JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

Publish Your Article Here

Spring bean auto-wiring modes


We have seen many examples in the previous pages on how to declare beans and how to inject dependencies using constructor-arg and property tags. Spring provides another feature called bean auto-wiring, which will cut down the above said configurations in the xml based configuration file. When using XML-based configuration metadata, the autowire mode for a bean definition is specified by using the autowire attribute of the <bean/> element.

Multiple autowiring modes are available to instruct spring container, the details are given below, more examples are followed in the next pages.

no: No autowiring at all. Bean references must be defined via a ref element. This is the default, and changing this is discouraged for larger deployments, since explicitly specifying collaborators gives greater control and clarity. To some extent, it is a form of documentation about the structure of a system.

byName: Autowiring by property name. This option will inspect the container and look for a bean named exactly the same as the property which needs to be autowired. For example, if you have a bean definition which is set to autowire by name, and it contains a master property (that is, it has a setMaster(..) method), Spring will look for a bean definition named master, and use it to set the property.

byType: Allows a property to be autowired if there is exactly one bean of the property type in the container. If there is more than one, a fatal exception is thrown, and this indicates that you may not use byType autowiring for that bean. If there are no matching beans, nothing happens; the property is not set. If this is not desirable, setting the dependency-check="objects" attribute value specifies that an error should be thrown in this case.

constructor: This is analogous to byType, but applies to constructor arguments. If there isn't exactly one bean of the constructor argument type in the container, a fatal error is raised.

autodetect: Chooses constructor or byType through introspection of the bean class. If a default constructor is found, the byType mode will be applied.

Note that explicit dependencies in property and constructor-arg settings always override autowiring. Please also note that it is not currently possible to autowire so-called simple properties such as primitives, Strings, and Classes (and arrays of such simple properties). (This is by-design and should be considered a feature.) When using either the byType or constructor autowiring mode, it is possible to wire arrays and typed-collections. In such cases all autowire candidates within the container that match the expected type will be provided to satisfy the dependency. Strongly-typed Maps can even be autowired if the expected key type is String. An autowired Map's values will consist of all bean instances that match the expected type, and the Map's keys will contain the corresponding bean names.

<< Previous Program | Next Program >>
blog comments powered by Disqus

Spring framework examples

  1. Spring 3 hello world example
  2. Spring bean java based configuration using @Configuration and @Bean
  3. How to get spring application context object reference?
  4. How to load multiple spring bean configuration files?
  5. Spring java based configuration @Import example
  6. Spring Dependency Injection and Types
  7. Spring Dependency Injection via setter method
  8. Spring Dependency Injection via Constructor
  9. Constructor overloading issue with spring constructor injection
  10. Constructor vs Setter dependency Injection in Spring
  11. How to inject value into spring bean instance variables?
  12. Spring bean tag properties
  13. Differen types of spring bean scopes
  14. How to inject inner bean in spring?
  15. Set spring bean scope using annotation
  16. How to invoke spring bean init and destroy methods?
  17. Spring bean initialization callback
  18. Spring bean destruction callback
  19. Configure default initialization and destroy method in all spring beans
  20. Spring bean init and destroy methods using annotations
  21. Spring Bean Post Processors
  22. How to read property file in spring using xml based configuration file?
  23. How to read property file in spring 3.0 using java based configuration?
  24. How to inject date into spring bean property?
  25. How to inject date into spring bean with CustomDateEditor?
  26. Spring bean inheritance configuration
  27. Spring dependency checking with @Required annotation
  28. How to define a custom Required-style annotation for dependency checking?
  29. How to inject List into spring bean?
  30. How to inject Set into spring bean?
  31. How to inject Map into spring bean?
  32. How to enable auto component scanning in spring?
  33. Difference between @Component, @Service, @Repository and @Controller
  34. How to filter components in auto scanning?
  35. Spring expression language basic example using xml based configuration.
  36. Spring expression language basic example using annotations.
  37. Bean reference example using spring expression language
  38. Spring expression language operators example
  39. Spring expression language ternary operator example
  40. How to use regular expressions with spring expression language?
  41. How to use collections with spring expression language?
  42. Spring bean auto-wiring modes
  43. Spring auto-wiring mode byName
  44. Spring auto-wiring mode byType
  45. Spring auto-wiring mode constructor
  46. Spring auto-wiring using @Autowired annotation example
  47. Spring auto-wiring using @Qualifier annotation example
  48. Spring log4j configuration
  49. How to schedule jobs using @Scheduled annotation in spring?
  50. Send E-mail using spring 3
  51. Send E-mail with attachment using spring 3
  52. Simple spring JDBC example
  53. Spring JDBC example with JdbcTemplate
  54. Spring JDBC example with JdbcDaoSupport
  55. Spring JDBC query example using JdbcDaoSupport
  56. How to query single column using spring JdbcTemplate?
  57. Spring JDBC batch updates using JdbcTemplate?
  58. Spring AOP Advices - Before advice example - xml based configuration
  59. Spring AOP Advices - After returning advice example - xml based configuration
  60. Spring AOP Advices - After throwing advice example - xml based configuration
  61. Spring AOP Advices - Around advice example - xml based configuration
  62. Spring AOP Advice - Pointcuts – Name match example
  63. Spring AOP Advice - Pointcuts – Regular expression example
  64. Spring AOP - AspectJ - @Before example
  65. Spring AOP - AspectJ - @After example
  66. Spring AOP - AspectJ - @AfterReturning example
  67. Spring AOP - AspectJ - @AfterThrowing example
  68. Spring AOP - AspectJ - @Around example
Knowledge Centre
Pass by value Vs Pass by reference
Pass by value: Passing a copy of the value, not the original reference.

Pass by reference: Passsing the address of the object, so that you can access the original object.
Famous Quotations
Good judgment comes from experience, and experience comes from bad judgment.
-- Barry LePatner

About Author

Most Visited Pages

Other Interesting Sites

Reference: Java™ Platform Standard Ed. 7 - API Specification | Java is registered trademark of Oracle.
Privacy Policy | Copyright © 2017 by Nataraja Gootooru. All Rights Reserved.