这一章节我们来继续具体讨论一下@autowired里面的參数required。在多构造器注入的情况。

1.domain(重点)

蛋糕类:

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_10;

public class Cake {

private String name = "";

public String getName() {
return name;
}

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

}


厨师类:

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_10;

import org.springframework.beans.factory.annotation.Autowired;

public class Chief {
private Cake cake = null;

private Oven oven = null;

@Autowired(required = false)
public Chief(Cake cake) {
this.cake = cake;
}

@Autowired(required = false)
public Chief(Cake cake, Oven oven) {
this.cake = cake;
this.oven = oven;
}

private String name = "";

public String getName() {
return name;
}

public Cake makeOneCake() {
if (cake != null) {
System.out.println(getName() + " use " + oven.getName() + " and make " + cake.getName());
} else {
System.out.println("null");
}
return cake;
}

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

}


厨师类这里须要注意的是,当出现多构造器注入的情况,尽管我们都能够使用@autowired标签。可是须要把required都弄成是false,不然抛异常

还有的是,当出现多构造器注入时。注入成功的是注入对象最多的那个构造器,也就是上面有两个參数的那个


烤炉类:(又一次引入)

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_10;

public class Oven {
private String name = "";

@Override
public String toString() {
return name;
}

public String getName() {
return name;
}

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

}



2.測试类:(不变)

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_10;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {
"/com/raylee/my_new_spring/my_new_spring/ch02/topic_1_10/ApplicationContext-test.xml" })
public class ChiefTest {

@Autowired
private ApplicationContext applicationContext;

@Test
public void testChief() {
Chief jack = applicationContext.getBean(Chief.class);
jack.makeOneCake();
}
}



3.配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.0.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<bean id="blueberryCheeseCake"
class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_10.Cake"
p:name="blueberryCheeseCake" scope="prototype" />
<bean id="bigOven"
class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_10.Oven"
p:name="bigOven" />
<bean id="jack"
class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_10.Chief"
p:name="jack" />
</beans>



測试输出:

jack use bigOven and make blueberryCheeseCake


总结:这一章节我们主要讨论了@autowired里面的參数required。