spring 3.0新特性学习

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>