8203059: (so) Closing a socket channel registered with Selector and with SO_LINGER set to 0 does not reset connection
Reviewed-by: chegar
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Provides the API for accessing and processing data stored in a
data source (usually a relational database) using the
Java™ programming language.
This API includes a framework whereby different
drivers can be installed dynamically to access different data sources.
Although the JDBC™ API is mainly geared
to passing SQL statements to a database, it provides for reading and
writing data from any data source with a tabular format.
The reader/writer facility, available through the
<code>javax.sql.RowSet</code> group of interfaces, can be customized to
use and update data from a spread sheet, flat file, or any other tabular
data source.
<h2>What the JDBC™ 4.3 API Includes</h2>
The JDBC™ 4.3 API includes both
the <code>java.sql</code> package, referred to as the JDBC core API,
and the <code>javax.sql</code> package, referred to as the JDBC Optional
Package API. This complete JDBC API
is included in the Java™ Standard Edition (Java SE™), version 7.
The <code>javax.sql</code> package extends the functionality of the JDBC API
from a client-side API to a server-side API, and it is an essential part
of the Java™ Enterprise Edition
(Java EE™) technology.
<h2>Versions</h2>
The JDBC 4.3 API incorporates all of the previous JDBC API versions:
<UL>
<LI> The JDBC 4.2 API</li>
<LI> The JDBC 4.1 API</li>
<LI> The JDBC 4.0 API</li>
<LI> The JDBC 3.0 API</li>
<LI> The JDBC 2.1 core API</li>
<LI> The JDBC 2.0 Optional Package API<br>
(Note that the JDBC 2.1 core API and the JDBC 2.0 Optional Package
API together are referred to as the JDBC 2.0 API.)</li>
<LI> The JDBC 1.2 API</li>
<LI> The JDBC 1.0 API</li>
</UL>
<P>
Classes, interfaces, methods, fields, constructors, and exceptions
have the following "since" tags that indicate when they were introduced
into the Java platform. When these "since" tags are used in
Javadoc™ comments for the JDBC API,
they indicate the following:
<UL>
<LI>Since 9 -- new in the JDBC 4.3 API and part of the Java SE platform,
version 9</li>
<LI>Since 1.8 -- new in the JDBC 4.2 API and part of the Java SE platform,
version 8</li>
<LI>Since 1.7 -- new in the JDBC 4.1 API and part of the Java SE platform,
version 7</li>
<LI>Since 1.6 -- new in the JDBC 4.0 API and part of the Java SE platform,
version 6</li>
<LI>Since 1.4 -- new in the JDBC 3.0 API and part of the J2SE platform,
version 1.4</li>
<LI>Since 1.2 -- new in the JDBC 2.0 API and part of the J2SE platform,
version 1.2</li>
<LI>Since 1.1 or no "since" tag -- in the original JDBC 1.0 API and part of
the JDK™, version 1.1</li>
</UL>
<P>
<b>NOTE:</b> Many of the new features are optional; consequently, there is
some variation in drivers and the features they support. Always
check your driver's documentation to see whether it supports a feature before
you try to use it.
<P>
<b>NOTE:</b> The class <code>SQLPermission</code> was added in the
Java™ 2 SDK, Standard Edition,
version 1.3 release. This class is used to prevent unauthorized
access to the logging stream associated with the <code>DriverManager</code>,
which may contain information such as table names, column data, and so on.
<h2>What the <code>java.sql</code> Package Contains</h2>
The <code>java.sql</code> package contains API for the following:
<UL>
<LI>Making a connection with a database via the <code>DriverManager</code> facility
<UL>
<LI><code>DriverManager</code> class -- makes a connection with a driver
<LI><code>SQLPermission</code> class -- provides permission when code
running within a Security Manager, such as an applet,
attempts to set up a logging stream through the
<code>DriverManager</code>
<LI><code>Driver</code> interface -- provides the API for registering
and connecting drivers based on JDBC technology ("JDBC drivers");
generally used only by the <code>DriverManager</code> class
<LI><code>DriverPropertyInfo</code> class -- provides properties for a
JDBC driver; not used by the general user
</UL>
<LI>Sending SQL statements to a database
<UL>
<LI><code>Statement</code> -- used to send basic SQL statements
<LI><code>PreparedStatement</code> -- used to send prepared statements or
basic SQL statements (derived from <code>Statement</code>)
<LI><code>CallableStatement</code> -- used to call database stored
procedures (derived from <code>PreparedStatement</code>)
<LI><code>Connection</code> interface -- provides methods for creating
statements and managing connections and their properties
<LI><code>Savepoint</code> -- provides savepoints in a transaction
</UL>
<LI>Retrieving and updating the results of a query
<UL>
<LI><code>ResultSet</code> interface
</UL>
<LI>Standard mappings for SQL types to classes and interfaces in the
Java programming language
<UL>
<LI><code>Array</code> interface -- mapping for SQL <code>ARRAY</code>
<LI><code>Blob</code> interface -- mapping for SQL <code>BLOB</code>
<LI><code>Clob</code> interface -- mapping for SQL <code>CLOB</code>
<LI><code>Date</code> class -- mapping for SQL <code>DATE</code>
<LI><code>NClob</code> interface -- mapping for SQL <code>NCLOB</code>
<LI><code>Ref</code> interface -- mapping for SQL <code>REF</code>
<LI><code>RowId</code> interface -- mapping for SQL <code>ROWID</code>
<LI><code>Struct</code> interface -- mapping for SQL <code>STRUCT</code>
<LI><code>SQLXML</code> interface -- mapping for SQL <code>XML</code>
<LI><code>Time</code> class -- mapping for SQL <code>TIME</code>
<LI><code>Timestamp</code> class -- mapping for SQL <code>TIMESTAMP</code>
<LI><code>Types</code> class -- provides constants for SQL types
</UL>
<LI>Custom mapping an SQL user-defined type (UDT) to a class in the
Java programming language
<UL>
<LI><code>SQLData</code> interface -- specifies the mapping of
a UDT to an instance of this class
<LI><code>SQLInput</code> interface -- provides methods for reading
UDT attributes from a stream
<LI><code>SQLOutput</code> interface -- provides methods for writing
UDT attributes back to a stream
</UL>
<LI>Metadata
<UL>
<LI><code>DatabaseMetaData</code> interface -- provides information
about the database
<LI><code>ResultSetMetaData</code> interface -- provides information
about the columns of a <code>ResultSet</code> object
<LI><code>ParameterMetaData</code> interface -- provides information
about the parameters to <code>PreparedStatement</code> commands
</UL>
<LI>Exceptions
<UL>
<LI><code>SQLException</code> -- thrown by most methods when there
is a problem accessing data and by some methods for other reasons
<LI><code>SQLWarning</code> -- thrown to indicate a warning
<LI><code>DataTruncation</code> -- thrown to indicate that data may have
been truncated
<LI><code>BatchUpdateException</code> -- thrown to indicate that not all
commands in a batch update executed successfully
</UL>
</UL>
<h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.3 API</h3>
<UL>
<LI>Added <code>Sharding</code> support</LI>
<LI>Enhanced <code>Connection</code> to be able to provide hints
to the driver that a request, an independent unit of work,
is beginning or ending</LI>
<LI>Enhanced <code>DatabaseMetaData</code> to determine if Sharding is
supported</LI>
<LI>Added the method <code>drivers</code> to <code>DriverManager</code>
to return a Stream of the currently loaded and
available JDBC drivers</LI>
<LI>Added support to <code>Statement</code> for enquoting literals
and simple identifiers</LI>
<LI>Clarified the Java SE version that methods were deprecated</LI>
</UL>
<h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.2 API</h3>
<UL>
<LI>Added <code>JDBCType</code> enum and <code>SQLType</code> interface</li>
<LI>Support for <code>REF CURSORS</code> in <code>CallableStatement</code>
</LI>
<LI><code>DatabaseMetaData</code> methods to return maximum Logical LOB size
and if Ref Cursors are supported</LI>
<LI>Added support for large update counts</LI>
</UL>
<h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.1 API</h3>
<UL>
<LI>Allow <code>Connection</code>,
<code>ResultSet</code> and <code>Statement</code> objects to be
used with the try-with-resources statement</LI>
<LI>Support added to <code>CallableStatement</code> and
<code>ResultSet</code> to specify the Java type to convert to via the
<code>getObject</code> method</LI>
<LI><code>DatabaseMetaData</code> methods to return PseudoColumns and if a
generated key is always returned</LI>
<LI>Added support to <code>Connection</code> to specify a database schema,
abort and timeout a physical connection.</LI>
<LI>Added support to close a <code>Statement</code> object when its dependent
objects have been closed</LI>
<LI>Support for obtaining the parent logger for a <code>Driver</code>,
<code>DataSource</code>, <code>ConnectionPoolDataSource</code> and
<code>XADataSource</code></LI>
</UL>
<h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 4.0 API</h3>
<UL>
<LI>auto java.sql.Driver discovery -- no longer need to load a
<code>java.sql.Driver</code> class via <code>Class.forName</code>
<LI>National Character Set support added
<li>Support added for the SQL:2003 XML data type
<lI>SQLException enhancements -- Added support for cause chaining; New SQLExceptions
added for common SQLState class value codes
<li>Enhanced Blob/Clob functionality -- Support provided to create and free a Blob/Clob instance
as well as additional methods added to improve accessibility
<li>Support added for accessing a SQL ROWID
<li>Support added to allow a JDBC application to access an instance of a JDBC resource
that has been wrapped by a vendor, usually in an application server or connection
pooling environment.
<li>Availability to be notified when a <code>PreparedStatement</code> that is associated
with a <code>PooledConnection</code> has been closed or the driver determines is invalid
</UL>
<h3><code>java.sql</code> and <code>javax.sql</code> Features Introduced in the JDBC 3.0 API</h3>
<UL>
<LI>Pooled statements -- reuse of statements associated with a pooled
connection
<LI>Savepoints -- allow a transaction to be rolled back to a designated
savepoint
<LI>Properties defined for <code>ConnectionPoolDataSource</code> -- specify
how connections are to be pooled
<LI>Metadata for parameters of a <code>PreparedStatement</code> object
<LI>Ability to retrieve values from automatically generated columns
<LI>Ability to have multiple <code>ResultSet</code> objects
returned from <code>CallableStatement</code> objects open at the
same time
<LI>Ability to identify parameters to <code>CallableStatement</code>
objects by name as well as by index
<LI><code>ResultSet</code> holdability -- ability to specify whether cursors
should be held open or closed at the end of a transaction
<LI>Ability to retrieve and update the SQL structured type instance that a
<code>Ref</code> object references
<LI>Ability to programmatically update <code>BLOB</code>,
<code>CLOB</code>, <code>ARRAY</code>, and <code>REF</code> values.
<LI>Addition of the <code>java.sql.Types.DATALINK</code> data type --
allows JDBC drivers access to objects stored outside a data source
<LI>Addition of metadata for retrieving SQL type hierarchies
</UL>
<h3><code>java.sql</code> Features Introduced in the JDBC 2.1 Core API</h3>
<UL>
<LI>Scrollable result sets--using new methods in the <code>ResultSet</code>
interface that allow the cursor to be moved to a particular row or to a
position relative to its current position
<LI>Batch updates
<LI>Programmatic updates--using <code>ResultSet</code> updater methods
<LI>New data types--interfaces mapping the SQL3 data types
<LI>Custom mapping of user-defined types (UDTs)
<LI>Miscellaneous features, including performance hints, the use of character
streams, full precision for <code>java.math.BigDecimal</code> values,
additional security, and
support for time zones in date, time, and timestamp values.
</UL>
<h3><code>javax.sql</code> Features Introduced in the JDBC 2.0 Optional
Package API</h3>
<UL>
<LI>The <code>DataSource</code> interface as a means of making a connection. The
Java Naming and Directory Interface™
(JNDI) is used for registering a <code>DataSource</code> object with a
naming service and also for retrieving it.
<LI>Pooled connections -- allowing connections to be used and reused
<LI>Distributed transactions -- allowing a transaction to span diverse
DBMS servers
<LI><code>RowSet</code> technology -- providing a convenient means of
handling and passing data
</UL>
<h3>Custom Mapping of UDTs</h3>
A user-defined type (UDT) defined in SQL can be mapped to a class in the Java
programming language. An SQL structured type or an SQL <code>DISTINCT</code>
type are the UDTs that may be custom mapped. The following three
steps set up a custom mapping:
<ol>
<li>Defining the SQL structured type or <code>DISTINCT</code> type in SQL
<li>Defining the class in the Java programming language to which the
SQL UDT will be mapped. This class must implement the
<code>SQLData</code> interface.
<li>Making an entry in a <code>Connection</code> object's type map
that contains two things:
<ul>
<li>the fully-qualified SQL name of the UDT
<li>the <code>Class</code> object for the class that implements the
<code>SQLData</code> interface
</ul>
</ol>
<p>
When these are in place for a UDT, calling the methods
<code>ResultSet.getObject</code> or <code>CallableStatement.getObject</code>
on that UDT will automatically retrieve the custom mapping for it. Also, the
<code>PreparedStatement.setObject</code> method will automatically map the
object back to its SQL type to store it in the data source.
<h2>Package Specification</h2>
<ul>
<li><a href="https://jcp.org/en/jsr/detail?id=221">JDBC 4.3 Specification</a>
</ul>
<h2>Related Documentation</h2>
<ul>
<li><a href="http://docs.oracle.com/javase/tutorial/jdbc/basics/index.html">
Lesson:JDBC Basics(The Javaxx Tutorials > JDBC™ Database Access)</a>
<li><a href="http://www.oracle.com/technetwork/java/index-142838.html">
<i>JDBC™ API Tutorial and Reference, Third Edition</i></a>
</ul>
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