Spring-IOC创建对象的方式
sjyvv 2020-01-05 16:25:31
spring
- 无参构造
- 有参构造
- 参数下标
- 参数名称
- 参数类型
- 工厂方法来创建对象
- 静态工厂
- 动态工厂
首先来个POJO类
public class User {
private String name;
public void setName(String name) {
this.name = name;
}
public User() {
System.out.println("无参构造");
}
public User(String name) {
System.out.println("有参构造");
this.name = name;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
'}';
}
}
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主函数
public class Test {
public static void main(String[] args) {
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("ApplicationContext.xml");
User user = applicationContext.getBean(User.class);
System.out.println(user);
}
}
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# 无参构造
# xml配置
<bean id="user" class="com.User"/>
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# 运行结果
# 有参构造
# 参数下标
# xml配置
<bean id="user" class="com.User">
<constructor-arg index="0" value="haha"/>
</bean>
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# 运行结果
# 参数名称
# xml配置
<bean id="user" class="com.User">
<constructor-arg name="name" value="hello"/>
</bean>
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# 运行结果
# 参数类型
# xml配置
<bean id="user" class="com.User">
<constructor-arg type="java.lang.String" value="stringValue"/>
</bean>
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# 运行结果
# 工厂方法来创建
# 静态工厂
# 静态工厂类
public class UserFactory {
public static User newInstance(String name) {
System.out.println("静态工厂创建");
return new User(name);
}
}
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# xml配置
<bean id="user" class="com.UserFactory" factory-method="newInstance">
<constructor-arg type="java.lang.String" value="stringValue"/>
</bean>
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# 运行结果
# 动态工厂
# 动态工厂类
public class UserDynamicFactory {
public User newInstance(String name) {
System.out.println("动态工厂创建");
return new User(name);
}
}
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# xml配置
<bean id="factory" class="com.UserDynamicFactory"/>
<bean id="user" factory-bean="factory" factory-method="newInstance">
<constructor-arg type="java.lang.String" value="dynamic"/>
</bean>
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