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());
}

}