目录
目录
1.对象依赖的分类
Spring中,给对象属性赋值的方法:
- 构造函数
- Set方法
- p命名空间
- 自动装配
- 注解
1.1构造函数
构造方法通过配置文件中constructor-arg标签实现,使用时候需要注意要有带参的构造函数
1.2.Set方法
通过配置文件中property标签实现,使用时候需要注意要有无参构造方法和Getter Setter函数
1.3p命名空间
通过配置文件中p:XXX-ref=""标签实现,这里的引用也可换成使用实际值。
Spring 3.0以上版本支持
1.4自动装配
分为两种方式:
byName:会自动在对应类中寻找注入类名称一致的对象注入
byType:会自动在对应类中寻找注入类同类型的对象自动注入,但是要注意的是,一个类中只能有一个类型,不同同类型!
这两种配置方式可以全局配置,配置位置:
http://www.springframework.org/schema/context/spring-context.xsd" default-autowire="byType">
简化开发,但是不利于后期维护,不推荐使用。
1.5注解
注解的的好出是简化配置文件的维护
1.5.1关键字
通过注解完成依赖和注入:
- @Repository:对应持久层
- @Service:对应业务层
- @Controller:对应控制层
- @Resource:表示要注入的对象
- 配置文件中,通过开启扫描告知Spring使用注解
1.5.2注意事项
- @Component做为通用关键字可以替代@Repository、@Service和@Controller,但是不建议在对应类中这么写,因为不利于理解和维护。
- 对应的注解关键字可以不写,Spring会自动根据需要的类按照类名首字母小写的方式自动查找。但是这样同样不利于开发维护,不建议。
2.实例
对于构造函数和Set方法,使用User类示例。p命名空间模拟开发过程
2.1先创建各对象,注意需要的构造和Getter Setter方法
package per.liyue.springlearing.structure;
/**
* Created by liyue on 2016/11/10.
*/
public class User
{
private int userId;
private String userName;
@Override
public String toString()
{
return "User{" +
"userId=" + userId +
", userName='" + userName + '\'' +
'}';
}
public User()
{
}
public User(int userId, String userName)
{
this.userId = userId;
this.userName = userName;
}
public int getUserId()
{
return userId;
}
public void setUserId(int userId)
{
this.userId = userId;
}
public String getUserName()
{
return userName;
}
public void setUserName(String userName)
{
this.userName = userName;
}
}
package per.liyue.springlearing.structure;
/**
* Created by liyue on 2016/11/10.
*/
public class UserDao
{
public void Save()
{
System.out.println("执行了Save方法保存数据");
}
}
package per.liyue.springlearing.structure;
/**
* Created by liyue on 2016/11/10.
*/
public class UserService
{
public UserDao getUserDao()
{
return userDao;
}
public void setUserDao(UserDao userDao)
{
this.userDao = userDao;
}
private UserDao userDao;
public void Save()
{
userDao.Save();
}
}
package per.liyue.springlearing.structure;
/**
* Created by liyue on 2016/11/10.
*/
public class UserAction
{
private UserService userService;
public String execute()
{
userService.Save();
return null;
}
public UserService getUserService()
{
return userService;
}
public void setUserService(UserService userService)
{
this.userService = userService;
}
}
2.2配置xml文件
<?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:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd" >
<!--1.构造函数方法
注意要有对应的带参构造方法
-->
<bean id="userC" class="per.liyue.springlearing.structure.User" scope="prototype">
<constructor-arg value="1"></constructor-arg>
<constructor-arg value="张三"></constructor-arg>
</bean>
<!--2.Set方法
注意要有无参构造方法和Getter Setter函数
-->
<bean id="userS" class="per.liyue.springlearing.structure.User" scope="prototype">
<property name="userId" value="2"></property>
<property name="userName" value="李四"></property>
</bean>
<!--3.p命名空间
注意要有Getter Setter函数
-->
<!--
<bean id="userDao" class="per.liyue.springlearing.structure.UserDao"></bean>
<bean id="userService" class="per.liyue.springlearing.structure.UserService" p:userDao-ref="userDao"></bean>
<bean id="userAction" class="per.liyue.springlearing.structure.UserAction" p:userService-ref="userService"></bean>
-->
<!--4.自动装配
分为两种方式:
byName:会自动在对应类中寻找注入类名称一致的对象注入
byType:会自动在对应类中寻找注入类同类型的对象自动注入,但是要注意的是,一个类中只能有一个类型,不同同类型!
这两种配置方式可以全局配置,配置位置:
http://www.springframework.org/schema/context/spring-context.xsd" default-autowire="byType">
-->
<bean id="userDao" class="per.liyue.springlearing.structure.UserDao"></bean>
<bean id="userService" class="per.liyue.springlearing.structure.UserService" autowire="byName"></bean>
<bean id="userAction" class="per.liyue.springlearing.structure.UserAction" autowire="byType"></bean>
</beans>
2.3模拟调用
package per.liyue.springlearing.structure;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* Created by liyue on 2016/11/10.
*/
public class App
{
private ApplicationContext applicationContext = new ClassPathXmlApplicationContext("per/liyue/springlearing/bean.xml");
@Test
public void Main()
{
User user1 = applicationContext.getBean("userC", User.class);
System.out.println("1.构造方法方式为对象属性赋值" + user1);
User user2 = applicationContext.getBean("userS", User.class);
System.out.println("2.Set方法方式为对象属性赋值" + user2);
UserAction userAction = applicationContext.getBean("userAction", UserAction.class);
System.out.println("3.p命名空间方法执行:");
userAction.execute();
}
}
2.4输出
1.构造方法方式为对象属性赋值User{userId=1, userName='张三'}
2.Set方法方式为对象属性赋值User{userId=2, userName='李四'}
3.p命名空间方法执行:
执行了Save方法保存数据
2.5注解方式
将上述的类修改:
2.5.1持久层
package per.liyue.springlearing.obj_dep;
import org.springframework.stereotype.Repository;
@Repository(value = "userDao")
public class UserDao
{
public void Save()
{
System.out.println("操作数据保存了数据");
}
}
2.5.2业务层
package per.liyue.springlearing.obj_dep;
import org.springframework.stereotype.Service;
import per.liyue.springlearing.structure.UserDao1;
import javax.annotation.Resource;
@Service(value = "userService")//这里等于配置文件中<bean id="userDao" class="per.liyue.springlearing.structure.UserDao"></bean>
//的方式
public class UserService
{
@Resource(name = "userDao")
private UserDao1 userDao;
public void Save()
{
userDao.Save();
}
}
2.5.3控制层
package per.liyue.springlearing.obj_dep;
import org.springframework.stereotype.Controller;
import per.liyue.springlearing.structure.UserService1;
import javax.annotation.Resource;
@Controller(value = "userAction")
public class UserAction
{
@Resource(name = "userService")
private UserService1 userService;
public void Excute()
{
userService.Save();
}
}
2.5.4配置文件
<?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:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd" >
<context:component-scan base-package="per.liyue.springlearing.obj_dep"></context:component-scan>
</beans>
2.5.5调用
package per.liyue.springlearing.obj_dep;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class App_Dep
{
private ApplicationContext applicationContext = new ClassPathXmlApplicationContext("per/liyue/springlearing/obj_dep/bean.xml");
@Test
public void Main()
{
UserAction userAction = applicationContext.getBean("userAction", UserAction.class);
System.out.println("使用注解生成:");
userAction.Excute();
}
}