react-native-storage

react-native-storage

This is a local storage wrapper for both react-native(AsyncStorage) and browser(localStorage). ES6/babel is needed.
You may need a Promise polyfill for legacy iOS devices/browsers.

这是一个本地持久存储的封装，可以同时支持react-native(AsyncStorage)和浏览器(localStorage)。由于代码使用ES6语法编写，因而需要babel库的支持。 如果iOS设备或浏览器版本较老（不支持Promise）,则还需要一个Promise的兼容库。

Install 安装

npm install react-native-storage --save

Usage 使用说明

Config 配置

You need to use babel to enable es6 modules for web development(I'll provide an example in the next version). For React-Native development, put this babel config file under your project directory.

对于Web开发你需要使用babel来支持es6模块导入功能。（我会在下个版本中提供一个示例） 如果是React-Native开发，把这个babel配置文件放到你的项目根目录中即可。

Import 导入

var Storage = require('react-native-storage');

or 或者

import Storage from 'react-native-storage';

Save & Load 保存和读取

Storage.save(id, data, global, expires)
Storage.load(id, global).then( data => {
	console.info(data);
}).catch(error){
	console.warn(error);
}

Use these methods to save/load any legal type of javaScript data. They will automatically transform data into JSON string and vice versa.
使用这两个方法来保存和读取任意合法类型的js数据。它们会自动转换JSON字符串或将JSON解析为数据对象。
Attention: By default, there is a private property map which records indices of stored data. And it has a default SIZE of 1000, which means the capacity would be 1000 records. And if exceeded, new data would overwrite the first record without warnings(but won't cause disorder), to prevent the size from uncontrollable increasing. You can alter the SIZE using:

Storage.SIZE = 1500

注意：默认情况下，会使用一个map来记录所存数据的索引，其默认大小为1000。也就是说Storage的默认容量为1000条记录。如果超出了容量，那么新保存的数据就会在不提示的情况下覆盖第一条数据(但并不会引起数据紊乱)，以避免Storage占用的空间不可控地持续增大。你可以修改这个默认SIZE的大小。

Or if you don't want some long term data to be "recycled", then you can set the param global to be true, which gets your data stored out of the map. And when you load it, global should also be true.
Expires has a default value of one whole day(24 * 3600 * 1000). When data expired, they won't be deleted but trigger a refresh operation if avaiable. Set it to null if you want it never expires.
或者如果你不想有些长期存放的数据被“回收”，那么可以将global参数设置为true，这样它就不会被记录到map中，也就不会被回收。而当你读取这种不会被回收的数据时，也需要将load方法中的global参数设为true.
Expires参数的默认值为一整天(24 * 3600 * 1000)。过期的数据不会被删除，而是会触发一个刷新的动作（需要你自己实现）。如果你希望某个数据永不过期，则将此参数设置为null 即可。

Sync remote data 同步远程数据（刷新）

Following is an example. You must implement it yourself under Storage.sync.
下面是一段示例代码。你必须在Storage.sync中自己实现。

Storage.sync = {
  user(id, resolve, reject){
   fetch('user/', {
     method: 'GET',
     body: 'id=' + id
     }).then(function(response) {
      return response.json();
     }).then(function(data) {
      //console.info(data);
      if(data && data.user){
        data = data.user;
        Storage.save('user_' + data.id, data);
        resolve && resolve(data);
      }
      else{
        reject && reject();
      }
    }).catch((error) => {
      console.warn(error);
    });
  }
}

With this example sync method, when you invoke:

Storage.load('user_123').then(...)

If there is no user_123 stored currently, then Storage.sync.user would be triggered to fetch remote data and returned.
有了上面这个sync方法，以后再调用Storage.load时，如果本地并没有存储相应的user，那么会自动触发Storage.sync.user去远程取回数据并无缝返回。

Load batch data 读取批量数据

Storage.getBatchDataWithKeys(keys)
Storage.getBatchDataWithIds(key, ids)

If you want to get several data in one action, then use these methods. Examples:
如果你想在一次操作中获取多个数据，那就使用上面的两个方法。示例：

Storage.getBatchDataWithKeys(['user_123', 'company_321', 'token'])
.then( results => {
	results.forEach( result => {
		console.info(result);
	})
})

Storage.getBatchDataWithIds('images', ['1001', '1002', '1003'])
.then( ... )

There is a notable difference between the two methods except the arguments. getBatchDataWithKeys will invoke different sync methods(since the keys are different) one by one when corresponding data is missing. However, getBatchDataWithIds will collect missing data, push their ids to an array, then pass the array to the corresponding sync method(to avoid too many requests), so you need to implement array query on server end.
这两个方法除了参数形式不同，还有个值得注意的差异。getBatchDataWithKeys会在数据缺失时挨个调用不同的sync方法(因为key不同)。但是getBatchDataWithIds却会把缺失的数据统计起来，将它们的id收集到一个数组中，然后一次传递给对应的sync方法(避免挨个查询导致同时发起大量请求)，所以你需要在服务端实现通过数组来查询返回。