spring 3.0新特性学习1

1 用注释
@ContextConfiguration("classpath:beans.xml")
public class UserDAOTest extends AbstractJUnit4SpringContextTests{

@Resource(name="userDAO")
private UserDAO userDAO;

@Test
public void testSave() {
this.userDAO.save(new User());
}

注意，extends AbstractJUnit4SpringContextTest的话，就不用再用以前的去根据ApplicationContext去读取了。

2 获得BEAN的时候支持泛型
@Test
public void testSave() {
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
UserDAO userDAO = context.getBean("userDAO", UserDAO.class);

//UserDAO userDAO = (UserDAO)context.getBean("userDAO");（这是以前的写法）
userDAO.save(new User());
3 将一个JAVA文件看作配置文件
在beans.xml中
<context:component-scan base-package="com.liao.config"></context:component-scan>
然后在类中，设置这个配置文件：
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.bjsxt.spring30.dao.UserDAO;
import com.bjsxt.spring30.dao.impl.UserDAOImpl;

@Configuration
public class AppConfig {
@Bean
public UserDAO userDAO() {
return new UserDAOImpl();
}

//xml
//<bean id = "userDAO" class="userDAO()"
}

又如：
@Bean
public UserDAO userDAO() {
return new UserDAOImpl();
}

@Bean
public UserService userService() {
UserServiceImpl service = new UserServiceImpl();
service.setUserDAO(userDAO());
return service;
}

4 SPEL：
@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));
5 SPEL中，可以在配置文件中赋予和计算一些表达式了，比如：
<property name="randomNumber" value="#{T(java.lang.Math).random() * 100}"></property>