spring实例化bean的方式

一、通过set方法实例化bean(set注入、使用property标签赋值)

bean：

package scope;

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class bean2 {
    private Integer id;
    private String name;
    private String[] fatherAndMother;
    private double source;
    private Map<String,String> shu;
    private List<String> home;
    private Set<String> xueLi;
    private bean1 bean;

    public bean2() {
    }

    public bean2(Integer id, String name, String[] fatherAndMother, double source, Map<String, String> shu, List<String> home, Set<String> xueLi, bean1 bean) {
        this.id = id;
        this.name = name;
        this.fatherAndMother = fatherAndMother;
        this.source = source;
        this.shu = shu;
        this.home = home;
        this.xueLi = xueLi;
        this.bean = bean;
    }

    @Override
    public String toString() {
        return "bean2{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ",\n fatherAndMother=" + Arrays.toString(fatherAndMother) +
                ",\n source=" + source +
                ",\n shu=" + shu +
                ",\n home=" + home +
                ",\n xueLi=" + xueLi +
                ",\n bean=" + bean +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String[] getFatherAndMother() {
        return fatherAndMother;
    }

    public void setFatherAndMother(String[] fatherAndMother) {
        this.fatherAndMother = fatherAndMother;
    }

    public double getSource() {
        return source;
    }

    public void setSource(double source) {
        this.source = source;
    }

    public Map<String, String> getShu() {
        return shu;
    }

    public void setShu(Map<String, String> shu) {
        this.shu = shu;
    }

    public List<String> getHome() {
        return home;
    }

    public void setHome(List<String> home) {
        this.home = home;
    }

    public Set<String> getXueLi() {
        return xueLi;
    }

    public void setXueLi(Set<String> xueLi) {
        this.xueLi = xueLi;
    }

    public bean1 getBean() {
        return bean;
    }

    public void setBean(bean1 bean) {
        this.bean = bean;
    }
}

在xml中对bean进行注入

	<bean class="scope.bean2" id="bean2">

        <!--当属性类型为基本数据类型的时候，赋值使用value-->
        <property name="id" value="13"></property>
        <property name="source" value="13.14"></property>
        <property name="name" value="张三"></property>


        <!--当属性为另外的一个bean的实例的时候，使用ref进行赋值，ref的值为对应bean的ID-->
        <property name="bean" ref="bean1"></property>


        <!--给list类型赋值的时候，使用内部标签进行赋值-->
        <!--当使用标签进行赋值的时候不需要再标签中为字符串加双引号-->
        <property name="home">
            <list>
                <value>张三</value>
                <value>李四</value>
                <value>王五</value>
                <value>麻子</value>
            </list>
        </property>
        
        
        <!--使用array标签为数组赋值-->
        <property name="fatherAndMother">
            <array>
                <value>阿大</value>
                <value>阿二</value>
            </array>
        </property>

        
        <!--使用map标签为map类型赋值，一个entry标签中包含了一个键值对-->
        <property name="shu">
            <map>
                <entry>
                    <key>
                        <value>阿尔法</value>
                    </key>
                    <value>作者：王五</value>
                </entry>

                <entry>
                    <key>
                        <value>思途来登</value>
                    </key>
                    <value>作者：麻子</value>
                </entry>
            </map>
        </property>

        
        <!--使用set标签为set类型赋值-->
        <property name="xueLi">
            <set>
                <value>我们都是中国人</value>
                <value>健健康康成长</value>
            </set>
        </property>
    </bean>

二、通过构造方法实例化bean（构造方法注入、使用）

bean：

package scope;

public class bean3 {
    private int age;
    private String name;

    public bean3() {
    }

    public bean3(int age, String name) {
        this.age = age;
        this.name = name;
    }

    @Override
    public String toString() {
        return "bean3{" +
                "age=" + age +
                ", name='" + name + '\'' +
                '}';
    }

}

在xml中对bean进行注入：

<bean class="scope.bean3" id="bean23">
        <constructor-arg value="12"></constructor-arg>
        <constructor-arg value="zhangsan"></constructor-arg>
   </bean>

如果constructor-arg与构造器顺序不一致，可以通过index或者name属性进行调整。

三、使用标签进行注入（c标签、p标签）

bean：

package scope;

public class bean3 {
    private int age;
    private String name;

    public bean3() {
    }

    public bean3(int age, String name) {
        this.age = age;
        this.name = name;
    }

    @Override
    public String toString() {
        return "bean3{" +
                "age=" + age +
                ", name='" + name + '\'' +
                '}';
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

1. 加入c标签和p标签的命名空间

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

2. 使用c标签进行赋值（constructor-arg，使用c标签也就是使用构造方法进行注入，所以必须要有对应的构造方法）

   <bean class="scope.bean3" id="bean3"
   c:age="12"
   c:name="张三"/>
   

3. 使用p标签进行赋值（property，使用p标签也就是使用set注入，bean必须要有set方法）

   <bean class="scope.bean3" id="bean3"
   p:age="12"
   p:name="李四"
   />