详解SpringDI依赖注入的方式和类型

public interface StudentDao {
  Student findById(int id);
}
public class StudentDaoImpl implements StudentDao{
  @Override
  public Student findById(int id) {
    // 模拟根据id查询学生
    return new Student(1,"程序员","北京");
 }
}
public class StudentService {
   // service依赖dao，手动注入属性值，即手动维护依赖关系
  private StudentDao studentDao = new StudentDaoImpl();
  public Student findStudentById(int id){
    return studentDao.findById(id);
 }
}

    public void setStudentDao(StudentDao studentDao){
        this.studentDao = studentDao;
    }

<bean id="studentDao" class="com.itbaizhan.dao.StudentDaoImpl"> </bean>
<bean id="studentService" class="com.itbaizhan.service.StudentService">
  <!--依赖注入-->
  <!--name:对象的属性名 ref:容器中对象的id值-->
  <property name="studentDao" ref="studentDao"></property>
</bean>

    // 测试依赖注入
    @Test
    public void t6(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        StudentService service = (StudentService) ac.getBean("studentService");
        System.out.println(service.findStudentById(8));
    }

    public StudentService(StudentDao studentDao){
        this.studentDao = studentDao;
    }

<bean id="studentDao" class="com.itbaizhan.dao.StudentDaoImpl"></bean>
<bean id="studentService" class="com.itbaizhan.service.StudentService">
  <!-- 依赖注入 -->
  <!-- name:对象的属性名 ref：配置文件中注入对象的id值 -->
  <constructor-arg name="studentDao" ref="studentDao"></constructor-arg>
</bean>

package com.example.service;
import com.example.dao.StudentDao;
import com.example.pojo.Student;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
public class StudentService {
    // service依赖dao，手动注入属性值，即手动维护依赖关系
    //private StudentDao studentDao;
    // bean属性
    private StudentDao studentDao;
    // 字符串类型
    private String name;
    // 基本数据类型
    private int count;
    // 字符串List集合
    private List<String> students1;
    // 对象类型List集合
    private List<Student> nameList;
    // 字符串类型Set集合
    private Set<String> students2;
    // 字符串类型Map集合
    private Map<String, String> students3;
    // 对象类型map集合
    private Map<String,Student> studentMap;
    // Properties类型
    private Properties properties;
    public StudentService(){}
    public StudentService(StudentDao studentDao){
        this.studentDao = studentDao;
    }
    public Student findStudentById(int id){
        return studentDao.findById(id);
    }
    public void setStudentDao(StudentDao studentDao){
        this.studentDao = studentDao;
    }
    public StudentDao getStudentDao() {
        return studentDao;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getCount() {
        return count;
    }
    public void setCount(int count) {
        this.count = count;
    }
    public List<String> getStudents1() {
        return students1;
    }
    public void setStudents1(List<String> students1) {
        this.students1 = students1;
    }
    public Set<String> getStudents2() {
        return students2;
    }
    public void setStudents2(Set<String> students2) {
        this.students2 = students2;
    }
    public Map<String, String> getNames2() {
        return students3;
    }
    public void setNames2(Map<String, Student> names2) {
        this.studentMap = names2;
    }
    public Map<String, String> getStudents3() {
        return students3;
    }
    public void setStudents3(Map<String, String> students3) {
        this.students3 = students3;
    }
    public Properties getProperties() {
        return properties;
    }
    public void setProperties(Properties properties) {
        this.properties = properties;
    }
    public List<Student> getNameList() {
        return nameList;
    }
    public void setNameList(List<Student> nameList) {
        this.nameList = nameList;
    }
    @Override
    public String toString() {
        return "StudentService[ " +
                "studentDao=" + studentDao +
                ", name='" + name + '\'' +
                ", count=" + count +
                ", students1=" + students1 +
                ", nameList=" + nameList +
                ", students2=" + students2 +
                ", students3=" + students3 +
                ", studentMap=" + studentMap +
                ", properties=" + properties +
                " ]";
    }
}

    // 测试注入类型
    @Test
    public void t7(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        StudentService service = (StudentService) ac.getBean("studentService");
        System.out.println(service);
    }

    <!-- 注入bean类型 -->
    <bean id="studentDao" class="com.example.dao.StudentDaoImpl1"/>
    <!-- 写法1 -->
    <bean id="studentService" class="com.example.service.StudentService">
        <property name="studentDao" ref="studentDao"/>
    </bean>
    <!-- 写法2 -->
    <!--<bean id="studentService" class="com.example.service.StudentService">
        <property name="studentDao">
            <ref bean="studentDao"/>
        </property>
    </bean>-->

        <!-- 注入基本数据类型 -->
        <!-- 写法一 name:属性名 value:属性值 -->
        <property name="name" value="程序员"/>
        <!-- 写法二 name：属性名 value:属性值-->
        <property name="count">
            <value>10</value>
        </property>

    <!-- 注入List集合 -->
        <!-- 简单的数据类型List集合 name:属性名 -->
        <property name="students1" >
            <list>
                <value>上海</value>
                <value>广州</value>
            </list>
        </property>
        <!-- 对象类型的List集合 name:属性名 -->
        <property name="nameList">
            <list>
                <bean class="com.example.pojo.Student">
                    <property name="id" value="1"/>
                    <property name="name" value="几何心凉"/>
                    <property name="address" value="北京"/>
                </bean>
                <bean class="com.example.pojo.Student">
                    <property name="id" value="2"/>
                    <property name="name" value="哈士奇"/>
                    <property name="address" value="上海"/>
                </bean>
            </list>
        </property>

        <!-- 注入Set集合 -->
        <property name="students2">
            <set>
                <value>深圳</value>
                <value>北京</value>
            </set>
        </property>

        <!-- 注入Map集合 -->
        <property name="students3">
            <map>
                <entry key="哈士奇" value="上海"/>
                <entry key="几何心凉" value="北京"/>
            </map>
        </property>
        <!-- 注入对象类型map类型 -->
        <property name="names2">
            <map>
                <entry key="student1" value-ref="s1"/>
                <entry key="student2" value-ref="s2"/>
            </map>
        </property>

    <bean id="s1" class="com.example.pojo.Student">
        <property name="id" value="1"/>
        <property name="name" value="几何心凉"/>
        <property name="address" value="北京"/>
    </bean>
    <bean id="s2" class="com.example.pojo.Student">
        <property name="id" value="2"/>
        <property name="name" value="哈士奇"/>
        <property name="address" value="上海"/>
    </bean>

        <!-- 注入properties -->
        <property name="properties">
            <props>
                <prop key="配置1">值1</prop>
                <prop key="配置2">值2</prop>
            </props>
        </property>