第65节：Java后端的学习之Spring基础

谁践踏了优雅 2021-09-17 09:30 237阅读 0赞

![标题图][2018122012011760]

> Java后端的学习之Spring基础

如果要学习`spring`,那么什么是框架,`spring`又是什么呢?学习`spring`中的`ioc`和`bean`,以及`aop`,`IOC`,`Bean`,`AOP`,(配置,注解,`api`)-`springFramework`.

![效果][20181220120117108]

各种学习的知识点:

spring expression language
    spring integration
    spring web flow
    spring security
    spring data
    spring batch

`spring`网站:  
`http://spring.io/`

![效果][20181220120117124]

`http://spring.io/projects/spring-framework`  
![效果][20181220120117155]

`spring`是一种开源框架,是为了解决企业应用开发的复杂性问题而创建的,现在的发展已经不止于用于企业应用了.

> `spring`是一种轻量级的**控制反转**(IoC)和**面向切面**(AOP)的容器框架.

一句名言:`spring`带来了复杂的`javaee`开发的春天.

jdbc orm
    oxm jms
    transactions
    websocket servlet
    web portlet
    aop aspects instrumentation messaging
    beans core context spel

`springmvc+spring+hibernate/ibatis`\->企业应用

## 什么是框架,为什么要用框架: ##

什么是框架:

![效果][20181220120117186]

![效果][20181220120117209]

框架就是别人制定好的一套规则和规范,大家在这个规范或者规则下进行工作,可以说,别人盖好了楼,让我们住.

![效果][20181220120117228]

![效果][20181220120117245]

软件框架是一种半成品,具有特定的处理流程和控制逻辑,成熟的,可以不断升级和改进的软件.

使用框架重用度高,开发效率和质量的提高,容易上手,快速解决问题.

> `spring ioc`容器

![效果][20181220120117261]

接口,是用于沟通的中介物的,具有抽象化,`java`中的接口,就是声明了哪些方法是对外公开的.

面向接口编程,是用于隐藏具体实现的组件.

案例:

// 声明一个接口
    public interface DemoInterface{
     String hello(String text);
     // 一个hello方法,接收一个字符串型的参数,返回一个`String`类型.
    }
    // 实现
    public class OneInterface implements DemoInterface{
     @Override
     public String hello(String text){
      return "你好啊: " + text;
     }
    }
    // 测试类
    public class Main{
     public static void main(String[] args){
      DemoInterface demo = new OneInterface();
      System.out.println(demo.hello("dashucoding");
     }
    }

什么是`IOC`,`IOC`是控制反转,那么什么控制反转,控制权的转移,应用程序不负责依赖对象的创建和维护,而是由外部容器负责创建和维护.

<?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="oneInterface" class="com.ioc.interfaces.OneInterfaceImpl"></bean>
    </beans>

`spring.xml`

测试:

import org.junit.Test;
    @RunWith(BlockJUnit4ClassRunner.class)
    public class TestOneInterface extends UnitTestBase {
     public TestOneInterface(){
      super("spring.xml");
     }
     @Test
     public void testHello(){
      OneInterface oneInterface = super.getBean("oneInterface");
      System.out.println(oneInterface.hello("dashucoding"));
     }
    }

单元测试

下载一个包`junit-*.jar`导入项目中,然后创建一个`UnitTestBase`类,用于对`spring`进行配置文件的加载和销毁,所有的单元测试都是继承`UnitTestBase`的,然后通过它的`getBean`方法获取想要的对象,子类要加注解`@RunWith(BlockJUnit4ClassRunner.class)`,单元测试方法加注解`@Test`.

public ClassPathXmlApplicationContext context;
     public String springXmlpath;
     public UnitTestBase(){}
     public UnitTestBase(String springXmlpath){
      this.springXmlpath = springXmlpath;
     }
    @Before
    public void before(){
     if(StringUtils.isEmpty(springXmlpath)){
      springXmlpath = "classpath*:spring-*.xml";
     }
     try{
      context = new ClassPathXmlApplicationContext(springXmlpath.split("[,\\s]+"));
      context.start();
     }catch(BeansException e){
      e.printStackTrace();
     }
     }
     @After
     public void after(){
      context.destroy();
     }
     @SuppressWarnings("unchecked")
     protected <T extends Object> T getBean(String beanId){
      return (T)context.getBean(beanId);
     }
     protected <T extends Object> T getBean(Class<T> clazz){
      return context.getBean(clazz);
     }
    }

`bean`容器:

`org.springframework.beans`和`org.springframework.context`  
`BeanFactory`提供配置结构和基本功能,加载并初始化`Bean`,`ApplicationContext`保存了`Bean`对象.

// 文件
    FileSystemXmlApplicationContext context = new FileSystemXmlApplicationContext("D:/appcontext.xml");
    // Classpath
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-context.xml");
    // Web应用
    <listener>
     <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
     <servlet-name>context</servlet-name>
     <servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
     <load-on-startup>1</load-on-startup>
    </servlet>

`spring`注入:启动`spring`加载`bean`的时候,完成对变量赋值的行为.注入方式:设值注入和构造注入.

// 设值注入
    <?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="iService" class="com.service.iServiceImpl">
      <property name="iDAO" ref="DAO"/>
     </bean>
     <bean id="DAO" class="com.iDAOImpl"></bean>
    </beans>

// 构造注入
    <?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="iService" class="com.service.iServiceImpl">
      <constructor-arg name="DAO" ref="DAO"/>
      <property name="injectionDAO" ref="injectionDAO"></property>
     </bean>
     <bean id="DAO" class="com.iDAOImpl"></bean>
    </beans>

`spring`注入:

<?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="injectionService" class="com.injection.service.InjectionServiceImpl"></bean>
     <bean id="injectionDAO" class="com.ijection.dao.InjectionDAOImpl"></bean>
    </beans>

// 接口-业务逻辑
    public interface InjectionService {
     public void save(String arg);
    }

// 实现类-处理业务逻辑
    public class InjectionServiceImpl implements InjecionService {
     private InjectionDAO injectionDAO;
     public InjectionServiceImpl(InjectionDAO injectionDAO) {
      this.injectionDAO = injectionDAO;
     }
     public void setInjectionDAO(InjectiionDAO injectionDAO) {
      this.injectionDAO = injectionDAO;
     }
     public void save(String arg) {
      System.out.println("接收" + arg);
      arg = arg + ":" + this.hashCode();
      injectionDAO.save(arg);
     }
    }

// 接口-数据库-调用DAO
    public interface InjectionDAO { 
     // 声明一个方法
     public void save(String arg);
    }

// 实现类
    public class InjectionDAOImpl implements InjectionDAO {
     // 实现接口中的方法
     public void save(String arg) {
      System.out.println("保存数据" + arg);
     }
    }

// 测试
    import org.junit.Test;
    @RunWith(BlockJUnit4ClassRunner.class)
    public class TestInjection extends UnitTestBase {
     public TestInjection(){
      super("classpath:spring-injection.xml");
     }
     @Test
     public void  testSetter(){
      InjectionService service = super.getBean("injectionService");
      service.save("保存的数据");
     }
     @Test 
     public void testCons() {
      InjectionService service = super.getBean("injectionService");
      service.save("保存的数据");
     }
    }

`bean`的配置:

id:id是整个ioc容器中,bean的标识
    class:具体要实例化的类
    scope:作用域
    constructor  arguments:构造器的参数
    properties:属性
    autowiring mode:自动装配的模式
    lazy-initialization mode:懒加载模式
    Initialization/destruction method:初始化和销毁的方法

作用域

singleton:单例
    prototype:每次请求都创建新的实例
    request:每次http请求都创建一个实例有且当前有效
    session:同上

`spring bean`配置之`Aware`接口:`spring`中提供了以`Aware`结尾的接口,为`spring`的扩展提供了方便.

> `bean`的自动装配`autowiring`

no是指不做任何操作
    byname是根据自己的属性名自动装配
    byType是指与指定属性类型相同的bean进行自动装配,如果有过个类型存在的bean,那么就会抛出异常,不能使用byType方式进行自动装配,如果没有找到,就不什么事都不会发生
    Constructor是与byType类似,它是用于构造器参数的,如果没有找到与构造器参数类型一致的bean就会抛出异常

> `spring bean`配置的`resource`

resources:
    urlresource是url的资源
    classpathresource是获取类路径下的资源
    filesystemresource是获取文件系统的资源
    servletcontextresource是servletcontext封装的资源
    inputstreamresource是针对输入流封装的资源
    bytearrayresource是针对字节数组封装的资源

public interface ResourceLoader{
     Resource getResource(String location);
    }

## `ResourceLoader` ##

classpath: Loaded from the classpath;
    file: Loaded as a URL, from the filesystem;
    http: Loaded as a URL;

案例:

public class MResource implements ApplicationContextAware{
      private ApplicationContext applicationContext;
     @Override
     public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
     this.applicationContext = applicationContext;
     }
     public void resource(){
      Resource resource = applicationContext.getResource("classpath:config.txt");
      System.out.println(resource.getFilename());
     }
    }

// 单元测试类
    import com.test.base.UnitTestBase;
    @RunWith(BlockJUnit4ClassRunner.class)
    public class TestResource extends UnitTestBase {
     public TestResource() {
      super("classpath:spring-resource.xml");
     }
     @Test
     public void testResource() {
      MResource resource = super.getBean("mResource");
      try{
       resource.resource();
      }catch(IOException e){
       e.printStackTrace();
      }
     }
    }

<?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="moocResource" class="com.resource.MResource"></bean>
    </beans>

`bean`的定义与学习:

<context:annotation-config/>
    @Component,@Repository,@Service,@Controller
    @Required,@Autowired,@Qualifier,@Resource

@Configuration,@Bean,@Import,@DependsOn
    @Component,@Repository,@Service,@Controller

1.  `@Repository`用于注解`DAO`类为持久层
2.  `@Service`用于注解`Service`类为服务层
3.  `@Controller`用于`Controller`类为控制层

元注解`Meta-annotations`是`spring`提供的注解可以作为字节的代码叫元数据注解,处理`value()`,元注解可以有其他的属性.

`spring`可以自动检测和注册`bean`

@Service
    public class SimpleMovieLister {
     private MovieFinder movieFinder;
     @Autowired
     public SimpleMovieLister(MovieFinder movieFinder){
      this.movieFinder = movieFinder;
     }
    }

@Repository
    public class JpaMovieFinder implements MovieFinder {
    
    }

> 类的自动检测以及`Bean`的注册

<?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">
     <context:component-scan base-package="org.example"/>
    </beans>

> 类被自动发现并注册`bean`的条件:

用@Component,@Repository,@Service,@Controller注解或者使用@Component的自定义注解

`@Required`用于`bean`属性的`setter`方法  
`@Autowired`注解

private MovieFinder movieFinder;
    @Autowired
    public void setMovieFinder(MovieFinder movieFinder) {
     this.movieFinder = movieFinder;
    }
    用于构造器或成员变量
    @Autowired
    private MovieCatalog movieCatalog;
    private CustomePreferenceDap customerPreferenceDao;
    @Autowired
    public MovieRecommender(CustomerPreferenceDao customerPreferenceDao) {
     this.customerPreferenceDao = customerPreferenceDao;
    }

`@Autowired`注解

使用这个注解,如果找不到`bean`将会导致抛出异常,可以使用下面代码避免,每个类只能有一个构造器被标记为`required=true`.

public class SimpleMovieLister {
     private MovieFinder movieFinder;
     @Autowired(required=false)
     public void setMovieFinder(MovieFinder movieFinder){
      this.movieFinder = movieFinder;
     }
    }

`spring`是一个开源框架，spring是用j2ee开发的mvc框架，spring boot呢就是一个能整合组件的快速开发框架，因为使用maven管理，所以很便利。至于spring cloud，就是微服务框架了。

`spring`是一个轻量级的`Java`开发框架,是为了解决企业应用开发的复杂性而创建的框架,框架具有分层架构的优势.

`spring`这种框架是简单性的,可测试性的和松耦合的,`spring`框架,我们主要是学习控制反转`IOC`和面向切面`AOP`.

// 知识点
    spring ioc
    spring aop
    spring orm
    spring mvc
    spring webservice
    spring transactions
    spring jms
    spring data
    spring cache
    spring boot
    spring security
    spring schedule

`spring ioc`为控制反转,控制反向,控制倒置,

![效果][20181220120117303]

![效果][20181220120117327]

![效果][20181220120117347]

`Spring`容器是 `Spring` 框架的核心。`spring`容器实现了相互依赖对象的创建,协调工作,对象只要关系业务逻辑本身,`IOC`最重要的是完成了对象的创建和依赖的管理注入等,控制反转就是将代码里面需要实现的对象创建,依赖的代码,反转给了容器,这就需要创建一个容器,用来让容器知道创建对象与对象的关系.(告诉spring你是个什么东西，你需要什么东西)

xml,properties等用来描述对象与对象间的关系
    classpath,filesystem,servletContext等用来描述对象关系的文件放在哪里了.

控制反转就是将对象之间的依赖关系交给了容器管理,本来是由应用程序管理的对象之间的依赖的关系.

`spring ioc`体系结构

BeanFactory
    BeanDefinition

`spring ioc`是`spring`的核心之一,也是`spring体系的基础,在`spring`中主要用户管理容器中的`bean`.`spring`的`IOC`容器主要使用`DI`方式实现的.`BeanFactory`是典型的工厂模式,`ioc`容器为开发者管理对象间的依赖关系提供了很多便利.在使用对象时,要`new object()`来完成合作.`ioc`:`spring`容器是来实现这些相互依赖对象的创建和协调工作的.(由`spring\`来复杂控制对象的生命周期和对象间的)

所有的类的创建和销毁都是由`spring`来控制,不再是由引用它的对象了,控制对象的生命周期在`spring`.所有对象都被`spring`控制.

`ioc`容器的接口(自己设计和面对每个环节):

`BeanFactory`工厂模式

public interface BeanFactory {
     String FACTORY_BEAN_PREFIX = "&"; 
     Object getBean(String name) throws BeansException;
     Object getBean(String name, Class requiredType) throws BeansException;
    
     boolean containsBean(String name); 
     boolean isSingleton(String name) throws NoSuchBeanDefinitionException;
     Class getType(String name) throws NoSuchBeanDefinitionException;
     String[] getAliases(String name); 
    }

`BeanFactory`三个子类:`ListableBeanFactory`,`HierarchicalBeanFactory`和`AutowireCapableBeanFactory`,实现类是`DefaultListableBeanFactory`.

控制反转就是所有的对象都被`spring`控制.`ioc`动态的向某个对象提供它所需要的对象.通过`DI`依赖注入来实现的.如何实现依赖注入`ID`,在`Java`中有一特性为反射,它可以在程序运行的时候进行动态的生成对象和执行对象的方法,改变对象的属性.

public static void main(String[] args){
     ApplicationContext context = new FileSystemXmlApplicationContext("applicationContext.xml");
     Animal animal = (Animal)context.getBean("animal");
     animal.say();
    }

// applicationContext.xml
    <bean id="animal" class="com.test.Cat">
     <property name="name" value="dashu"/>
    </bean>

public class Cat implements Animal {
     private String name;
     public void say(){
      System.out.println("dashu");
     }
     public void setName(String name){
      this.name = name;
     }
    }

public interface Animal {
     public void say();
    }

// bean
    private String id;
    private String type;
    private Map<String,Object> properties=new HashMap<String, Object>();

public static Object newInstance(String className) {
     Class<?> cls = null;
     Object obj = null;
     try {
      cls = Class.forName(className);
      obj = cls.newInstance();
     } catch (ClassNotFoundException e) {
      throw new RuntimeException(e);
     } catch (InstantiationException e) {
      throw new RuntimeException(e);
     } catch (IllegalAccessException e) {
      throw new RuntimeException(e);
     }
     return obj;
    }

> 核心是控制反转（`IOC`）和面向切面（`AOP`）,`spring`是一个分层的`JavaSE/EE`的轻量级开源框架.

`web`:

struts,spring-mvc

`service`:

spring

`dao`:

mybatis,hibernate,jdbcTemplate,springdata

## `spring`体系结构 ##

`ioc`

// 接口
    public interface UserService {
     public void addUser();
    }
    // 实现类
    public class UserServiceImpl implements UserService {
     @Override
     public void addUser(){
      System.out.println("dashucoding");
     }
    }

配置文件:

<?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="userServiceId" class="com.dashucoding.UserServiceImpl"></bean>
    </beans>

测试:

@Test
    public void demo(){
    	String xmlPath = "com/beans.xml";
    	ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    	UserService userService = (UserService) applicationContext.getBean("userServiceId");
    	userService.addUser();
    }

依赖注入:

class DemoServiceImpl{
     private daDao daDao;
    }

> 创建`service`实例,创建`dao`实例,将`dao`设置给`service`.

接口和实现类:

public interface BookDao {
    	public void addBook();
    }
    public class BookDaoImpl implements BookDao {
    	@Override
    	public void addBook() {
    		System.out.println("dashucoding");
    	}
    }

public interface BookService {
    	public abstract void addBook();
    }
    public class BookServiceImpl implements BookService {
    	private BookDao bookDao;
    	public void setBookDao(BookDao bookDao) {
    		this.bookDao = bookDao;
    	}
    	@Override
    	public void addBook(){
    		this.bookDao.addBook();
    	}
    }

配置文件:

测试:

@Test
    public void demo(){
    	String xmlPath = "com/beans.xml";
    	ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
    	BookService bookService = (BookService) applicationContext.getBean("bookServiceId");
    		
    	bookService.addBook();
    }

> `IDE`建立`Spring`项目

File—>new—>project—>Spring

`spring`

// Server.java
    public class Server {
     privete String name;
     public void setName(String name){
      this.name = name;
     }
     public void putName(){
      System.out.println(name);
     }
    }

// Main.java
    public class Main{
     public static void main(String[] args){
      ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
      Server hello = (Server)context.getBean("example_one");
      hello.putName();
     }
    }

`spring-config.xml`:

使用`Maven`来声明`Spring`库.`Maven`是一个项目管理的工具,`maven`提供了开发人员构建一个完整的生命周期框架.`Maven`的安装和配置,需要的是`JDK 1.8`,`Maven`,`Windows`,配置`jdk`,`JAVA_HOME`变量添加到`windows`环境变量.下载`Apache Maven`,添加 `M2_HOME` 和 `MAVEN_HOME`,添加到环境变量`PATH`,值为`%M2_HOME%\bin`.执行`mvn –version`命令来显示结果.

`Maven`启用代理进行访问,找到文件路基,找到`/conf/settings.xml`,填写代理,要阿里的哦.

`Maven`中央存储库地址:  
`https://search.maven.org/`

![效果][20181220120117365]

// xml
    <dependency>
           <groupId>org.jvnet.localizer</groupId>
            <artifactId>localizer</artifactId>
            <version>1.8</version>
    </dependency>

// pom.xml
    <repositories>
    	<repository>
    	    <id>java.net</id>
    	    <url>https://maven.java.net/content/repositories/public/</url>
    	</repository>
    </repositories>

`Maven`添加远程仓库:

// pom.xml
    <project ...>
    <repositories>
        <repository>
          <id>java.net</id>
          <url>https://maven.java.net/content/repositories/public/</url>
        </repository>
     </repositories>
    </project>
    
    <project ...>
        <repositories>
          <repository>
    	<id>JBoss repository</id>
    	<url>http://repository.jboss.org/nexus/content/groups/public/</url>
          </repository>
        </repositories>
    </project>

`Maven`依赖机制,使用`Maven`创建`Java`项目.

<dependency>
    	<groupId>junit</groupId>
    	<artifactId>junit</artifactId>
    	<version>4.11</version>
    	<scope>test</scope>
    </dependency>

`Maven`打包:

<project ...>
    	<modelVersion>4.0.0</modelVersion>
    	<groupId>com.dashucoding</groupId>
    	<artifactId>NumberGenerator</artifactId>	
    	<packaging>jar</packaging>	
    	<version>1.0-SNAPSHOT</version>

`spring`框架:

![效果][20181220120117393]

public interface HelloWorld{
     public void sayHello();
    }
    public class SpringHelloWorld implements HelloWorld {
     public void sayHello(){
      System.out.println("Spring Hello");
     }
    }
    
    public class StrutsHelloWorld implements HelloWorld {
     public void sayHello(){
      System.out.println("Struts Hello");
     }
    }
    
    public class HelloWorldServie {
     private HelloWorld helloWorld;
     public HelloWorldService(){
      this.helloWorld = new StrutsHelloWorld();
     }
    }

控制反转:

public class HelloWorldService{
     private HelloWorld helloWorld;
     public HelloWorldService(){
     }
     public void setHelloWorld(HelloWorld helloWorld){
      this.helloWorld = helloWorld;
     }
     public HelloWorld getHelloWorld(){
      return this.helloWorld;
     }
    }

`ioc`创建了`HelloWorldService`对象.

spring->HelloProgram.java
    helloworld->
    HelloWorld.java
    HelloWorldService.java
    impl实现类->
    SpringHelloWorld.java
    StrutsHelloWorld.java
    resources->beans.xml
    // 总结
    一个spring:HelloProgram.java
    接口:
    实现类:
    资源:beans.xml

// HelloWorld.java
    public interface HelloWorld {
     public void sayHello();
    }
    // public class HelloWorldService {
     private HelloWorld helloWorld;
     public HelloWorldService(){
     }
     public void setHelloWorld(HelloWorld helloWorld){
      this.helloWorld = helloWorld;
     }
     public HelloWorld getHelloWorld(){
      return this.helloWorld;
     }
    }

// SpringHelloWorld.java
    public class SpringHelloWorld implements HelloWorld {
      
        @Override
        public void sayHello() {
            System.out.println("Spring Hello!");
        }
    }
    // StrutsHelloWorld.java
    public class StrutsHelloWorld implements HelloWorld {
      
        @Override
        public void sayHello() {
            System.out.println("Struts Hello!");
        }
    }

// HelloProgram.java
    public class HelloProgram {
        public static void main(String[] args) {
            ApplicationContext context =
                    new ClassPathXmlApplicationContext("beans.xml");
            HelloWorldService service =
                 (HelloWorldService) context.getBean("helloWorldService");
            HelloWorld hw= service.getHelloWorld();
            hw.sayHello();
        }
    }

// beans.xml
    <beansxmlns="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="springHelloWorld"
            class="com.spring.helloworld.impl.SpringHelloWorld"></bean>
        <bean id="strutsHelloWorld"
            class="com.spring.helloworld.impl.StrutsHelloWorld"></bean>
      
      
        <bean id="helloWorldService"
            class="com.spring.helloworld.HelloWorldService">
            <property name="helloWorld" ref="springHelloWorld"/>
        </bean>
      
    </beans>

<propertyname="helloWorld"ref="strutsHelloWorld"/>

`ioc`创建`beans`实现类`springHelloWorld`,创建一个`helloWorldService`类,`beans.xml`实现参数导入:

// helloWorldService
    // springHelloWorld
    // Hello Program.java
    ApplicationContext context = new ClassPathXmlApplicationContxt("beans.xml");
    HelloWorldService service = (HelloWorldService) context.getBean("helloWorldService");
    HelloWorld hw = service.getHelloWorld();
    hw.sayHello();
    
    // HelloWorldService
    public class HelloWorldService {
     private HelloWorld helloWorld;
     public HelloWorldService(){
     }
     public void setHelloWorld(HelloWorld helloWorld){
      this.helloWorld = helloWorld;
     }
     public HelloWorld = getHelloWorld() {
      return this.helloWorld;
     }
    }

// beans.xml
    <bean id="名称" class="路径"/>
    <bean id="helloWorldService"
     class="">
     <property name="helloWorld" ref="springHelloWorld"/>
    </bean>

`spring`库地址:  
`http://maven.springframework.org/release/org/springframework/spring/`

`hello-world`:

public class HelloWorld {
    	private String name;
    	public void setName(String name) {
    		this.name = name;
    	}
    	public void printHello() {
    		System.out.println("Spring" + name);
    	}
    }

// xml
    <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-3.0.xsd">
    
    	<bean id="helloBean" class="">
    		<property name="name" value="dashu" />
    	</bean>
    
    </beans>

// 执行
    public class App {
    	public static void main(String[] args) {
    		ApplicationContext context = new ClassPathXmlApplicationContext(
    				"applicationContext.xml"); 
                    HelloWorld obj = (HelloWorld) context.getBean("helloBean");
    		obj.printHello();
    	}
    }

> 达叔小生：往后余生，唯独有你  
> You and me, we are family !  
> 90后帅气小伙，良好的开发习惯；独立思考的能力；主动并且善于沟通  
> 简书博客： 达叔小生  
> [https://www.jianshu.com/u/c785ece603d1][https_www.jianshu.com_u_c785ece603d1]

## 结语 ##

*  下面我将继续对 其他知识 深入讲解 ，有兴趣可以继续关注
 *  小礼物走一走 or 点赞

[2018122012011760]: /images/20210724/1e6e7ea5a66d417c9c5b08dfbf9f3a77.png
[20181220120117108]: /images/20210724/f341af70136b4737981b2c893a3dbb08.png
[20181220120117124]: /images/20210724/c27f7943b1ec4847b1f554b43af7c85d.png
[20181220120117155]: /images/20210724/f71c3e963ca746979038f084953b1d85.png
[20181220120117186]: /images/20210724/41f5aaa6156c461cb3563fd717128852.png
[20181220120117209]: /images/20210724/0cee6ce627424d078a0913b39bc8da3a.png
[20181220120117228]: /images/20210724/a7546defdf704a50871d408f5055cd35.png
[20181220120117245]: /images/20210724/a17dd21aab0e4b53b1b418f2ef7717f8.png
[20181220120117261]: /images/20210724/4dddd674240248d6a97b239f8993e5e3.png
[20181220120117303]: /images/20210724/5eae5f0d3d5249e0b01159fdad0ed34f.png
[20181220120117327]: /images/20210724/7d77449a3e9a4f3bb9e756c72852442d.png
[20181220120117347]: /images/20210724/1e5cdce13d254103b6775ca4d90e9c8a.png
[20181220120117365]: /images/20210724/f531ffafb7044d2b87d49caddfbcd65b.png
[20181220120117393]: /images/20210724/50344da2ea3742cf85db8ac07681d28f.png
[https_www.jianshu.com_u_c785ece603d1]: https://www.jianshu.com/u/c785ece603d1