Spring part 1：IoC和DI

 

 

http://repo.springsource.org/libs-release-local/

 

 

这是Spring所包含的模块，但随着Spring的发展壮大，模块也是越来越多

传统的实例化对象方式是，我需要什么对象，我来new，SpringIoC实例化对象的思想是，你需要什么对象？告诉我，我给你（注入）。

注入的方式有三种：接口注入、方法注入、构造注入

SpringIoC职责：对象的构建与管理、对象间依赖绑定

管理对象间依赖方式：编码、配置文件、注解（元数据）

 

导入所需要的底层4个核心jar包

spring-beans-3.2.5.RELEASE.jar
spring-context-3.2.5.RELEASE.jar
spring-core-3.2.5.RELEASE.jar
spring-expression-3.2.5.RELEASE.jar

还需要日志包

commons.logging-1.1.1.jar
log4j-1.2.15.jar

创建两个配置文件

log4j.properties
applictionContext.xml

 工程目录结构如下

 

案例1：创建一个实例对象，将该对象交由SpringIoC容器管理，通过SpringIoC容器为其初始化

public class InstanceBean {
public InstanceBean() {
System.out.println("...");
}
public void method() {
System.out.println("InstanceBean--method()");
}
}

在applicationContext.xml中配置InstanceBean

<?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="instanceBean" class="ioc.InstanceBean"></bean>
</beans>

该配置文件中的schema可以通过官方文档找到，以Spring3.2.5为例

spring-framework-3.2.5.RELEASE\docs\spring-framework-reference\html\xsd-config.html

 该文档中有所有关于Spring配置的xml约束，bean的约束在xsd-config.html的最下方

使用SpringIoC容器初始化InstanceBean

ApplicationContext context = new ClassPathXmlApplicationContext("classpath:ioc/applictionContext.xml");
InstanceBean instance = context.getBean("instanceBean", InstanceBean.class);
instance.getMethod();

我把applicationContext.xml放在了src下的ioc包中，所以路径前加上了“ioc/”，编译后的项目结构为

 

案例二：SpringIoC容器通过构造实例化对象，案例一中的方式是通过默认构造器实例化InstanceBean，也可以使用有参数的构造器实例化InstanceBean

public class InstanceBean {
private String info;

public InstanceBean() {
System.out.println("..." + this);
}

public InstanceBean(String info) {
this.info = info;
}
}

 applicationContext.xml配置，采用index+value方式，index表示构造器中参数位置，value表示参数的值

<!-- 默认构造器 -->
<bean id="instaceBean" class="ioc.InstanceBean">
</bean>
<!-- 指定构造器 -->
<bean id="constructor" class="ioc.InstanceBean">
<constructor-arg index="0" value="springIoC"></constructor-arg>
</bean>

 案例三：静态工厂初始化

创建一个工厂类，有两个静态方法，一个使用默认构造器，一个使用有参数的构造器

public class StaticFactory {
public static InstanceBean getInstanceBean() {
return new InstanceBean();
}
public static InstanceBean getInstanceBeanPara(String info) {
return new InstanceBean(info);
}
}

 对静态工厂进行配置，使用SpringIoC初始化

<!-- 静态工厂 -->
<bean id="staticFactory" class="ioc.StaticFactory" factory-method="getInstanceBean">
</bean>
<!-- 静态工厂 有参数 -->
<bean id="staticFactoryParam" class="ioc.StaticFactory" factory-method="getInstanceBeanPara">
<constructor-arg index="0" value="staticFacotryParam"></constructor-arg>
</bean>

 

 测试

@Test
public void testIoCStaticFactory() {
ApplicationContext context = new ClassPathXmlApplicationContext("classpath:ioc/applicationContext.xml");
InstanceBean instance = context.getBean("staticFactory",InstanceBean.class);
instance.getMethod();
}
@Test
public void testIoCStaticFactoryParam() {
ApplicationContext context = new ClassPathXmlApplicationContext("classpath:ioc/applicationContext.xml");
InstanceBean instance = context.getBean("staticFactoryParam",InstanceBean.class);
System.out.println(instance.getInfo());
}

 案例三：实例工厂

创建实例工厂类

public class InstanceFacotry {
public InstanceBean getInstanceBean() {
return new InstanceBean();
}
}

 配置时需要先配置实例工厂，然后通过factory-bean引用实例工厂的id，通过factory-method指定调用实例工厂中的哪个方法

<!-- 实例工厂 -->
<bean id="instanceFactory" class="ioc.InstanceFacotry"></bean>
<bean id="insFactory" factory-bean="instanceFactory" factory-method="getInstanceBean"></bean>

案例四：setter注入

创建一个包含setter()的类

public class InstanceBean {
private String info;

public InstanceBean() {
System.out.println("..." + this);
}

public String getInfo() {
return this.info;
}

public void setInfo(String info) {
this.info = info;
}
}

配置

<!-- setter注入 -->
<bean id="instanceBeanSetter" class="ioc.InstanceBean">
<property name="info" value="setInfo()"></property>
</bean>

案例五：集合注入

创建一个类，包含常用的集合容器，生成setter()，使用SpringIoC容器注集合容器的内容

public class CollectionBean {
private String[] arr;
private String[][] array;
private List<String> list;
private Set<Integer> set;
private Properties properties;
private Collection<String> collection;
private Map<String, String> map;
}

配置集合注入

<!-- 集合注入 -->
<bean id="collectionDI" class="ioc.CollectionBean">
<!-- 一维数组 -->
<property name="arr">
<array>
<value>arr1</value>
<value>arr2</value>
</array>
</property>
<!-- 二维数组 -->
<property name="array">
<array>
<array>
<value>array1</value>
</array>
<array>
<value>array2</value>
</array>
</array>
</property>
<!-- List集合 -->
<property name="list">
<!-- value-type:可选，相当于泛型 -->
<list value-type="java.lang.String" merge="default">
<value>list1</value>
<value>list2</value>
<value>list3</value>
</list>
</property>
<!-- Set集合 -->
<property name="set">
<set value-type="java.lang.Integer">
<value>1</value>
<value>2</value>
<value>3</value>
</set>
</property>
<!-- Properties -->
<property name="properties">
<props>
<prop key="1">pop1</prop>
<prop key="2">pop2</prop>
</props>
</property>
<!-- Collection -->
<property name="collection">
<set value-type="java.lang.String">
<value>collction1</value>
<value>collction2</value>
<value>collction3</value>
</set>
</property>
<!-- Map集合 -->
<property name="map">
<map key-type="java.lang.String" value-type="java.lang.String">
<!-- 复杂配置 -->
<entry>
<key>
<value>key1</value>
</key>
<value>value1</value>
</entry>
<!-- 简化配置 -->
<entry key="key2" value="value2"></entry>
</map>
</property>
</bean>

案例六：depends-on配置，在依赖情况下，depends-on配置的bean要先与当前bean初始化，晚于当前bean销毁

创建Resources、Dependency两个类，Dependency依赖Resources

public class Resources {
public Resources() {
super();
System.out.println("Resources Constructor() ");
}
public void init(){
System.out.println("Resources init()");
}
public void destroy(){
System.out.println("Resources destroy()");
}
}
public class Dependency {
Resources resources;
public Dependency() {
super();
System.out.println("Dependency Constructor() ");
}
public void init() {
System.out.println("Dependency init()");
}
public void destroy() {
System.out.println("Dependency destroy()");
}
public Resources getResources() {
return resources;
}
public void setResources(Resources resources) {
this.resources = resources;
}
}

 配置

<bean id="resources" class="ioc.Resources" init-method="init" destroy-method="destroy"></bean>
<bean id="dependency" class="ioc.Dependency" init-method="init" destroy-method="destroy" depends-on="resources">
<property name="resources" ref="resources"></property>
</bean>

 测试时使用ClassPathXmlApplicationContext获得IoC容器，因为只有容器个关闭才能看到调用destroy()

ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
Dependency dependency = context.getBean("dependency",Dependency.class);
context.close();
/**output:
Resources Constructor()
Resources init()
Dependency Constructor()
Dependency init()
Dependency destroy()
Resources destroy()
*/

 案例七：单例bean

方式一：单例bean构造私有化

public class Singletion {

private Singletion() {
}

public static class SingletionHandler {
public static final Singletion INSTANCE = new Singletion();
}

public static Singletion getInstance() {
return SingletionHandler.INSTANCE;
}
}

方式二：将单例的bean通过唯一键注册到注册表，然后通过键值来获取，通过实现SingletonBeanRegistry接口来实现，不考虑多线程问题，Spring采用这种方式实现singleton

public class SingleonBeanRegister implements SingletonBeanRegistry {

private final Map<String, Object> BEANS = new HashMap<String, Object>();

public void registerSingleton(String beanName, Object singletonObject) {
if (BEANS.containsKey(beanName)) {
throw new RuntimeException("[" + beanName + "] already exist");
}
BEANS.put(beanName, singletonObject);
}

public Object getSingleton(String beanName) {
return BEANS.get(beanName);
}

public boolean containsSingleton(String beanName) {
return BEANS.containsKey(beanName);
}

public String[] getSingletonNames() {
return BEANS.keySet().toArray(new String[0]);
}

public int getSingletonCount() {
return BEANS.size();
}

}

Spring配置方式，通过SpringIoC容器获得单例bean

定义bean

public class ScopeBean {}

 配置，不配置scope时默认就是singleton

<bean id="singleton" class="bean.ScopeBean" scope="singleton"></bean>

 测试

ScopeBean singleton1 =  context.getBean("singleton",ScopeBean.class);
ScopeBean singleton2 =  context.getBean("singleton",ScopeBean.class);
ScopeBean singleton3 =  context.getBean("singleton",ScopeBean.class);
System.out.println(singleton1);
System.out.println(singleton2);
System.out.println(singleton3);
/**
bean.ScopeBean@30db7df3
bean.ScopeBean@30db7df3
bean.ScopeBean@30db7df3
*/

 案例八：prototype bean

模拟Spring实现，定义个bean

public class BeanDefinition {
// 单例
public static final int SCOPE_SINGLETON = 0;
// 原型
public static final int SCOPE_PROTOTYPE = 1;
// 唯一标识
private String id;
// class全限定名
private String clazz;
// 作用域
private int scope = SCOPE_SINGLETON;
}

 这侧表类

public class BeanDifinitionRegister {
private final Map<String, BeanDefinition> DEFINITIONS = new HashMap<String, BeanDefinition>();

public void registerBeanDefinition(String beanName, BeanDefinition bd) {
if (DEFINITIONS.containsKey(bd.getId())) {
throw new RuntimeException("[" + beanName + "] already exist");
}
DEFINITIONS.put(bd.getId(), bd);
}

public BeanDefinition getBeanDefinition(String beanName) {
return DEFINITIONS.get(beanName);
}

public boolean containsBeanDefinition(String beanName) {
return DEFINITIONS.containsKey(beanName);
}
}

 定义工厂类用于获取bean实例

public class DefaultBeanFactory {
// Bean定义注册表
private BeanDifinitionRegister DEFINITIONS = new BeanDifinitionRegister();
// 单例注册表
private final SingletonBeanRegistry SINGLETONS = new SingletonBeanRegister();

public Object getBean(String beanName) {
// 1.验证Bean定义是否存在
if (!DEFINITIONS.containsBeanDefinition(beanName)) {
throw new RuntimeException("[" + beanName + "] already exist");
}
// 2.获取Bean定义
BeanDefinition bd = DEFINITIONS.getBeanDefinition(beanName);
// 3.是否该Bean定义是单例作用域
if (bd.getScope() == BeanDefinition.SCOPE_SINGLETON) {
// 3.1 如果单例注册表包含Bean，则直接返回该Bean
if (SINGLETONS.containsSingleton(beanName)) {
return SINGLETONS.getSingleton(beanName);
}
// 3.2单例注册表不包含该Bean， 则创建并注册到单例注册表，从而缓存
SINGLETONS.registerSingleton(beanName, createBean(bd));
return SINGLETONS.getSingleton(beanName);
}
// 4.如果是原型Bean定义,则直接返回根据Bean定义创建的新Bean，每次都是新的，无缓存
if (bd.getScope() == BeanDefinition.SCOPE_PROTOTYPE) {
return createBean(bd);
}
// 5.其他情况错误的Bean定义
throw new RuntimeException("错误的Bean定义");
}

public void registerBeanDefinition(BeanDefinition bd) {
DEFINITIONS.registerBeanDefinition(bd.getId(), bd);
}

private Object createBean(BeanDefinition bd) {
// 根据Bean定义创建Bean
try {
Class clazz =
20000
Class.forName(bd.getClazz());
// 通过反射使用无参数构造器创建Bean
return clazz.getConstructor().newInstance();
} catch (ClassNotFoundException e) {
throw new RuntimeException("没有找到Bean[" + bd.getId() + "]类");
} catch (Exception e) {
throw new RuntimeException("创建Bean[" + bd.getId() + "]失败");
}
}
}

 测试

public class PrototypeTest {
DefaultBeanFactory factory = null;

@Before
public void initContext() {
factory = new DefaultBeanFactory();
}

@Test
public void testPrototype() {
BeanDefinition bd = new BeanDefinition();
bd.setId("bean");
bd.setScope(BeanDefinition.SCOPE_PROTOTYPE);
bd.setClazz(BeanDefinition.class.getName());
factory.registerBeanDefinition(bd);
System.out.println(factory.getBean("bean"));
System.out.println(factory.getBean("bean"));
System.out.println(factory.getBean("bean"));
System.out.println(factory.getBean("bean"));
}
}

 Spring配置prototype

<bean id="singleton" class="bean.ScopeBean" scope="prototype"></bean>

 Spring中的bean的作用于出路Singleton和Prototype外还有三个与web有关的作用于分别为request（一起请求，比如一次表单提交）、session、global session，也可以通过实现Scope接口自己实现作用域范围

 

 

 

构造器注入：1、构造器参数索引 2、构造器参数类型 3、构造器参数类型

构造器注入通过<constructor-arg>标签配置，案例1、2、3使用第一种方式

 

SpringIoC容器依赖有两层含义：Bean初始化依赖于容器、容器注入Bean的依赖资源
 

二、DI

当一个对象的创建依赖于另外一个对象时，依赖就发生了，Spring的依赖是方法级的与对象中的属性无关

class A {
void setName(String name){
// 就可以说 A 对象 依赖 String 类型参数
}
void setB(B b){
// 就可以说 A 对象 依赖 B 类型参数
}
}

 实例bean，可以没有info属性，但必须有setXxxx()

public class InstanceBean {
private String info;

public InstanceBean() {
System.out.println("...");
}

public void method() {
System.out.println("InstanceBean--method()");
}

public String getInfo() {
return this.info;
}

public void setInfo(String info) {
this.info = info;
}

}

 配置

<bean id="instance" class="demo01.InstanceBean">
<property name="info" value="注入"></property>
</bean>

 通过DI的方式为InstanceBean注入String类型对象

@Test
public void demo2(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
InstanceBean bean = (InstanceBean) applicationContext.getBean("instance");
System.out.println(bean.getInfo());
}

 这种对象间的依赖关系，通过Spring的使用配置文件的方式注入到InstanceBean中

 

三、Spring配置文件读取

一般有两个位置：

1、src根目录

2、WEB-INF下

最好命名为applicationContext.xml

读取方式

加载classpath：
ew ClassPathXmlApplicationContext("applicationContext.xml");
加载磁盘路径：
FileSystemXmlApplicationContext("WebContent/WEB-INF/applicationContext.xml");

 

 四、Spring实例化Bean的三种方式

1、使用构造器

实例化对象必须提供默认构造方法，配置如下

<bean id="instance" class="demo01.InstanceBean"></bean>

实例化

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
InstanceBean bean = applicationContext.getBean("instance",InstanceBean.class);

2、静态工厂方法

工厂类

public class BeanFactory {
public static InstanceBean getInstanceBean() {
return new InstanceBean();
}
}

 配置

<bean id="instance1" class="demo01.BeanFactory" factory-method="getInstanceBean">
<property name="info" value="静态工厂注入"></property>
</bean>

实例化

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
InstanceBean bean =  applicationContext.getBean("instance1",InstanceBean.class);

 3、实力工厂

工厂

public class BeanFactory {
public  InstanceBean getInstanceBeen() {
return new InstanceBean();
}
}

配置

<bean id="beanFactory"  class="demo01.BeanFactory"></bean>
<bean id="instance2"  factory-bean="beanFactory" factory-method="getInstanceBeen">
<property name="info" value="实例工厂注入"></property>
</bean>

 实例化

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
InstanceBean bean =  applicationContext.getBean("instance2",InstanceBean.class);
System.out.println(bean.getInfo());

 

 五、Spring中Bean的作用域

Spring加载配置文件时，会默认为文件中所配置的所有bean实例化，实例化后，默认bean的实例为单利模式

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
InstanceBean bean1 =  applicationContext.getBean("instance",InstanceBean.class);
InstanceBean bean2 =  applicationContext.getBean("instance",InstanceBean.class);
System.out.println(bean1);
System.out.println(bean2);

 还有其他几种类型