Navigating the SDO data graph
XPath expressions are used to obtain data from the data objects present in the data graph after the XML file is loaded.
Figure | -23 shows the data graph for the accounts.xml file.
Figure 10-23 Accounts data graph
| Add the code shown in Example | -8 to the main method. |
Example 10-8 Java code for navigating the SDO data graph
// navigating the SDO data graph
AccountsType accountsType = documentRoot.getAccounts();
DataObject accountsTypeImpl = (AccountsTypeImpl) accountsType;
DataObject account1 = accountsTypeImpl.getDataObject("account.0");
System.out.println("\n\nThe first account is: " + account1 + "\n");
DataObject account2 = accountsTypeImpl.getDataObject
("account[accountID = '123457']");
System.out.println("The second account is: " + account2 + "\n");
DataObject account2CustomerInfo = accountsTypeImpl.getDataObject
("account[accountID = '123457']/customerInfo");
System.out.println("The second account customer information is: " +
account2CustomerInfo + "\n");
String account1CustomerName = account1.getString("customerInfo/firstName");
System.out.println("The first account customer first name is " +
account1CustomerName + "\n");
The XPath dot notation is used to index data objects. The first object has index 0, therefore account.0 returns the first account data object.
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The XPath expression account[accountID = '123457'] returns the account data object whose account ID equals 123457.
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account[accountID = '123457']/customerInfo is an XPath expression that returns a data object multiple levels below the root data object.
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| Right-click SDOSample and select Run As Æ Java Application. You can also select Run Æ Run History Æ SDOSample. |
The Console output from the SDO graph navigation code is shown here:
The first account is: com.xml.rad75.itso.impl.AccountImpl@d8d0d8d (accountID: 123456, accountType: Savings, balance: 20000, interest: 3.5)
The second account is: com.xml.rad75.itso.impl.AccountImpl@64d764d7 (accountID: 123457, accountType: Fixed, balance: 50000, interest: 6)
The second account customer information is: com.xml.rad75.itso.impl.CustomerInfoTypeImpl@65506550 (firstName: Ueli, lastName: Wahli, phoneNumber: (408) 345-6780)
The first account customer first name is Brian
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