SpringIOC容器-对象依赖

1 概述

Spring中，如何给对象的属性赋值? 【DI, 依赖注入】

1) 通过构造函数

2) 通过set方法给属性注入值

3) p名称空间

4) 自动装配

5) 注解

1.1 通过构造函数

<!-- ###############对象属性赋值############### -->
<!--  1) 通过构造函数 -->
<bean id="user1" class="cn.itcast.c_property.User" scope="prototype">
<constructor-arg value="100"></constructor-arg>
<constructor-arg value="Tom"></constructor-arg>
</bean>

1.2 (常用)Set方法注入值

<!-- dao instance -->
<bean id="userDao" class="c_property.UserDao"></bean>

<!-- service instance -->
<bean id="userService" class="c_property.UserService">
<property name="userDao" ref="userDao"></property>
</bean>

<!-- action instance -->
<bean id="userAction" class="c_property.UserAction">
<property name="userService" ref="userService"></property>
</bean>

User.java

public class User {

private int id;
private String name;

//////////////////  --> 通过容器注入属性值
public void setId(int id) {
this.id = id;
}
// //--> 通过容器注入属性值
public void setName(String name) {
this.name = name;
}

////////////////
public int getId() {
return id;
}

public String getName() {
return name;
}

@Override
public String toString() {
return "User [id=" + id + ", name=" + name + "]";
}

public User() {
super();
System.out.println("------User对象创建【无参数构造器】------");
}

public User(int id, String name) {
System.out.println("-----User对象创建【带参数构造器】--------");
this.id = id;
this.name = name;
}

public void init_user() {
System.out.println("创建对象之后，初始化");
}
public void destroy_user() {
System.out.println("IOC容器销毁，user对象回收!");
}

}

UserAction.java

public class UserAction {

// Service: springIOC容器注入
private UserService userService;
public void setUserService(UserService userService) {
this.userService = userService;
}

public String execute() {
userService.save();
return null;
}
}

UserService.java

public class UserService {

private UserDao userDao; // = new UserDao();
// IOC：对象的创建交给spring的外部容器完成
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}

public void save() {
userDao.save();
}
}

UserDao.java

public class UserDao {

public void save() {
System.out.println("zmiagen:保存用户");
}
}

1.3 内部bean

<!-- ##############内部bean############## -->
<bean id="userAction" class="c_property.UserAction">
<property name="userService">
<bean class="c_property.UserService">
<property name="userDao">
<bean class="c_property.UserDao"></bean>
</property>
</bean>
</property>
</bean>