使用ioc来创建对象有三种方式

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通过无参构造方法来创建

User.java

public class Hello {    private String name;    public Hello() {        System.out.println("hello的无参构造方法");    }    public void setName(String name) {        this.name = name;    }}

beans.xml

    <bean name="hello" class="com.zfy.bean.Hello">        <property name="name" value="spring"></property>    </bean>

通过有参构造方法来创建

public class Hello {    private String name;    public Hello(String name) {        this.name = name;    }    public void setName(String name) {        this.name = name;    }}

beans.xml
第一种根据参数的下标来设置

    <bean id="hello" class="com.zfy.bean.Hello">        <!-- index指构造方法下标 从0开始 -->        <constructor-arg index="0" value="张三"></constructor-arg>    </bean>

第二种根据参数名称来设置

    <bean id="hello" class="com.zfy.bean.Hello">        <!-- name指参数名称 -->        <constructor-arg name="name" value="李四"></constructor-arg>    </bean>

第三种根据参数类型来设置

    <bean id="hello" class="com.zfy.bean.Hello">        <!-- type指参数类型 -->        <constructor-arg type="java.lang.String" value="Dylan"></constructor-arg>    </bean>

通过工厂方法来创建

静态工厂

public class UserStaticFactory {    public static User newInstance(String name) {        return new User(name);    }}

    <bean id="user" class="com.zfy.factory.UserStaticFactory" factory-method="newInstance">        <constructor-arg index="0" value="张三"></constructor-arg>    </bean>

动态工厂

public class UserDyanmicFactory {    public User newInstance(String name) {        return new User(name);    }}

    <bean id="userFactory" class="com.zfy.factory.UserDyanmicFactory"></bean>    <bean id="user" factory-bean="userFactory" factory-method="newInstance">        <constructor-arg index="0" value="李四"></constructor-arg>    </bean>

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