Java Spring 配置非自定义Bean Java Spring 配置非自定义Bean0.介绍实际开发中会使用第三方jar包中的功能类，这些Bean要想让Spring进行管理，也需要对其进行配置两个问题：被配置的Bean实例化方式是什么被配置的Bean是否需要注入必要属性1.配置Druid数据源交由Spring管理maven配置文件导入相应jar包pom.xml <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.1.23</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.49</version> </dependency>beans.xml <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/java"/> <property name="username" value="root"/> <property name="password" value="root"/> </bean>主函数调用 public static void main(String[] args) { ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml"); Object dataSource = applicationContext.getBean("dataSource"); System.out.println(dataSource); }运行结果{ CreateTime:"2023-02-26 17:23:51", ActiveCount:0, PoolingCount:0, CreateCount:0, DestroyCount:0, CloseCount:0, ConnectCount:0, Connections:[ ] }2.配置Connection交由Spring管理Connection的产生是通过DriverManager的静态方法getConnection获取的，所以我们要用静态工厂的方式配置beans.xml（getConnection报红不用管） <bean id="connection" class="java.sql.DriverManager" factory-method="getConnection" scope="prototype"> <constructor-arg name="url" value="jdbc:mysql://localhost:3306/java"/> <constructor-arg name="user" value="root"/> <constructor-arg name="password" value="root"/> </bean>主函数调用 public static void main(String[] args) { ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml"); Object connection = applicationContext.getBean("connection"); System.out.println(connection);; }执行结果（报错不用管，看到有类字节码地址输出即可）com.mysql.jdbc.JDBC4Connection@42a15bdc3.配置日期对象交由Spring管理原生使用日期对象 SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Date date = simpleDateFormat.parse("2023-08-27 12:00:00"); System.out.println(date);结果输出Sun Aug 27 12:00:00 CST 2023配置日期对象交由Spring管理beans.xml <bean id="simpleDateFormat" class="java.text.SimpleDateFormat"> <constructor-arg name="pattern" value="yyyy-MM-dd HH:mm:ss"/> </bean> <bean id="date" factory-bean="simpleDateFormat" factory-method="parse"> <constructor-arg name="source" value="2023-08-27 12:00:00"/> </bean>主函数执行 ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml"); SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Object date1 = applicationContext.getBean("date"); System.out.println(date1);结果输出Sun Aug 27 12:00:00 CST 20234.配置MyBatis的SqlSessionFactory交由Spring管理导入MyBatis的相关坐标 <!-- mybatis框架 --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.5</version> </dependency> <!-- mysql驱动 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.49</version> </dependency>4.1 原生实现 // 静态工厂方法方式 InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml"); // 无参构造实例化 SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder(); // 实例工厂方法 SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream); System.out.println(sqlSessionFactory);执行结果org.apache.ibatis.session.defaults.DefaultSqlSessionFactory@79efed2d4.2 Bean实现resources目录下创建mybatis-config.xml<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "https://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/java"/> <property name="username" value="root"/> <property name="password" value="root"/> </dataSource> </environment> </environments> </configuration>beans.xml <!-- 静态工厂方法 --> <bean id="resources" class="org.apache.ibatis.io.Resources" factory-method="getResourceAsStream"> <constructor-arg name="resource" value="mybatis-config.xml"/> </bean> <!-- 无参构造实例化 --> <bean id="sqlSessionFactoryBuilder" class="org.apache.ibatis.session.SqlSessionFactoryBuilder"/> <!-- 实例工厂方法 --> <bean id="sqlSessionFactory" factory-bean="sqlSessionFactoryBuilder" factory-method="build"> <constructor-arg name="inputStream" ref="resources"/> </bean>主函数调用 ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml"); Object sqlSessionFactory = applicationContext.getBean("sqlSessionFactory"); System.out.println(sqlSessionFactory);执行结果org.apache.ibatis.session.defaults.DefaultSqlSessionFactory@5026735c

Java Spring 获取Bean的三种方式 Java Spring 获取Bean的三种方式

Java Spring beans的profile属性切换环境 Java Spring beans的profile属性切换环境<beans>标签，除了经常用的作为根标签外，还可以嵌套在根标签内，使用profile属性切换开发环境可以使用以下两种方式指定被激活的环境（dev为环境名）：使用命令行动态参数，虚拟机参数位置加载 -Dspring.profiles.active=dev使用代码的方式设置环境变量System.setProperty("spring.profiles.active","dev")beans.xml <bean class="org.example.UserDaoImpl" id="userDao"/> <bean class="org.example.UserServiceImpl" id="userService"/> <beans profile="dev"> <bean id="userService1" class="org.example.UserServiceImpl"/> </beans> <beans profile="test"> <bean id="userDao1" class="org.example.UserDaoImpl"/> </beans>主函数调用 public static void main(String[] args) { // 指定环境 System.setProperty("spring.profiles.active","dev"); ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml"); System.out.println(((UserService) applicationContext.getBean("userService"))); System.out.println(((UserDao) applicationContext.getBean("userDao"))); System.out.println(((UserService) applicationContext.getBean("userService1"))); System.out.println(((UserDao) applicationContext.getBean("userDao1"))); }执行结果org.example.UserServiceImpl@589b3632 org.example.UserDaoImpl@45f45fa1 org.example.UserServiceImpl@4c6e276e Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'userDao1' available

Java Spring 命名空间 Java Spring 命名空间Spring的默认标签用到的是Spring的默认命名空间beans.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"> </beans>该命名空间约束下的默认标签如下：创建命名空间创建名为context的命名空间beans.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:property-placeholder/> </beans>import引入其他配置文件<import>标签，用于导入其他配置文件，项目变大后，就会导致一个配置文件内容过多，可以将一个配置文件根据业务某块进行拆分，拆分后，最终通过<import>标签导入到一个主配置文件中，项目加载主配置文件就连同<import>导入的文件一并加载了<import resource="classpath:beans.xml"></import>alias指定Bean别名断点调试中，BeanFactory下aliasMap中保存了alias指定的别名，并不会影响bean中name标签指定的值，但是也能通过alias指定的别名进行获取bean<bean class="org.example.UserDaoImpl" id="userDao"/> <bean class="org.example.UserServiceImpl" id="userService"/> <alias name="userDao" alias="dao"></alias> <alias name="userService" alias="service"></alias>

Java Spring 自动装配 Java Spring 自动装配如果被注入的属性类型是Bean引用的话，那么可以在<bean>标签中使用autowire属性去配置自动注入方式，属性值有两个byName：通过属性名自动装配，即去匹配setXxx与id="xxx"(name="xxx")是否一致；byType：通过Bean的类型从容器中匹配，匹配出多个相同Bean类型，报错。beans.xml<bean class="org.example.UserDaoImpl" id="userDao"/> <bean class="org.example.UserServiceImpl" id="userService" autowire="byName"/> <bean class="org.example.UserServiceImpl" id="userService1" autowire="byType"/>UserServicepublic interface UserService { public void show(); }UserServiceImplpublic class UserServiceImpl implements UserService { private UserDao userDao; public void setUserDao(UserDao userDao){ this.userDao = userDao; } @Override public void show() { System.out.println(userDao); } }主函数调用public static void main(String[] args) { ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml"); ((UserService) applicationContext.getBean("userService")).show(); ((UserService) applicationContext.getBean("userService1")).show(); }执行结果org.example.UserDaoImpl@1f0f1111 org.example.UserDaoImpl@1f0f1111如果xml文件自动装配中有多个同类型的bean容器将会报错例如：<bean class="org.example.UserDaoImpl" id="userDao"/> <bean class="org.example.UserDaoImpl" id="userDao1"/> <bean class="org.example.UserServiceImpl" id="userService" autowire="byName"/> <bean class="org.example.UserServiceImpl" id="userService1" autowire="byType"/>IDEA报错提示无法自动装配。存在多个 'UserDao' 类型的 Bean。Bean: userDao1,userDao。属性: 'userDao'运行结果提示警告: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService1' defined in class path resource [beans.xml]: Unsatisfied dependency expressed through bean property 'userDao'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'org.example.UserDao' available: expected single matching bean but found 2: userDao,userDao1 Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService1' defined in class path resource [beans.xml]: Unsatisfied dependency expressed through bean property 'userDao'; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'org.example.UserDao' available: expected single matching bean but found 2: userDao,userDao1