Spring 泛型依赖注入

Spring 4.x可以支持泛型依赖注入，也就是子类可以继承父类的依赖，注入相应的泛型成员变量子类。

比如，有泛型基类 BaseService<T>和BaseController<T>，Controller包含Service成员，分别有Teacher和Student两个子类，TeacherService和StudentService、TeacherController和StudentController。

1、 BaseService<T>

package com.generic.di;

public class BaseService<T> {

}

2、 BaseController<T>

package com.generic.di;

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

public class BaseController<T> {

@Autowired
protected BaseService<T> service;

public void execute() {
System.out.println("execute...");
System.out.println(service); // 此处打印出实际的子类对象
}

}

3、TeacherService

package com.generic.di.teacher;

import org.springframework.stereotype.Service;

import com.generic.di.BaseService;

@Service

public class TeacherService extends BaseService<Teacher> {

}

4、TeacherController

package com.generic.di.teacher;

import org.springframework.stereotype.Controller;

import com.generic.di.BaseController;

@Controller

public class TeacherController extends BaseController<Teacher> {

}

5、StudentService

package com.generic.di.student;

import org.springframework.stereotype.Service;

import com.generic.di.BaseService;

@Service

public class StudentService extends BaseService<Student> {

}

6、StudentController

package com.generic.di.student;

import org.springframework.stereotype.Controller;

import com.generic.di.BaseController;

@Controller

public class StudentController extends BaseController<Student> {

}

7、配置文件

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">
<context:component-scan 
base-package="com.generic">
</context:component-scan>

</beans>

8、main

public class Main {
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("ApplicationContext.xml");

StudentController studentController = (StudentController) context.getBean("studentController");
studentController.execute();

TeacherController teacherController = (TeacherController) context.getBean("teacherController");
teacherController.execute();
}

}

执行结果

execute...
com.generic.di.student.StudentService@d6da883

execute...
com.generic.di.teacher.TeacherService@45afc369

从结果可以看出，StudentController注入的是StudentSerive对象，TeacherController注入的是TeacherService对象，说明泛型基类的依赖关系，被子类自动继承，并根据泛型找到对应的子类。