Spring3.0的几个新特性

1、利用Spring自带的测试工具测试的时候属性可以自己注入

import javax.annotation.Resource;
import org.junit.Test;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.AbstractJUnit4SpringContextTests;
import com.bjsxt.spring30.model.User;

@ContextConfiguration("classpath:beans.xml")
public class UserDAOTest extends AbstractJUnit4SpringContextTests{
	
	@Resource(name="userDAO")
	private UserDAO userDAO;
	
	@Test
	public void testSave() {
		this.userDAO.save(new User());
	}

}

2、context.getBean可以使用泛型不用强制类型转换了

public class UserDAOTest2 {
	@Test
	public void testSave() {
		ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
		UserDAO userDAO = context.getBean("userDAO", UserDAO.class);
		
		//UserDAO userDAO = (UserDAO)context.getBean("userDAO");
		userDAO.save(new User());
	}
}

3、配置文件可以写在java文件里面（没什么多大作用，Spring的文档里面说如果你不想脱离java风格的配置文件，就可以这么写）

<?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-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
	<context:component-scan base-package="bruce.zhao.spring3_0.config"></context:component-scan>
</beans>

@Configuration
public class AppConfig {
	@Bean
	public UserDAO userDAO() {
		return new UserDAOImpl();
	}
	
	//xml
	//<bean id = "userDAO" class="userDAO()"
}

4、SpEL语言
动态语言的主要特性：能把一个字符串"new HelloWorld().sayHello()"当成语法运行，用现有的代码产生新的代码。
如js里面eval("alert('ok');");
java做不到这一点，所以他是静态语言，除非用java6里面的Compiler动态编译下。

@Test
	public void test01() {
		ExpressionParser parser = new SpelExpressionParser();
		Expression exp = parser.parseExpression("'Hello,World'");
		System.out.println((String)exp.getValue());
	}
	
	@Test
	public void test02() {
		
		User u = new User();
		u.setUsername("zhangsan");
		
		EvaluationContext context = new StandardEvaluationContext(u);
		
		ExpressionParser parser = new SpelExpressionParser();
		Expression exp = parser.parseExpression("username"); //u.getUsername()
		System.out.println((String)exp.getValue(context));
		System.out.println((String)exp.getValue(u));
	}

eg2 可以用在配置文件里面，更加灵活的给我们一些属性进行初始化的赋值

<?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-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">

	<!--
	<context:component-scan base-package="bruce.zhao.spring3_0.config"></context:component-scan>
-->

<bean id="my" class="bruce.zhao.spring3_0.spel.MyBean">
	<property name="randomNumber" value="#{T(java.lang.Math).random() * 100}"></property>
	<property name="userRegion" value="#{systemProperties['user.country']}"></property>
</bean>

</beans>

public class MyBean {
	private double randomNumber;
	private String userRegion;
	public double getRandomNumber() {
		return randomNumber;
	}
	public void setRandomNumber(double randomNumber) {
		this.randomNumber = randomNumber;
	}
	public String getUserRegion() {
		return userRegion;
	}
	public void setUserRegion(String userRegion) {
		this.userRegion = userRegion;
		//System.getProperty("user.country");
	}
	
}

@ContextConfiguration("classpath:beans.xml")
public class SpELTest extends AbstractJUnit4SpringContextTests{
	
	@Resource
	private MyBean my;
	
	@Test
	public void test01() {
		System.out.println(my.getRandomNumber());
		System.out.println(my.getUserRegion());
	}

}