android 中 webview 怎么用 localStorage

mainWebView = (WebView)this.findViewById(R.id.mainWebView);
    WebSettings settings = mainWebView.getSettings();
    settings.setJavaScriptEnabled(true);
    settings.setAllowFileAccess(true); 
    settings.setDatabaseEnabled(true);
     String dir = this.getApplicationContext().getDir("database", Context.MODE_PRIVATE).getPath();  
    settings.setDatabasePath(dir);  
    settings.setDomStorageEnabled(true);
    settings.setGeolocationEnabled(true);

mWebView.getSettings().setDomStorageEnabled(true);  
mWebView.getSettings().setAppCacheMaxSize(1024*1024*8); 
String appCachePath = getApplicationContext().getCacheDir().getAbsolutePath(); 
mWebView.getSettings().setAppCachePath(appCachePath); 
mWebView.getSettings().setAllowFileAccess(true); 

mWebView.getSettings().setAppCacheEnabled(true);