方法一
SpringContextUtil
public class SpringContextUtil {
private static ApplicationContext applicationContext;
//获取上下文
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
//设置上下文
public static void setApplicationContext(ApplicationContext applicationContext) {
SpringContextUtil.applicationContext = applicationContext;
}
//通过名字获取上下文中的bean
public static Object getBean(String name){
return applicationContext.getBean(name);
}
//通过类型获取上下文中的bean
public static Object getBean(Class<?> requiredType){
return applicationContext.getBean(requiredType);
}
}
启动类
@SpringBootApplication
public class Application {
public static void main(String[] args) {
ApplicationContext app = SpringApplication.run(Application.class, args);
SpringContextUtil.setApplicationContext(app);
}
}
测试bean
@Component
public class TestService {
public String doService(String contxt){
System.err.printf(contxt+"hello service");
return "hello service";
}
}
//无注入
public class TestController implements InitializingBean {
@Autowired
private TestService testService;
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("我是动态注册的你,不是容器启动的时候注册的你");
}
public String toAction(String content){
return "-->" + testService.doService(content);
}
}
测试
@RestController
public class CallCSBController {
@GetMapping("/bean")
public String registerBean() {
//将applicationContext转换为ConfigurableApplicationContext
ConfigurableApplicationContext configurableApplicationContext = (ConfigurableApplicationContext) SpringContextUtil.getApplicationContext();
// 获取bean工厂并转换为DefaultListableBeanFactory
DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) configurableApplicationContext.getBeanFactory();
// 通过BeanDefinitionBuilder创建bean定义
BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(TestController.class);
// 设置属性userService,此属性引用已经定义的bean:userService,这里userService已经被spring容器管理了.
// beanDefinitionBuilder.addPropertyReference("testService", "testService");
// 注册bean
defaultListableBeanFactory.registerBeanDefinition("testController", beanDefinitionBuilder.getRawBeanDefinition());
TestController userController = (TestController) SpringContextUtil.getBean("testController");
return userController.toAction("动态注册生成调用");
//删除bean.
//defaultListableBeanFactory.removeBeanDefinition("testService");
}
}
以上参考
链接:spring boot 获取bean注入bean - 简书
方法二(略有不同)
工具类
package com.theeternity.beans.applicationContextRegister;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
/**
* @program: apiboot
* @description: 获取ApplicationContext, 实现动态注入bean
* @author: TheEternity Zhang
* @create: 2019-06-22 12:15
*/
@Component
@Slf4j
public class ApplicationContextRegister implements ApplicationContextAware {
private static ApplicationContext APPLICATION_CONTEXT;
/**
* 设置spring上下文
* @param applicationContext spring上下文
* @throws BeansException
* */
@Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
log.debug("ApplicationContext registed-->{}", applicationContext);
APPLICATION_CONTEXT = applicationContext;
}
/**
* 获取容器
* @return
*/
public static ApplicationContext getApplicationContext() {
return APPLICATION_CONTEXT;
}
/**
* 获取容器对象
* @param type
* @param <T>
* @return
*/
public static <T> T getBean(Class<T> type) {
return APPLICATION_CONTEXT.getBean(type);
}
public static <T> T getBean(String name,Class<T> clazz){
return APPLICATION_CONTEXT.getBean(name, clazz);
}
public static Object getBean(String name){
return APPLICATION_CONTEXT.getBean(name);
}
}
测试bean
@Component
public class TestService {
public String doService(String contxt){
System.err.printf(contxt+"hello service");
return "hello service";
}
}
//无注入
public class TestController implements InitializingBean {
@Autowired
private TestService testService;
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("我是动态注册的你,不是容器启动的时候注册的你");
}
public String toAction(String content){
return "-->" + testService.doService(content);
}
}
测试
@RestController
public class CallCSBController {
@GetMapping("/bean")
public String registerBean() {
//将applicationContext转换为ConfigurableApplicationContext
ConfigurableApplicationContext configurableApplicationContext = (ConfigurableApplicationContext) ApplicationContextRegister.getApplicationContext();
// 获取bean工厂并转换为DefaultListableBeanFactory
DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) configurableApplicationContext.getBeanFactory();
// 通过BeanDefinitionBuilder创建bean定义
BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(TestController.class);
// 设置属性userService,此属性引用已经定义的bean:userService,这里userService已经被spring容器管理了.
// beanDefinitionBuilder.addPropertyReference("testService", "testService");
// 注册bean
defaultListableBeanFactory.registerBeanDefinition("testController", beanDefinitionBuilder.getRawBeanDefinition());
TestController userController = (TestController) ApplicationContextRegister.getBean("testController");
return userController.toAction("动态注册生成调用");
//删除bean.
//defaultListableBeanFactory.removeBeanDefinition("testService");
}
第一种方法的另外一种形式
/**
//获取ApplicationContext
ApplicationContext ctx=ApplicationContextRegister.getApplicationContext();
//获取BeanFactory
DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) ctx.getAutowireCapableBeanFactory();
//创建bean信息.
BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(TestService.class);
beanDefinitionBuilder.addPropertyValue("name","张三");
//动态注册bean.
defaultListableBeanFactory.registerBeanDefinition("testService", beanDefinitionBuilder.getBeanDefinition());
//获取动态注册的bean.
TestService testService =ctx.getBean(TestService.class);、testService.print();
*/
@GetMapping("/bean2")
public String registerBean2() {
TestController userController = (TestController) ApplicationContextRegister.getBean(TestController.class);
return userController.toAction("动态注册生成调用");
}
}
以上参考:
主力:spring boot 获取bean注入bean - 简书
辅助:关于SpringBoot获取IOC容器中注入的Bean(推荐)_java_脚本之家
拓展理解
我们通过getBean来获得对象,但这些对象都是事先定义好的,我们有时候要在程序中动态的加入对象.因为如果采用配置文件或者注解,我们要加入对象的话,还要重启服务,如果我们想要避免这一情况就得采用动态处理bean,包括:动态注入,动态删除。
本节大纲 :
(1)动态注入bean思路;
(2)动态注入实现代码;
(3)多次注入同一个bean的情况;
(4)动态删除;
接下来我们看下具体的内容:
(1)动态注入bean思路;
在具体进行代码实现的时候,我们要知道,Spring管理bean的对象是BeanFactory,具体的是DefaultListableBeanFactory,在这个类当中有一个注入bean的方法:registerBeanDefinition,在调用registerBeanDefinition方法时,需要BeanDefinition参数,那么这个参数怎么获取呢?Spring提供了BeanDefinitionBuilder可以构建一个BeanDefinition,那么我们的问题就是如何获取BeanFactory了,这个就很简单了,只要获取到ApplicationContext对象即可获取到BeanFacory了。
(2)动态注入实现代码;
综上所述,如果我们要编写一个简单里的例子的话,那么分以个几个步骤进行编码即可进行动态注入了:
<1>. 获取ApplicationContext;
<2>. 通过ApplicationContext获取到BeanFacotory;
<3>. 通过BeanDefinitionBuilder构建BeanDefiniton;
<4>. 调用beanFactory的registerBeanDefinition注入beanDefinition;
<5>. 使用ApplicationContext.getBean获取bean进行测试;
很明显我们需要先定义个类进行测试,比如TestService代码如下:
package com.kfit.demo.service;
public class TestService {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void print(){
System.out.println("动态载入bean,name="+name);
}
}
注意:这里没有使用@Service和配置文件进行注入TestService。
那么下面我们的目标就是动态注入TestService了,根据以上的分析,我们进行编码,具体代码如下:
//获取context. -- Angel -守护天使
ApplicationContext ctx = (ApplicationContext) SpringApplication.run(App.class, args);
//获取BeanFactory
DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) ctx.getAutowireCapableBeanFactory();
//创建bean信息.
BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(TestService.class);
beanDefinitionBuilder.addPropertyValue("name","张三");
//动态注册bean.
defaultListableBeanFactory.registerBeanDefinition("testService", beanDefinitionBuilder.getBeanDefinition());
//获取动态注册的bean.
TestService testService =ctx.getBean(TestService.class);
testService.print();
执行代码我们会在控制台看到如下打印信息:
动态载入bean,name=张三
到这里,就证明我们的代码很成功了。
(3)多次注入同一个bean的情况;
多次注入同一个bean的,如果beanName不一样的话,那么会产生两个Bean;如果beanName一样的话,后面注入的会覆盖前面的。
第一种情况:beanName一样的代码:
beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(TestService.class);
defaultListableBeanFactory.registerBeanDefinition("testService", beanDefinitionBuilder.getBeanDefinition());
TestService testService =ctx.getBean(TestService.class);
testService.print();
运行看控制台: 动态载入bean,name=李四
第二种情况:beanName不一样的代码:
beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(TestService.class);
defaultListableBeanFactory.registerBeanDefinition("testService1", beanDefinitionBuilder.getBeanDefinition());
TestService testService =ctx.getBean(TestService.class);
testService.print();
此时如果没有更改别的代码直接运行的话,是会报如下错误的:
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.kfit.demo.service.TestService] is defined: expected single matching bean but found 2: testService1,testService
大体意思就是在getBean的时候,找到了两个bean,这时候就不知道要获取哪个了,所以在获取的时候,我们就要指定我们是要获取的testService还是testService1,只需要修改一句代码:
将代码:
TestService testService =ctx.getBean(TestService.class);
修改为:
TestService testService =ctx.getBean("testService");
(4)动态删除;
相对于动态注入,动态删除就很简单了,直接奉上代码:
//删除bean.
defaultListableBeanFactory.removeBeanDefinition("testService");