13 java in oracle

Java Training
Java in Oracle
Written by Jeff Smith

Introduction -1
Modern databases such as Oracle support Java Stored
Procedures
These slides will be geared towards Oracle Java stored
procedures, but many of the concepts would translate to
other databases as well
Java stored procedures are simply static methods of plain
old Java classes which have been loaded into Oracle and
published with a call specification (call spec).
So why write PL/SQL when you can write your stored
procedures in a beautiful language like Java, using a
powerful IDE like Eclipse? :-)

Introduction -2
Advantages of Java Stored Procedures
Java has robust type checking, so the compiler catches
many bugs for you. PL/SQL has relaxed (poor) type
checking, so many bugs don't show up until run time
Java is a true OOP language that supports and
encourages encapsulation, inheritance, interfaces, etc.
Java stored procedures can access many resources
unavailable to PL/SQL, such as EJBs, web services,
JavaMail, other external JARs, etc.
You could even have your Java stored procedure
send instant messages via AIM!

Introduction -3
Advantages of Java Stored Procedures (continued..)
Java is faster than PL/SQL for computation intensive
operations
Java can read files larger than 32k
You can develop and debug your Java stored
procedures in a slick IDE like Eclipse
Database independence--your Java stored procedures
will be portable from one database to the next
The logic in your Java stored procedures could also be
ported to a different tier in your architecture

Introduction -4
Disadvantages of Java Stored Procedures
An extra step in creating them (publishing them in
Oracle through a utility like Loadjava)
Support for database objects, types, and features is not
as complete as PL/SQL
Some data intensive operations (such as batching data
sets) is faster in PL/SQL than in Java
Slightly longer time (overhead) required to call a Java
procedure.
Bradley Brown, chief architect of TUSC, reported a
tenth of a second overhead involved in calling Java
stored procedures in Oracle 8/9

Introduction -5
This is your classic J2EE architecture
If you are starting a system from scratch,
this would be one good way to design it
O/R mapping could be JDO, Toplink,
Hibernate, or Entity beans
DAO/JDBC might work better than O/R if
you need to write complex SQL
There might be Oracle stored
procedures, but they would only deal
with data operations, not business logic
Stored procedures would probably need
to call each other, but they wouldn't need
to call business functions in the middle
tier
But what if you already have lots of
stored procedures with business logic?

Introduction -6
Java code in stateless session
beans (SSB) can call Oracle stored
procedures, but there is no way for
PL/SQL code to call Java logic in
the SSBs
So if you write a new business
function in a Java middle tier
(JBOSS), other Java code there
can access it (of course)
But what if some existing PL/SQL
code also needs to call this new
business function?
Would you have to duplicate the
function in both places?

Introduction -7
Adding Java stored
procedures to your system
doesn't require changing your
architecture
You get the benefits of writing
Java code using sound OOP
principles, and yet your
existing PL/SQL procedures
can access this new code as
easily as if it were written in
PL/SQL

Introduction -8
Java stored procedures (and functions)
can be called directly by another PL/SQL procedure or
function
can be called by Pro C
can themselves call PL/SQL stored procedures and
functions (either using JDBC/SQLExecutor or SQLJ)
can call EJBs running inside Oracle 9iAS (but not
JBOSS)
You can also write your triggers in Java

Oracle JVM-1
Oracle 8i was first version to support Java
Oracle 9i is J2SE 1.3 compatible
Starting with Oracle 9i release 2 (version 9.2), Oracle no
longer supports the Java 2 Enterprise Edition (J2EE) and
CORBA stacks in the database
Oracle has moved these capabilities to Oracle 9iAS, the
App Server version of Oracle 9. Oracle 9iAS supports EJBs,
JSPs, servlets, CORBA, etc.

Oracle JVM-2
Oracle 9i supports
Standard J2SE features
Java stored procedures
Java triggers
JDBC 2.0 (and some JDBC 3.0 support)
SQLJ
Calling out to web components, servlets, JSPs using
HTTP client
Calling out to EJBs deployed in Oracle 9iAS
JMS interface for advanced queuing systems (JMS
compatible message provider)

Oracle JVM-3
The Oracle JVM can run any Java method as a stored
procedure except for methods that instantiate a GUI
For example, the database can't create a Swing (JPanel)
window
The Oracle JVM supports
Java stored functions and procedures
Java triggers
Java database objects (general purpose)
You can either load your java classes by
using the loadjava utility
using CREATE JAVA statements
using an IDE like Oracle JDeveloper

Oracle JVM-4
Java Stored Procedures must comply with the following
rules:
No constructor
Variables and methods must be declared static
Use the default database connection (no userid/
password required, run in session)
Declare output variables as arrays pu
Java Stored Procedures can call other classes that do not
have these restrictions.
So you can write POJO classes and only the Java
stored procedure class has the restrictions listed above

Console Output (System.out)
What happens to console output from a Java Stored
Procedure?
System.out.println() statements will be written to trace
files in the Oracle UDUMP destination directory.
Alternatively, you can redirect output to a SQLPlus text
buffer (size 5000 bytes) by doing the following:
SQL> SET SERVEROUTPUT ON
SQL> EXEC dbms_java.set_output(5000);
Next call your stored procedure:
SQL> call StoredProcTest_createTable('jeff');
Your System.out.println() statements and stack traces will
appear in SQLPlus!

Create Java Function-1
You can create Java procedures and functions by typing the
Java code directly into SQLPlus or some other tool:
SQL> CREATE JAVA SOURCE NAMED "Hello" AS
public class Hello
{
public static String world()
{
return "Hello World from Java!";
}
};
/
You should get back the message "Java created".

Next you "publish" your new Java routine by creating a call
spec. You can think of a call spec as a PL/SQL function or
procedure wrapper for your Java code. Here is an example
(typed into SQLPlus):
SQL> CREATE OR REPLACE FUNCTION hello_world return
VARCHAR2 as language java
name 'Hello.world() return java.lang.String';
You should get back the message "Function created."

Your Java function is now available for use. To test it,
create a variable and call your stored function like so:
SQL> select hello_world() from dual;
OR
SQL> variable myString varchar2(40);
SQL> call hello_world() into :myString;
SQL> print myString;
You should get back the message "Hello world from Java!"
You can also call this stored function, hello_world, from any
PL/SQL blocks

Create Java Procedure-1
When you create a Java stored procedure, the process is
the same (instead of a function) but your call spec has a
different signature. Here is an example
create or replace procedure MyClass_createTable
(table_name IN VARCHAR2) as language java name
'mypackage.MyClass.createTable(java.lang.String)';
/
Note that this example illustrates how to create a call spec
for a class that resides in a package (mypackage)

Java Compile Error Debug Tip
If you get a message like "Warning: Java created with
compilation errors", you can determine the cause of the
error like so:
SQL> select * from user_errors

Call Spec Tip-1
You'll confuse Oracle if you give your stored procedure the
same name as your class--it needs to be different.
So when you create your Java stored procedure, use the
following naming convention when creating your call spec.
For example
CREATE OR REPLACE FUNCTION classname_methodname return
name 'Classname.methodname() return java.lang.String';
Here is our Hello world example:
CREATE OR REPLACE FUNCTION hello_world return

Call Spec Tip-2
Java stored procedures can follow the same notation. For
example, the following call spec is for a class named
com.cexp.StoredProcTest with a method named
createTable that takes a single (String) parameter:
CREATE OR REPLACE PROCEDURE
StoredProcTest_createTable(table_name IN VARCHAR2) AS
language java name
'com.cexp.StoredProcTest.createTable(java.lang.String)';

Review
Why would you choose to use Java stored procedures
instead of PL/SQL?
Why would you choose to use PL/SQL?
Why might you use Java stored procedures instead of
writing your Java business logic in a J2EE container (middle
tier)?
What is a call spec?
How can you view the output of System.out.println()
statements?

Create Java Class Using Bfile-1
Instead of typing the Java class directly into a tool like
SQLPlus, you probably would prefer to compile and test the
class using another tool (perhaps Eclipse) and just load it
into the database
First you need to declare the directory in Oracle.
If Oracle is running from a UNIX server, you need to specify
a directory on that server (not your C: drive). For example,
you can type the following into SQLPlus
SQL> create or replace directory MyDir as
'/home/jesmith';
You should get back the message "Directory created."

Once you have defined the directory in Oracle, you can
create the Java class in Oracle by typing the following into
SQLPlus
SQL> create or replace java class using bfile (MyDir,
'Hello.class');
/
You should get back the message "Java created."
You can delete your directory now that we are finished with
it:
drop directory MyDir;

Next, create your call spec for the stored function:
SQL> CREATE OR REPLACE FUNCTION hello_world return
Your Java function (created from the binary file) is now
available for use.
You can request that Oracle describe your call spec like so:
SQL> desc hello_world;
Oracle returns:
FUNCTION hello_world RETURNS VARCHAR2

Your Java stored function (created from the binary file) is
now available for use. To test it, type the following into
SQLPlus
SQL> select hello_world() from dual;
OR
SQL> variable myString varchar2(40);
SQL> call hello_world() into :myString;
SQL> print myString;
Note that you can also call your stored function from any
other PL/SQL procedure or function.

Which Classes Are Loaded? -1
You can determine which Java "system" classes are
currently loaded in Oracle by selecting from the
dba_objects table.
To determine which "user" classes are loaded, you can
select from the user_objects table. For example, to
determine the class name, created date, and status of your
Java classes loaded in Oracle:
select OBJECT_NAME, CREATED, STATUS
from user_objects
where object_type = 'JAVA CLASS'
Note: classes with status "invalid" aren't necessarily invalid,
they just haven't been compiled in Oracle yet.

Which Classes Are Loaded? -2
If you use Toad, you can click on the Java tab of the
schema browser to see which classes are loaded.
In Toad, you can right-click on one of these classes and
select "compile".
If Oracle likes your class, you'll see the message,
"Compiled without errors".
If Oracle has rejected your class, you'll get an error
message about why Oracle rejected it.
(see next slide)

Viewing Java Classes With Toad
Viewing Java classes in a schema and compiling

Loadjava Utility-1
Instead of using a tool like SQLPlus to load your Java class
into Oracle, you might prefer using a command line tool like
the loadjava utility
This tool exists on the Oracle server in the
$ORACLE_HOME/bin directory
So if Oracle is installed on a UNIX server, the tool will reside
on that server (not the Oracle client directory on a user's
Windows machine).
You can also run loadjava from an application like SQLPlus
by calling sys.dbms_java.loadjava(...)

Loadjava Utility-2
Loadjava loads Java source files, classes, JAR files, and
other resources into the database where they are stored as
Java schema objects
Note: In Toad, you can find these Java schema objects
on the Java tab of the Schema Browser window

Loadjava Utility-3
With Oracle 9i (version 9.2), loadjava allows you to
automatically publish Java classes as stored procedures by
creating the corresponding call specs for methods
contained in the processed classes
With Oracle 8i, you have to create the call spec
(procedure or function) yourself

Loadjava Utility-4
According to Oracle, the Loadjava syntax is (assumes
loadjava.bat is installed in the Oracle Home directory and
the HelloWorld.class file is in the current directory of the
same server)
loadjava -user schema/password HelloWorld.class
or
loadjava -user schema/password HelloWorld.java
I got an Oracle error with the syntax above. To load a java
file to wdevprja on snowmass, I had to use
loadjava -force -user
wdevprja/wdevprja@snowmass:1521:wdev -thin
MyClass.java

Loadjava Utility-5
You can also execute this from SQLPlus like so:
SQL> host loadjava -force -user
wdevprja/mypassword@snowmass:1521:wdev
-thin MyClass.java
To load a jar file into wdevcnv (Oracle 9.2), you log into
snowmass as user wdevcnv and
wdevcnv/mypassword@snowmass:1526:wdevcnv -thin
SQLExecutorFramework.jar

Loadjava Utility-6
You can also use the sys.dbms_java.loadjava function in
SQLPlus to load your Java class
SQL>call sys.dbms_java.loadjava('-v -r -grant PUBLIC
-synonym HelloWorld.java');
This example would load the class HelloWorld into the
schema you logged into

Class Resolver-1
The Oracle JVM uses a resolver to search for supporting
classes when you call a method in the HelloWorld class.
A supporting class is just a class that is referenced by
your class. For example, if your class uses String
objects, then the String class is a "supporting class"
Oracle provides a default class resolver which searches the
current schema and then PUBLIC
PUBLIC classes include all the standard JDK classes
If you want to access classes defined in another schema,
you specify this other resolver on the loadjava command
line

Class Resolver-2
If you want to access classes defined in another schema,
you specify this other resolver on the loadjava command
line
The following example uses a custom resolver spec which
includes the SCHEMA1 schema, SCHEMA2 schema, and
PUBLIC
loadjava -resolve -resolver
"((* SCHEMA1)(* SCHEMA2)(* PUBLIC))"
This command would search SCHEMA1, SCHEMA2, and
PUBLIC to resolve all class references in your code

Class Resolver-3
You can also narrow the resolver spec to search for a
subset of classes within a schema:
loadjava -resolve -resolver
'(("com/cexp/*" SCHEMA1)(* SCHEMA2)(* PUBLIC))'
This command would search all classes whose package
name begins with com.cexp in SCHEMA1, all classes in
SCHEMA2, and all PUBLIC classes

Compiling Classes In Oracle-1
You may be surprised to see that after you've loaded your
classes into Oracle with the LoadJava utility, they are
uncompiled (status "invalid").
Don't worry! Your classes will either be compiled
automatically on first use or you can manually compile them
yourself in a tool like SQLPlus:
SQL> ALTER JAVA CLASS "com.cexp.wms.MyClass" RESOLVE;
or
SQL> ALTER JAVA SOURCE "com.cexp.wms.MyClass" COMPILE;
You can also compile them in Toad (see next slide)

Here is Oracle's easy to understand diagram of Alter Java...
ALTER JAVA SOURCE - used to compile a Java source
ALTER JAVA CLASS - used to resolve (find classes
referenced) a Java class
ALTER JAVA CLASS "Agent" RESOLVER (("/home/java/bin/*"
pm)(* public)) RESOLVE;

The invoker_rights_clause lets you specify whether the
methods of the class execute with the privileges and in the
schema of the user who defined it or with the privileges and
in the schema of CURRENT_USER.
It also determines how Oracle resolves external names in
queries, DML operations, and dynamic SQL statements in
the member functions and procedures of the type.
Specify CURRENT_USER if you want the methods of
the class to execute with the privileges of
CURRENT_USER. This clause is the default and
creates an "invoker-rights class."
Specify DEFINER if you want the methods of the class
to execute with the privileges of the user who defined it.

Granting Permissions-1
Sometimes you will need to grant the Oracle JVM
permissions in order for your Java stored procedure (or
trigger) to function
For example, if your Java class reads or writes from disk,
you may need to grant the Oracle JVM certain file system
permissions. For example:
EXEC dbms_Java.Grant_Permission('wdevcnv',
'java.io.FilePermission', '<<ALL FILES>>', 'read,
write, execute, delete');
where 'wdevcnv' is the schema name)
For an example of exporting the contents of a BLOB
datatype to the file system, see:
http://www.oracle-base.com/Articles/8i/ExportBlob.asp

Loading JAR files
To load a JAR file into an Oracle 8.1.7 server named
wdev.snowmass with user wdevprja on the standard port
1521, you could type the following in SQLPlus
SQL> host loadjava -force -user
wdevprja/mypassword@snowmass:1521:wdev
-thin MyProject.jar
(this command assumes that MyProject.jar is in the current
directory)

Compiling JARs With Toad
Once you load your JAR file in Oracle 8.1.7, you'll need to
compile the classes. Using a tool like Toad makes this easy

Loadjava Summary
The only drawback of loadjava is that it only works on the
operating system on which Oracle resides. It also requires
you to manually create a call spec.
To recap, if you are developing your Java code on Windows
and Oracle resides elsewhere (perhaps on UNIX), you need
to do the following
first copy the file somewhere on the UNIX box
(perhaps via FTP)
next call the loadjava utility
next create a call spec (function or procedure)
This is rather tedious. Ideally, we would find a tool that
automates this whole process for us.

Loadjava And Toad-1
You can use Toad to load Java classes into Oracle (it uses
the loadjava utility). Go to the Tools Menu, Java Manager
option. It must be able to find loadjava.bat in order to work.

Drop Java Source/Class-1
You may want to drop a source file or class you've loaded
into Oracle. Use the drop java source or drop java class
command to do this. For example:
SQL> drop java source "HelloWorld";
SQL> drop java source "com.cexp.wms.oracle.HelloWorld"
SQL> drop java class "HelloWorld";
To drop your function (call spec) named HelloWorld:
SQL> drop function hello_world;
Toad makes it easy to drop classes and sources. Just go to
the Java tab of the schema browser, right click on the
object you want to drop, select "drop object".
You can also drop the function on the Procs tab

Drop Java Source/Class-2
You can also use the dropjava command line utility
(installed on the same server as the database). For
example:
dropjava -u username/password myPackage.myClass
dropjava -u username/password myJar.jar

Exercise
Using SQLPlus, create a test table in wdevprja called something like
"MyName_Test". The table should have the following fields: EMPID
(Number), FNAME (VARCHAR2) and LName (VARCHAR2). Put a
couple records in it.
Using Eclipse, create a Java stored procedure in package
com.cexp.wms.oracle. Your class should be called
"MyName_StoredProcTest" and your method should be called
"insertRecord(String firstName, lastName)". This stored procedure can
use standard JDBC or the SQLExecutor framework to insert records
into your table.
Load your Java stored procedure into the database and create a call
spec for it. SQLPlus commands may be the easiest way to do this.
Test your stored procedure by calling it from SQLPlus. Redirect
System.out.println() output to the SQLPlus window to aid in debugging.
Remember to drop your table when you are done. Also drop your Java
stored procedure and your call spec.

Problems Loading Java-1
Occasionally, one of your class files may compile fine with
Sun JDK 1.3, but be rejected by Oracle.
For example, one of the classes in my
SQLExecutorFramework.jar file was rejected by Oracle
because a function returned its value in a finally block
(see next slide)

static int getDbType(Connection con)
{
try
{
....
}
catch (SQLException e)
{
....
}
finally
{
return(dbType);
}
}

When I compiled this class in Toad (go to Java tab of
Schema browser and right click on Java classname), I got
the following error from Oracle:
JAVA CLASS WDEVPRJA.com/cexp/wms/jdbc/DatabaseType
On line: 0
ORA-29545: badly formed class: at offset 78 of
com.cexp.wms.jdbc.DatabaseType.getDbType return type
is inconsistent with return opcode

When I rewrote my code like this, Oracle was happy:
static int getDbType(Connection con)
{
try
{
....
}
catch (SQLException e)
{
....
}
return(dbType);
}

The new code is probably better, so it was an easy decision
to make the code change
SQLExecutorFramework.jar now works in Oracle 8.1.7
The point here is that there may be times your Java classes
are rejected by Oracle when you try to load them
Use a tool like Toad to get the compile error from Oracle
and then fix your classes accordingly

Problems Using LoadJava-1
There is a bug in Oracle 8 that occurs when you use
loadjava to re-load an already loaded CLASS file. Oracle
seems to get confused and doesn't recompile the new class
file correctly. Loading the .java (source) instead of the class
file seems to work every time:
host loadjava -force -user
wdevprja/wdevprja@snowmass:1521:wdev -thin
JeffStoredProcTest.java
I don't know if this is a problem in Oracle 9.2 or not. To be
safe, I'd recommend loading Java source files instead of
class files (since Oracle has to recompile them anyway).

Problems Using LoadJava-2
You can load a JAR file into Oracle with a single loadjava
command:
wdevprja/password@snowmass:1521:wdev -thin
SQLExecutorFramework.jar
Occasionally, a class in your JAR file might not get loaded
into Oracle (version 8 at least). When you try to compile
another class which uses this missing JAR file class, you'll
get a compile error.
My advice is to check that each class in your JAR is loaded
into Oracle

Problems Compiling/Running-1
If you ever get an error message like this:
The following error has occurred:
ORA-29549: class WDEVPRJA.com/cexp/wms/oracle/StoredProcTest has
changed, Java session state cleared
ORA-06512: at "WDEVPRJA.STOREDPROCTEST_CREATETABLE", line0
ORA-06512: at line 2
The Oracle docs say "Cause: A class in use by the current
session was redefined or dropped, invalidating the current
Java session state and requiring that it be cleared."
It means that you've reloaded a Java class in Oracle and
the new version is different (and needs to be recompiled)
Just ignore this error and re-run the stored procedure. The
error should go away on the 2nd attempt

Problems Debugging-1
To view System.out.println in SQLPlus, you'll need to:
set serveroutput on
call dbms_java.set_output(5000);
(Note: I had to execute this before EACH call to my
stored procedure)
If a runtime exception is thrown, you may not see any of
your System.out.println statements (that preceded the
runtime exception) at all!

Problems Setting Query Timeout
When I set a query timeout in a Java stored procedure like
so:
prepStatement.setQueryTimeout(15);
prepStatement.executeUpdate(); //null pointer exception
I got a NullPointerException when the executeUpdate()
statement executed.
Hence, I don't recommend setting a query timeout :-)

Creating a Java Trigger-1
You can also write your Oracle triggers in Java. For
example, you could write the following trigger class:
import java.sql.*;
public class EmployeeInsertTrigger
{
public static void onInsert(Connection con,
Long[] newid)
{
Long NextSeqValue = new Long(0); //def to zero

try
{
//Get next id from the sequence
String sql = "select emp_seq.nextval from dual";
PreparedStatement ps = con.prepareStatement(sql);
ResultSet rs = ps.executeQuery();
while (rs.next ())
NextSeqValue = new Long(rs.getLong(1));
newid[0] = NextSeqValue;
// Close the Statement stmt.close();
ps.close();
} catch(SQLException e) {}
}
}

Next, compile your Java class and then load it into the
database:
CREATE OR REPLACE JAVA CLASS USING BFILE (MyFolder,
'EmployeeInsertTrigger.class');
/
Next you create your call spec:
CREATE OR REPLACE PROCEDURE
EMPLOYEE_INSERT( NEWID IN OUT NUMBER )
AS LANGUAGE JAVA NAME
'EmployeeInsertTrigger.onInsert( java.sql.Connection,
java.lang.Long[])';
/

Finally, create your trigger which will fire before each insert
into the Employee table:
CREATE OR REPLACE TRIGGER EMPLOYEE_BEF_INS_TRG
BEFORE INSERT ON EMPLOYEE FOR EACH ROW
EMPLOYEE_INSERT( new.EMPLOYEE_ID );
/
That's all there is to it!

My Loadjava Utility-1
I've written a utility called JavaLoader which replaces the
Oracle version. My LoadJava program (written in Java, of
course) automates the whole process.
Copies your class file to the UNIX server hosting Oracle
Creates an Oracle directory alias
Creates the Java class in Oracle using the "CREATE
JAVA CLASS USING BFILE" command
Creates the corresponding call spec
Compiles the Java class in Oracle
Deletes the temporary class file from the UNIX server

JavaLoader uses a properties file to store the information
required to perform all these tasks
You can edit the "template" javaloader.properties file to load
your own, custom Java classes

# Properties for Jeff Smith's Load Java Program
ftp.servername=uscobrmfa-ub-14.cexp.com
ftp.username=jesmith
oracle.connurl=jdbc:oracle:thin:@SNOWMASS:1521:WDEVCNV
oracle.username=wdevcnv
oracle.password=wdevcnv
java.classname=StoredProcTest.class
java.package=com.cexp.wms.oracle
java.methodname=createTable

#STORED PROCEDURE EXAMPLE (ORACLE CALL SPEC)
cs0=CREATE OR REPLACE PROCEDURE
cs1=StoredProcTest_createTable(table_name IN VARCHAR2) AS language java
cs2=NAME 'com.cexp.wms.oracle.StoredProcTest.createTable(java.lang.String)'
cs3=
cs4=
cs5=
#STORED FUNCTION EXAMPLE (ORACLE CALL SPEC)
#cs0=CREATE OR REPLACE FUNCTION StoredProcTest_getFullName(fname IN
#cs1=VARCHAR2, lname IN VARCHAR2)
#cs2=return VARCHAR2 AS language java
#cs3= NAME 'com.cexp.wms.oracle.StoredProcTest.getFullName(java.lang.String,
#cs4=java.lang.String) return java.lang.String'
#cs5=

Syntax: Javaloader [password] [optional: properties filename].
If you leave the properties filename blank, the name
"javaloader.properties" is assumed (similar to the way Ant
assumes a file called build.xml will exist)
Example: javaloader mypassword
Example: javaloader mypassword javaloader.properties

For more information and to download the utility, see:
http://expressway2.cexp.com/info_services/D&L_Systems/java/
JavaLoader.htm

A Look Into The Crystal Ball
Given the rising popularity of Java, Oracle will likely migrate
the database in that direction. While PL/SQL support won't
be going away, new development at Oracle will probably
focus on Java stored procedures, functions and triggers
Other databases are also moving in the direction of Java
Postgres supports Java stored procedures (PL/PGJ)
MySQL may follow suit
But you probably won't see Microsoft add Java stored
procedures to SQL Server before hell freezes over!

Resources
Oracle's Java Stored Procedure Samples:
http://technet.oracle.com/sample_code/tech/java/jsp/oracle9ijsp.html

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