Spring Autowiring autodetect

Question

I want to clarify about this:

Regarding Autowiring "autodetect"

In some resources, I found if "Default constructor is found, then "auto wiring constructor" applies. If not "auto wiring by type" applies.

And in some resources, I found if "Default constructor is found, then "auto wiring by type" applies. If not "auto wiring constructor" applies.

can anyone confirm which is the right one? confused with this.

Are you getting incorrect instances injected? What is the difference you are asking about? — Elliott Frisch, Dec 05 '14 at 09:33
No, I'm confused about the statements, I want to know which one is right. — Rahul Raj, Dec 05 '14 at 09:34
[check this link it will help you][1] [1]: http://stackoverflow.com/questions/3153546/how-does-autowiring-work-in-spring — MiDhuN, Dec 05 '14 at 09:53
These look like poorly-translated statements, which may explain the confusion. Do you have a link to the original? — chrylis -cautiouslyoptimistic-, Dec 05 '14 at 09:59

MiDhuN · Answer 1 · 2014-12-05T10:02:53.360

In Spring framework, you can wire beans automatically with auto-wiring feature. To enable it, just define the “autowire” attribute in .

<bean id="customer" class="com.midhun.common.Customer" autowire="byName" />

In Spring, 5 Auto-wiring modes are supported.

1.no – Default, no auto wiring, set it manually via “ref” attribute

2.byName – Auto wiring by property name. If the name of a bean is same as the name of other bean property, auto wire it.

3.byType – Auto wiring by property data type. If data type of a bean is compatible with the data type of other bean property, auto wire it.

4.constructor – byType mode in constructor argument.

5.autodetect – If a default constructor is found, use “autowired by constructor”; Otherwise, use “autowire by type”.

No, you are not required to use default (no arg) constructors. If there is no constructor defined in bean it will chose it, if u want you can use .. the type of auto wiring dependent up on your requirements

@Qualifier can also help you to specify your injection

you can youse @Quanlifier to tell Spring about which bean should autowired.

package com.midhun.pgm;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

public class Customer {

    @Autowired
    @Qualifier("personA")
    private Person person;
    //...

}

score 1 · Accepted Answer · answered Dec 05 '14 at 09:53

There should be no confusion in this.

Autowiring by autodetect uses either of two modes i.e. constructor or byType modes. First it will try to look for valid constructor with arguments, If found the constructor mode is chosen. If there is no constructor defined in bean, or explicit default no-args constructor is present, the autowire byType mode is chosen.

Spring Autowiring autodetect

2 Answers2