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spring ioc 泛型保留

2020年03月13日  | 移动技术网IT编程  | 我要评论

spring ioc 泛型保留

在上一篇中,说到spring中并不能自动注入泛型，如何生成泛型类型已经讲的很清楚了，在本篇着重讲在spring中如何自动注入。

环境

这里所有代码基于如下环境，如有出入请参考当前环境。

java version "1.8.0_201"
java(tm) se runtime environment (build 1.8.0_201-b09)
java hotspot(tm) 64-bit server vm (build 25.201-b09, mixed mode)
 implementation 'org.aspectj:aspectjweaver:1.9.2' 
 implementation "org.springframework:spring-context:5.1.9.release" 
 implementation 'org.javassist:javassist:3.25.0-ga'

方法一

通过实现org.springframework.beans.factory.support.beandefinitionregistrypostprocessor和org.springframework.beans.factory.config.instantiationawarebeanpostprocessor 自定义bean泛型的注入

mainconfig.java

 @configuration
public class mainconfig
{

     @bean
    public static mybeanfactorypostprocessor newmybeanfactorypostprocessor()
    {
        return new mybeanfactorypostprocessor();
    }
....

mybeanfactorypostprocessor.java

public class mybeanfactorypostprocessor implements beandefinitionregistrypostprocessor
{

    @override
    public void postprocessbeanfactory(configurablelistablebeanfactory beanfactory) throws beansexception
    {
        system.out.println("beanfactory=" + beanfactory);
         beanfactory.addbeanpostprocessor(new mybeanpostprocessor(beanfactory));

    }
...

mybeanpostprocessor.java

public class mybeanpostprocessor implements instantiationawarebeanpostprocessor
{
    public object postprocessbeforeinstantiation(class<?> beanclass, string beanname) throws beansexception
    {
        // system.out.println("创建类:" + beanclass);
        list<field> fields = new arraylist<>();
        for (field field : beanclass.getdeclaredfields())
        {
            if (field.getannotation(autowired.class) != null && myprovider.class.isassignablefrom(field.gettype()))
            {
                type type = field.getgenerictype();
                if (type != null && type instanceof parameterizedtype)
                {
                    fields.add(field);
                }
            }
        }
        if (!fields.isempty())
        {
            //创建bean，请参考上一篇文章
            ....
        }
        return null;
    }
...

输出结果如下:

beanfactory=org.springframework.beans.factory.support.defaultlistablebeanfactory@51081592: defining beans [org.springframework.context.annotation.internalconfigurationannotationprocessor,org.springframework.context.annotation.internalautowiredannotationprocessor,org.springframework.context.annotation.internalcommonannotationprocessor,org.springframework.context.event.internaleventlistenerprocessor,org.springframework.context.event.internaleventlistenerfactory,main,mainconfig,baseprovider,myaspect,testservice,testservice2,newmybeanfactorypostprocessor,newbeanconfig,org.springframework.aop.config.internalautoproxycreator]; root of factory hierarchy
service=test.spring.service.testservice2@1817d444
superclass=test.spring.provider.myprovider<test.spring.model.user>
userproviderfieldtype=[]
resolvabletype=test.spring.service.testservice2

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