Spring中xml配置文件的基礎(chǔ)使用方式詳解
1. xml配置文件的讀取
目錄結(jié)構(gòu)
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"> <!--通過無參構(gòu)造創(chuàng)建對象--> <bean id = "userDao" class="org.example.POI.UserDaoImpl"/> </beans>
1.1 通過類路徑讀取配置文件
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() { //讀取配置文件,創(chuàng)建Spring容器, 根據(jù)類路徑讀取 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); //根據(jù)id獲取對象 UserDao userDao = (UserDao) context.getBean("userDao"); UserDao userDao2 = (UserDao) context.getBean("userDao"); //使用對象調(diào)用方法 userDao.say(); //默認(rèn)單例 System.out.println(userDao == userDao2); }
1.2 通過文件系統(tǒng)絕對路徑讀取配置文件
@Test public void Test01(){ //根據(jù)文件系統(tǒng)的絕對路徑讀取配置文件 ApplicationContext context1 = new FileSystemXmlApplicationContext("E:\\絕對路徑 "+ "\\src\\main\\resource\\applicationContext.xml"); UserDao userDao1 = (UserDao) context1.getBean("userDao"); UserDao userDao2 = (UserDao) context1.getBean("userDao"); userDao1.say(); //默認(rèn)單例 System.out.println(userDao1 == userDao2); }
1.3使用BeanFactory接口讀取配置文件
@Test public void diffrentTest(){ //將配置文件信息封裝到Resource對象中 ClassPathResource resource = new ClassPathResource("applicationContext.xml"); //通過Resource對象創(chuàng)建容器 BeanFactory beanFactory = new XmlBeanFactory(resource); //通過id獲取對應(yīng)的對象 UserDao userDao = (UserDao) beanFactory.getBean("userDao"); UserDao userDao1 = (UserDao) beanFactory.getBean("userDao"); userDao.say(); System.out.println(userDao == userDao1); }
BeanFactory 創(chuàng)建對象時才調(diào)用構(gòu)造函數(shù)創(chuàng)建對象 延遲加載
ApplicationContext 在創(chuàng)建容器時就調(diào)用構(gòu)造創(chuàng)建對象(讀取配置文件后馬上創(chuàng)建對象) 立即加載
2.帶參構(gòu)造對象的創(chuàng)建(constructor-arg標(biāo)簽)
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 + '\'' + '}'; } }
<!-- 調(diào)用有參構(gòu)造,反射創(chuàng)建對象--> <bean id = "user" class="org.example.pojo.User"> <constructor-arg name="age" value="18"></constructor-arg> <constructor-arg name="userName" value="貂蟬"></constructor-arg> </bean>
//創(chuàng)建帶參構(gòu)造對象 @Test public void haveArgStruct(){ ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); User user = (User) context.getBean("user"); System.out.println(user); }
3.使用另一個類中的方法創(chuàng)建對象,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,我創(chuàng)建了UserDao----"); UserDao userDao = new UserDaoImpl(); return userDao; } @Override public void say() { this.userDao.say(); System.out.println("userService say hello World!"); } }
<!--調(diào)用另一個類中的方法創(chuàng)建對象并將其加入到Spring容器中--> <bean id="userDaoService" class="org.example.POI.UserServiceImpl"></bean> <!--factory-bean: 另一個類的id factory-method: 另一個類中創(chuàng)建指定對象的方法名--> <bean id="userDaoByService" factory-bean="userDaoService" factory-method="createUserDao"></bean>
//調(diào)用另一個類中的方法創(chuàng)建對象 @Test public void userDaoByUserService(){ ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); UserDao userDao = (UserDao) context.getBean("userDaoByService"); userDao.say(); }
4.調(diào)用另一個類中的靜態(tài)方法創(chuàng)建對象,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,我創(chuàng)建了UserDao----"); return new UserDaoImpl(); } @Override public void say() { this.userDao.say(); System.out.println("userService say hello World!"); } }
<!--調(diào)用類中的靜態(tài)方法創(chuàng)建對象存放到Spring容器中--> <bean id="userDaoByService1" class="org.example.POI.UserServiceImpl" factory-method="createUserDao1"></bean>
//調(diào)用另一個類中的靜態(tài)方法創(chuàng)建對象 @Test public void userDaoByUserService1(){ ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); UserDao userDao = (UserDao) context.getBean("userDaoByService1"); userDao.say(); }
5.對象的生命周期
package org.example.POI; public class UserDaoImpl implements UserDao{ public UserDaoImpl(){ System.out.println("UserDaoImpl無參構(gòu)造調(diào)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!"); } }
//對象的生命周期 @Test public void lifecycle(){ //創(chuàng)建容器 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); //銷毀容器 ((ClassPathXmlApplicationContext)context).close(); }
<!--對象的生命周期--> <!--init-method: 創(chuàng)建容器時調(diào)用demo01函數(shù)--> <!--destroy-method: 銷毀容器時調(diào)用demo02函數(shù)--> <bean id="lifecycle" init-method="demo01" destroy-method="demo02" class="org.example.POI.UserDaoImpl"></bean>
6.單例多例的測試
package org.example.POI; public class UserDaoImpl implements UserDao{ public UserDaoImpl(){ System.out.println("UserDaoImpl無參構(gòu)造調(diào)用--------"); } @Override public void say() { System.out.println("userDao say Hello World!"); } }
@Test public void shouldAnswerWithTrue() { //讀取配置文件,讀取Spring容器, 根據(jù)類路徑讀取 ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); //根據(jù)id獲取對象 UserDao userDao = (UserDao) context.getBean("userDao"); UserDao userDao2 = (UserDao) context.getBean("userDao"); //使用對象調(diào)用方法 userDao.say(); //默認(rèn)單例 System.out.println(userDao == userDao2); }
多例
<bean id = "userDao" scope="prototype" class="org.example.POI.UserDaoImpl"/>
默認(rèn)單例
<bean id = "userDao" scope="singleton" class="org.example.POI.UserDaoImpl"/>
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