Spring三种注入方式

一、构造方法注入(死的应用)   通过constructor-arg指定构造方法的参数 Source.java

1. package com.gary.test;
3. public class Source {
5. public void helloWorld(){
6. System.out.println("Hello World!");
7. }
8. }

 Target.java

1. package com.gary.test;
3. public class Target {
5. private Source source;
7. public Target(Source source){
8. this.source = source;
9. }
11. public void sayHelloWorld(){
12. source.helloWorld();
13. }
15. }

applicationContext.xml 

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans
3. xmlns="http://www.springframework.org/schema/beans"
4. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5. xmlns:p="http://www.springframework.org/schema/p"
6. xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
8. <bean id="source" class="com.gary.test.Source" />
9. <bean id="target" class="com.gary.test.Target">
10. <constructor-arg ref="source" />
11. </bean>
12. </beans>

TargetTest.java 

1. package com.gary.test;
3. import org.junit.AfterClass;
4. import org.junit.BeforeClass;
5. import org.junit.Test;
6. import org.springframework.beans.factory.BeanFactory;
7. import org.springframework.context.support.ClassPathXmlApplicationContext;
9. public class TargetTest {
11. static BeanFactory factory = null;
12. static Target target = null;
14. @BeforeClass
15. public static void setUpBeforeClass() throws Exception {
16. try{
17. factory = new ClassPathXmlApplicationContext("applicationContext.xml");
18. target = (Target) factory.getBean("target");
19. }catch(Exception e){
20. e.printStackTrace();
21. }
22. }
24. @AfterClass
25. public static void tearDownAfterClass() throws Exception {
27. }
29. @Test
30. public void testSayHelloWorld() {
31. target.sayHelloWorld();
32. }
34. }

二、getter()和setter()方法注入(比较常用)   通过访问器方法(set)注入此方法较为常用.在目标类中,定义要注入的属性,并添加访问器方法,则spring会自动注入.Source.java

1. package com.gary.test;
3. public class Source {
5. public void helloWorld(){
6. System.out.println("Hello World!");
7. }
8. }

Target.java

1. package com.gary.test;
3. public class Target {
5. private Source source;
7. public void setSource(Source source) {
8. this.source = source;
9. }
11. public Source getSource() {
12. return source;
13. }
15. public void sayHelloWorld(){
16. getSource().helloWorld();
17. }
19. }

applicationContext.xml

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans
3. xmlns="http://www.springframework.org/schema/beans"
4. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5. xmlns:p="http://www.springframework.org/schema/p"
6. xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"
7. default-autowire="byType">
9. <bean id="source" class="com.gary.test.Source" />
10. <bean id="target" class="com.gary.test.Target">
11. <!-- 在beans标签添加default-autowire="byType"属性后,下面这行可以省略 -->
12. <!-- <property name="source" ref="source" /> -->
13. </bean>
14. </beans>

TargetTest.java 

1. package com.gary.test;
3. import org.junit.AfterClass;
4. import org.junit.BeforeClass;
5. import org.junit.Test;
6. import org.springframework.beans.factory.BeanFactory;
7. import org.springframework.context.support.ClassPathXmlApplicationContext;
9. public class TargetTest {
11. static BeanFactory factory = null;
12. static Target target = null;
14. @BeforeClass
15. public static void setUpBeforeClass() throws Exception {
16. try{
17. factory = new ClassPathXmlApplicationContext("applicationContext.xml");
18. target = (Target) factory.getBean("target");
19. }catch(Exception e){
20. e.printStackTrace();
21. }
22. }
24. @AfterClass
25. public static void tearDownAfterClass() throws Exception {
27. }
29. @Test
30. public void testSayHelloWorld() {
31. target.sayHelloWorld();
32. }
34. }

 三、接口方式注入(不推荐使用)   通过接口方式注入建议使用前两种方法Source.java

1. package com.gary.test;
3. public class Source {
5. public void helloWorld(){
6. System.out.println("Hello World!");
7. }
8. }

ISource.java

1. package com.gary.test;
3. public interface ISource {
4. //方法名任意,方法参数是所依赖对象的类型
5. public void injectSource(Source source);
6. }

Target.java 

1. package com.gary.test;
3. public class Target implements ISource{
5. private Source source;
7. @Override
8. public void injectSource(Source source) {
9. this.source = source;
10. }
12. public void sayHelloWorld(){
13. source.helloWorld();
14. }
16. }

applicationContext.xml

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans
3. xmlns="http://www.springframework.org/schema/beans"
4. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5. xmlns:p="http://www.springframework.org/schema/p"
6. xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"
7. default-autowire="byType">
9. <bean id="source" class="com.gary.test.Source" />
10. <bean id="target" class="com.gary.test.Target" />
11. </beans>

TargetTest.java 

1. package com.gary.test;
3. import org.junit.AfterClass;
4. import org.junit.BeforeClass;
5. import org.junit.Test;
6. import org.springframework.beans.factory.BeanFactory;
7. import org.springframework.context.support.ClassPathXmlApplicationContext;
9. public class TargetTest {
11. static BeanFactory factory = null;
12. static Source source = null;
13. static Target target = null;
15. @BeforeClass
16. public static void setUpBeforeClass() throws Exception {
17. try{
18. factory = new ClassPathXmlApplicationContext("applicationContext.xml");
19. target = (Target) factory.getBean("target");
20. source = (Source) factory.getBean("source");
21. }catch(Exception e){
22. e.printStackTrace();
23. }
24. }
26. @AfterClass
27. public static void tearDownAfterClass() throws Exception {
29. }
31. @Test
32. public void testSayHelloWorld() {
33. target.injectSource(source);
34. target.sayHelloWorld();
35. }
37. }