SharedPreferences存取特殊數據

說到SharePrefrence，簡稱sp，大家一點不陌生，經常會用它存儲一些簡單數據，那麼簡單數據是什麼？這裏總結下

SharePrefrence中有個抽象類叫Editor，包含以下方法：

    存儲普通數據：

    putBoolean(String key,boolean value)，保存整型

    putInt(String key,int value)，保存int類型

    putFloat(String key,float value)，保存float類型


    putLong(String key,long value)，保存long類型

    putString(String key,String value)，保存字符串

 存儲set集合


    putStringSet(String key,Set<String> values)，保存set集合

 以上是Editor中存儲數據的方法




 那麼，實際開發中經常會遇到存儲某個對象，某個list，怎麼辦呢？


 利用Gson、FastJson等把某個Objectt或者某個ListObject轉成普通String,用putString()保存,需要展示緩存內容時，get到String,利用Gson轉成Object或者ListObject

    存儲Object對象

<code class="language-java hljs  has-numbering"><span class="hljs-keyword">    public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">saveObject</span>(String key, Object obj) {
       SharedPreferences.Editor edit = settings.edit();
       String str = gson.toJson(obj, obj.getClass());
       edit.putString(key, str);
       edit.commit();
    }</code>

     獲取Object對象

    public <T> T getObject(String key, Class<?> classItem) {
      try {
        String str = settings.getString(key, null);
        if (str != null) {
            return (T) gson.fromJson(str, classItem);
        }
      } catch (Exception e) {
 <pre name="code" class="java">      }

}

    存儲ListObeject對象

<code class="language-java hljs  has-numbering">    <span class="hljs-keyword">public</span> <T> <span class="hljs-keyword">void</span> <span class="hljs-title">saveListObject</span>(String key, List<T> list) {
        SharedPreferences.Editor edit = settings.edit();
        String str = gson.toJson(list);
        edit.putString(key, str);
        edit.commit();
    }</code>

    獲取ListObeject對象

<code class="language-java hljs  has-numbering"></code><pre class="prettyprint" name="code"><code class="language-java hljs  has-numbering"><span class="hljs-keyword">    public</span> List <span class="hljs-title">getListObject</span>(String key,Class<?> classItem) {
      JavaType javaType = mapper.getTypeFactory().constructCollectionType(ArrayList.class, classItem);
      <span class="hljs-keyword">try</span> {
          String str = settings.getString(key, <span class="hljs-keyword">null</span>);
          <span class="hljs-keyword">if</span> (str != <span class="hljs-keyword">null</span>) {
              <span class="hljs-keyword">return</span> mapper.readValue(str,javaType);
          }
      } <span class="hljs-keyword">catch</span> (Exception e) {

      }
    <span class="hljs-keyword">  return</span> <span class="hljs-keyword">null</span>;
    } </code>