Note that prior to annotating classes, you should set up and configure the database connection, as well as add JPA support to your Eclipse project.

To annotate an existing Java class, follow this procedure:

1. Right-click your project in the Project Explorer and select JPA > Generate Entity from Java Class from the drop-down menu, as Figure 1 shows. This will open the Generate JPA Mapping dialog, shown in Figure 2.
   
   

   
   
   Figure 1. Generate Entity from Java Class

   
   Alternatively, you can open the Generate JPA Mapping wizard by right-clicking your project in the Project Explorer and selecting New > Other > JPA > Generate Entity from Java Class.


2. In the Generate JPA Mapping > Java Class dialog, click Browse to select from the Choose Type dialog the Java class you want annotated, as Figure 2 shows. Select the entity access level, and then click Next.
   Note that if you select property from the Entity Access combo box, the JPA annotations will be added to the class' getter methods. If you select field, the annotations will be added to the Java fields.
   
   

   
   
   Figure 2. Selecting Java Class to Annotate



3. On the next Generate JPA Mapping > Class Mapping Properties screen, shown in Figure 4, specify the following:
   • the database connection;
   • the database schema;
   • the table in the database that you are using to annotate your class. To do so, click Browse. This will open the Select Table dialog, as Figure 3 shows. Select the table, and then click OK.
     
     

     
     
     Figure 3. Select Table Dialog

   
   
   • the primary key from the selected table.
   • Click Next.
     
     

     
     
     Figure 4. Generate JPA Mapping - Class Mapping Properties Dialog

   
   
   As the example in Figure 4 demonstrates, the EMPLOYEE table from the HR schema will be mapped to the Employee class. The class's employeeId field will be mapped to the table's primary key.


4. On the next Generate JPA Mapping > Bean Properties Mapping screen, shown in Figure 5, verify or edit mappings between database columns and fields discovered in the Java class you are annotating.
   
   

   
   
   Figure 5. Generate JPA Mapping - Bean Properties Mapping Dialog

   
   Note that you can click Edit to display a dialog appropriate for a specific annotation. Use this dialog to edit a selected property mapping.
   
   An example illustration represented by Figure 6 shows the Basic Annotation dialog.
   
   

   
   
   Figure 6. Basic Annotation Dialog

   
   For information on how to annotate more complex types, see Annotating Complex Types.


5. Click Finish on the Generate JPA Mapping dialog.

Figure 7. Annotated Class Example

2. Related Information