Bean dependency injection property, use xml configuration
1, Constructor injection
Case code demonstrates
public class User {
private String username;
private String password;
private Integer age;
public User() {}
public User(String username, String password, Integer age) {
this.username = username;
this.password = password;
this.age = age;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "User{" +
"username='" + username + '\'' +
", password='" + password + '\'' +
", age=" + age +
'}';
}
}
========================================================================================
通过构造方法注入参数
<?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.xsd">
<!---->
<bean id="user" class="com.example.demo.testservice.User">
<!--相当于调用了有参构造
public User(String username, String password, Integer age) {...}
-->
<constructor-arg name="username" value="zhangsan"/>
<constructor-arg name="password" value="123456"/>
<constructor-arg name="age" value="99"/>
</bean>
</beans>
========================================================================================
测试函数
public class ServiceTest {
public static void main(String[] args) {
ApplicationContext context1 = new ClassPathXmlApplicationContext("beans.xml");
User user = (User) context1.getBean("user");
System.out.println(user);
}
} Function test is performed to obtain the following results:
User{username='zhangsan', password='123456', age=99}
上面的bean.xml还可以通过索引注入参数，其他不变，修改 bean.xml 如下
通过索引注入参数
<?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.xsd">
<bean id="user" class="com.example.demo.testservice.User">
<!--相当于调用了有参构造
public User(String username, String password, Integer age) {...}
-->
<constructor-arg index="0" value="李四" type="java.lang.String"/>
<constructor-arg index="1" value="112233" type="java.lang.String"/>
<constructor-arg index="2" value="44" type="java.lang.Integer"/>
</bean>
</beans>Function test is performed to obtain the following results:
User{username='李四', password='112233', age=44}
2, injection property setter method (two)
The above User and test functions ServiceTest the same, only you need to modify bean.xml
<?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.xsd">
<bean id="user" class="com.example.demo.testservice.User">
<property name="age" value="11"/>
<property name="password" value="666"/>
<property name="username" value="王麻子"/>
</bean>
</beans>
=========================================================================================
<?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.xsd">
<bean id="user" class="com.example.demo.testservice.User">
<property name="age">
<value>11</value>
</property>
<property name="password">
<value>666</value>
</property>
<property name="username">
<value>王麻子</value>
</property>
</bean>
</beans>Bean.xml above two configurations are used simply to facilitate comparison of the first configuration.
The test results are as follows:
User{username='王麻子', password='666', age=11}
3, p namespace injection
The above User and test functions ServiceTest the same, only need to modify bean.xml.
<?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:p ="http://www.springframework.org/schema/p"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="user" class="com.example.demo.testservice.User" p:age="111" p:password="888" p:username="秦始皇" />
</beans>This approach is not commonly used, interested friends can compare bean.xml and Constructor injection at p namespace, setter method injection bean.xml difference is the addition of a === "xmlns: p =" http: // www.springframework.org/schema/p ", you can use the namespace p.
Results are as follows:
User {username = 'First Emperor', password = '888', age = 111}
4, the set injection
List、Set、Map、Properties
public class Coder {
private List<String> cars; // 车
private Set<String> pats; // 宠物
private Map<String,String> information; // 信息
private Properties mysqlInfo; // Mysql 连接信息
public Properties getMysqlInfo() {
return mysqlInfo;
}
public void setMysqlInfo(Properties mysqlInfo) {
this.mysqlInfo = mysqlInfo;
}
public Map<String, String> getInformation() {
return information;
}
public void setInformation(Map<String, String> information) {
this.information = information;
}
public Set<String> getPats() {
return pats;
}
public void setPats(Set<String> pats) {
this.pats = pats;
}
public List<String> getCars() {
return cars;
}
public void setCars(List<String> cars) {
this.cars = cars;
}
@Override
public String toString() {
return "Coder{" +
"cars=" + cars +
", pats=" + pats +
", information=" + information +
", mysqlInfo=" + mysqlInfo +
'}';
}
}
=========================================================================================
<?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.xsd">
<bean id="coder" class="com.example.demo.testservice.Coder">
<!--List 数据注入-->
<property name="cars">
<list>
<value>ofo</value>
<value>宝马</value>
<value>奔驰</value>
</list>
</property>
<!--Set数据注入-->
<property name="pats">
<set>
<value>猪</value>
<value>马</value>
<value>牛</value>
</set>
</property>
<!--Map 数据注入-->
<property name="information">
<map>
<entry key="name" value="王八蛋"/>
<entry key="age" value="99"/>
<entry key="password" value="8888"/>
</map>
</property>
<!--Properties 数据注入-->
<property name="mysqlInfo">
<props>
<prop key="url">mysql:jdbc://localhost:3306/sample</prop>
<prop key="username">root</prop>
<prop key="password">root</prop>
</props>
</property>
</bean>
</beans>
=========================================================================================测试函数
public class ServiceTest {
public static void main(String[] args) {
ApplicationContext context1 = new ClassPathXmlApplicationContext("beans.xml");
Coder coder = (Coder) context1.getBean("coder");
System.out.println("车："+coder.getCars());
System.out.println("宠物："+coder.getPats());
System.out.println("个人信息："+coder.getInformation());
System.out.println("数据库信息信息："+coder.getMysqlInfo());
}
} Results are as follows:
Car: [ofo, BMW, Mercedes-Benz]
Pet: [pigs, horses, cows]
Personal Information: {name = bastard, age = 99, password = 8888}
Database information: {password = root, url = mysql: jdbc: // localhost: 3306 / sample, username = root}