Scope, execution process and life cycle of bean

Catalog

1.Bean Scope （ Very important , The interview will take ）

1.1Bean Scope definition

1.2Bean Of 6 Planting ⽤ Domain

1.2.1 A single example is ⽤ Domain (singleton) Work with the overall situation ⽤ Domain (application) difference

2.Bean Of board ⾏ technological process

3.Bean ⽣ Life cycle （ It is divided into 5 Parts of ）

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1.Bean Scope （ Very important , The interview will take ）

1.1Bean Scope definition

Bean Works of ⽤ Domain means Bean stay Spring Something in the whole framework ⾏ For mode

1.2Bean Of 6 Planting ⽤ Domain

1. singleton（ yes Bean The default scope for ）

 

The book ⽤ Under domain Bean stay IoC Only exist in container ⼀ An example ： obtain Bean（ That is, through applicationContext.getBean etc. ⽅ Can't get ） And assembly Bean（ That is, through @Autowired notes ⼊） It's all the same ⼀ Objects , So when other ⼈ After changing this value , So another way ⼀ individual ⼈ What you read is the modified value

Use scenarios ： Usually ⽆ State of Bean（Bean The property state of the object does not need to be updated ） send ⽤ The book ⽤ Domain

Look at one other ⼈ After changing this value , So another way ⼀ individual ⼈ What you read is the case of the modified value ：

2. prototype

Every time I do ⽤ Under domain Bean All requests will create new instances ： obtain Bean（ Instant communication applicationContext.getBean etc. ⽅ Can't get ） And assembly Bean（ That is, through @Autowired notes ⼊） Are all new object instances .
Usage scenario ： Usually stateful Bean（Bean The property state of the object needs to be updated ） send ⽤ The book ⽤ Domain

give an example ：

3. request

Every time http The request creates a new Bean example , Be similar to prototype

Use scenarios ：⼀ Time http Sharing of requests and responses Bean
4. session

stay ⼀ individual http session in , Definition ⼀ individual Bean example

Use scenarios ：⽤ Sharing of user replies Bean, ⽐ Such as ： Record ⼀ individual ⽤ Login information of the user
5. application

stay ⼀ individual http servlet Context in , Definition ⼀ individual Bean example

Use scenarios ：Web Should be ⽤ Up and down ⽂ Information ,⽐ Such as ： Record ⼀ One should ⽤ Share information for
6. websocket

stay ⼀ individual HTTP WebSocket Of ⽣ In the life cycle , Definition ⼀ individual Bean example

Use scenarios ：WebSocket In every conversation , Save the ⼀ individual Map Structure header information , take ⽤ To wrap client messages
head . The first ⼀ After the first initialization , until WebSocket The end is the same ⼀ individual Bean

 

1.2.1 A single example is ⽤ Domain (singleton) Work with the overall situation ⽤ Domain (application) difference

1. The difference between acting on ：singleton yes Spring Core Works of ⽤ Domain ,application yes Spring Web The works in the book ⽤ Domain

2. The difference between containers ：singleton do ⽤ On IoC The container of ,⽽ application do ⽤ On Servlet Containers .

 

2.Bean Of board ⾏ technological process

start-up Spring Containers -> Instantiation Bean（ Allocate memory space , from ⽆ To have ）-> Bean Sign up to Spring in （ Save operation ） -> take Bean Assemble into the required class （ Take operation ）

 

3.Bean ⽣ Life cycle （ It is divided into 5 Parts of ）

⽣ Life cycle refers to ⼀ Objects from birth ⽣ To destroy the whole ⽣ Life process

 

Life cycle Demo ：