动开发]Android与Flutter混合开发，超详细讲解

在跳转之前需要先在AndroidManifest.xml注册FlutterActivity。

在需要跳转的时候，使用FlutterActivity.withNewEngine()进行跳转：

startActivity(FlutterActivity.withNewEngine()
.initialRoute(“params”)
.build(xxxxActivity.this));

其中initialRoute是Android跳转到flutter需要的参数，非必需。 在flutter接收参数如下

…
class _MyHomePageState extends State {

String route = window.defaultRouteName;
…
}

window.defaultRouteName就是获取Android传递过来的参数，当Android端需要跳转多个flutter页面，通常这个用于路由分发，若需要的信息比较多的时候可以传递json字符串。注：window.defaultRouteName的导包为’dart:ui’，而不是’dart:html’。

• FlutterActivity间接跳转

所谓的间接跳转其实就是通过继承FlutterActivity来实现的

public class Hybrid extends FlutterActivity {

public final static String PARAMS = “params”;
private String params;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
params = getIntent().getStringExtra(PARAMS);
}

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@Override
public String getInitialRoute() {
return params == null ? super.getInitialRoute() : params;
}

public static void toFlutter(Context context, String params) {
Intent intent = new Intent(context, Hybrid.class);
intent.putExtra(PARAMS, params);
context.startActivity(intent);
}

}

在AndroidManifest.xm注册Hybrid后就可以通过

Hybrid.toFlutter(xxxxxActivity.this,“params”);

进行跳转。

• 通过FlutterEngine和BasicMessageChannel进行跳转

为什么会有这种方式，是因为使用前两种方式跳转时会有短暂的空白，使用起来感觉非常不流畅，严重影响用户体验。这种跳转方式和上面的两种不同，边跳边发，适用于多种场景。这里也不一定非要使用BasicMessageChannel，也可使用MethodChannel或EventChannel，只是混合开发通常涉及到两端频繁通信，个人更加倾向使用BasicMessageChannel，不分主客，使用和通信更方便。

1. FlutterEngine和BasicMessageChannel的初始化和使用

public class HyBridRouteAndMessageHandleCenter{
private static FlutterEngine flutterEngine;
private static BasicMessageChannel basicMessageChannel;
private static String channelName = “com.hybrid.basic.message.channel”;
public static final String ENGINE_ID = “default_engine_id”;
private static Context mContext;
private static BasicMessageChannel.Reply mReplay;

public static void init(Context context) {
mContext = context;
if (flutterEngine == null) {
flutterEngine = new FlutterEngine(context);
flutterEngine.getDartExecutor().executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault());
FlutterEngineCache.getInstance().put(ENGINE_ID, flutterEngine);
}

if (basicMessageChannel == null) {
if (flutterEngine != null) {
basicMessageChannel = new BasicMessageChannel(flutterEngine.getDartExecutor(), channelName, StandardMessageCodec.INSTANCE);
basicMessageChannel.setMessageHandler(new BasicMessageChannel.MessageHandler() {
@Override
public void onMessage(@Nullable @org.jetbrains.annotations.Nullable Object message, @NonNull @NotNull BasicMessageChannel.Reply reply) {
mReplay = reply;
// 接收消息并处理
handleMessage(message, reply);
}
});
}
}
}

// 处理消息
private static void handleMessage(Object message, BasicMessageChannel.Reply reply) {
…
}

public static void toFlutter(Context context, Object params) {
sendMessage(params);
context.startActivity(FlutterActivity.withCachedEngine(ENGINE_ID).build(context));
}

public static void sendMessage(Object object) {
if (basicMessageChannel != null) {
basicMessageChannel.send(object, new BasicMessageChannel.Reply() {
@Override
public void reply(@Nullable @org.jetbrains.annotations.Nullable Object reply) {
// 发送回调
…

}
});
}
}

public static void destroyEngine() {
if (flutterEngine != null) {
flutterEngine.destroy();
}
}
}