Java Doc for SqlMapClient.java in  » Database-ORM » iBATIS » com » ibatis » sqlmap » client » Java Source Code / Java DocumentationJava Source Code and Java Documentation

The SqlMapClient is the central class for working with SQL Maps. This class will allow you to run mapped statements (select, insert, update, delete etc.), and also demarcate transactions and work with batches. Once you have an SqlMapClient instance, everything you need to work with SQL Maps is easily available.

The SqlMapClient can either be worked with directly as a multi-threaded client (internal session management), or you can get a single threaded session and work with that. There may be a slight performance increase if you explicitly get a session (using the openSession() method), as it saves the SqlMapClient from having to manage threads contexts. But for most cases it won't make much of a difference, so choose whichever paradigm suits your needs or preferences.

An SqlMapClient instance can be safely made static or applied as a Singleton. Generally it's a good idea to make a simple configuration class that will configure the instance (using SqlMapClientBuilder) and provide access to it.

The following example will demonstrate the use of SqlMapClient.

 
 //
 // autocommit simple query --these are just examples...not patterns
 //
 
 Employee emp = (Employee) sqlMap.queryForObject("getEmployee", new Integer(1));
 
 //
 // transaction --these are just examples...not patterns
 //
 
 try {
 sqlMap.startTransaction()
 Employee emp2 = new Employee();
 // ...set emp2 data
 Integer generatedKey = (Integer) sqlMap.insert ("insertEmployee", emp2);
 emp2.setFavouriteColour ("green");
 sqlMap.update("updateEmployee", emp2);
 sqlMap.commitTransaction();
 } finally {
 sqlMap.endTransaction();
 }
 
 //
 // session --these are just examples...not patterns
 //
 
 try {
 SqlMapSession session = sqlMap.openSession()
 session.startTransaction()
 Employee emp2 = new Employee();
 // ...set emp2 data
 Integer generatedKey = (Integer) session.insert ("insertEmployee", emp2);
 emp2.setFavouriteColour ("green");
 session.update("updateEmployee", emp2);
 session.commitTransaction();
 } finally {
 try {
 session.endTransaction();
 } finally {
 session.close();
 }
 // Generally your session scope would be in a wider context and therefore the
 // ugly nested finally block above would not be there.  Realize that sessions
 // MUST be closed if explicitly opened (via openSession()).
 }
 
 //
 // batch --these are just examples...not patterns
 //
 
 try {
 sqlMap.startTransaction()
 List list = (Employee) sqlMap.queryForList("getFiredEmployees", null);
 sqlMap.startBatch ();
 for (int i=0, n=list.size(); i < n; i++) {
 sqlMap.delete ("deleteEmployee", list.get(i));
 }
 sqlMap.executeBatch();
 sqlMap.commitTransaction();
 } finally {
 sqlMap.endTransaction();
 }
 

An SqlMapSession instance.

This particular implementation takes a user provided connection as a parameter. This connection will be used for executing statements, and therefore overrides any configured datasources. Using this approach allows the developer to easily use an externally supplied connection for executing statements.

Important: Using a user supplied connection basically sidesteps the datasource so you are responsible for appropriately handling your connection lifecycle (i.e. closing). Here's a (very) simple example (throws SQLException):

 try {
 Connection connection = dataSource.getConnection();
 SqlMapSession session = sqlMap.openSession(connection);
 // do work
 connection.commit();
 } catch (SQLException e) {
 try {
 if (connection != null) commit.rollback();
 } catch (SQLException ignored) {
 // generally ignored
 }
 throw e;  // rethrow the exception
 } finally {
 try {
 if (connection != null) connection.close();
 } catch (SQLException ignored) {
 // generally ignored
 }
 }