2.2 依赖注入 - 依赖注入 - 《Java企业级框架》

1. 有参构造函数注入
- 1.1 搭建环境
- 1.2 测试结果
2. set方法注入
3. 拓展方式注入
- 3.1 p命名空间
- 3.2 c命名空间

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。
具体可以查看官方文档

1. 有参构造函数注入

1.1 搭建环境

public class User {
    private String name;
    public User(String name) {
        this.name = name;
        System.out.println("User类的有参构造函数被调用");
    }
    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                '}';
    }
}

<?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.comprehensive.pojo.User">
        <constructor-arg name="name" value="comprehensive"/>
        <!--<constructor-arg index="0" value="comprehensive"/>-->
    </bean>
</beans>

public class Test_User {
    @Test
    public void test() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        User user = context.getBean("user", User.class);
        System.out.println(user);
    }
}

1.2 测试结果

2. set方法注入

2.1 搭建环境

//Adress实体类
public class Address {

    private String address;

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "Address{" +
                "address='" + address + '\'' +
                '}';
    }
}

//Student实体类
public class Student {

    private String name;
    private Address address;
    private String[] books;
    private List<String> hobbies;
    private Map<String,String> card;
    private Set<String> games;
    private String wife;
    private Properties info;

    public void setName(String name) {
        this.name = name;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public void setBooks(String[] books) {
        this.books = books;
    }

    public void setHobbies(List<String> hobbies) {
        this.hobbies = hobbies;
    }

    public void setCard(Map<String, String> card) {
        this.card = card;
    }

    public void setGames(Set<String> games) {
        this.games = games;
    }

    public void setWife(String wife) {
        this.wife = wife;
    }

    public void setInfo(Properties info) {
        this.info = info;
    }

    public String getName() {
        return name;
    }

    public Address getAddress() {
        return address;
    }

    public String[] getBooks() {
        return books;
    }

    public List<String> getHobbies() {
        return hobbies;
    }

    public Map<String, String> getCard() {
        return card;
    }

    public Set<String> getGames() {
        return games;
    }

    public String getWife() {
        return wife;
    }

    public Properties getInfo() {
        return info;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", address=" + address +
                ", books=" + Arrays.toString(books) +
                ", hobbies=" + hobbies +
                ", card=" + card +
                ", games=" + games +
                ", wife='" + wife + '\'' +
                ", info=" + info +
                '}';
    }
}

2.2 常量注入

<?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="address" class="com.comprehensive.pojo.Address">
        <property name="address" value="572456720@qq.com"/>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test1() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Address address = context.getBean("address", Address.class);
        System.out.println(address);
    }
}

2.3 bean ref注入

<?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">

    <!-- 常量注入 -->
    <bean id="address" class="com.comprehensive.pojo.Address">
        <property name="address" value="572456720@qq.com"/>
    </bean>

    <!-- bean ref注入 -->
    <bean id="student1" class="com.comprehensive.pojo.Student">
        <property name="address" ref="address"/>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test2() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = context.getBean("student1", Student.class);
        System.out.println(student.getAddress());
    }
}

2.4 array注入

<?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">

    <!-- array注入 -->
    <bean id="student2" class="com.comprehensive.pojo.Student">
        <property name="books">
            <array>
                <value>西游记</value>
                <value>红楼梦</value>
                <value>水浒传</value>
            </array>
        </property>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test3() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = context.getBean("student2", Student.class);
        System.out.println(Arrays.toString(student.getBooks()));
    }
}

2.5 list注入

<?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">

    <!-- list注入 -->
    <bean id="student3" class="com.comprehensive.pojo.Student">
        <property name="hobbies">
            <list>
                <value>听歌</value>
                <value>看电影</value>
                <value>爬山</value>
            </list>
        </property>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test4() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = context.getBean("student3", Student.class);
        System.out.println(student.getHobbies());
    }
}

2.6 map注入

<?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">

    <!-- map注入 -->
    <bean id="student4" class="com.comprehensive.pojo.Student">
        <property name="card">
            <map>
                <entry key="中国邮政" value="456456456465456"/>
                <entry key="建设" value="1456682255511"/>
            </map>
        </property>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test5() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = context.getBean("student4", Student.class);
        System.out.println(student.getCard());
    }
}

2.7 set注入

<?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">

    <!-- set注入 -->
    <bean id="student5" class="com.comprehensive.pojo.Student">
        <property name="games">
            <set>
                <value>LOL</value>
                <value>BOB</value>
                <value>COC</value>
            </set>
        </property>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test6() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = context.getBean("student5", Student.class);
        System.out.println(student.getGames());
    }
}

2.8 null注入

<?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">

    <!-- null注入 -->
    <bean id="student6" class="com.comprehensive.pojo.Student">
        <property name="wife"><null/></property>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test7() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = context.getBean("student6", Student.class);
        System.out.println(student.getWife());
    }
}

2.9 properties注入

<?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">

    <!-- properties注入 -->
    <bean id="student7" class="com.comprehensive.pojo.Student">
        <property name="info">
            <props>
                <prop key="学号">20190604</prop>
                <prop key="性别">男</prop>
                <prop key="姓名">小明</prop>
            </props>
        </property>
    </bean>

</beans>

public class Test_DI {
    @Test
    public void test8() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = context.getBean("student7", Student.class);
        System.out.println(student.getInfo());
    }
}

3. 拓展方式注入

3.1 p命名空间

public class User {
    private String name;
    private int age;

    public void setName(String name) {
        this.name = name;
        System.out.println("setName方法被调用[set方法注入]");
    }

    public void setAge(int age) {
        this.age = age;
        System.out.println("setAge方法被调用[set方法注入]");
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

<?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">

    <!-- p命名空间 注入 -->
    <bean id="user1" class="com.comprehensive.pojo.User" p:name="comprehensive" p:age="22"/>

</beans>

public class Test_DI {
    @Test
    public void test9() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans_p.xml");
    }
}

3.2 c命名空间

public class User {
    private String name;
    private int age;

    public User(String name, int age) {
        this.name = name;
        this.age = age;
        System.out.println("有参构造函数被调用[有参构造函数注入]");
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

<?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:c="http://www.springframework.org/schema/c"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- c命名空间 注入 -->
    <bean id="user2" class="com.comprehensive.pojo.User" c:name="comprehensive" c:age="22"/>

</beans>

public class Test_DI {
    @Test
    public void test10() {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans_c.xml");
    }
}