mirror of
https://github.com/berkeleydb/je.git
synced 2024-09-09 03:56:13 +00:00
337 lines
14 KiB
HTML
337 lines
14 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
<html xmlns="http://www.w3.org/1999/xhtml">
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
||
<title>ExampleDatabasePut.java</title>
|
||
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
|
||
<link rel="start" href="index.html" title="Getting Started with Berkeley DB Java Edition" />
|
||
<link rel="up" href="dpl_example.html" title="Chapter 6. A DPL Example" />
|
||
<link rel="prev" href="dataaccessorclass.html" title="DataAccessor.java" />
|
||
<link rel="next" href="dpl_exampleinventoryread.html" title="ExampleInventoryRead.java" />
|
||
</head>
|
||
<body>
|
||
<div xmlns="" class="navheader">
|
||
<div class="libver">
|
||
<p>Library Version 12.2.7.5</p>
|
||
</div>
|
||
<table width="100%" summary="Navigation header">
|
||
<tr>
|
||
<th colspan="3" align="center">ExampleDatabasePut.java</th>
|
||
</tr>
|
||
<tr>
|
||
<td width="20%" align="left"><a accesskey="p" href="dataaccessorclass.html">Prev</a> </td>
|
||
<th width="60%" align="center">Chapter 6. A DPL Example</th>
|
||
<td width="20%" align="right"> <a accesskey="n" href="dpl_exampleinventoryread.html">Next</a></td>
|
||
</tr>
|
||
</table>
|
||
<hr />
|
||
</div>
|
||
<div class="sect1" lang="en" xml:lang="en">
|
||
<div class="titlepage">
|
||
<div>
|
||
<div>
|
||
<h2 class="title" style="clear: both"><a id="dpl_exampledatabaseput"></a>ExampleDatabasePut.java</h2>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<p>
|
||
Our example reads inventory and vendor information from
|
||
flat text files, encapsulates this data in objects of
|
||
the appropriate type, and then writes each object to an
|
||
<code class="classname">EntityStore</code>.
|
||
</p>
|
||
<p>
|
||
To begin, we import the Java classes that our example
|
||
needs. Most of the imports are related to reading the raw
|
||
data from flat text files and breaking them apart for usage
|
||
with our data classes. We also import classes from the
|
||
JE package, but we do not actually import any classes
|
||
from the DPL. The reason why is because we have
|
||
placed almost all of our DPL work off into
|
||
other classes, so there is no need for direct usage of
|
||
those APIs here.
|
||
</p>
|
||
<pre class="programlisting">package persist.gettingStarted;
|
||
|
||
import java.io.BufferedReader;
|
||
import java.io.File;
|
||
import java.io.FileInputStream;
|
||
import java.io.FileNotFoundException;
|
||
import java.io.IOException;
|
||
import java.io.InputStreamReader;
|
||
import java.util.ArrayList;
|
||
import java.util.List;
|
||
|
||
import com.sleepycat.je.DatabaseException; </pre>
|
||
<p>
|
||
Now we can begin the class itself. Here we set default paths
|
||
for the on-disk resources that we require (the environment
|
||
home, and the location of the text files containing our sample
|
||
data). We also declare <code class="classname">DataAccessor</code>
|
||
and <code class="classname">MyDbEnv</code> members. We describe these
|
||
classes and show their implementation in
|
||
<a class="xref" href="dataaccessorclass.html" title="DataAccessor.java">DataAccessor.java</a>
|
||
and
|
||
<a class="xref" href="mydbenv-persist.html" title="MyDbEnv">MyDbEnv</a>.
|
||
</p>
|
||
<pre class="programlisting">public class ExampleDatabasePut {
|
||
|
||
private static File myDbEnvPath = new File("/tmp/JEDB");
|
||
private static File inventoryFile = new File("./inventory.txt");
|
||
private static File vendorsFile = new File("./vendors.txt");
|
||
|
||
private DataAccessor da;
|
||
|
||
// Encapsulates the environment and data store.
|
||
private static MyDbEnv myDbEnv = new MyDbEnv();</pre>
|
||
<p>
|
||
Next, we provide our <code class="methodname">usage()</code>
|
||
method. The command line options provided there are necessary
|
||
only if the default values to the on-disk resources are not
|
||
sufficient.
|
||
</p>
|
||
<pre class="programlisting"> private static void usage() {
|
||
System.out.println("ExampleDatabasePut [-h <env directory>]");
|
||
System.out.println(" [-i <inventory file>]");
|
||
System.out.println(" [-v <vendors file>]");
|
||
System.exit(-1);
|
||
} </pre>
|
||
<p>
|
||
Our <code class="methodname">main()</code> method is also reasonably
|
||
self-explanatory. We simply instantiate an
|
||
<code class="classname">ExampleDatabasePut</code> object there and then
|
||
call its <code class="methodname">run()</code> method. We also provide a
|
||
top-level <code class="literal">try</code> block there for any exceptions that might be thrown
|
||
during runtime.
|
||
</p>
|
||
<p>
|
||
Notice that the <code class="literal">finally</code> statement in the
|
||
top-level <code class="literal">try</code> block calls
|
||
<code class="methodname">MyDbEnv.close()</code>. This method closes our
|
||
<code class="classname">EntityStore</code> and <code class="classname">Environment</code>
|
||
objects. By placing it here in the <code class="literal">finally</code>
|
||
statement, we can make sure that our store and environment are
|
||
always cleanly closed.
|
||
</p>
|
||
<pre class="programlisting"> public static void main(String args[]) {
|
||
ExampleDatabasePut edp = new ExampleDatabasePut();
|
||
try {
|
||
edp.run(args);
|
||
} catch (DatabaseException dbe) {
|
||
System.err.println("ExampleDatabasePut: " + dbe.toString());
|
||
dbe.printStackTrace();
|
||
} catch (Exception e) {
|
||
System.out.println("Exception: " + e.toString());
|
||
e.printStackTrace();
|
||
} finally {
|
||
myDbEnv.close();
|
||
}
|
||
System.out.println("All done.");
|
||
} </pre>
|
||
<p>
|
||
Our <code class="methodname">run()</code> method does four
|
||
things. It calls <code class="methodname">MyDbEnv.setup()</code>,
|
||
which opens our <code class="classname">Environment</code> and
|
||
<code class="classname">EntityStore</code>. It then instantiates a
|
||
<code class="classname">DataAccessor</code> object, which we will use
|
||
to write data to the store. It calls
|
||
<code class="methodname">loadVendorsDb()</code> which loads all of the
|
||
vendor information. And then it calls
|
||
<code class="methodname">loadInventoryDb()</code> which loads all of
|
||
the inventory information.
|
||
</p>
|
||
<p>
|
||
Notice that the <code class="classname">MyDbEnv</code>
|
||
object is being setup as read-write. This results in the
|
||
<code class="classname">EntityStore</code> being opened for
|
||
transactional support.
|
||
(See <a class="xref" href="mydbenv-persist.html" title="MyDbEnv">MyDbEnv</a>
|
||
for implementation details.)
|
||
</p>
|
||
<pre class="programlisting"> private void run(String args[])
|
||
throws DatabaseException {
|
||
// Parse the arguments list
|
||
parseArgs(args);
|
||
|
||
myDbEnv.setup(myDbEnvPath, // Path to the environment home
|
||
false); // Environment read-only?
|
||
|
||
// Open the data accessor. This is used to store
|
||
// persistent objects.
|
||
da = new DataAccessor(myDbEnv.getEntityStore());
|
||
|
||
System.out.println("loading vendors db....");
|
||
loadVendorsDb();
|
||
|
||
System.out.println("loading inventory db....");
|
||
loadInventoryDb();
|
||
} </pre>
|
||
<p>
|
||
We can now implement the <code class="methodname">loadVendorsDb()</code>
|
||
method. This method is responsible for reading the vendor
|
||
contact information from the appropriate flat-text file,
|
||
populating <code class="classname">Vendor</code> class objects with the
|
||
data and then writing it to the <code class="classname">EntityStore</code>.
|
||
As explained above, each individual object is written with
|
||
transactional support. However, because a transaction handle is
|
||
not explicitly used, the write is performed using auto-commit.
|
||
This happens because the <code class="classname">EntityStore</code>
|
||
was opened to support transactions.
|
||
</p>
|
||
<p>
|
||
To actually write each class to the
|
||
<code class="classname">EntityStore</code>, we simply call the
|
||
<code class="methodname">PrimaryIndex.put()</code> method for the
|
||
<code class="classname">Vendor</code> entity instance. We obtain this
|
||
method from our <code class="classname">DataAccessor</code>
|
||
class.
|
||
</p>
|
||
<pre class="programlisting"> private void loadVendorsDb()
|
||
throws DatabaseException {
|
||
|
||
// loadFile opens a flat-text file that contains our data
|
||
// and loads it into a list for us to work with. The integer
|
||
// parameter represents the number of fields expected in the
|
||
// file.
|
||
List vendors = loadFile(vendorsFile, 8);
|
||
|
||
// Now load the data into the store.
|
||
for (int i = 0; i < vendors.size(); i++) {
|
||
String[] sArray = (String[])vendors.get(i);
|
||
Vendor theVendor = new Vendor();
|
||
theVendor.setVendorName(sArray[0]);
|
||
theVendor.setAddress(sArray[1]);
|
||
theVendor.setCity(sArray[2]);
|
||
theVendor.setState(sArray[3]);
|
||
theVendor.setZipcode(sArray[4]);
|
||
theVendor.setBusinessPhoneNumber(sArray[5]);
|
||
theVendor.setRepName(sArray[6]);
|
||
theVendor.setRepPhoneNumber(sArray[7]);
|
||
|
||
// Put it in the store.
|
||
da.vendorByName.put(theVendor);
|
||
}
|
||
} </pre>
|
||
<p>
|
||
Now we can implement our <code class="methodname">loadInventoryDb()</code>
|
||
method. This does exactly the same thing as the
|
||
<code class="methodname">loadVendorsDb()</code>
|
||
method.
|
||
</p>
|
||
<pre class="programlisting"> private void loadInventoryDb()
|
||
throws DatabaseException {
|
||
|
||
// loadFile opens a flat-text file that contains our data
|
||
// and loads it into a list for us to work with. The integer
|
||
// parameter represents the number of fields expected in the
|
||
// file.
|
||
List inventoryArray = loadFile(inventoryFile, 6);
|
||
|
||
// Now load the data into the store. The item's sku is the
|
||
// key, and the data is an Inventory class object.
|
||
|
||
for (int i = 0; i < inventoryArray.size(); i++) {
|
||
String[] sArray = (String[])inventoryArray.get(i);
|
||
String sku = sArray[1];
|
||
|
||
Inventory theInventory = new Inventory();
|
||
theInventory.setItemName(sArray[0]);
|
||
theInventory.setSku(sArray[1]);
|
||
theInventory.setVendorPrice(
|
||
(new Float(sArray[2])).floatValue());
|
||
theInventory.setVendorInventory(
|
||
(new Integer(sArray[3])).intValue());
|
||
theInventory.setCategory(sArray[4]);
|
||
theInventory.setVendor(sArray[5]);
|
||
|
||
// Put it in the store. Note that this causes our secondary key
|
||
// to be automatically updated for us.
|
||
da.inventoryBySku.put(theInventory);
|
||
}
|
||
} </pre>
|
||
<p>
|
||
The remainder of this example simple parses the command line
|
||
and loads data from a flat-text file. There is nothing here
|
||
that is of specific interest to the DPL, but we
|
||
show this part of the example anyway in the interest of
|
||
completeness.
|
||
</p>
|
||
<pre class="programlisting"> private static void parseArgs(String args[]) {
|
||
for(int i = 0; i < args.length; ++i) {
|
||
if (args[i].startsWith("-")) {
|
||
switch(args[i].charAt(1)) {
|
||
case 'h':
|
||
myDbEnvPath = new File(args[++i]);
|
||
break;
|
||
case 'i':
|
||
inventoryFile = new File(args[++i]);
|
||
break;
|
||
case 'v':
|
||
vendorsFile = new File(args[++i]);
|
||
break;
|
||
default:
|
||
usage();
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
private List loadFile(File theFile, int numFields) {
|
||
List<String[]> records = new ArrayList<String[]>();
|
||
try {
|
||
String theLine = null;
|
||
FileInputStream fis = new FileInputStream(theFile);
|
||
BufferedReader br =
|
||
new BufferedReader(new InputStreamReader(fis));
|
||
while((theLine=br.readLine()) != null) {
|
||
String[] theLineArray = theLine.split("#");
|
||
if (theLineArray.length != numFields) {
|
||
System.out.println("Malformed line found in " +
|
||
theFile.getPath());
|
||
System.out.println("Line was: '" + theLine);
|
||
System.out.println("length found was: " +
|
||
theLineArray.length);
|
||
System.exit(-1);
|
||
}
|
||
records.add(theLineArray);
|
||
}
|
||
// Close the input stream handle
|
||
fis.close();
|
||
} catch (FileNotFoundException e) {
|
||
System.err.println(theFile.getPath() + " does not exist.");
|
||
e.printStackTrace();
|
||
usage();
|
||
} catch (IOException e) {
|
||
System.err.println("IO Exception: " + e.toString());
|
||
e.printStackTrace();
|
||
System.exit(-1);
|
||
}
|
||
return records;
|
||
}
|
||
|
||
protected ExampleDatabasePut() {}
|
||
} </pre>
|
||
</div>
|
||
<div class="navfooter">
|
||
<hr />
|
||
<table width="100%" summary="Navigation footer">
|
||
<tr>
|
||
<td width="40%" align="left"><a accesskey="p" href="dataaccessorclass.html">Prev</a> </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="u" href="dpl_example.html">Up</a>
|
||
</td>
|
||
<td width="40%" align="right"> <a accesskey="n" href="dpl_exampleinventoryread.html">Next</a></td>
|
||
</tr>
|
||
<tr>
|
||
<td width="40%" align="left" valign="top">DataAccessor.java </td>
|
||
<td width="20%" align="center">
|
||
<a accesskey="h" href="index.html">Home</a>
|
||
</td>
|
||
<td width="40%" align="right" valign="top"> ExampleInventoryRead.java</td>
|
||
</tr>
|
||
</table>
|
||
</div>
|
||
</body>
|
||
</html>
|