如何在 Android 上正确读取 AsyncStorage [英] How to Read AsyncStorage on Android Correctly
问题描述
似乎可以从 Android(本机)访问 AsyncStorage
;但我仍在努力完成这项工作.
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)
用户缩减器
export class Actions {
...
}
const initialState = {
first_name: : null,
last_name: : null,
email: null,
addresses: [
{ ... }
]
}
}
}
export const reducer = (state = initialState, action) => {
switch (action.type) {
...
}
}
从商店获取用户
const user = store.getState().user
console.log(user.first_name) // Steve
...
<小时>
现在,当我尝试从 Android 获取相同用户时,问题就开始了,在我所有失败的尝试中,这就是我所拥有的:
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 User 是一个对象,我不知道这是否是获取 'first_name'
的正确方法,我尝试获取 'user'
但没有没用.
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 在哪里我会知道我的数据结构,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:我想访问 AsyncStorage
而不是 SharedPreferences
PS: I want access AsyncStorage
not SharedPreferences
Lib 版本
react-native: 0.48.4
redux: 3.7.2
redux-persist: 5.4.0
一些没有用的问题
- 从本机代码访问 AsyncStorage
- 可以我从 java 层访问存储在 React Native 的 AsyncStorage 中的数据?
- React Native:如何使用 Java 代码通过 React Native 异步存储获取数据
推荐答案
AsyncStorage
它是一个独特的 JSON 对象,而我期待的是多行 key
和 价值
;这就是我得到 null 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()) {
然后我去取货
do {
// JSONObject will ask for try catch
JSONObject obj = new JSONObject(catalystLocalStorage.getString(catalystLocalStorage.getColumnIndex("value")));
} while(catalystLocalStorage.moveToNext());
我确信可能有更好的方法来做到这一点,但我知道我对此很好.
I'm sure that may have better ways to do this, but right know I'm fine with that.
如果您有更好的想法,请留下您的想法.
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 "";
}
}
}
调用类
AsyncStorage as = new AsyncStorage(context);
as.getFullname()
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