React Native：用java编写AsyncStorage
所以我在java端上有这个来自Intent文本，我想保存到AsyncStorage ，以便之后可以通过React访问它。
我有机会实现这个目标吗？
我有：
package com.myapp; import android.app.Activity; import android.os.Bundle; import android.view.KeyEvent; import android.content.Intent; import com.facebook.react.LifecycleState; import com.facebook.react.ReactInstanceManager; import com.facebook.react.ReactRootView; import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler; import com.facebook.react.shell.MainReactPackage; import com.facebook.soloader.SoLoader; public class MainActivity extends Activity implements DefaultHardwareBackBtnHandler { private ReactInstanceManager mReactInstanceManager; private ReactRootView mReactRootView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mReactRootView = new ReactRootView(this); mReactInstanceManager = ReactInstanceManager.builder() .setApplication(getApplication()) .setBundleAssetName("index.android.bundle") .setJSMainModuleName("index.android") .addPackage(new MainReactPackage()) .setUseDeveloperSupport(BuildConfig.DEBUG) .setInitialLifecycleState(LifecycleState.RESUMED) .build(); mReactRootView.startReactApplication(mReactInstanceManager, "BrowseItLater", null); setContentView(mReactRootView); // This code is from http://developer.android.com/training/sharing/receive.html Intent intent = getIntent(); String action = intent.getAction(); String type = intent.getType(); if (Intent.ACTION_SEND.equals(action) && type != null) { handleSendText(intent); } } void handleSendText(Intent intent) { String sharedText = intent.getStringExtra(Intent.EXTRA_TEXT); if (sharedText != null) { // How can I handle this ???? } } // ... }
或者是否有任何其他解决方案使MainActivity.java与JS通信？
经过一番争吵， 我终于找到了解决方案 。 它不使用AsyncStorage因为我在源代码中读到AsyncStorage实际上可能位于不同的位置（SQLite，或其他东西），具体取决于手机。 复制这个逻辑会很脏。
相反，我创建了一个像doc建议的模块，并将inputText作为参数传递给MainActivity.java的.addPackage(new EphemeralStoragePackage(inputText))调用。
该模块将一个方法readOnceAsync暴露给JS世界，我稍后可以调用它：
NativeModules.EphemeralStorage.readOnceAsync((text :string) => { if (text.length) { this._addValue(text); // this method is in charge of storing in AsyncStorage } })
这是详细信息：
// android/app/src/main/java/com/appname/modules/ephemeralstorage/EphemeralStorageModule.java package com.browseitlater.modules.ephemeralstorage; import com.facebook.react.bridge.NativeModule; import com.facebook.react.bridge.ReactApplicationContext; import com.facebook.react.bridge.ReactContext; import com.facebook.react.bridge.ReactContextBaseJavaModule; import com.facebook.react.bridge.ReactMethod; import com.facebook.react.bridge.Callback; import java.util.Map; public class EphemeralStorageModule extends ReactContextBaseJavaModule { private String inputText; public EphemeralStorageModule(ReactApplicationContext reactContext, String _inputText) { super(reactContext); this.inputText = _inputText; } @Override public String getName() { return "EphemeralStorage"; } public String getInputText() { return inputText; } @ReactMethod public void readOnceAsync(Callback successCallback) { successCallback.invoke(getInputText()); this.inputText = null; } }
和
// android/app/src/main/java/com/appname/modules/ephemeralstorage/EphemeralStoragePackage.java package com.browseitlater.modules.ephemeralstorage; import android.app.Activity; import java.util.*; import com.facebook.react.ReactPackage; import com.facebook.react.bridge.JavaScriptModule; import com.facebook.react.bridge.NativeModule; import com.facebook.react.bridge.ReactApplicationContext; import com.facebook.react.uimanager.ViewManager; public class EphemeralStoragePackage implements ReactPackage { private String inputText; public EphemeralStoragePackage(String _inputText) { super(); this.inputText = _inputText; } @Override public List createNativeModules(ReactApplicationContext reactContext) { List modules = new ArrayList<>(); modules.add(new EphemeralStorageModule(reactContext, getInputText())); return modules; } @Override public List> createJSModules() { return Collections.emptyList(); } @Override public List createViewManagers(ReactApplicationContext reactContext) { return Collections.emptyList(); } public String getInputText() { return inputText; } }
最后在MainActivity.java ，我的onCreate方法如下所示：
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mReactRootView = new ReactRootView(this); Intent intent = getIntent(); String action = intent.getAction(); String type = intent.getType(); String inputText = intent.getStringExtra(Intent.EXTRA_TEXT); mReactInstanceManager = ReactInstanceManager.builder() .setApplication(getApplication()) .setBundleAssetName("index.android.bundle") .setJSMainModuleName("index.android") .addPackage(new MainReactPackage()) .addPackage(new EphemeralStoragePackage(inputText)) .setUseDeveloperSupport(BuildConfig.DEBUG) .setInitialLifecycleState(LifecycleState.RESUMED) .build(); mReactRootView.startReactApplication(mReactInstanceManager, "BrowseItLater", null); setContentView(mReactRootView); }
如果您不想编写本机模块，可以在MainActivity.java执行此操作
在MainActivity类中声明一个全局变量（不要忘记导入com.facebook.react.modules.storage.ReactDatabaseSupplier ）：
private ReactDatabaseSupplier mReactDatabaseSupplier;
在onCreate方法里面初始化全局变量：
mReactDatabaseSupplier = ReactDatabaseSupplier.getInstance(getApplicationContext());
声明一个私有方法来保存AsyncStorage的键/值对
private void saveKeyValuePair(String key, String value) { String sql = "INSERT OR REPLACE INTO catalystLocalStorage VALUES (?, ?);"; SQLiteStatement statement = mReactDatabaseSupplier.get().compileStatement(sql); try { mReactDatabaseSupplier.get().beginTransaction(); statement.clearBindings(); statement.bindString(1, key); statement.bindString(2, value); statement.execute(); mReactDatabaseSupplier.get().setTransactionSuccessful(); } catch (Exception e) { Log.w("YOUR_TAG", e.getMessage(), e); } finally { try { mReactDatabaseSupplier.get().endTransaction(); } catch (Exception e) { Log.w("YOUR_TAG", e.getMessage(), e); } } }
然后你可以像这样保存键/值对（例如在onCreate ）：
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mReactDatabaseSupplier = ReactDatabaseSupplier.getInstance(getApplicationContext()); saveKeyValuePair("myAsyncStorageKey", "myValueInAsyncStorageKey");
}
这是一种在React Native应用程序的AsyncStorage中保存的简单方法。 考虑编写本机模块。