Spring jdbc

DATA ACCESS WITH JDBC
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OUTLINE
 Spring Data Access
 DAO Support
 Introduction to Spring Framework JDBC
 Using JDBC Core Classes
 Controlling Database connections
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DAO SUPPORT IN SPRING
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INTRODUCTION
 The Data Access Object (DAO) is a pattern to access the data of the database
 DAO Support in Spring makes it easy to work with data access technologies in a consistent
way
 This allows to switch between different persistence technologies easily and without catching
technology specific exceptions
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CONSISTENT EXCEPTION HIERARCHY
 Spring provides a convenient translation from technology-specific exception to its own exception class
hierarchy.
 These exceptions wrap the original exception so there is never risk to loose any information
 DataAccessException is the root exception in Spring, which is a Runtime Exception and developers are
not forced to handle the exception
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SPRING EXCEPTION HIERARCHY
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ANNOTATION FOR CONFIGURING DAO CLASSES
 @Repository
 Provides exception translation
 Allows component scanning support
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OVERVIEW
 Spring JDBC Framework allows developers to focus on core logic
 Spring handles all the low level details and repetitive tasks like opening and closing of connections,
exceptions, iteration of resultsets, transactions etc.
 The table in next slide shows what actions spring take care of and which actions are responsibility of
application developer
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SPRING JDBC – WHO DOES WHAT?
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Action Spring You
Define connection parameters. X
Open the connection. X
Specify the SQL statement. X
Declare parameters and provide
parameter values
X
Prepare and execute the statement. X
Set up the loop to iterate through
the results (if any).
X
Do the work for each iteration. X
Process any exception. X
Handle transactions. X
Close the connection, statement and
resultset.
X

SPRING DATA ACCESS APPROACHES
 JdbcTemplate –
 JdbcTemplate approach works for JDK 1.4 onwards and is widely used.
 It is used internally in other three approaches.
 handles the repetitive operations like opening and closing of connections and can execute select, insert, update statements, calls to stored procedures.
 This class is thread safe.
 NamedParameterJdbcTemplate –
 supports the use of named parameters in place of traditional place holders ( ? ) and works with JDK 1.4 onwards.
 SimpleJdbcTemplate-
 Uses both JdbcTemplate and NamedParameterJdbcTemplate approaches and provides additional support of Java 5 features etc.
 This approach requires JDK 5 onwards.
 Deprecated in Spring 4.x onwards
 SimpleJdbcInsert and SimpleJdbcCall –
 utilizes the database metadata and hence reduces the configuration overhead.
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PACKAGE HIERARCHY
 The framework consists of 4 packages
 Core
 Contains JDBCTemplate class and its various call back interfaces
Subpackages of Core
 Simple
 Contains the SimpleJdbcInsert and SimpleJdbcCall classes
 Namedparam
 Contains the NamedParameterJdbcTemplate class
 Datasource
 Utility class for easy DataSource access and various simple DataSource implementations
 Object
 Contains classes that represent RDBMS queries, updates and stored procedures as thread-safe reusable objects
 Support
 Provides SQLException translation functionality and some utility classes. Exceptions thrown during JDBC processing are translated to exceptions defined in
org.springframework.dao package
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JDBCTEMPLATE CLASS
 Central class in the JDBC core package
 Handles creation and release of resources, and statement creation and execution
 Executes SQL queries, update statements and stored procedure calls, perform iteration over ResultSet and
extraction of returned parameter values.
 Catches SQL Exceptions and translate them to related subclass of DataAccessException
 JdbcTemplate class requires a DataSource object which can be injected either programmatically or
declaratively
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QUERY (SELECT)
 Simple Query for getting the number of rows
 Simple query using BindVariable
 Querying and populating a single domain object
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QUERY (SELECT)
 Querying and populating a number of domain objects:
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ROWMAPPER INTERFACE
 RowMapper interface is used for mapping rows of a ResultSet on a per row basis to a custom object
 It need to be implemented to provide the actual logic of mapping of ResultSet to a custom object
 Defines one method:
public Object mapRow(ResultSet rs, int rowNum) throws SQLException
 SQLException will be caught and handled by the calling JdbcTemplate
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UPDATING (INSERT/UPDATE/DELETE)
 Insert Query
 Delete Query
 Update Query
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NAMEDPARAMETER JDBC TEMPLATE
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OVERVIEW
 The class adds support for programming JDBC statements using named parameters instead of the placeholders (?)
 It wraps a JdbcTemplate and delegates much of its task to wrapped JdbcTemplate
 Usage Example of NamedParameterJdbcTemplate
 For giving more than one Parameter
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Named
Parameter Class to provide the values
for the named parameters

SQLPARAMETERSOURCE INTERFACE
 SQLParameterSource interface is a source of named parameter values to a
NamedJdbcParameterTemplate.
 Implementations of SQLParameterSource
 MapSqlParameterSource
 An adapter around a java.util.Map, where the keys are the parameter names and the values
are the parameter values
 BeanPropertySqlParameterSource
 This class wraps an arbitrary Java Bean and uses the properties of the wrapped JavaBean as
the source of named parameter values
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USING JAVABEAN TO PROVIDE PARAMETERS
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Class to provide Java
Bean parameters

CONTROLLING DATABASE CONNECTIONS
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DATASOURCE
 Spring obtains a connection to the database through DataSource
 A DataSource is a generalized connection factory
 It allows container to hide connection pooling and transaction management issues from the
application code
 DataSource can be obtained from JNDI or third party connection pool
implementation can also be provided
 Popular implementations are
 Apache Jakarta Commons DBCP
 C3P0
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DRIVERMANAGERDATASOURCE
 Spring’s DataSource implementation
 Doesnot provide pooling and will perform poorly when multiple requests for a connection are made
 Should be used only for testing purpose
 Configuring in xml file
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Spring jdbc

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