1 Overview
- rely
- Object A has a reference to object B, and some operations need to be completed using object B.
- Object A depends on B
- injection
- Assigning values to B objects that are dependent on by object A is called injection
2 Injection method
1. Set injection
2. Structural injection
3. Automatic injection
4. P namespace injection
3 Data types that can be injected
Basic Type
Custom Objects
Container Type
Array
Collection
Map
Properties
4 set injection
- When creating an object, the Spring factory will call the set method to assign values to the properties in the object.
- If the property in an object does not add the set method, an error will be reported when using property assignment.
Error:(11, 13) java: Symbol not found symbol: method setId(int) Location: Variable of type user
import ;
@Data
public class User {
private Integer id;
private String username;
private String password;
private String addr;
private String info;
}<!-- definitionuser -->
<bean class="">
<property name="id" value="100111"></property>
<property name="username" value="Guan Yu"></property>
<property name="info" value="Guan Yu, who sells miscellaneous grains"></property>
</bean>5 Constructor Injection
Injecting properties through the object's constructor
<constructor-arg name="id" value="100110"></constructor-arg>
package ;
public class Hero {
private Integer id;
private String username;
private String password;
private String addr;
private String info;
public Hero() {
}
public Hero(String username, String password) {
= username;
= password;
}
public Hero(Integer id, String username) {
= id;
= username;
}
public Hero(Integer id, String username, String password, String addr, String info) {
= id;
= username;
= password;
= addr;
= info;
}
@Override
public String toString() {
return "Hero{" +
", username='" + username + '\'' +
", password='" + password + '\'' +
", addr='" + addr + '\'' +
", info='" + info + '\'' +
'}';
}
} <!-- definitionHero -->
<bean class="">
<constructor-arg name="id" value="100110"></constructor-arg>
<constructor-arg name="username" value="Liu Bei"></constructor-arg>
</bean>
<bean class="">
<constructor-arg name="username" value="Zhao Yun"></constructor-arg>
<constructor-arg name="password" value="zhao"></constructor-arg>
</bean>6 Automatic injection
How to declare autowire in bean tag
Spring framework will find data that matches parameters in the container for injection
- byType
- byName
package ;
import ;
import ;
import ;
public class HeroServiceImpl implements HeroService {
private HeroDao heroDao;
public void setHeroDao(HeroDao heroDao) {
= heroDao;
}
@Override
public Hero queryHeroById(Integer id) {
return (id);
}
} <!-- heroService -->
<bean class="" autowire="byType"></bean>
<!-- heroService -->
<bean class="" autowire="byName"></bean> @Test
public void getHero01(){
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("");
HeroService heroService = ("heroService01",);
Hero hero = (10010);
(hero);
}
@Test
public void getHero02(){
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("");
HeroService heroService = ("heroService02",);
Hero hero = (1001111);
(hero);
}Automatic injection or set injection
7p namespace injection
- Use p as the prefix of the attribute to call the attribute to perform the copy operation
- In essence, it is still used to assign values using the set method
xmlns:p=“/schema/p”
<!-- stu -->
<bean class="" p: p:username="Zhang San"></bean> @Test
public void getStu(){
ClassPathXmlApplicationContext ioc =
new ClassPathXmlApplicationContext("");
Stu stu = ();
(stu);
}8 Data source injection
- Injecting Druid data source using Spring factory
- rely
<dependency>
<groupId></groupId>
<artifactId>druid</artifactId>
<version>1.1.10</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>Declare references to data sources in dao
package ;
import ;
import ;
import ;
import ;
public class HeroDaoImpl implements HeroDao {
private DruidDataSource dataSource;
public DruidDataSource getDataSource() {
return dataSource;
}
public void setDataSource(DruidDataSource dataSource) {
= dataSource;
}
@Override
public Hero selectHeroById(Integer id) {
try {
(());
} catch (SQLException e) {
();
}
Hero hero = new Hero();
(id);
return hero;
}
}Configuration
<!-- Introduce external configuration files -->
<context:property-placeholder location="classpath:"></context:property-placeholder>
<!-- Configure data source -->
<bean class="">
<property name="driverClassName" value="${}"></property>
<property name="url" value="${}"></property>
<property name="username" value="${}"></property>
<property name="password" value="${}"></property>
</bean>
<!-- heroDao -->
<bean class="">
<property name="dataSource" ref="dataSource"></property>
</bean>test
package ;
import ;
import ;
import ;
import ;
import ;
public class TestHeroDao {
@Test
public void getHeroDao() {
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("");
HeroDao heroDao = ();
Hero hero = (222);
}
}4.9 Container type data injection
package ;
import ;
import ;
import ;
@Data
public class Person {
private Integer id;
private String username;
private String gender;
private String info;
private String[] hobby;
private List<String> friend;
private Map<String,String> phones;
}<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="/schema/beans"
xmlns:xsi="http:///2001/XMLSchema-instance"
xmlns:p="/schema/p"
xmlns:context="/schema/context"
xsi:schemaLocation="/schema/beans
/schema/beans/
/schema/context
/schema/context/">
<!-- personBasic attribute injection -->
<bean class="">
<property name="id" value="100100"></property>
<property name="username" value="Song Jiang"></property>
<property name="gender" value="male"></property>
<property name="info" value="Liangshantou"></property>
</bean>
<!-- Inject an array -->
<bean class="">
<property name="hobby">
<array>
<value>basketball</value>
<value>football</value>
<value>table tennis</value>
</array>
</property>
</bean>
<bean class="">
<property name="friend">
<list>
<value>Chao Gai</value>
<value>Hu Sanniang</value>
<value>Wang Po</value>
<value>Wu Song</value>
</list>
</property>
</bean>
<!-- mapparameter -->
<bean class="">
<property name="phones">
<map>
<entry key="Lu Zhishen" value="10010"></entry>
<entry key="Lin Chong" value="10086"></entry>
<entry key="Li Kui" value="10000"></entry>
<entry key="Farewell" value="100000"></entry>
</map>
</property>
</bean>
</beans>package ;
import ;
import ;
import ;
public class TestPerson {
@Test
public void getPerson01(){
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("");
Person person01 = ("person01", );
(person01);
}
@Test
public void getPerson02(){
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("");
Person person02 = ("person02", );
(person02);
}
@Test
public void getPerson03(){
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("");
Person person03 = ("person03", );
(person03);
}
@Test
public void getPerson04(){
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("");
Person person04 = ("person04", );
(person04);
}
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