1. 依赖注入：
1.1 set注入：
基于set方法实现的, 底层会通过反射机制调用属性对应的set方法然后给属性赋值
这种方式要求属性必须对外提供set方法
set注入的核心实现原理: 通过反射机制调用set方法来给属性赋值, 让俩个对象之间产生关系
-
// xml
-
<!-- 配置userDao -->
-
<bean id=
"userDaoBean" class=
"com.powernode.bean.UserDao"/>
-
-
<!-- 配置vipDao -->
-
<bean id=
"vipDaoBean" class=
"com.powernode.bean.VipDao"/>
-
-
<!-- 配置User -->
-
<bean id=
"userBean" class=
"com.powernode.bean.User">
-
<!-- 想让Spring调用对应的set方法， 需要配置property标签
-
name属性怎么知道值： set方法的方法名， 去掉set， 然后把剩下的首字母小写
-
ref翻译为引用， ref后面指定的是要注入的bean的id -->
-
<property name=
"userDao" ref=
"userDaoBean"/>
-
<property name=
"vipDao" ref=
"vipDaoBean"/>
-
</bean>
-
-
// User类
-
public
class
User {
-
private UserDao userDao;
-
private VipDao vipDao;
-
-
public
void
setVipDao
(VipDao vipDao) {
-
this.vipDao = vipDao;
-
}
-
-
// set注入, 必须提供一个set方法
-
// Spring容器会调用这个set方法, 来给userDao属性赋值
-
public
void
setUserDao
(UserDao userDao) {
-
this.userDao = userDao;
-
}
-
-
public
void
saveUser
(){
-
userDao.saveId();
-
vipDao.save();
-
}
-
}
-
-
// @Test
-
public
void
setDI
(){
-
ApplicationContext
ctx
=
new
ClassPathXmlApplicationContext(
"spring.xml");
-
User
userBean
= ctx.getBean(
"userBean", User.class);
-
userBean.saveUser();
-
}
1.2 构造注入:
核心原理: 调用构造方法来给属性赋值
set注入是在对象构建好了之后调用set方法来完成赋值, 构造注入是在对象实例化的过程中赋值的
-
// xml
-
<bean id=
"userDaoBean" class=
"com.powernode.bean.UserDao"/>
-
-
<bean id=
"vipDaoBean" class=
"com.powernode.bean.VipDao"/>
-
-
<!-- 构造注入
3种方式 -->
-
<bean id=
"customerBean" class=
"com.powernode.bean.Customer">
-
<!-- 指定构造方法的第一个参数, 下标是
0 -->
-
<constructor-arg index=
"0" ref=
"userDaoBean"/>
-
<!-- 指定构造方法的第二个参数, 下标是
1 -->
-
<constructor-arg index=
"1" ref=
"vipDaoBean"/>
-
-
<!-- 根据构造方法参数的名字进行注入 -->
-
<constructor-arg name=
"userDao" ref=
"userDaoBean"/>
-
<constructor-arg name=
"vipDao" ref=
"vipDaoBean"/>
-
-
<!-- 这种方式实际上是根据类型进行注入, Spring会自动根据类型来判断把ref注入给哪个参数-->
-
<constructor-arg ref=
"userDaoBean"/>
-
<constructor-arg ref=
"vipDaoBean"/>
-
</bean>
-
-
// Customer类
-
public
class
Customer {
-
private UserDao userDao;
-
private VipDao vipDao;
-
-
public
Customer
(UserDao userDao, VipDao vipDao) {
-
this.userDao = userDao;
-
this.vipDao = vipDao;
-
}
-
public
void
insert
(){
-
userDao.saveId();
-
vipDao.save();
-
}
-
}
-
-
// @Test
-
public
void
constructorDI
(){
-
ApplicationContext
ctx
=
new
ClassPathXmlApplicationContext(
"beans.xml");
-
Customer
customerBean
= ctx.getBean(
"customerBean", Customer.class);
-
customerBean.insert();
-
}
2. set注入专题:
2.1 注入外部Bean:
-
// xml
-
<bean id="orderDaoBean" class="com.powernode.bean.dao.OrderDao"/>
-
-
<bean id="orderBean" class="com.powernode.bean.Order">
-
// 使用ref属性来引入, 这就是注入外部bean
-
<property name="orderDao" ref="orderDaoBean"/>
-
</bean>
-
-
// Order类
-
public class Order {
-
private OrderDao orderDao;
-
-
public void setOrderDao(OrderDao orderDao) {
-
this.orderDao = orderDao;
-
}
-
-
public void generate(){
-
orderDao.insert();
-
}
-
}
2.2 注入内部Bean:
-
// xml
-
<bean id="orderBean2" class="com.powernode.bean.Order">
-
<property name="orderDao">
-
<!-- 在property标签中使用嵌套的bean标签, 这就是内部bean -->
-
<bean class="com.powernode.bean.dao.OrderDao"/>
-
</property>
-
</bean>
-
-
// Order类
-
public class Order {
-
private OrderDao orderDao;
-
-
public void setOrderDao(OrderDao orderDao) {
-
this.orderDao = orderDao;
-
}
-
-
public void generate(){
-
orderDao.insert();
-
}
-
}
2.3 注入简单类型:
简单类型有哪些:
8 种基本类型和8种包装类型
枚举
String字符串
数字
日期(java.util.Date), 在实际的开发中, 一般不会把Date当做简单类型, 一般采用ref给Date类型的属性赋值
时间时区类型
URI
URL
语言类
-
// xml
-
<bean id=
"peopleBean" class=
"com.powernode.bean.People">
-
// 如果是给简单类型赋值, 就不能使用ref, 需要使用value
-
<property name=
"name" value=
"二狗"/>
-
<property name=
"age" value=
"16"/>
-
<property name=
"classId" value=
"1"/>
-
</bean>
-
-
// People类
-
public
class
People {
-
private String name;
-
private
int age;
-
private
int classId;
-
-
public
void
setName
(String name) {
this.name = name;}
-
public
void
setAge
(int age) {
this.age = age;}
-
public
void
setClassId
(int classId) {
this.classId = classId;}
-
@Override
-
public String
toString
() {
-
return
"People{" +
-
"name='" + name +
'\'' +
-
", age=" + age +
-
", classId=" + classId +
-
'}';
-
}
-
}
-
-
// @Test
-
public
void
setDI3
(){
-
ApplicationContext
ctx
=
new
ClassPathXmlApplicationContext(
"set-DI.xml");
-
People
peopleBean
= ctx.getBean(
"peopleBean", People.class);
-
System.out.println(peopleBean);
-
}
2.4 注入数组:
基本类型和非基本类型的数组注入, 如下:
-
// xml
-
<bean id=
"friend1" class=
"com.powernode.bean.Friend">
-
<property name=
"name" value=
"小北"/>
-
</bean>
-
-
<bean id=
"friend2" class=
"com.powernode.bean.Friend">
-
<property name=
"name" value=
"小爱"/>
-
</bean>
-
-
<bean id=
"friend3" class=
"com.powernode.bean.Friend">
-
<property name=
"name" value=
"小花"/>
-
</bean>
-
-
<bean id=
"stu" class=
"com.powernode.bean.Student">
-
// 这个数组当中的元素类型是String简单类型
-
<property name=
"stus">
-
<array>
-
<value>
"张三"</value>
-
<value>
"李四"</value>
-
<value>
"王二蛋"</value>
-
<value>
"大锤"</value>
-
</array>
-
</property>
-
// 这个数组当中的类型就不是简单类型
-
<property name=
"friends">
-
<array>
-
<ref bean=
"friend1"/>
-
<ref bean=
"friend2"/>
-
<ref bean=
"friend3"/>
-
</array>
-
</property>
-
</bean>
-
-
// Student类
-
public
class
Student {
-
private String[] stus;
-
private Friend[] friends;
-
-
public
void
setStus
(String[] stus) {
this.stus = stus;}
-
-
public
void
setFriends
(Friend[] friends) {
this.friends = friends;}
-
-
@Override
-
public String
toString
() {
-
return
"Student{" +
-
"stus=" + Arrays.toString(stus) +
-
", friends=" + Arrays.toString(friends) +
-
'}';
-
}
-
}
-
-
// Friend类
-
public
class
Friend {
-
private String name;
-
-
public
void
setName
(String name) {
this.name = name;}
-
-
@Override
-
public String
toString
() {
-
return
"Friend{" +
-
"name='" + name +
'\'' +
-
'}';
-
}
-
}
-
-
// @Test
-
public
void
setDI5
(){
-
ApplicationContext
ctx
=
new
ClassPathXmlApplicationContext(
"set-DI.xml");
-
Student
stu
= ctx.getBean(
"stu", Student.class);
-
System.out.println(stu);
-
}
2.5 注入List集合和Set集合:
简单类型
-
// xml
-
<bean id=
"people" class=
"com.powernode.bean.People">
-
<property name=
"names">
-
<list>
// list集合有序可重复
-
<value>张三</value>
-
<value>达尔</value>
-
<value>溜达</value>
-
<value>张三</value>
-
<value>张三</value>
-
</list>
-
</property>
-
-
<property name=
"addrs">
-
<set>
// set集合无序不可重复
-
<value>张二</value>
-
<value>达</value>
-
<value>溜达</value>
-
</set>
-
</property>
-
</bean>
-
-
// People类
-
public
class
People {
-
private List<String> names;
-
private Set<String> addrs;
-
public
void
setNames
(List<String> names) {
this.names = names;}
-
public
void
setAddrs
(Set<String> addrs) {
this.addrs = addrs;}
-
-
@Override
-
public String
toString
() {
-
return
"People{" +
-
", names=" + names +
-
", addrs=" + addrs +
-
'}';
-
}
-
}
-
-
// @Test
-
public
void
setDI5
(){
-
ApplicationContext
ctx
=
new
ClassPathXmlApplicationContext(
"set-DI.xml");
-
People
people
= ctx.getBean(
"people", People.class);
-
System.out.println(people);
-
}
2.6 注入Map集合和properties:
Properties本质上也是一个Map集合
Properties的父类HashTable, HashTable实现了Map接口
虽然这个也是Map集合, 但是和Map的注入方式不完全一样
Properties的key和value只能是String类型
-
// xml
-
<bean id=
"people" class=
"com.powernode.bean.People">
-
<property name=
"phones">
// 注入map集合
-
<map>
-
<entry key-ref=
"" value-ref=
""/>
// 如果key和value不是简单类型就用这个
-
<entry key=
"1" value=
".."/>
-
<entry key=
"2" value=
".."/>
-
<entry key=
"3" value=
".."/>
-
</map>
-
</property>
-
-
<property name=
"properties">
// 注入properties属性类对象
-
<props>
-
<prop key=
"..">...</prop>
-
<prop key=
"..">...</prop>
-
<prop key=
"..">...</prop>
-
</props>
-
</property>
-
</bean>
-
-
// People类
-
public
class
People {
-
private Map<Integer,String> phones;
-
private Properties properties;
-
public
void
setPhones
(Map<Integer, String> phones) {
this.phones = phones;}
-
public
void
setProperties
(Properties properties) {
this.properties = properties;}
-
-
@Override
-
public String
toString
() {
-
return
"People{" +
-
"phones=" + phones +
-
", properties=" + properties +
-
'}';
-
}
-
}
-
-
// @Test
-
public
void
setDI5
(){
-
ApplicationContext
ctx
=
new
ClassPathXmlApplicationContext(
"set-DI.xml");
-
People
people
= ctx.getBean(
"people", People.class);
-
System.out.println(people);
-
}
2.7 注入null和空字符串:
注入空字符串使用: <value/> 或者value=""
-
// xml
-
<bean id=
"dog" class=
"com.powernode.bean.Dog">
-
// 注入空字符串的第一种方式
-
<property name=
"name">
-
<value/>
-
</property>
-
// 注入空字符串的第二种方式
-
<property name=
"age" value=
""/>
-
</bean>
-
-
// Dog类
-
public
class
Dog {
-
private String name;
-
private
int age;
-
public
void
setName
(String name) {
this.name = name;}
-
public
void
setAge
(int age) {
this.age = age;}
-
-
@Override
-
public String
toString
() {
-
return
"Dog{" +
-
"name='" + name +
'\'' +
-
", age=" + age +
-
'}';
-
}
-
}
-
-
// @Test
-
public
void
setEmpty
(){
-
ApplicationContext
ctx
=
new
ClassPathXmlApplicationContext(
"set-DI.xml");
-
Dog
dog
= ctx.getBean(
"dog", Dog.class);
-
System.out.println(dog);
-
}
注入null使用: <null/> 或者不为该属性赋值
-
// xml
-
<bean id=
"dog" class=
"com.powernode.bean.Dog">
-
// 不给属性注入, 属性的默认值就是null
-
// <property name="name" value=""/>
-
// 手动注入null
-
<property name=
"age">
-
<
null/>
-
</property>
-
</bean>
2.8 注入特殊字符:
-
// xml
-
<bean id=
"math" class=
"com.powernode.bean.Dog">
-
// 第一种方案
-
<property name=
"result" value=
"2 < 3"/>
-
-
// 第二种方案
-
<property name=
"result">
-
// 只能使用value标签
-
<value><![CDATA[
2 <
3]]></value>
-
</property>
-
</bean>
3. 引入外部的属性配置文件:
引入外部的properties文件
第一步: 引入context命名空间
第二步: 使用标签context: property-placeholder的location属性来指定属性配置文件的路径
location默认从类的根路径下开始加载资源
-
// xml
-
<context: property-placeholder location="jdbc.properties"/>
-
-
// 配置数据源
-
<bean id="ds" class="com....jdbc.MyDataSource">
-
// 怎么取值呢? ${key}
-
<property name="driver" value="${jdbc.driverClass}"/>
-
<property name="url" value="${jdbc.url}"/>
-
<property name="username" value="${jdbc.username}"/>
-
<property name="password" value="${jdbc.password}"/>
-
</bean>
-
-
// jdbc.properties
-
jdbc.driverClass=com.mysql.cj.jdbc.Driver
-
jdbc.url=jdbc:mysql://localhost:3306/spring6
-
jdbc.username=root
-
jdbc.password=123
转载：https://blog.csdn.net/qq_68993495/article/details/128906959
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