Cache usage in AngularJS

Caching

A cache is a component that can store data transparently so that future requests can be served faster. Obtaining resources repeatedly may cause data duplication and consume time. Therefore, caching is suitable for some data with little variability. The more requests the cache can serve, the more the overall system performance can be improved.

$cacheFactory and cache objects

$cacheFactory is a service that produces cache objects for Angular services. To create a cache object, use $cacheFactory passing an ID and capacity. Among them, ID is the name of a cache object, and capacity describes the maximum number of cache key-value pairs. To give a vivid example, $cacheFactory is the tenant. She has a building with large and small houses for rent. As long as you give enough money, the tenant will rent the house to you (obtain the cache object). This house Including its room number (ID) and room size (capacity-capacity).

var myCache = $cacheFactory('myCache');

Among them, the cache object has the following methods

1. myCache.info() returns the ID, size and options of the cache object

2. myCache.put() new value key-value pair and put it into the cache object myCache.put("name", "Ben")

3. myCache.get() returns the corresponding cache value, if If not found, undefined is returned myCache.get("name")

4. myCache.remove() removes the key-value pair from the corresponding cache object myCache.remove("name")

5. myCache.remvoeAll() clears the cache object

The cache in $http() method allows us to pass a cache parameter. The default $http cache is particularly useful when the data does not change frequently. Among them, the default $http cache object is var cache = $cacheFactory('$http'); You can set it like this

$http({
   method: 'GET',
   url: 'api/user.json',
   cache: true
})

where the cache key value is url, var userCache = cache.get('api/user.json')

Custom cache

It is also very simple to make $http initiate a request through a custom cache, just set the cache value to the corresponding The cache object name can be

$http({
   method: 'GET',
   url: 'api/user.json',
   cache: myCache
})

or set the cache object for each $http request through config configuration, instead of adding configuration to each $http request as in the above example.

app.config(function($httpProvider){
$httpProvider.defaults.cache = $cacheFactory('myCache',{capacity: 20})

Among them, capacity will use the "recent cache and the longest unused algorithm". That is to say, if the cache capacity is 20, and now 20 caches have been cached, when the 21st one wants to When being cached, the oldest and smallest unused cache key-value pairs will be cleared to make room for the 21st cache.

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