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@Import注解的作用是把类加入Spring IOC容器。

有多种方式能让类加IOC容器管理，如@Bean、@Component等，@Import是另外一种方式，更加快捷。

1. 定义普通类

package com.demo;

public class TestA {
    private Integer id = 1;
    private String name = "TestA";

    public void print(){
        System.out.println(this.toString());
    }
}

2. 定义配置类，并引入普通类

package com.demo;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;


@Import({TestA.class})
@Configuration
public class ImportConfig {

}

另外一种写法是不需要配置类，直接在启动类中引入需要注入spring容器的类。

package com.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Import;

@SpringBootApplication
@Import({TestA.class})
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

3. 定义测试类

package com.demo.controller;

import com.demo.TestA;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/importtest")
public class DemoController {

    @Autowired
    private TestA testA;

    @RequestMapping("/test1")
    public String test() {

        testA.print();
        return "";
    }
}

4. 启动springboot启动程序

package com.demo;

import com.demo.util.SpringUtil;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

5. 启动应用程序，执行测试，可以看到testA已经被自动注入了。