使用SAP OData offline库实现Android应用的离线(offline)模式

2020 年 3 月 9 日
筆記

打开Android studio，在工程的build.gradle里加入下面的依赖，导入SAP OData offline库：

implementation group:‘com.sap.cloud.android’, name:‘offline-odata’, version: sdkVersion

点击Sync now：

新建一个java文件：SAPServiceManager.java

使用的import如下：

import android.content.Context;  import android.util.Log;  import android.widget.Toast;  import com.sap.cloud.mobile.odata.core.AndroidSystem;  import com.sap.cloud.mobile.odata.offline.OfflineODataDefiningQuery;  import com.sap.cloud.mobile.odata.offline.OfflineODataException;  import com.sap.cloud.mobile.odata.offline.OfflineODataParameters;  import com.sap.cloud.mobile.odata.offline.OfflineODataProvider;  import java.net.MalformedURLException;  import java.net.URL;    // 将OfflineODataProvider注释掉，改为OfflineODataProvider  //private OnlineODataProvider provider;  private OfflineODataProvider provider;  private static final String TAG = SAPServiceManager.class.getName();        OData offiline datastore的setup方法：    public void openODataStore(Action0 callback, Context context) {      setupOfflineOData(callback, context);  }    private void setupOfflineOData(Action0 callback, Context context) {      try {          if (configurationData.loadData()) {              Toast.makeText(context, "Opening the offline store which may take a few moments the first time it is opened.", Toast.LENGTH_LONG).show();              //Initialize application context for use by OfflineODataProvider              AndroidSystem.setContext(context);              //commonly set parameters include setStoreEncryptionKey, setStoreName, setStorePath              OfflineODataParameters offParam = new OfflineODataParameters();              String serviceUrl = configurationData.getServiceUrl();              URL url = new URL(serviceUrl + CONNECTION_ID_ESPMCONTAINER);              provider = new OfflineODataProvider(url, offParam, ClientProvider.get());              //Specifies which entities we wish to include in the offline store              provider.addDefiningQuery(new OfflineODataDefiningQuery("Customers", "Customers", false));          }    } catch (MalformedURLException e) {        e.printStackTrace();    } catch (OfflineODataException e) {        e.printStackTrace();    }    //opens the offline store.  This can take a minute or so the first time it is called as it is created and populated.    Log.d(TAG, "About to call open on the offline store.");    provider.open(() -> {        Log.d(TAG, "Offline store opened.");        eSPMContainer = new ESPMContainer(provider);        callback.call();        syncOfflineData();  //TODO could be triggered via a menu action    }, (OfflineODataException offlineODataException) -> {        Log.d(TAG, "Offline store did not open.", offlineODataException);    });  }    public void syncOfflineData() {      //send the local changes to the back end OData service      Log.d(TAG, "About to call provider.upload.");      provider.upload(() -> {          Log.d(TAG, "Successfully uploaded the changed data.");          //get changes from the back end OData service.          provider.download(() -> {              Log.d(TAG, "Successfully downloaded the changed data.");          }, (error) -> {              Log.d(TAG, "Failed when downloading the changed data with error: " + error.getMessage());          });      }, (error) -> {          Log.d(TAG, "Failed when uploading the changed data with error: " + error.getMessage());      });  }    public String getServiceRoot() {      if (configurationData.loadData()) {          String serviceUrl = configurationData.getServiceUrl();          if (serviceRoot == null) {              serviceRoot = serviceUrl + "/" + CONNECTION_ID_ESPMCONTAINER;          }      }      else {          throw new IllegalStateException("SAPService manager configurationData.loadData() failed.");      }      return serviceRoot;  }

新建LogonActivity.java，调用之前实现的sapServiceManager.openODataStore: