Spring通过dataSource获取数据库的连接

<?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:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd"> 
<!--加载properties文件 -->
<bean
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>db.properties</value>
</property>
</bean>

<!--配置数据源 -->
<bean id="DataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="${jdbc.driverClassName}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</bean>

<!--UserDao -->
<bean id="UserDao" class="com.zmj.web.dao.UserDao">
<property name="dataSource">
<ref bean="DataSource" />
</property>
</bean>

</beans>

public class UserDao {

DriverManagerDataSource dataSource;

public DriverManagerDataSource getDataSource() {
return dataSource;
}

public void setDataSource(DriverManagerDataSource dataSource) {
this.dataSource = dataSource;
}

public List<User> queryAll() {
Connection conn = null;
PreparedStatement ppst = null;
ResultSet rs = null;
try {
conn = dataSource.getConnection();
ppst = conn.prepareStatement("select * from usertable");
rs = ppst.executeQuery();
List<User> list = new ArrayList<>();
while (rs.next()) {
User user = new User(rs.getString(1), rs.getString(2));
list.add(user);
}
return list;

} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
rs.close();
ppst.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}

return null;
}

public static void main(String[] args) throws SQLException {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

UserDao dao = (UserDao) context.getBean("UserDao");

List<User> list = dao.queryAll();
for (User user : list) {
System.out.println(user.getUserId() + "---" + user.getUserName());
}

}
}

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/user
jdbc.username=root
jdbc.password=1234