Spring基础：Bean的装配

Posted 2021-06-26 nuist__NJUPT

Spring基础：Bean的装配

• Bean的装配可以理解为将Bean依赖注入到Spring容器中
• Bean的装配方式即依赖注入方式
• 常用的Bean的装配方式有基于Xml的装配，基于注解的装配
• 最常用的是基于注解的装配

下面介绍基于Xml的装配方式
1-在eclipse中创建名为ch14的web应用，并导入相关jar包，如图所示。

2-在ch14的src目录下assemble包，并在该包下创建ComplexUser类，在该类中分别使用构造方法注入和使用属性setter方法注入。

import java.util.List;
import java.util.Map;
import java.util.Set;
public class ComplexUser {
	private String uname ;
	private List<String> hobbyList ;
	private Map<String,String> residenceMap ;
	private Set<String> aliasSet ;
	private String [] array ;
	//使用构造方法注入，需要提供带参数的构造方法
	public ComplexUser(String uname, List hobbyList, Map residenceMap, Set aliasSet, String [] array) {
		this.uname = uname ;
		this.hobbyList = hobbyList ;
		this.residenceMap = residenceMap ;
		this.aliasSet = aliasSet ;
		this.array = array ;
	}
	//使用属性的setter方法注入
	public ComplexUser() {}
	public void setUname(String uname) {
		this.uname = uname ;
	}
	public void setHobbyList(List<String> hobbyList) {
		this.hobbyList = hobbyList;
	}
	public void setResidenceMap(Map<String, String> residenceMap) {
		this.residenceMap = residenceMap;
	}
	public void setAliasSet(Set<String> aliasSet) {
		this.aliasSet = aliasSet;
	}
	public void setArray(String[] array) {
		this.array = array;
	}
 	public String toString() {
		return "uname = " + uname + ";hobbyList = " + hobbyList + ";residenceMap = " + residenceMap + ";aliasSet = " + aliasSet + ";array = " + array ;
	}
}

2-配置Bean,在Spring配置文件中使用实现类ComplexUser配置Bean的两个实例。

<?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">
<!-- 使用构造方法方式装配注入ComplexUser实例user1 -->
<bean id = "user1" class = "assemble.ComplexUser">

<constructor-arg index = "0" value = "王国栋"/>

<constructor-arg index = "1" >
<list>
<value>唱歌</value>
<value>打球</value>
<value>爬山</value>
</list>
</constructor-arg>

<constructor-arg index = "2">
<map>
<entry key = "nanjing" value = "南京"/>
<entry key = "nanchang" value = "南昌"/>
<entry key = "shanghai" value = "上海"/>
</map>
</constructor-arg>

<constructor-arg>
<set>
<value>王国栋 101</value>
<value>王国栋 102</value>
<value>王国栋 103</value>
</set>
</constructor-arg>

<constructor-arg>
<array>
<value>努力</value>
<value>加油</value>
<value>坚强</value>
</array>
</constructor-arg>
</bean>

<!-- 使用属性的setter方法装配ComplexUser实例user2 -->
<bean id = "user2" class = "assemble.ComplexUser">
<property name = "uname" value = "王国栋2"/>

<property name="hobbyList">
<list>
<value>看书</value>
<value>学习</value>
<value>睡觉</value>
</list>
</property>

<property name ="residenceMap" >
<map>
<entry key = "beijing" value = "北京"/>
<entry key = "shanghai" value = "上海"/>
<entry key = "nanjing" value = "南京"/>
</map>
</property>

<property name = "aliasSet">
<set>
<value>王国栋 104</value>
<value>王国栋 105</value>
<value>王国栋 106</value>
</set>
</property>

<property name = "array">
<array>
<value>挫折</value>
<value>困难</value>
</array>
</property>
</bean>
</beans>

3-在ch3中创建test包，在该包中创建TestAssemble测试类。

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import assemble.ComplexUser;

public class TestAssemble {
	public static void main(String[] args) {
		//初始化Spring容器，架子啊配置文件
		ApplicationContext appCon = new ClassPathXmlApplicationContext("applicationContext.xml") ;
		//使用构造方法装配测试
		ComplexUser u1 = (ComplexUser) appCon.getBean("user1") ;
		System.out.println(u1);
		//使用属性的setter方法装配测试 
		ComplexUser u2 = (ComplexUser) appCon.getBean("user2") ;
		System.out.println(u2) ;
	}
}

4-测试结果如下：

接下来，使用注解的方式装配Bean
1-导入所需的jar包，如下图所示。

2-在src目录下创建annotation.dao包，并在该包中创建TestDao接口和接口的实现方法TestDaoImpl方法

public interface TestDao {
	public void save() ;
}

import org.springframework.stereotype.Repository;

@Repository("testDao") 
public class TestDaoImpl implements TestDao{

	@Override
	public void save() {
		System.out.println("testDao save") ;
	}
}

3-在src文件下创建TestService接口和该接口的实现类TestServiceImpl类

public interface TestService {
	public void save() ;
}

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

import annotation.dao.TestDao;

@Service("testService")
public class TestServiceImpl implements TestService{
@Resource(name = "testDao")
private TestDao testDao ;
	@Override
	public void save() {
		testDao.save();
		System.out.println("testService save") ;
	}
}

4-在src目录下创建annotation.controller包，并在该包中创建TestController实现类

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

import annotation.service.TestService;

@Controller
public class TestController {
	@Autowired
	private TestService testService ;
	public void save() {
		testService.save();
		System.out.println("testController save") ;
	}
	
}

5-在src目录下创建annotationContext.xml文件，在该文件中配置扫描包为annotation

<?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">
<!-- 使用context命名空间，通过Spring扫描包annotation及其子包下所有Bean的实现类，进行注释解析 -->
<context:component-scan base-package = "annotation"/>
</beans>

6-在test包中创建测试类TestMoreAnnotation

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import annotation.contoller.TestController;

public class TestMoreAnnotaion {
	public static void main(String[] args) {
		//初始化Spring容器，加载配置文件
		ApplicationContext appCon = new ClassPathXmlApplicationContext("annotationContext.xml") ;
		//实例化
		TestController tc = (TestController)appCon.getBean("testController") ;
		//调用对象的方法
		tc.save();
	}
}

7-测试结果如下：