Spring属性注入的几种方式详解

我会带着你远行 2021-09-24 16:24 326阅读 0赞

项目路径：[https://gitee.com/wuhan1/spring-parent.git][https_gitee.com_wuhan1_spring-parent.git] 下的spring-01  
给各种类型的对象赋值  
Student类和MathTeacher类

package com.xqc;
    
    import java.util.Arrays;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    
    public class Student {
        //学号
        private Integer stuNo;
        //姓名
        private String stuName;
        //爱好
        private List<String> hobbies;
        //性别
        private String[] sexs[];
        //map
        private Map<String,String> mapElement;
        //set
        private Set<String> stEment;
        //数学老师
        private MathTeacher mathTeacher;
        //赋null值
        private String stNull;
        //赋值""
        private String str;
    
        public Integer getStuNo() {
            return stuNo;
        }
    
        public void setStuNo(Integer stuNo) {
            this.stuNo = stuNo;
        }
    
        public String getStuName() {
            return stuName;
        }
    
        public void setStuName(String stuName) {
            this.stuName = stuName;
        }
    
        public void setHobbies(List<String> hobbies) {
            this.hobbies = hobbies;
        }
    
        public void setSexs(String[][] sexs) {
            this.sexs = sexs;
        }
    
        public void setMapElement(Map<String, String> mapElement) {
            this.mapElement = mapElement;
        }
    
        public MathTeacher getMathTeacher() {
            return mathTeacher;
        }
    
        public void setMathTeacher(MathTeacher mathTeacher) {
            this.mathTeacher = mathTeacher;
        }
    
        public Set<String> getStEment() {
            return stEment;
        }
    
        public void setStEment(Set<String> stEment) {
            this.stEment = stEment;
        }
    
        public Student(Integer stuNo, String stuName) {
            this.stuNo = stuNo;
            this.stuName = stuName;
        }
    
        public Student() {
        }
    
        public String getStNull() {
            return stNull;
        }
    
        public void setStNull(String stNull) {
            this.stNull = stNull;
        }
    
        public String getStr() {
            return str;
        }
    
        public void setStr(String str) {
            this.str = str;
        }
    
        @Override
        public String toString() {
            return "Student{" +
                    "stuNo=" + stuNo +
                    ", stuName='" + stuName + '\'' +
                    ", hobbies=" + hobbies +
                    ", sexs=" + Arrays.toString(sexs) +
                    ", mapElement=" + mapElement +
                    ", stEment=" + stEment +
                    ", mathTeacher=" + mathTeacher +
                    ", stNull='" + stNull + '\'' +
                    ", str='" + str + '\'' +
                    '}';
        }
    }

package com.xqc;
    //数学老师
    public class MathTeacher {
        //姓名
        private String tccName;
        //年龄
        private Integer age;
    
        public String getTccName() {
            return tccName;
        }
    
        public void setTccName(String tccName) {
            this.tccName = tccName;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public MathTeacher(String tccName, Integer age) {
            this.tccName = tccName;
            this.age = age;
        }
    
        public MathTeacher() {
        }
    
        @Override
        public String toString() {
            return "MathTeacher{" +
                    "tccName='" + tccName + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

1.set方式，applicationContext配置

其中List,Set,数组都可以用list的方式赋值，但最好各自对应  
![20200914225358655.png][]

2.构造器方式，可以指定name属性或者index

<bean id="student2" class="com.xqc.Student">
            
            <constructor-arg value="111119" index="0" ></constructor-arg>
            <constructor-arg value="赵老师" index="1"></constructor-arg>
        </bean>

3.p名称空间注入，需要引入p标签空间  
![2020091423100772.png][]

<bean id="student3" class="com.xqc.Student" p:stuNo="14444" p:stuName="黄老师"></bean>

4.自动装配，使用autowire

byName:本质就是通过ID，在容器中找bean的id与student中的引用类型mathTeacher一致的名称  
byType:会自动根据autowire找到容器中的其他bean，是否与student中的引用类型MathTeacher类型一致的，有则自动注入，如果有重复的则报错，比如  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RoajE5OTE4MQ_size_16_color_FFFFFF_t_70][]

![20200914232303678.png][]

[https_gitee.com_wuhan1_spring-parent.git]: https://gitee.com/wuhan1/spring-parent.git
[20200914225358655.png]: /images/20210923/952eafe5614e45aab9610ae83841e5dd.png
[2020091423100772.png]: /images/20210923/63340c3b151245ffaca308c5daf75103.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2RoajE5OTE4MQ_size_16_color_FFFFFF_t_70]: /images/20210923/5538db1c04394884a31666f1498adb40.png
[20200914232303678.png]: /images/20210923/d52db51444844f548a3ad9934f1bb962.png