Spring IoC — 基于Java类的配置

普通的POJO只要标注@Configuration注解，就可以为Spring容器提供Bean定义的信息了，每个标注了@Bean的类方法都相当于提供一个Bean的定义信息。

基于Java类的配置方法和基于XML或基于注解的配置方式相比，前者通过代码的方式更加灵活地实现Bean的实例化及Bean之间的装配，但后面两者都是通过配置声明的方式，在灵活性上要稍逊一些，但是配置上要更简单一些。

 

UserDao类：

package com.ioc.cha4_11;public class UserDao {    private String name;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "UserDao{" +                "name='" + name + '\t' +                '}';    }    public UserDao() {        System.out.println("userDao");    }}

 

logDao类：

package com.ioc.cha4_11;public class LogDao {    private String name;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "LogDao{" +                "name='" + name + '\t' +                '}';    }    public LogDao() {        System.out.println("LogDao");    }}

 logonService类：

package com.ioc.cha4_11;public class LogonService {    private LogDao logDao;    private UserDao userDao;    public LogDao getLogDao() {        return logDao;    }    public void setLogDao(LogDao logDao) {        this.logDao = logDao;    }    public UserDao getUserDao() {        return userDao;    }    public void setUserDao(UserDao userDao) {        this.userDao = userDao;    }        public void printHelllo(){        System.out.println("hello!");    }}

AppConf类：

package com.ioc.cha4_11;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;//将一个POJO标注为定义Bean的配置类@Configurationpublic class AppConf {    //以下两个方法定义了两个Bean，并提供了Bean的实例化逻辑    @Bean    public UserDao userDao() {        return new UserDao();    }    @Bean    public LogDao logDao() {        return new LogDao();    }    //定义了logonService的Bean    @Bean    public LogonService logonService() {        LogonService logonService = new LogonService();        //将前面定义的Bean输入到LogonService Bean中        logonService.setLogDao(logDao());        logonService.setUserDao(userDao());        return logonService;    }}

beans1.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:p="http://www.springframework.org/schema/p"    xsi:schemaLocation="http://www.springframework.org/schema/beans          http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">    <bean id="userDao" class="com.ioc.cha4_11.UserDao"/>    <bean id="logDao" class="com.ioc.cha4_11.LogDao"/>    <bean id="logonService" class="com.ioc.cha4_11.LogonService"          p:logDao-ref="logDao" p:userDao-ref="userDao"/></beans>

测试类：

package com.ioc.cha4_11;/** * Created by gao on 16-3-25. */public class Test {    public static void main(String[] args) {        AppConf ac = new AppConf();        LogonService ls = ac.logonService();        ls.printHelllo();    }}

输出结果：

LogDao

userDao

hello!

 

 

DaoConfig类：

package com.ioc.cha4_11;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Scope;@Configurationpublic class DaoConfig {            @Bean(name="userDao")    public UserDao userDao(){        return new UserDao();    }    //每次调用该方法都会返回一个新的LogDao Bean     @Scope("prototype")    @Bean    public LogDao logDao(){        return new LogDao();    }}

 ServiceConfig类：

package com.ioc.cha4_11;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Import;@Configuration@Import(DaoConfig.class)public class ServiceConfig {    //像普通Bean一样注入DaoConfig    @Autowired    private DaoConfig daoConfig;    @Bean    public LogonService logonService(){        LogonService logonService = new LogonService();        System.out.println(daoConfig.logDao() == daoConfig.logDao());        //像普通Bean一样，调用Bean相关的方法        logonService.setLogDao(daoConfig.logDao());        logonService.setUserDao(daoConfig.userDao());        return logonService;    }}

LogonAppConfig类：

package com.ioc.cha4_11;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.ImportResource;@Configuration@ImportResource("classpath:com\\ioc\\cha4_11\\beans3.xml")public class LogonAppConfig {        @Bean    @Autowired    public LogonService logonService(UserDao userDao,LogDao logDao){        LogonService logonService = new LogonService();        logonService.setUserDao(userDao);        logonService.setLogDao(logDao);        return logonService;            }}

beans2.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-3.0.xsd         http://www.springframework.org/schema/context         http://www.springframework.org/schema/context/spring-context-3.0.xsd">    <context:component-scan base-package="com.ioc.cha4_11"        resource-pattern="AppConf.class" /></beans>

beans3.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-3.0.xsd">    <bean id="userDao" class="com.ioc.cha4_11.UserDao"/>    <bean id="logDao" class="com.ioc.cha4_11.LogDao"/></beans>

测试类：

package com.ioc.conf;import org.springframework.context.ApplicationContext;import org.springframework.context.annotation.AnnotationConfigApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class JavaConfigTest {    public static void main(String[] args) {        //1.通过构造函数加载配置类        //         ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConf.class);//2.通过编码方式注册配置类//         AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();//         ctx.register(DaoConfig.class);//         ctx.register(ServiceConfig.class);//         ctx.refresh();//3.通过XML组装@Configuration配置类所提供的配置信息//         ApplicationContext ctx = new ClassPathXmlApplicationContext("com/baobaotao/conf/beans2.xml");//4.通过@Configuration组装XML配置所提供的配置信息//         ApplicationContext ctx = new AnnotationConfigApplicationContext(LogonAppConfig.class);        //5.@Configuration的配置类相互引用         ApplicationContext ctx = new AnnotationConfigApplicationContext(DaoConfig.class,ServiceConfig.class);         LogonService logonService = ctx.getBean(LogonService.class);         System.out.println((logonService.getLogDao() !=null));         logonService.printHelllo();       }}

转自:https://www.cnblogs.com/yangyquin/p/5322591.html