Spring 2 for Enterprise applications

Chapter 1 Introduction


Chapter 2 Core container
Use of abstract factory methods and abstract factory objects:

Example of a ReaderFactory:

BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(new File(
someFile.txt")));

public class ReaderFactory {
	public static Reader createReader(ReaderType readerType, File file) throw IOException {
		if (readerType.equals(ReaderType.FILE) {
			return new FileReader(file);
		} else if (readerType.equals(ReaderType.BUFFERED) {
			return new BufferedReader(new InputStreamReader(new FileInputStream(new File(file))));
		} else {throw new IOException("No ReaderType.");
		}
	}

private enum ReaderType{FILE, BUFFERED};
		
}

BeanFactory interface:

package org.springframework.beans.factory;

import org.springframework.beans.BeansException;

public interface BeanFactory {

	String FACTORY_BEAN_SUFFIX = "B";
	Object getBean(String beanName) throws  BeanException;
	Object getBean(String beanName, Class requiredType) throws  BeanException;
	boolean containsBean(String beanName);
	boolean isSingleton(String beanName) throws NoSuchBeanDefinitionException;
	Class<?> getType(String beanName) throws NoSuchBeanDefinitionException;
	String[] getAliases(String beanName) throws NoSuchBeanDefinitionException;

}



Chapter 3 AOP

Chapter 4 Spring AOP


Chapter 5 Data access using Spring

Working with database transactions
Appropriate connection life
Abstract transaction management API
Transaction demarcation

The org.springframework.transaction.PlatformTransactionManager is an abstract class used for handling transactions. A concrete implementation is org.springframework.jdbc.datasource.DataSourceTransactionManager.

This class obtains DataSource Connection objects. Spring offers various techniques for handing the transactions:
programmatic
Java 5 annotation @Transactional
transaction advice
transaction aspect using AspectJ
a factory class to generate proxy instances

DataSource interface and Connection pools
Simple implementations
java.sql.DriverManager
org.springframework.jdbc.datasource.DriverManagerDataSource

These return a Connection object from the internal pool when the getConnection() method is called. 

Datasources that support distributed transactions must be acquired through JNDI. 

Setting up  a connection pool
Use the Apache Commons data connection pooling jar:

<bean id="dataSource" class="org.apache.comons.dhcp.BasicDataSource" destroy-method="close">
	<property name="driveClassName" value="${jdbc.driverClassName}" />
	<property name="url" value="${jdbc.URL}" />
	<property name="username" value="${jdbc.username}" />
	<property name="password" value="${jdbc.password}" />
</bean>

Or

<bean id="dataSource" class="org.springframework.beans.factory.config.PrpoertyPlaceholderConfigurer">
	<property name="location" value="classpath:jdbc.properties" />
</bean>

jdbc.properties file

jdbc.driverClassName=com.mysql.jdbc.MySqLDriver
jdbc.URL=jdbc://mysq1:3360/someDatabase
jdbc.username=wendell
jdbc.password=modica1970

JdbcTemplate class methods:

execute()
query()
queryForInt()
queryForLong()
queryForMap()
queryForList()
queryForObject()
queryForRowSet()

public int getTotal() {
	String query = "select count(0) from people";
	return new JdbcTemplate(dataSource).queryForInt(query);
}

Advantages:
1. no resource management. The connection to the data source is managed automatically and closed
2. automatic participation in transactions
3. no need for exception handling

JdbcDaoSupport class:

public class PeopleDaoImplementation extends JdbcDaoSupport implements PeopleDao {
public int getTotal() {
	String query = "select count(0) from people";
	return getJdbcTemplate().queryForInt(query);
}

<bean id="peopleDao" class="com.wpmassociates.dao.PeopleDaoImplementation">
	<property name="dataSource" ref="dataSource" />
</bean>

For updates to the database:

getJdbcTemplate().update
	(update, 
\		new Object[] {
			person.getFirstName();
			person.getLastName();
			...
		}
	);
}

Aggregate functions
AVG(column)
COUNT(0)
COUNT(column)
MAX(column)
MIN(column)
SUM(column)

Callbacks
CallableStatementCreator
CallableStatementCallback
ConnectCallback
PreparedStatementCallback
PreparedStatementCreator
PreparedStatementSetter
RowMapper
RowCallbackHandler
StatementCallback


public Person load(int id) {
	return (Person)getJdbcTemplate.queryForObject(
		query,
		new Object[] {id},
		new RowMapper() {
			public Object mapRow(ResultSet set, int row) throws SQLException {
				Person person = new Person;
				person.setId(set.getInt("id"));
				...
				return person;
			}
		}
	);
}