spring FactoryBean 是創(chuàng)建 復(fù)雜的bean，一般的bean 直接用xml配置即可，如果一個(gè)bean的創(chuàng)建過程中涉及到很多其他的bean 和復(fù)雜的邏輯，用xml配置比較困難，這時(shí)可以考慮用FactoryBean
例子如下：
1：創(chuàng)建一個(gè)Car類（是為了簡便）一般不能直接給出Car類，如果是這樣直接注入就可以或者Car對象了，這里只是為了簡便。
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
package com.myapp.core.factorybean; public class Car { private String make; private int year; public String getMake() { return make; } public void setMake(String make) { this.make = make; } public int getYear() { return year; } public void setYear(int year) { this.year = year; } } |
2：一個(gè)FactoryBean的實(shí)現(xiàn)擁有創(chuàng)建car
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
package com.myapp.core.factorybean; import org.springframework.beans.factory.FactoryBean; public class MyCarFactoryBean implements FactoryBean<Car>{ private String make; private int year; public void setMake(String make) { this.make = make; } public void setYear(int year) { this.year = year; } @Override public Car getObject() throws Exception { // TODO Auto-generated method stub //Here is a complex car object created // wouldn't be a very useful FactoryBean // if we could simply instantiate the object! Car car = new Car(); if(year != 0){ car.setYear(this.year); } if("make".equals(make)){ car.setMake("we are making bla bla bla"); }else{ car.setMake(this.make); } return car; } @Override public Class<?> getObjectType() { // TODO Auto-generated method stub return Car.class; } @Override public boolean isSingleton() { // TODO Auto-generated method stub return false; } } |
以上中創(chuàng)建car太簡單了，如果太簡單就沒有必要用FactoryBean創(chuàng)建了，可以寫的復(fù)雜些。
3：Person 引用一個(gè)car
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
package com.myapp.core.factorybean; public class Person { private Car car; public Car getCar() { return car; } public void setCar(Car car) { this.car = car; } public String toString(){ return car.getMake()+"::::"+car.getYear(); } } |
4：配置引用xml格式：
|
1
2
3
4
5
6
7
8
9
10
|
<bean id="car" class="com.myapp.core.factorybean.MyCarFactoryBean"> <property name="make" value="makeing car"/> <property name="year" value="123"/> </bean> <bean id="person" class="com.myapp.core.factorybean.Person"> <property name="car" ref="car"/> </bean> |
5：編寫測試類測試：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
|
package com.myapp.core.factorybean; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainTest { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("resource/others.xml"); Person person = (Person)context.getBean("person"); // Car car = (Car)context.getBean("car"); // System.out.println(car); System.out.println(person); } } |
測試結(jié)果 makeing car::::123
利用FactoryBean創(chuàng)建car成功
只是為了說明思想。因?yàn)檫@個(gè)接口太重要了。在Spring中有很多類實(shí)現(xiàn)了該接口。
以上所述是小編給大家介紹的詳解Spring中的FactoryBean，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會(huì)及時(shí)回復(fù)大家的。在此也非常感謝大家對服務(wù)器之家網(wǎng)站的支持！
原文鏈接：http://blog.csdn.net/topwqp/article/details/8678061
