如何在Android上正确阅读AsyncStorage [英] How to Read AsyncStorage on Android Correctly

问题描述

似乎可以从Android(本机)访问AsyncStorage；但我仍在努力使之工作.

It seems that it's possible access the AsyncStorage from Android (native); but I still struggling to make this work.

在我的React Native应用程序中，我有类似的东西:

In my React Native application, I have something like:

商店

const config = {
  ...
}

export const reducers = {
  ...
  user: user
}


let rootReducer = combineReducers(reducers)
let reducer = persistReducer(config, rootReducer)

User Reducer

export class Actions {
    ...
}

const initialState = {
      first_name: : null,
      last_name: : null,
      email: null,
      addresses: [
          { ... }
      ]
    }
  }
}

export const reducer = (state = initialState, action) => {
  switch (action.type) {
    ...
  }
}

从商店中获取用户

const user = store.getState().user
console.log(user.first_name) // Steve
...

---

现在，当我尝试从Android获取同一用户时，问题就开始了，这是我所有沮丧的尝试:

---

Now the issue starts when I try to get the same user from Android, of all my frustrated attempts this is what I have:

try {
    readableDatabase = ReactDatabaseSupplier.getInstance(getReactApplicationContext()).getReadableDatabase();
    catalystLocalStorage = readableDatabase.query("catalystLocalStorage", new String[]{"value"}, "key = ?", new String[] { "full_name" }, null, null, null);
    String[] names = catalystLocalStorage.getColumnNames();
    if (catalystLocalStorage.moveToFirst()) {
        final String value = catalystLocalStorage.getString(catalystLocalStorage.getColumnIndex("value"));
        Log.d(TAG, value);
    }
} finally {
    if (catalystLocalStorage != null) {
        catalystLocalStorage.close();
    }

    if (readableDatabase != null) {
        readableDatabase.close();
    }
}

由于用户是对象，所以我不知道这是否是获取'first_name'的正确方法，所以我尝试获取'user'但没有用.

Since the User it's an object, I don't know if this is the right way to get the 'first_name', I tried get 'user' but didn't worked.

我开始认为我应该使用 react-native-sqlite-storage 我会在哪里知道我的数据结构，但我不知道我是否能够在Android上访问该数据库.

I'm starting to think that I should use react-native-sqlite-storage where I would know my data structure, but I don't know if I would be able to access that database on Android.

PS:我要访问AsyncStorage而不是SharedPreferences

PS: I want access AsyncStorage not SharedPreferences

库版本

react-native: 0.48.4
redux: 3.7.2
redux-persist: 5.4.0

一些无法解决的问题

• 从本机代码访问AsyncStorage
• 可以我可以从Java层访问存储在React Native的AsyncStorage中的数据吗?
• React Native:如何使用Java代码通过React Native异步存储获取数据

• Access AsyncStorage from native code
• Can I access data stored in React Native's AsyncStorage from java layer?
• React Native: How to use Java code to fetch data via React Native async storage

推荐答案

AsyncStorage这是一个唯一的JSON对象，相反，我期望key和value的许多行；这就是为什么我变得空着的原因.

AsyncStorage it's an unique JSON Object and instead I was expecting many rows of key and value; That's why I was getting null.

所以首先我继续查询

catalystLocalStorage = readableDatabase.query("catalystLocalStorage", new String[]{"key", "value"}, null, null, null, null, null);

然后我检查以避免空指针

then I check to avoid null pointer

if (catalystLocalStorage.moveToFirst()) {

然后我抓取

do {
    // JSONObject will ask for try catch
    JSONObject obj = new JSONObject(catalystLocalStorage.getString(catalystLocalStorage.getColumnIndex("value")));
} while(catalystLocalStorage.moveToNext());

我敢肯定，这样做可能会有更好的方法，但是我知道我可以接受.

I'm sure that may have better ways to do this, but right know I'm fine with that.

如果您有更好的主意，请离开您的思想.

If you have better ideas please leave your thought.

更新

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.modules.storage.ReactDatabaseSupplier;
import org.json.JSONArray;
import org.json.JSONObject;
import java.util.ArrayList;

public class AsyncStorage {

    public static String TAG = "RNAsyncStorage";
    public ReactApplicationContext context;
    public ArrayList<JSONObject> collection;
    public JSONObject data;
    public JSONObject user;

    Cursor catalystLocalStorage = null;
    SQLiteDatabase readableDatabase = null;

    public AsyncStorage (ReactApplicationContext context) {
        this.context = context;
        this.collection = new ArrayList<JSONObject>();
        this.fetch();
        this.setUser();
    }

    public void fetch() {
        try {
            readableDatabase = ReactDatabaseSupplier.getInstance(context).getReadableDatabase();
            catalystLocalStorage = readableDatabase.query("catalystLocalStorage", new String[]{"key", "value"}, null, null, null, null, null);

            if (catalystLocalStorage.moveToFirst()) {
                do {
                    try {
                        // one row with all AsyncStorage: { "user": { ... }, ... }
                        String json = catalystLocalStorage.getString(catalystLocalStorage.getColumnIndex("value"));
                        JSONObject obj = new JSONObject(json);

                        String user = obj.getString("user");

                        JSONObject res = new JSONObject();
                        res.put("user", new JSONObject(user));

                        collection.add(res);
                    } catch(Exception e) {
                        // do something
                    }
                } while(catalystLocalStorage.moveToNext());
            }
        } finally {
            if (catalystLocalStorage != null) {
                catalystLocalStorage.close();
            }

            if (readableDatabase != null) {
                readableDatabase.close();
            }

            data = this.collection.get(0);
        }
    }

    public String getFullname () {
        try {
            return user.getString("fullname");
        } catch (Exception e) {
            return "";
        }
    }
}

叫课

AsyncStorage as = new AsyncStorage(context);
as.getFullname()

这篇关于如何在Android上正确阅读AsyncStorage的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！