There are three types of Bean dependency injection, which are ordinary data types, collections, and reference data types.
The set dependency injection method I mainly use here
1. Common data types
public class Book{
private String bid;
private String bname;
private String btype;
public void setBid(String bid){
this.bid = bid;
}
public void setBname(String bname){
this.bname = bname;
}
public void setBtype(String btype){
this.btype = btype;
}
}
I need to perform dependency injection on bid, bname, and btype in the Book class
Configuration file
<bean id="book" class="book">
<property name="bid" value="123" />
<property name="bname" value="java spring学习笔记" />
<property name="btype" value="计算机" />
</bean>
2. Collection
In order to be simple and easy to understand, I directly add a collection to the Book class
public class Book{
// 为了简单易懂，我将集合写到了这里来
private List<Book> bookList;
private Map<String,Book> bookMap;
private Properties properties; // 配置文件也可依赖注入
// 同样需要创建set方法
public void setBookList(List<Book> bookList){
this.bookList = bookList;
}
public void setBookMap(Map<String,Book> bookMap){
this.bookMap = bookMap;
}
public void setProperties(Properties properties){
this.properties = properties;
}
private String bid;
private String bname;
private String btype;
public void setBid(String bid){
this.bid = bid;
}
public void setBname(String bname){
this.bname = bname;
}
public void setBtype(String btype){
this.btype = btype;
}
}
Configuration file
<!-- 由于是Book类的集合，所以需要提前准备好几个Book对象 -->
<bean id="book1" class="book">
<property name="bid" value="123" />
<property name="bname" value="java spring学习笔记" />
<property name="btype" value="计算机" />
</bean>
<bean id="book2" class="book">
<property name="bid" value="124" />
<property name="bname" value="C++学习笔记" />
<property name="btype" value="计算机" />
</bean>
<bean id="book3" class="book">
<property name="bid" value="125" />
<property name="bname" value="Python学习笔记" />
<property name="btype" value="计算机" />
</bean>
<bean id="book" class="book">
<!-- List -->
<property name="bookList">
<list>
<!-- 若是普通数据类型的话，直接在value标签中输入值即可,如下 -->
<!-- <value>b1</value> -->
<ref bean="book1"/>
<ref bean="book2"/>
<ref bean="book3"/>
</list>
</property>
<!-- Map -->
<property name="bookMap">
<map>
<!-- key为map的关键字，value-ref为具体对象 -->
<entry key="b1" value-ref="book1"></entry>
<entry key="b2" value-ref="book2"></entry>
<entry key="b3" value-ref="book3"></entry>
</map>
</property>
<property name="properties">
<props>
<prop key="p1">1</prop>
<prop key="p2">2</prop>
<prop key="p3">3</prop>
</props>
</property>
</bean>
3. Quote
Object reference injection requires two classes. For example, I use a BookDao and a BookService class
BookDao class
public class BookDao{
}
BookService class
public class BookService{
private BookDao bookDao;
public void setBookDao(BookDao bookDao){
this.bookDao = bookDao;
}
}
Configuration file
<!-- 对象注入，首先要创建一个对象，名为bookDao -->
<bean id="bookDao" class="bookDao"></bean>
<bean id="bookService" class="bookService">
<!-- 此处的name是为BookService中的属性名的bookDao -->
<!-- ref是用于对象引用的，所以ref的bookDao是上面创建的对象 -->
<property name="bookDao" ref="bookDao"></property>
</bean>
The above is my personal learning experience, if there are any mistakes, please correct me!