SpringIOC的三种配置与使用方式
1.基于XML配置文件的bean模式
applicationContext.xml文件配置(名字可以随意，置于resources文件夹下)
<?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-3.1.xsd></bean>
bean模式下需要在xml文件中书写的代码：
<?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-3.1.xsd>
<bean id="studentDao" class="com.Dao.StudentDaoImpl" ></bean>
<bean id="studentService" class="com.services.studentSerImpl" scope="prototype">
<property name="studentDao" ref="studentDao"></property>
<property name="info" value="小屁孩"></property>
</bean>
</bean>
//dao接口
package com.Dao;
import java.util.List;
public interface studentDao {
List selectAllStudent();
}
//dao实现类
package com.Dao;
import org.springframework.stereotype.Component;
import java.util.List;
@Component
public class StudentDaoImpl implements studentDao {
@Override
public List selectAllStudent() {
System.out.println("查询所有学生！");
return null;
}
}
//services接口
package com.services;
public interface studentServices {
void findAllstudent();
}
//services实现类
package com.services;
import com.Dao.StudentDaoImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
public class studentSerImpl implements studentServices {
private StudentDaoImpl studentDao;
private String info;
//通过set，必须有set方法
public void setInfo(String info) {
System.out.println(info);
this.info = info;
}
public void setStudentDao(StudentDaoImpl studentDao) {
this.studentDao = studentDao;
}
@Override
public void findAllstudent() {
studentDao.selectAllStudent();
}
}
//controller
package com.controller;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.services.*;
public class selectStudent {
public static void main(String[] args) {
ClassPathXmlApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext");
studentServices studetnServices = (studentServices) applicationContext.getBean("studentService");//bean
studetnServices.findAllstudent();
}
}
说明：上面的bean中的id是唯一标示，class是java实现类的路径，（首先先说明一下依赖关系，controller依赖service，service依赖dao），在services中有两个成员变量，StudentDao和Info，在applicationContext.xml文件中配置bean来将所需的元素注入，services实现类中的成员变量注入的前提是在其中必须有set方法。
<bean id="studentDao" class="com.Dao.StudentDaoImpl" ></bean>
<bean id="studentService" class="com.services.studentSerImpl" scope="prototype">
<property name="studentDao" ref="studentDao"></property>
<property name="info" value="小屁孩"></property>
</bean>
第一个bean对应的是dao实现类，第二个bean对应的是services实现类，其中的property的name是成员变量的变量名，注入对象时使用ref，注入普通变量时使用value。
bean中的scope属性，是用来控制bean的作用范围和是否是单利模式的，值有：prototype、single、request、session
bean中的autowire属性，是用来开启自动映射的，常用的值有：byType用过类型自动映射（前提是）、byName（前提是成员变量名必须和bean的id一致）
上面所述的是使用set方法注入（其实依赖的是无参构造），还有一种方法是通过构造方法注入：
<bean id="studentService02" class="com.services.studentSerImpl">-->
<constructor-arg index="0" ref="studentDao"/>
<constructor-arg index="1" value="asdfsadf"/>
</bean>
package com.services;
import com.Dao.StudentDaoImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component("studentService")
public class studentSerImpl implements studentServices {
private StudentDaoImpl studentDao;
private String info;
//通过构造器，
public studentSerImpl(StudentDaoImpl studentDao, String info) {
System.out.println(info);
this.studentDao = studentDao;
this.info = info;
}
@Override
public void findAllstudent() {
studentDao.selectAllStudent();
}
}
2.基于XML配置文件的注解方式
首先需要扫描包在applicationcontext.xml配置文件中：
<context:component-scan base-package="com"/>
上面的代码表示扫描com整个文件夹，
services类：
package com.services;
import com.Dao.StudentDaoImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component("studentService")
public class studentSerImpl implements studentServices {
@Autowired//默认
private StudentDaoImpl studentDao;
@Autowired//默认
private String info;
@Override
public void findAllstudent() {
studentDao.selectAllStudent();
}
}
// dao类：
package com.Dao;
import org.springframework.stereotype.Component;
import java.util.List;
@Component
public class StudentDaoImpl implements studentDao {
@Override
public List selectAllStudent() {
System.out.println("查询所有学生！");
return null;
}
}
// controller类：
package com.controller;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.services.*;
public class selectStudent {
public static void main(String[] args) {
ClassPathXmlApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext");
studentServices studetnServices = (studentServices) applicationContext.getBean("studentService");
studetnServices.findAllstudent();
}
}
controller类中的getBean中的值和Services中的注解@Component中的值保持一致，dao类中的类前面还需要加上注解@Component
基于Java的配置类的方式
基于bean的java配置类
使用java配置类的方式，就不需要xml配置文件了，需要重新建一个java类，为了好区分就叫他applicationContext，在里面书写代码如下：
applicationContext配置类：
```java
@Configuration//声明此类为配置类
public class applicationConfig {
// @Bean(name = "getStudenDaoImpl")
// public StudentDaoImpl getStudenDaoImpl(){
// return new StudentDaoImpl();
// }
// @Bean(name = "getStudentSerImpl")
// public studentSerImpl getStudentSerImpl(){
// studentSerImpl studentSer = new studentSerImpl();
// studentSer.setInfo("ASAS");
// studentSer.setStudentDao(getStudenDaoImpl());
// return studentSer;
// }
}
dao类和上面的模式一致（需要加上@Component）；
services类也是一致（需要加上@Component）；
```java
controller类：
package com.controller;
import com.config.applicationConfig;
import com.services.studentServices;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class selectStudent02 {
public static void main(String[] args) {
AnnotationConfigApplicationContext acc = new AnnotationConfigApplicationContext(applicationConfig.class);
studentServices studetnServices = (studentServices) acc.getBean("studentService");//bean
studetnServices.findAllstudent();
}
}
说明：此种方式就不能在使用加载xml配置文件的形式来获取操作类了，因为此时就没有xml配置文件了，使用需要加载java配置类，
之前的使用的加载配置文件的类是：
ClassPathXmlApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext");
使用java配置文件使用的是：
AnnotationConfigApplicationContext acc = new AnnotationConfigApplicationContext(applicationConfig.class);
3.基于注解的java配置类
applicationContext配置类：
@Configuration//生命此类为配置类
@ComponentScan("com")//扫描包
public class applicationConfig {
}
services类：
@Component("studentService")
public class studentSerImpl implements studentServices {
@Autowired//默认
private StudentDaoImpl studentDao;
private String info;
@Override
public void findAllstudent() {
studentDao.selectAllStudent();
}
}
controller类：
public class selectStudent02 {
public static void main(String[] args) {
AnnotationConfigApplicationContext acc = new AnnotationConfigApplicationContext(applicationConfig.class);
studentServices studetnServices = (studentServices) acc.getBean("studentService");//bean
studetnServices.findAllstudent();
}
}