Difference between using bean id and name in Spring configuration file

Question

Is there any difference between using an id attribute and name attribute on a  lt bean gt  element in a Spring configuration file

User · Answer

let me answer below question

Is there any difference between using an id attribute and using a name attribute on a <bean> tag,

There is no difference. you will experience same effect when id or name is used on a <bean> tag .

How?

Both id and name attributes are giving us a means to provide identifier value to a bean (For this moment, think id means id but not identifier). In both the cases, you will see same result if you call applicationContext.getBean("bean-identifier"); .

Take @Bean, the java equivalent of <bean> tag, you wont find an id attribute. you can give your identifier value to @Bean only through name attribute.

Let me explain it through an example :
Take this configuration file, let's call it as spring1.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans ...>
  <bean id="foo" class="com.intertech.Foo"></bean>
  <bean id="bar" class="com.intertech.Bar"></bean>
</beans>

Spring returns Foo object for, Foo f = (Foo) context.getBean("foo"); . Replace id="foo" with name="foo" in the above spring1.xml, You will still see the same result.

Define your xml configuration like,

<?xml version="1.0" encoding="UTF-8"?>
<beans ...>
  <bean id="fooIdentifier" class="com.intertech.Foo"></bean>
  <bean name="fooIdentifier" class="com.intertech.Foo"></bean>
</beans>

You will get BeanDefinitionParsingException. It will say, Bean name 'fooIdentifier' is already used in this element. By the way, This is the same exception you will see if you have below config
<bean name="fooIdentifier" class="com.intertech.Foo"></bean>
<bean name="fooIdentifier" class="com.intertech.Foo"></bean>

If you keep both id and name to the bean tag, the bean is said to have 2 identifiers. you can get the same bean with any identifier. take config as

<?xml version="1.0" encoding="UTF-8"?><br>
<beans ...>
  <bean id="fooById" name="fooByName" class="com.intertech.Foo"></bean>
  <bean id="bar" class="com.intertech.Bar"></bean>
</beans>

the following code prints true

FileSystemXmlApplicationContext context = new FileSystemXmlApplicationContext(...);
Foo fooById = (Foo) context.getBean("fooById")// returns Foo object;
Foo fooByName = (Foo) context.getBean("fooByName")// returns Foo object;
System.out.println(fooById == fooByName) //true

User · Answer

Since Spring 3 1 the id attribute is an xsd string and permits the same range of characters as the name attribute   The only difference between an id and a name is that a name can contain multiple aliases separated by a comma  semicolon or whitespace  whereas an id must be a single value   From the Spring 3 2 documentation      In XML-based configuration metadata  you use the id and or name attributes to specify the bean identifier s   The id attribute allows you to specify exactly one id  Conventionally these names are alphanumeric   myBean    fooService   etc   but may special characters as well  If you want to introduce other aliases to the bean  you can also specify them in the name attribute  separated by a comma      semicolon      or white space  As a historical note  in versions prior to Spring 3 1  the id attribute was typed as an xsd ID  which constrained possible characters  As of 3 1  it is now xsd string  Note that bean id uniqueness is still enforced by the container  though no longer by XML parsers

User · Answer

Both id and name are bean identifiers in Spring IOC container ApplicationContecxt  The id attribute lets you specify exactly one id but using name attribute you can give alias name to that bean   You can check the spring doc here

User · Answer

Is there difference in defining Id  amp  name in ApplicationContext xml   No     As of 3 1 spring   id is also defined as an xsd string type      It means whatever characters allowed in defining name are also allowed in Id      This was not possible prior to Spring 3 1   Why to use name when it is same as Id       It is useful for some situations  such as allowing each component in an application to refer to a common dependency by using a bean name that is specific to that component itself   For example  the configuration metadata for subsystem A may refer to a DataSource via the name subsystemA-dataSource  The configuration metadata for subsystem B may refer to a DataSource via the name subsystemB-dataSource  When composing the main application that uses both these subsystems the main application refers to the DataSource via the name myApp-dataSource  To have all three names refer to the same object you add to the MyApp configuration metadata the following    lt bean id  myApp-dataSource  name  subsystemA-dataSource subsystemB-dataSource        gt   Alternatively  You can have separate xml configuration files for each sub-system and then you can make use of alias to define your own names    lt alias name  subsystemA-dataSource  alias  subsystemB-dataSource   gt   lt alias name  subsystemA-dataSource  alias  myApp-dataSource    gt

User · Answer

Either one would work  It depends on your needs  If your bean identifier contains special character s  for example   viewSummary html   it wont be allowed as the bean id  because it s not a valid XML ID  In such cases you could skip defining the bean id and supply the bean name instead  The name attribute also helps in defining aliases for your bean  since it allows specifying multiple identifiers for a given bean

User · Answer

From the Spring reference  3 2 3 1 Naming Beans      Every bean has one or more ids  also   called identifiers  or names  these   terms refer to the same thing   These   ids must be unique within the   container the bean is hosted in  A   bean will almost always have only one   id  but if a bean has more than one   id  the extra ones can essentially be   considered aliases       When using XML-based configuration   metadata  you use the  id  or  name    attributes to specify the bean   identifier s   The  id  attribute   allows you to specify exactly one id    and as it is a real XML element ID   attribute  the XML parser is able to   do some extra validation when other   elements reference the id  as such  it   is the preferred way to specify a bean   id  However  the XML specification   does limit the characters which are   legal in XML IDs  This is usually not   a constraint  but if you have a need   to use one of these special XML   characters  or want to introduce other   aliases to the bean  you may also or   instead specify one or more bean ids    separated by a comma      semicolon        or whitespace in the  name    attribute    So basically the id attribute conforms to the XML id attribute standards whereas name is a little more flexible  Generally speaking  I use name pretty much exclusively  It just seems more  Spring-y

[spring] Difference between using bean id and name in Spring configuration file

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