Spring in Action

annotation-wired

注释@Component
注释不会自动生效，使用@ComponentScan或<context:component-scan>开启扫描

类似注释：
@Component("identifierName")，recommend
@Name("identifierName")，可互用，于@Component略有不同

制定特定的扫描包
@ComponentScan(basePackages="soundsystem")  // 扫描单个包
@ComponentScan(basePackages={"soundsystem", "video"})  // 扫描多个包
@ComponentScan(basePackageClasses={CDPlayer.class, DVDPlayer.class})  // 扫描类所在包


@Autowired，通过注释形式wire对象
@Autowired(required=false)，未发现匹配的对象时，不抛出异常，会产生NullPointerException
@Inject，可互用，于@Autowired略有不同



---
使用于构造函数
  @Autowired
  public CDPlayer(CompactDisc cd) {
    this.cd = cd;
  }
使用于set方法
@Autowired
public void setCompactDisc(CompactDisc cd) {
  this.cd = cd;
}
使用在其他方法上
@Autowired
public void insertDisc(CompactDisc cd) {
  this.cd = cd;
}




CompactDisc.java
---
package soundsystem;

public interface CompactDisc {
  void play();
}

SgtPeppers.java
---
package soundsystem;

import org.springframework.stereotype.Component;

@Component
public class SgtPeppers implements CompactDisc {
  
  private String title = "Sgt. Pepper's Lonely Hearts Club Band";
  private String artist = "The Beatles";
  
  public void play() {
    System.out.println("Playing " + title + " by " + artist);
  }
}

CDPlayerConfig.java
---
package soundsystem;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan
public class CDPlayerConfig {
}

annotation.xml
---
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:context="http://www.springframework.org/schema/context"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">
  
  <context:component-scan base-package="soundsystem" />
</beans>

AOP

本例展示Spring的AOP

BraveKnight.java是基本的POJO
Minstrel.java是AOP的处理对象
aop.xml声明了切面的位置，以及处理方法

BraveKnight.java
---
package com.springinaction.knights;

public class BraveKnight implements Knight {
  
  private Quest quest;
  
  public BraveKnight(Quest quest) {
    this.quest = quest;
  }
  
  public void embarkOnQuest() {
    quest.embark();
  }
}



Minstrel.java
---
package com.springinaction.knights;
import java.io.PrintStream;

public class Minstrel {
  
  private PrintStream stream;
  
  public Minstrel(PrintStream stream) {
      this.stream = stream;
  }
  
  public void singBeforeQuest() {
    stream.println("Fa la la, the knight is so brave!");
  }
  
  public void singAfterQuest() {
    stream.println("Tee hee hee, the brave knight " +
        "did embark on a quest!");
  }
}

aop.xml
---
<?xml version="1.0" encoding="UTF-8"?>>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:aop="http://www.springframework.org/schema/aop"
  xsi:schemaLocation="http://www.springframework.org/schema/aop
      http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
    http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans.xsd">
      
  <bean id="knight" class="com.springinaction.knights.BraveKnight">
    <constructor-arg ref="quest" />
  </bean>
  
  <bean id="quest" class="com.springinaction.knights.SlayDragonQuest">
    <constructor-arg value="#{T(System).out}" />
  </bean>
  
  <bean id="minstrel" class="com.springinaction.knights.Minstrel">
    <constructor-arg value="#{T(System).out}" />
  </bean>
  
  <aop:config>
    <aop:aspect ref="minstrel">
      <aop:pointcut id="embark"
        expression="execution(* *.embarkOnQuest(..))"/> <!-- Define pointcut -->
        
      <aop:before pointcut-ref="embark"
          method="singBeforeQuest"/> <!-- Declare before advice -->
      <aop:after pointcut-ref="embark"
          method="singAfterQuest"/> <!-- Decalre after advice -->
    </aop:aspect>
  </aop:config>
</beans>

DI

本例展示Spring的Dependency Injection

启动类: KnightMain.java
对象: BraveKnight.java
依赖对象: SlayDragonQuest.java
配置: knight.xml

BraveKnight.java
---
package com.springinaction.knights;

public class BraveKnight implements Knight {
  
  private Quest quest;
  
  public BraveKnight(Quest quest) {
    this.quest = quest;
  }
  
  public void embarkOnQuest() {
    quest.embark();
  }
}

SlayDragonQuest.java
---
package com.springinaction.knights;

import java.io.PrintStream;

public class SlayDragonQuest implements Quest {
  private PrintStream stream;
  
  public SlayDragonQuest(PrintStream stream) {
    this.stream = stream;
  }
  
  public void embark() {
    stream.println("Embarking on quest to slay the dragon!");
  }
}


knight.xml
---
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd">
  <bean id="knight" class="com.springinaction.knights.BraveKnight">
    <constructor-arg ref="quest" />
  </bean> <!-- Inject quest bean -->
  
  <bean id="quest" class="com.springinaction.knights.SlayDragonQuest">
    <constructor-arg value="#{T(System).out}" />
  </bean>
</beans>


KnightMain.java
---
package com.springinaction.knights;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class KnightMain {
  public static void main(String[] args) throws Exception {
    // Load Spring context
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(
            "META-INF/spring/knight.xml");

    //Get knight bean
    Knight knight = context.getBean(Knight.class);
    knight.embarkOnQuest();
    context.close();
  }
}

java-config

@Configuration，创建ApplicationContext配置
@ComponentScan，自动扫描

CDPlayerConfig.java
---
package soundsystem;

import org.springframework.context.annotation.Configuration;
        
@Configuration
public class CDPlayerConfig {

  /**
   * Declare Simple Bean
   */
  @Bean
  @Bean(name="lonelyHeartsClubBand")  // 声明特定名字
  public CompactDisc sgtPeppers() {
    return new SgtPeppers();
  }
  
  /**
   * constructor injection 1
   */
  @Bean
  public CDPlayer cdPlayer() {
    return new CDPlayer(sgtPeppers());
  }

  /**
   * constructor injection 2
   */
  @Bean
  public CDPlayer cdPlayer(CompactDisc compactDisc) {
    return new CDPlayer(compactDisc);
  }
  
  /**
   * property injection
   */
  @Bean
  public CDPlayer cdPlayer(CompactDisc compactDisc) {
    CDPlayer cdPlayer = new CDPlayer(compactDisc);
    cdPlayer.setCompactDisc(compactDisc);
    return cdPlayer;
  }
}

mixed-up

混合使用

CDConfig.java
---
package soundsystem;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class CDConfig {
  @Bean
  public CompactDisc compactDisc() {
    return new SgtPeppers();
  }
}

CDPlayerConfig.java
---
package soundsystem;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

@Configuration
@Import(CDConfig.class)
public class CDPlayerConfig {

  @Bean
  public CDPlayer cdPlayer(CompactDisc compactDisc) {
    return new CDPlayer(compactDisc);
  }
}

JavaConfig整合两个JavaConfig
===
package soundsystem;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

@Configuration
@Import({CDPlayerConfig.class, CDConfig.class})
public class SoundSystemConfig {
}

JavaConfig整合JavaConfig和XML
===
package soundsystem;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.ImportResource;

@Configuration
@Import(CDPlayerConfig.class)
@ImportResource("classpath:cd-config.xml")
public class SoundSystemConfig {
}

XML整合JavaConfig和XML
===
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:c="http://www.springframework.org/schema/c"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd">
  
  <bean class="soundsystem.CDConfig" />
  <import resource="cdplayer-config.xml" />

</beans>

xml-config

注意XSD: XML Schema Definition
相比JavaConfig方式，XML配置不会做类型检查

如果用c-namespace，需要用响应的XSD

XML配置模版
---
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context">
  
  <!-- configuration details go here -->
  
  <!-- Declare simple Bean -->
  <bean class="soundsystem.SgtPeppers" />
  <!-- 通过id给Bean做标识 -->
  <bean id="compactDisc" class="soundsystem.SgtPeppers" />
  
  <!-- constructor injection -->
  <bean id="cdPlayer" class="soundsystem.CDPlayer">
    <constructor-arg ref="compactDisc" />
  </bean>
  
  <!-- 传参数值 -->
  <bean id="compactDisc"
      class="soundsystem.BlankDisc">
    <constructor-arg value="Sgt. Pepper's Lonely Hearts Club Band" />
    <constructor-arg value="The Beatles" />
  </bean>
  
  <!-- 可以使用NULL -->
  <bean id="compactDisc" class="soundsystem.BlankDisc">
    <constructor-arg value="Sgt. Pepper's Lonely Hearts Club Band" />
    <constructor-arg value="The Beatles" />
    <constructor-arg><null/></constructor-arg>
  </bean>
  
  <!-- 使用List -->
  <bean id="compactDisc" class="soundsystem.BlankDisc">
    <constructor-arg value="Sgt. Pepper's Lonely Hearts Club Band" />
    <constructor-arg value="The Beatles" />
    <constructor-arg>
      <list>
        <value>Sgt. Pepper's Lonely Hearts Club Band</value>
        <value>With a Little Help from My Friends</value>
        <value>Lucy in the Sky with Diamonds</value>
        <value>Getting Better</value>
        <value>Fixing a Hole</value>
        <!-- ...other tracks omitted for brevity... -->
        <!-- 也可以使用引用 -->
        <ref bean="xxx" />
      </list>
    </constructor-arg>
  </bean>
  
  <!-- Set -->
  <bean id="compactDisc" class="soundsystem.BlankDisc">
    <constructor-arg value="Sgt. Pepper's Lonely Hearts Club Band" />
    <constructor-arg value="The Beatles" />
    <constructor-arg>
      <set>
        <value>Sgt. Pepper's Lonely Hearts Club Band</value>
        <value>With a Little Help from My Friends</value>
        <value>Lucy in the Sky with Diamonds</value>
        <value>Getting Better</value>
        <value>Fixing a Hole</value>
        <!-- ...other tracks omitted for brevity... -->
      </set>
    </constructor-arg>
  </bean>


</beans>

c-namespace
---
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:c="http://www.springframework.org/schema/c"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
  http://www.springframework.org/schema/beans/spring-beans.xsd">

  <!-- c-namespace -->
  <!-- 这里的cd时参数的名字-->
  <bean id="cdPlayer" class="soundsystem.CDPlayer"
    c:cd-ref="compactDisc" />
  
  <!-- 这里也能使用参数的位置 -->
  <bean id="cdPlayer" class="soundsystem.CDPlayer"
    c:_0-ref="compactDisc" />
  
  <!-- 唯一参数 -->
  <bean id="cdPlayer" class="soundsystem.CDPlayer"
    c:_-ref="compactDisc" />

  <bean id="compactDisc"
    class="soundsystem.BlankDisc"
    c:_title="Sgt. Pepper's Lonely Hearts Club Band"
    c:_artist="The Beatles" />
  
  <bean id="compactDisc"
    class="soundsystem.BlankDisc"
    c:_0="Sgt. Pepper's Lonely Hearts Club Band"
    c:_1="The Beatles" />

</beans>

p-namespace
---

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:p="http://www.springframework.org/schema/p"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd">
  
  <!-- 引用 -->
  <bean id="cdPlayer"
    class="soundsystem.CDPlayer"
    p:compactDisc-ref="compactDisc" />
    
</bean>

property injection
---
<bean id="compactDisc"
      class="soundsystem.BlankDisc">
  <property name="title"
               value="Sgt. Pepper's Lonely Hearts Club Band" />
  <property name="artist" value="The Beatles" />
  <property name="tracks">
    <list>
      <value>Sgt. Pepper's Lonely Hearts Club Band</value>
      <value>With a Little Help from My Friends</value>
      <value>Lucy in the Sky with Diamonds</value>
      <value>Getting Better</value>
      <value>Fixing a Hole</value>
      <!-- ...other tracks omitted for brevity... -->
    </list>
  </property>
</bean>

util-namespace
---
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:p="http://www.springframework.org/schema/p"
  xmlns:util="http://www.springframework.org/schema/util"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/util
    http://www.springframework.org/schema/util/spring-util.xsd">
  ... 
</beans>

创建List
<util:list id="trackList">
  <value>Sgt. Pepper's Lonely Hearts Club Band</value>
  <value>With a Little Help from My Friends</value>
  <value>Lucy in the Sky with Diamonds</value>
  <value>Getting Better</value>
  <value>Fixing a Hole</value>
  <!-- ...other tracks omitted for brevity... -->
</util:list>

然后再用property injection
<bean id="compactDisc"
      class="soundsystem.BlankDisc"
      p:title="Sgt. Pepper's Lonely Hearts Club Band"
      p:artist="The Beatles"
      p:tracks-ref="trackList" />