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<h2 class="title"><a id="dpl_example"></a>Chapter 6. A DPL Example</h2>
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<div class="toc">
<p>
<b>Table of Contents</b>
</p>
<dl>
<dt>
<span class="sect1">
<a href="dpl_example.html#vendorclass">Vendor.class</a>
</span>
</dt>
<dt>
<span class="sect1">
<a href="inventoryclass.html">Inventory.class</a>
</span>
</dt>
<dt>
<span class="sect1">
<a href="mydbenv-persist.html">MyDbEnv</a>
</span>
</dt>
<dt>
<span class="sect1">
<a href="dataaccessorclass.html">DataAccessor.class</a>
</span>
</dt>
<dt>
<span class="sect1">
<a href="dpl_exampledatabaseput.html">ExampleDatabasePut.class</a>
</span>
</dt>
<dt>
<span class="sect1">
<a href="dpl_exampleinventoryread.html">ExampleInventoryRead.class</a>
</span>
</dt>
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<p>
In order to illustrate DPL usage, we provide a
complete working example in this chapter. This example
reads and writes inventory and vendor information for a
mythical business. The application consists of the
following classes:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
Several classes used to encapsulate our
application's data. See
<a href="dpl_example.html#vendorclass">Vendor.class</a>
and
<a href="inventoryclass.html">Inventory.class</a>.
</p>
</li>
<li>
<p>
A convenience class used to open and close
our environment and entity store. See
<a href="mydbenv-persist.html">MyDbEnv</a>.
</p>
</li>
<li>
<p>
A class that loads data into the store. See
<a href="dpl_exampledatabaseput.html">ExampleDatabasePut.class</a>.
</p>
</li>
<li>
<p>
Finally, a class that reads data from the
store. See
<a href="dpl_exampleinventoryread.html">ExampleInventoryRead.class</a>.
</p>
</li>
</ul>
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<h2 class="title" style="clear: both"><a id="vendorclass"></a>Vendor.class</h2>
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</div>
<div></div>
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<p>
The simplest class that our example wants to store contains
vendor contact information. This class contains no
secondary indices so all we have to do is identify it
as an entity class and identify the field in the
class used for the primary key.
</p>
<p>
In the following example, we identify the
<tt class="literal">vendor</tt> data member as containing the
primary key. This data member is meant to contain a
vendor's name. Because of the way we will use our
<tt class="classname">EntityStore</tt>, the value
provided for this data member must be unique within
the store or runtime errors will result.
</p>
<p>
When used with the DPL, our
<tt class="classname">Vendor</tt> class appears as
follows. Notice that the <tt class="literal">@Entity</tt>
annotation appears immediately before the class
declaration, and the <tt class="literal">@PrimaryKey</tt>
annotation appears immediately before the
<tt class="literal">vendor</tt> data member declaration.
</p>
<pre class="programlisting">package persist.gettingStarted;
import com.sleepycat.persist.model.Entity;
import com.sleepycat.persist.model.PrimaryKey;
@Entity
public class Vendor {
private String address;
private String bizPhoneNumber;
private String city;
private String repName;
private String repPhoneNumber;
private String state;
// Primary key is the vendor's name
// This assumes that the vendor's name is
// unique in the database.
@PrimaryKey
private String vendor;
private String zipcode;
public void setRepName(String data) {
repName = data;
}
public void setAddress(String data) {
address = data;
}
public void setCity(String data) {
city = data;
}
public void setState(String data) {
state = data;
}
public void setZipcode(String data) {
zipcode = data;
}
public void setBusinessPhoneNumber(String data) {
bizPhoneNumber = data;
}
public void setRepPhoneNumber(String data) {
repPhoneNumber = data;
}
public void setVendorName(String data) {
vendor = data;
}
public String getRepName() {
return repName;
}
public String getAddress() {
return address;
}
public String getCity() {
return city;
}
public String getState() {
return state;
}
public String getZipcode() {
return zipcode;
}
public String getBusinessPhoneNumber() {
return bizPhoneNumber;
}
public String getRepPhoneNumber() {
return repPhoneNumber;
}
} </pre>
<p>
For this class, the <tt class="literal">vendor</tt> value is set for an individual
<tt class="classname">Vendor</tt> class object by
the <tt class="methodname">setVendorName()</tt>
method. If our example code fails to set this
value before storing the object, the data
member used to store the primary key is set to a
null value. This would result in a runtime
error.
</p>
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