文章目录

6.1 概念6.2 构造器注入6.2 Set 注入 （重点）6.2.1 常量注入6.2.2 Bean注入6.2.3 数组注入6.2.4 List注入6.2.5 Map注入6.2.6 set注入6.2.7 Null注入6.2.8 Properties注入 6.3 p命名和c命名注入

6.1 概念

依赖注入（Dependency Injection,DI）

依赖 : 指Bean对象的创建依赖于容器 . Bean对象的依赖资源 .

注入 : 指Bean对象所依赖的资源 , 由容器来设置和装配

6.2 构造器注入

实体类User

package com.jl.pojo; public class User { private String name; public User() { } public User(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } public void show(){ System.out.println("name=" + name); } }

构造器注入

<bean id="user" class="com.jl.pojo.User"> <constructor-arg name="name" value="哈哈哈哈哈哈"/> </bean>

6.2 Set 注入 （重点）

实体类Address

package com.jl.pojo; public class Address { private String address; public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } }

实体类Student

package com.jl.pojo; import java.util.*; public class Student { private String name; private Address address; private String[] books; private List<String> hobbys; private Map<String,String> card; private Set<String> games; private String wife; private Properties info; public String getName() { return name; } public void setName(String name) { this.name = name; } public Address getAddress() { return address; } public void setAddress(Address address) { this.address = address; } public String[] getBooks() { return books; } public void setBooks(String[] books) { this.books = books; } public List<String> getHobbys() { return hobbys; } public void setHobbys(List<String> hobbys) { this.hobbys = hobbys; } public Map<String, String> getCard() { return card; } public void setCard(Map<String, String> card) { this.card = card; } public Set<String> getGames() { return games; } public void setGames(Set<String> games) { this.games = games; } public String getWife() { return wife; } public void setWife(String wife) { this.wife = wife; } public Properties getInfo() { return info; } public void setInfo(Properties info) { this.info = info; } @Override public String toString() { return "Student{" + "name='" + name + '\'' + ", address=" + address + ", books=" + Arrays.toString(books) + ", hobbys=" + hobbys + ", card=" + card + ", games=" + games + ", wife='" + wife + '\'' + ", info=" + info + '}'; } }

6.2.1 常量注入

beans.xml

<bean id="student" class="com.jl.pojo.Student"> <!-- 普通值注入 value --> <property name="name" value="张三"/> </bean>

Test测试

public class Test1 { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); Student student = (Student) context.getBean("student"); System.out.println(student.getName()); }

6.2.2 Bean注入

注意点：这里的值是一个引用，用ref

<bean id="address" class="com.jl.pojo.Address"> <property name="address" value="天津"/> </bean> <bean id="student" class="com.jl.pojo.Student"> <property name="address" ref="address"/> </bean>

6.2.3 数组注入

<bean id="student" class="com.jl.pojo.Student"> <property name="books"> <array> <value>西游记</value> <value>红楼梦</value> <value>水浒传</value> </array> </property> </bean>

6.2.4 List注入

<!-- list注入 --> <property name="hobbys"> <list> <value>听歌</value> <value>玩</value> <value>吃</value> <value>乐</value> </list> </property>

6.2.5 Map注入

<!-- Map注入 --> <property name="card"> <map> <entry key="身份证" value="123456"/> <entry key="银行卡" value="1234567890"/> </map> </property>

6.2.6 set注入

<!-- Set注入 --> <property name="games"> <set> <value>LOL</value> <value>BOB</value> </set> </property>

6.2.7 Null注入

<!-- null注入 --> <property name="wife"> <null/> </property>

6.2.8 Properties注入

<!-- Properties --> <property name="info"> <props> <prop key="学号">1950410914</prop> <prop key="性别">男</prop> </props> </property>

测试

public class Test1 { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); Student student = (Student) context.getBean("student"); System.out.println(student.toString()); } }

结果：

Student{ name='张三', address=Address{address='天津'}, books=[红楼梦, 西游记, 水浒传, 三国演义], hobbys=[听歌, 玩, 吃, 乐], card={身份证=123456, 银行卡=1234567890}, games=[LOL, BOB], wife='null', info={学号=1950410914, 性别=男} }

6.3 p命名和c命名注入

p命名注入：对应Set注入c命名注入：对应构造器注入

创建一个实体类User 【注意：这里没有有参构造器！】

package com.jl.pojo; public class User { private String name; private int age; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "User{" + "name='" + name + '\'' + ", age=" + age + '}'; } }

P命名注入：需要在头文件中加入约束文件

导入约束 : xmlns:p="http://www.springframework.org/schema/p" <!--P(属性: properties)命名空间 , 属性依然要设置set方法--> <bean id="user" class="com.jl.pojo.User" p:name="李四" p:age="18"/>

C命名注入 (实体类需要有有参构造方法)

导入约束 : xmlns:c="http://www.springframework.org/schema/c" <!-- C命名注入,通过构造器注入, construct-args --> <bean id="user2" class="com.jl.pojo.User" c:age="18" c:name="张三" />

注意：

p命名和c命名空间不能直接使用，需要 导入xml约束！

xmlns:p="http://www.springframework.org/schema/p" xmlns:c="http://www.springframework.org/schema/c"