spring中擷取自定義的Bean

public static void main(String[] args) {
		ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
		DBSpringDao bean = context.getBean(DBSpringDao.class);
		//BeanFactory factory = context;
		//DBSpringDao bean = factory.getBean(DBSpringDao.class);
		String sql="select * from i_user";
		List<Map<String, Object>> list=bean.queryForList(sql);
	}
           

擷取Bean的其他方式

注意 ClassPathXmlApplicationContext 和 FileSystemXmlApplicationContext 的差別

// 用classpath路徑，不加classpath預設字首
 ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

// ClassPathXmlApplicationContext使用了file字首是可以使用絕對路徑的
ApplicationContext context = new ClassPathXmlApplicationContext("file:F:/workspace/project/src/applicationContext.xml");

// 用檔案系統的路徑,預設指項目的根路徑
ApplicationContext context = new FileSystemXmlApplicationContext("src/applicationContext.xml");
ApplicationContext context = new FileSystemXmlApplicationContext("webRoot/WEB-INF/applicationContext.xml");


// 使用了classpath:字首,這樣,FileSystemXmlApplicationContext也能夠讀取classpath下的相對路徑
ApplicationContext context = new FileSystemXmlApplicationContext("classpath:applicationContext.xml");
ApplicationContext context = new FileSystemXmlApplicationContext("file:F:/workspace/project/src/applicationContext.xml");

// 不加file字首
ApplicationContext context = new FileSystemXmlApplicationContext("F:/workspace/project/src/applicationContext.xml");
           

為了避免重新裝載applicationContext.xml并執行個體化上下文bean不用類似

new ClassPathXmlApplicationContext()的方式，從已有的spring上下文取得已執行個體化的bean。

首先建立一個工具類

//實作ApplicationContextAware
public class ApplicationContextUtil implements ApplicationContextAware {
 
	private  ApplicationContext context;//聲明一個靜态變量
	@Override
	public void setApplicationContext(ApplicationContext applicationContext)
			throws BeansException {
		this.context=applicationContext;
	}
 
	public  ApplicationContext getContext(){
		  return context;
	}
}
           

注入

springboot使用注解進行注入

//初始化并注入
<bean id="applicationContextUtil" class="com.service.utils.ApplicationContextUtil"></bean>
//業務類進行注入applicationContextUtil執行個體
<bean id="xxxx" class="com.service.xx.xx.xx" >
  <property name="appContextUtil" ref="applicationContextUtil" /> 
 </bean>
           

使用

ApplicationContext context=appContextUtil.getContext();
 DBSpringDao bean = context.getBean(DBSpringDao.class);
 String sql="select * from i_user";
 List<Map<String, Object>> list=bean.queryForList(sql);