Spring中的依赖原理

代码描述依赖过程

Dao层代码

package com.cloud.reply;
public interface UserDao {
void printInfo();
}

实现层代码

package com.cloud.reply;
public class UserDaoImpl implements UserDao{
private String jdbcUrl;
private String driverClass;
private String username;
private String password;
@Override
public void printInfo() {
System.out.println("jdbcUrl"+jdbcUrl);
System.out.println("driverClass"+driverClass);
System.out.println("username"+username);
System.out.println("password"+password);
}
public String getJdbcUrl() {
return jdbcUrl;
}
public void setJdbcUrl(String jdbcUrl) {
this.jdbcUrl = jdbcUrl;
}
public String getDriverClass() {
return driverClass;
}
public void setDriverClass(String driverClass) {
this.driverClass = driverClass;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}

服务层代码

package com.cloud.reply;

public class UserDaoServiceImpl {
private UserDao userDao;
public UserDao getUserDao() {
return userDao;
}
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
}

配置文件

<span style="white-space:pre">	</span><!-- 配置一个userdao -->
<bean id="userDao" class="com.cloud.reply.UserDaoImpl">
<property name="jdbcUrl" value="jdbc:mysql:///test"/>
<property name="driverClass" value="com.mysql.jdbc.Driver"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</bean>
<!-- 配置UserService对象，依赖UserDao对象 -->
<bean id="userServiceImpl" class="com.cloud.reply.UserDaoServiceImpl">
<property name="userDao" ref="userDao"></property>
</bean>

测试代码

package com.cloud.reply;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MyTest {
public static void main(String[] args) {
ApplicationContext ac= new ClassPathXmlApplicationContext("applicationContext.xml");
UserDao userDao = (UserDao) ac.getBean("userDao");
UserDaoServiceImpl userServiceImpl = (UserDaoServiceImpl) ac.getBean("userServiceImpl");
System.out.println(userDao);
System.out.println(userServiceImpl.getUserDao());
userDao.printInfo();
}
}