#### Example 3: Developing reports from Java object data source UDS

The JReport Designer UDS can use any Java object as a data source for you to create reports. To implement this function, JReport Designer provides a class UDSForJavaBean, in which the getResultSet() method creates instances for the interface JavaBeanDataProvider, and then uses the method init() to initialize the data of the created instances.

Below is the Java code for class definition:

    public class UDSForJavaBean implements JRUserDataSource
    {
    	// Define data.
    	public ResultSet getResultSet(String param)
    			throws JRUserDataSourceException
    	{
    		// Method body.
       }

    	/**
    	 * Free the resources such as : Connection, Statement, ResultSet.
    	 */
    	public void releaseResultSet() throws JRUserDataSourceException
       {
    		// Method body.
    	}
    }

The interface JavaBeanDataProvider is defined as follows:

    public interface JavaBeanDataProvider
    {
        public void init(String dataID, Properties initprops)
    		  throws JavaBeanDataProviderException;
    	 public Class getMetadataJavaBean()
    		  throws ClassNotFoundException;
    	 public Object next() throws JavaBeanDataProviderException;
    	 public boolean requireDetails(String collectionPropName);
    	 public int getMaxShareTimes(String collectionPropName);
    	 public int getTimeoutForSubCollection(String collectionPropName);
    	 public void exit()throws JavaBeanDataProviderException;
    }

For examples of how to create reports using the Java object data interface, JReport provides you with two demos which are available in `<install_root>\help\samples\APIUDS\javaUDS`.

- Demo 1: Creating reports from simple Java object UDS
- Demo 2: Creating reports from Java object UDS with multi-levels of collections

Before running the demo, you need to do the following:

1. Copy all the content in `<install_root>\help\samples\APIUDS\javaUDS` to `<install_root>\help\UDSForJavaBean`. You need to create the UDSForJavaBean directory.
2. Compile all the java files.

   `javac -classpath <install_root>\help\UDSForJavaBean;<install_root>\lib\JREngine.jar;<install_root>\lib\log4j-1.2.8.jar; <install_root>\help\UDSForJavaBean\jreport\uds\javabean\*.java`

3. Copy data.txt in `<install_root>\help\UDSForJavaBean` to `<install_root>\bin`.
4. Add the path `<install_root>\help\UDSForJavaBean` in the ADDCLASSPATH variable in setenv.bat in the `<install_root>\bin` directory.

##### Demo 1: Creating reports from simple Java object UDS

In this demo, a Java object named Person will be used as the data source, you can find the person.java file in `<install_root>\help\UDSForJavaBean\jreport\uds\javabean\beans`. It is defined as follows:

    public class Person implements Serializable
        {

        private String gender;
    	 private String ssn;
    	 private String emailAddress;
    	 private Date birthDate;
    	 private Long newbornWeight;
    	 private YesNo isDataVerified;
    	 private Name name;
    	 private Address currentMailingAddress;
    	 private Phone currentWorkPhone;n;
    /**
    * @return the birthDate.
    */
    public Date getBirthDate()
       {
       return birthDate;
       }
    }

Similar to the code above, other attributes of the Person object are defined by other Java objects, such as currentMailingAddress which is defined by the Address class.

###### Creating a report from the Person Java object

Take the following steps:

1. In JReport Designer, open an existing catalog, then in the Data tab of the Catalog Browser, expand the data source to which the UDS is to be added.
2. This demo uses generated data, in order to get the real collection of the data objects, create two parameters before importing the Person Java object as follows:
   - Name: pUseFakeData (Specify whether to use generated data when running the report.)
     Value Type: Boolean
     Prompt Value: True
   - Name: pNumOfFakeData (Specify the number of data records to generate that will be shown when running the report.)
     Value Type: Integer
     Prompt Value: Any integer number

   For details about how to create parameters, see Creating a parameter.

3. Right-click the data source node, and select Add User Defined Data Source from the shortcut menu.
4. In the Add User Defined Data Source dialog, enter Person in the Name text field.
5. For the Class Name field, click the Browse button, go to `<install_root>\help\UDSForJavaBean\jreport\uds\javabean`, and then choose UDSForJavaBean.class, which will import the class jreport.uds.javabean.beans.Person with full class name.
6. In the Parameter box, type in the following string:

   `JavaBeanDS_DataProvider=jreport.uds.javabean.GenericBeanDataProvider&JavaBeanDS_RuntimeDataID=persions&GBeanProvider_BeanClsName=jreport.uds.javabean.beans.Person&GBeanProvider_UseFakeData=true&GBeanProvider_NumOfFakeData=@pNumOfFakeData&GBeanProvider_RptDataInitializer=jreport.uds.javabean.SubRptCollectionDataInitializer`

   All the highlighted names in the parameter string above are the key words for the information required by this UDS and related Java class. See the detailed explanation below:

   - JavaBeanDS_DataProvider is used to specify the Java class which implements jreport.uds.javabean.JavaBeanDataProvider interface, and will return the list of required data objects at runtime – in this demo, it is a list of Person objects.
   - JavaBeanDS_RuntimeDataID is a reserved value used as a key to get data objects from the DataCenter.
   - GBeanProvider_* are required values for the special data provider - jreport.uds.javabean.GenericBeanDataProvider - which is specified by JavaBeanDS_DataProvider.

   You can use this provider (jreport.uds.javabean.GenericBeanDataProvider) or create your own provider by implementing the interface jreport.uds.javabean.JavaBeanDataProvider.

7. Click OK to add the UDS.
8. Create a standard banded report with this UDS using the report wizard.
9. Click the View tab to run the report. In the Enter Parameter Values dialog, type 3 as the value of the parameter pNumOfFakeData, and click OK. Three records will be returned. However, the data you get now is the generated data, because in the parameter string of the UDS, you have specified the value of the key word GBeanProvider_UseFakeData to true.
10. In order to get the real collection of data objects, the parameter pUseFakeData will be used to control the value of the key GBeanProvider_UseFakeData value dynamically as follows.

    In the Catalog Browser, right-click the UDS Person and click Edit User Defined Data Source on the shortcut menu. In the Edit User Defined Data Source dialog, modify the value of GBeanProvider_UseFakeData to @pUseFakeData in the Parameter box.

11. Run the report again and specify the value of pUseFakeData as false to get the real collection of data at runtime.

    Note: The key word GBeanProvider_RptDataInitializer in the data provider jreport.uds.javabean.GenericBeanDataProvider is used to specify the Java class name which implements jreport.uds.javabean.RptDataInitializer interface. So if you are using the data provider jreport.uds.javabean.GenericBeanDataProvider, you just need to provide a class which implements jreport.uds.javabean.RptDataInitializer to return a collection, list, or array of the data objects according to different reports and parameters. Also, jreport.uds.javabean.GenericBeanDataProvider can recognize vector, collection and array of objects and retrieve the objects inside of the collection one by one.

###### Methods in the demo

jreport.uds.javabean.GenericBeanDataProvider

jreport.uds.javabean.GenericBeanDataProvider implements the interface of jreport.uds.javabean.JavaBeanDataProvider by using the following methods:

public void init(String dataID, Properties initprops) throws JavaBeanDataProviderException;
public Class getMetadataJavaBean() throws ClassNotFoundException;
public Object next() throws JavaBeanDataProviderException;
public boolean requireDetails(String collectionPropName);
public int getMaxShareTimes(String collectionPropName);
public void exit()throws JavaBeanDataProviderException;

- init()
  This method is called by UDSForJavaBean to ask the data provider to prepare the data collection/list by the given initProperties. Basically, the initProperties are the name and value pairs parsed from the UDS parameter string.

  For example, the GenericBeanDataProvider will get the list of properties with the following keys:

  JavaBeanDS_DataProvider
  JavaBeanDS_RuntimeDataID
  GBeanProvider_BeanClsName
  GBeanProvider_UseFakeData
  GBeanProvider_NumOfFakeData
  GBeanProvider_RptDataInitializer

  The values for those keys will be used by GenericBeanDataProvider to prepare the data collection. For example, if the value of GBeanProvider_UseFakeData is true, the GeneridBeanDataProvider will use the fake data, otherwise it will create an instance by the class name provided by GBeanProvider_RptDataInitializer and ask the data initializer object to return the collection of data objects.

- getMetadataJavaBean()
  This method is called back from the UDS to get the bean class in order to construct the meta data for UDS. For GenericBeanDataProvider, the Java bean class in the collection is passed in by the key GBeanProvider_BeanClsName when you define this data source by UDS.
- next()
  This method is called back from the UDS to fetch the next data object as a record for the report at runtime. For GenericBeanDataProvider, the init() method constructs the data object collection, and the next() method is going to check if the collection is a Vector, Collection, or array of objects to determine automatically how to get the next object from the constructed collection.
- exit()
  This method is called back from theUDS when the JReport engine closes the result set returned by UDS. For GenericBeanDataProvider, it will call the data initializer to close if the data is constructed by data initializer.
- requireDetails()
  This method is called back by the UDS to check if a certain collection attribute from Java bean needs to be displayed in the metadata.
- getMaxShareTimes()
  The sub-collection attribute from the Java data object could be shared among subreports. This is the call-back method from the UDS to determine the maximum number of times that a certain sub-collection object is going to be shared by the current report. If your report is trying to share the same sub-collection of a Java data object more than this specified value, you will get an error at runtime. However, if your report actually needs to be shared less than the number specified, the data will stay in the buffer without being cleaned.

jreport.uds.javabean.RptDataInitializer

The implementation of this interface will be used by GenericBeanDataProvider to provide the collection of Java objects for different reports and parameters.

The following methods need to be implemented for this interface:

public Object getDataCollection(Properties props)throws RptDataInitializerException;
public void close();

- getDataCollection()
  This method is called by GenericBeanDataProvider to return the data collection object. The input props are passed down from GenericBeanDataProvider and includes all the values passed down into the init() method of the GenericBeanDataProvider.
- close()
  This method is called back by GenericBeanDataProvider when exit() function is called there.

##### Demo 2: Creating reports from Java object UDS with multi-levels of collections

Before running the demo, you need to do the following:

1. Copy all the content in `<install_root>\help\samples\APIUDS\javaUDS` to `<install_root>\help\UDSForJavaBean`. You need to create the UDSForJavaBean directory.
2. Compile all the java files.

   `javac -classpath <install_root>\help\UDSForJavaBean;<install_root>\lib\JREngine.jar;<install_root>\lib\log4j-1.2.8.jar; <install_root>\help\UDSForJavaBean\jreport\uds\javabean\*.java`

3. Copy data.txt in `<install_root>\help\UDSForJavaBean` to `<install_root>\bin`.
4. Add the path `<install_root>\help\UDSForJavaBean` in the ADDCLASSPATH variable in setenv.bat in the `<install_root>\bin` directory.

Sometimes, the attributes of a Java object are defined by other lists/collections, such as the Java object SimpleBeanTest in `<install_root>\help\UDSForJavaBean\jreport\uds\javabean\beans`. It is defined as follows:

    public class SimpleBeanTest implements Serializable {
        private String test;
        private long l;
        private int i;
        private int[] intarray;
        private Person[] persons;
        private Collection addresses;
       	private Date dMyDate;
    }

From the code above, you can see that the Java class SimpleTestBean contains an array of Persons, a collection of addresses and an array of Int values.

For this kind of Java object, JReport Designer can create a report that gets records from the SimpleTestBean, but it cannot show the list of persons information in the same report. If you want to create such a report - each record comes from the SimpleBeanTest object, and for each record, display the list of persons information - you have to use the primary report and subreport to implement this function. For how to do it, see the demo below.

###### Creating the primary report

1. In JReport Designer, open an existing catalog, then in the Data tab of the Catalog Browser, expand the data source to which the UDS is to be added.
2. Create a parameter as follows, which is used to specify the number of data records to generate that will be shown when running the report.

   Name: pNumOfFakeData
   Value Type: Integer
   Prompt Value: Any integer number. Note that the parameter must have at least one value that is larger than 0, otherwise you will get exceptions when viewing reports.

   For details about how to create parameters, see Creating a parameter.

3. Right-click the data source node and click Add User Defined Data Source on the shortcut menu.
4. In the Add User Defined Data Source dialog, type SimpleTestBean in the Name text field.
5. For the Class Name filed, click the Browse button, go to `<install_root>\help\UDSForJavaBean\jreport\uds\javabean`, and then choose UDSForJavaBean.class. The UDS class UDSForJavaBean.class will import the class jreport.uds.javabean.beans.SimpleTestBean with full class name.
6. In the Parameter box, type in the following string:

   `JavaBeanDS_DataProvider=jreport.uds.javabean.GenericBeanDataProvider
   &JavaBeanDS_RuntimeDataID=&GBeanProvider_BeanClsName=jreport.uds.javabean.beans.SimpleBeanTest
   &GBeanProvider_UseFakeData=true&GBeanProvider_NumOfFakeData=@pNumOfFakeData
   &GBeanProvider_FakeDateSubCollectionInfo=persons,jreport.uds.javabean.beans.Person
   &GBeanProvider_RptDataInitializer=&GBeanProvider_ListOfDetailProps=persons,1,30000`

   All the highlighted names in the parameter string above are the key words for the information required by this UDS and related Java class. See the detailed explanation below:

   - GBeanProvider_ListOfDetailProps specifies the following items:
     - The list of property names of sub-collections that will be displayed in the meta-data
     - How many times that this report is going to share the sub-collection per main object
     - The timeout for the shared data in the DataCenter in milliseconds (the default value is 1 minute).

     In this demo, only the sub-collection property persons will be imported from the SimpleTestBean class, and the share time is 1. If you want to create another subreport using addresses, you have to specify the value for this key word as the following:

     =&GBeanProvider_ListOfDetailProps=persons,1,30000$addresses,1,30000

     and different properties are separated by the symbol $.

   - GBeanProvider_FakeDateSubCollectionInfo
     The value of this key word is used to construct the fake data for SimpleTestBean collections. Each Java class can have multiple sub-collection objects, and it is allowed to not construct the values of these sub-collection objects if you do not want to use it. However, if you do not specify them here in this parameter string as `<property name>,<property class name>$<property name>,<property class name>`, the fake data for those sub-collections will not be constructed, and problems will occur when running the report on fake data.
7. Click OK and the UDS SimpleTestBean is added. In the Catalog Browser, you will see that persons appears in the resource tree in the SimpleTestBean node.
8. Create a page report named MainRpt.cls, and create a standard banded report in it as the primary report based on the UDS SimpleTestBean.

###### Creating the subreport

1. Expand the data source in the catalog to which you want to add the UDS for the subreport.
2. Create a parameter as follows, which is used to specify whether to use generated data when running the report.

   Name: pUseFakeData
   Value Type: Boolean
   Prompt Value: True

3. Create another parameter named pRunTimeDataInfo of String type, which will be used when setting up the link between the primary report and the subreport.

   Name: pRunTimeDataInfo
   Value Type: String
   Prompt Value: persons

4. Right-click the data source node and click Add User Defined Data Source on the shortcut menu.
5. In the Add User Defined Data Source dialog, type PersonsAsSubRpt in the Name text field.
6. For the Class Name text box, click the Browse button, go to `<install_root>\help\UDSForJavaBean\jreport\uds\javabean`, and then choose UDSForJavaBean.class.
7. In the Parameter box, type in the following string:

   `JavaBeanDS_DataProvider=jreport.uds.javabean.GenericBeanDataProvider&JavaBeanDS_RuntimeDataID=@pRunTimeDataInfo&GBeanProvider_BeanClsName=jreport.uds.javabean.beans.Person&GBeanProvider_UseFakeData=@pUseFakeData&GBeanProvider_NumOfFakeData=@pNumOfFakeData&GBeanProvider_RptDataInitializer=jreport.uds.javabean.SubRptCollectionDataInitializer`

   All the highlighted names in the parameter string above are the key words for the information required by this UDS and related Java class. See the detailed explanation below:

   - JavaBeanDS_RuntimeDataID is defined to use a parameter which will be the link point from the subreport to the sub-collections in the primary report
   - GBeanProvider_RptDataInitializer's value is jreport.uds.javabean.SubRptCollectionDataInitializer, which is our built-in data provider set up especially for the subreport to return the collection of data by referencing the sub-collection in the primary report. The referencing information is passed via the parameter value @pRunTimeDataInfo which will be used when we set up the link between the primary report and the subreport.
   - The class name for GBeanProvider_BeanClsName is Person because the subreport will use the Person object.
8. Click OK, and the UDS PersonsAsSubRpt is added.
9. Create a page report named SubRpt.cls, and create a table report in it as the subreport based on the UDS PersonsAsSubRpt.

###### Linking the primary report and the subreport

1. In the Catalog Browser, create a formula named NotUseFakeData to return false all the time, for example, `return false`. This formula will be passed into the subreport as the value of the parameter pUseFakeData in the subreport, so that when the subreport runs with the primary report, it will always use the data from the primary report instead of constructing the fake data itself.
2. Open MainRpt.cls, add a new detail panel into the report.
3. Selected the newly added panel and click Insert > Subreport. When a box attached to your mouse pointer, click in the panel and the Subreport dialog is displayed.
4. Click the Browse button, choose SubRpt.cls as the subreport, then in the Parameters tab, specify values for the parameters as follows:

   Parameter | Value
   --- | ---
   pNumOfFakeData | pNumOfFakeData
   pUseFakeData | NotUseFakeData (gives a false value to the parameter)
   pRunTimeDataInfo | persons (specifies to use the sub-collection persons of the primary report as the data source of the subreport at runtime)

5. Click OK to insert the subreport.
6. Run the primary report, and you will find that the corresponding persons information is displayed in the subreport.
7. If you want to insert another subreport which shares the same sub-collection with SubRpt.cls, you should modify the value of the key word GBeanProvider_ListOfDetailProps in the primary report UDS parameter string to GBeanProvider_ListOfDetailProps=persons,2,30000. That changes the share amount of the persons property from 1 to 2.

For more information about subreport in JReport, see the section Subreports.