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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