Spring中xml配置文件的基础使用方式详解
目录
- 1. xml配置文件的读取
- 1.1 通过类路径读取配置文件
- 1.2 通过文件系统绝对路径读取配置文件
- 1.3使用BeanFactory接口读取配置文件
- 2.带参构造对象的创建(constructor-arg标签)
- 3.使用另一个类中的方法创建对象,并放到Spring容器中
- 4.调用另一个类中的静态方法创建对象,并放到Spring容器中
- 5.对象的生命周期
- 6.单例多例的测试
1. xml配置文件的读取
目录结构
applicationContext.xml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-4.3.xsd"> <!--通过无参构造创建对象--> <bean id = "userDao" class="org.example.POI.UserDaoImpl"/> </beans>
1.1 通过类路径读取配置文件
package org.example.POI; public interface UserDao { public void say(); }
package org.example.POI; public class UserDaoImpl implements UserDao{ @Override public void say() { System.out.println("userDao say Hello World!"); } }
@Test public void shouldAnswerWithTrue() { //读取配置文件,创建Spring容器, 根据类路径读取 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); //根据id获取对象 UserDao userDao = (UserDao) context.getBean("userDao"); UserDao userDao2 = (UserDao) context.getBean("userDao"); //使用对象调用方法 userDao.say(); //默认单例 System.out.println(userDao == userDao2); }
1.2 通过文件系统绝对路径读取配置文件
@Test public void Test01(){ //根据文件系统的绝对路径读取配置文件 ApplicationContext context1 = new FileSystemXmlApplicationContext("E:\\绝对路径 "+ "\\src\\main\\resource\\applicationContext.xml"); UserDao userDao1 = (UserDao) context1.getBean("userDao"); UserDao userDao2 = (UserDao) context1.getBean("userDao"); userDao1.say(); //默认单例 System.out.println(userDao1 == userDao2); }
1.3使用BeanFactory接口读取配置文件
@Test public void diffrentTest(){ //将配置文件信息封装到Resource对象中 ClassPathResource resource = new ClassPathResource("applicationContext.xml"); //通过Resource对象创建容器 BeanFactory beanFactory = new XmlBeanFactory(resource); //通过id获取对应的对象 UserDao userDao = (UserDao) beanFactory.getBean("userDao"); UserDao userDao1 = (UserDao) beanFactory.getBean("userDao"); userDao.say(); System.out.println(userDao == userDao1); }
BeanFactory 创建对象时才调用构造函数创建对象 延迟加载
ApplicationContext 在创建容器时就调用构造创建对象(读取配置文件后马上创建对象) 立即加载
2.带参构造对象的创建(constructor-arg标签)
public class User { private Integer age; private String userName; public User() { } public User(Integer age, String userName) { this.age = age; this.userName = userName; } @Override public String toString() { return "User{" + "age=" + age + ", userName='" + userName + '\'' + '}'; } }
<!-- 调用有参构造,反射创建对象--> <bean id = "user" class="org.example.pojo.User"> <constructor-arg name="age" value="18"></constructor-arg> <constructor-arg name="userName" value="貂蝉"></constructor-arg> </bean>
//创建带参构造对象 @Test public void haveArgStruct(){ ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); User user = (User) context.getBean("user"); System.out.println(user); }
3.使用另一个类中的方法创建对象,并放到Spring容器中
package org.example.POI; public interface UserService { public void say(); }
public class UserServiceImpl implements UserService{ private UserDao userDao; public void setUserDao(UserDao userDao){ this.userDao = userDao; } public UserDao createUserDao(){ System.out.println("我是UserServiceImpl,我创建了UserDao----"); UserDao userDao = new UserDaoImpl(); return userDao; } @Override public void say() { this.userDao.say(); System.out.println("userService say hello World!"); } }
<!--调用另一个类中的方法创建对象并将其加入到Spring容器中--> <bean id="userDaoService" class="org.example.POI.UserServiceImpl"></bean> <!--factory-bean: 另一个类的id factory-method: 另一个类中创建指定对象的方法名--> <bean id="userDaoByService" factory-bean="userDaoService" factory-method="createUserDao"></bean>
//调用另一个类中的方法创建对象 @Test public void userDaoByUserService(){ ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); UserDao userDao = (UserDao) context.getBean("userDaoByService"); userDao.say(); }
4.调用另一个类中的静态方法创建对象,并放到Spring容器中
public class UserServiceImpl implements UserService{ private UserDao userDao; public void setUserDao(UserDao userDao){ this.userDao = userDao; } public static UserDao createUserDao1(){ System.out.println("我是static createUserDao1,我创建了UserDao----"); return new UserDaoImpl(); } @Override public void say() { this.userDao.say(); System.out.println("userService say hello World!"); } }
<!--调用类中的静态方法创建对象存放到Spring容器中--> <bean id="userDaoByService1" class="org.example.POI.UserServiceImpl" factory-method="createUserDao1"></bean>
//调用另一个类中的静态方法创建对象 @Test public void userDaoByUserService1(){ ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); UserDao userDao = (UserDao) context.getBean("userDaoByService1"); userDao.say(); }
5.对象的生命周期
package org.example.POI; public class UserDaoImpl implements UserDao{ public UserDaoImpl(){ System.out.println("UserDaoImpl无参构造调用--------"); } @Override public void say() { System.out.println("userDao say Hello World!"); } public void demo01(){ System.out.println("init obj!"); } public void demo02(){ System.out.println("destroy obj!"); } }
//对象的生命周期 @Test public void lifecycle(){ //创建容器 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); //销毁容器 ((ClassPathXmlApplicationContext)context).close(); }
<!--对象的生命周期--> <!--init-method: 创建容器时调用demo01函数--> <!--destroy-method: 销毁容器时调用demo02函数--> <bean id="lifecycle" init-method="demo01" destroy-method="demo02" class="org.example.POI.UserDaoImpl"></bean>
6.单例多例的测试
package org.example.POI; public class UserDaoImpl implements UserDao{ public UserDaoImpl(){ System.out.println("UserDaoImpl无参构造调用--------"); } @Override public void say() { System.out.println("userDao say Hello World!"); } }
@Test public void shouldAnswerWithTrue() { //读取配置文件,读取Spring容器, 根据类路径读取 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); //根据id获取对象 UserDao userDao = (UserDao) context.getBean("userDao"); UserDao userDao2 = (UserDao) context.getBean("userDao"); //使用对象调用方法 userDao.say(); //默认单例 System.out.println(userDao == userDao2); }
多例
<bean id = "userDao" scope="prototype" class="org.example.POI.UserDaoImpl"/>
默认单例
<bean id = "userDao" scope="singleton" class="org.example.POI.UserDaoImpl"/>
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