【Spring Boot】004-给属性赋值的几种方式

缺乏、安全感 2023-10-05 09:57 41阅读 0赞

# 一、原生的Spring方式 #

### 使用@Value注解赋值： ###

package com.zibo.pojo;
    
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.stereotype.Component;
    
    @Component
    public class Dog {
        @Value("旺财")
        private String name;
        @Value("2")
        private int age;
    
        public Dog() {
        }
    
        public Dog(String name, int age) {
            this.name = name;
            this.age = 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 "Dog{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

### 修改springboot默认测试类： ###

package com.zibo;
    
    import com.zibo.pojo.Dog;
    import org.junit.jupiter.api.Test;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.test.context.SpringBootTest;
    
    @SpringBootTest
    class StudySpringBootApplicationTests {
    
    	@Autowired
    	private Dog dog;
    
    	@Test
    	void contextLoads() {
    		System.out.println(dog);
    	}
    
    }

### 测试结果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70][]

# 二、通过yaml赋值 #

### 编写Person实体类： ###

package com.zibo.pojo;
    
    import org.springframework.boot.context.properties.ConfigurationProperties;
    import org.springframework.stereotype.Component;
    
    import java.util.Date;
    import java.util.List;
    import java.util.Map;
    
    /*
        @ConfigurationProperties作用：
        将配置文件中配置的每一个属性的值，映射到这个组件中；
        告诉SpringBoot将本类中的所有属性和配置文件中相关的配置进行绑定
        参数 prefix = “person” : 将配置文件中的person下面的所有属性一一对应
    */
    @Component
    @ConfigurationProperties(prefix = "person") //绑定配置文件里面的配置
    public class Person {
        private String name;
        private Integer age;
        private Boolean happy;
        private Date birth;
        private Map<String,Object> map;
        private List<Object> list;
        private Dog dog;
    
        public Person() {
        }
    
        public Person(String name, Integer age, Boolean happy, Date birth, Map<String, Object> map, List<Object> list, Dog dog) {
            this.name = name;
            this.age = age;
            this.happy = happy;
            this.birth = birth;
            this.map = map;
            this.list = list;
            this.dog = dog;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Boolean getHappy() {
            return happy;
        }
    
        public void setHappy(Boolean happy) {
            this.happy = happy;
        }
    
        public Date getBirth() {
            return birth;
        }
    
        public void setBirth(Date birth) {
            this.birth = birth;
        }
    
        public Map<String, Object> getMap() {
            return map;
        }
    
        public void setMap(Map<String, Object> map) {
            this.map = map;
        }
    
        public List<Object> getList() {
            return list;
        }
    
        public void setList(List<Object> list) {
            this.list = list;
        }
    
        public Dog getDog() {
            return dog;
        }
    
        public void setDog(Dog dog) {
            this.dog = dog;
        }
    
        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    ", happy=" + happy +
                    ", birth=" + birth +
                    ", map=" + map +
                    ", list=" + list +
                    ", dog=" + dog +
                    '}';
        }
    }

### 编写application.yaml配置文件： ###

person:
      name: 訾博
      age: 24
      happy: true
      birth: 1996/04/27
      map: {k1: v1,k2: v2}
      list: [学习,运动,社交]
      dog:
        name: 豆子
        age: 3

### 修改测试类： ###

package com.zibo;
    
    import com.zibo.pojo.Dog;
    import com.zibo.pojo.Person;
    import org.junit.jupiter.api.Test;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.test.context.SpringBootTest;
    
    @SpringBootTest
    class StudySpringBootApplicationTests {
    
    	@Autowired
    	private Dog dog;
    
    	@Autowired
    	private Person person;
    
    	@Test
    	void contextLoads() {
    		System.out.println(dog);
    		System.out.println(person);
    	}
    
    }

### 测试结果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 1][]

# 三、加载指定的配置文件 #

### 新建配置文件my.properties： ###

name = zibo

### 修改Person类： ###

package com.zibo.pojo;
    
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.boot.context.properties.ConfigurationProperties;
    import org.springframework.context.annotation.PropertySource;
    import org.springframework.stereotype.Component;
    
    import java.util.Date;
    import java.util.List;
    import java.util.Map;
    
    /*
        @ConfigurationProperties作用：
        将配置文件中配置的每一个属性的值，映射到这个组件中；
        告诉SpringBoot将本类中的所有属性和配置文件中相关的配置进行绑定
        参数 prefix = “person” : 将配置文件中的person下面的所有属性一一对应
    */
    @Component
    @PropertySource("classpath:my.properties")
    //@ConfigurationProperties(prefix = "person") //绑定配置文件里面的配置
    public class Person {
        @Value("${name}")
        private String name;
        private Integer age;
        private Boolean happy;
        private Date birth;
        private Map<String,Object> map;
        private List<Object> list;
        private Dog dog;
    
        public Person() {
        }
    
        public Person(String name, Integer age, Boolean happy, Date birth, Map<String, Object> map, List<Object> list, Dog dog) {
            this.name = name;
            this.age = age;
            this.happy = happy;
            this.birth = birth;
            this.map = map;
            this.list = list;
            this.dog = dog;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Boolean getHappy() {
            return happy;
        }
    
        public void setHappy(Boolean happy) {
            this.happy = happy;
        }
    
        public Date getBirth() {
            return birth;
        }
    
        public void setBirth(Date birth) {
            this.birth = birth;
        }
    
        public Map<String, Object> getMap() {
            return map;
        }
    
        public void setMap(Map<String, Object> map) {
            this.map = map;
        }
    
        public List<Object> getList() {
            return list;
        }
    
        public void setList(List<Object> list) {
            this.list = list;
        }
    
        public Dog getDog() {
            return dog;
        }
    
        public void setDog(Dog dog) {
            this.dog = dog;
        }
    
        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    ", happy=" + happy +
                    ", birth=" + birth +
                    ", map=" + map +
                    ", list=" + list +
                    ", dog=" + dog +
                    '}';
        }
    }

### 测试结果： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 2][]

### 备注： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 3][]

**yaml中还有很多其他配置属性的写法，比如：**

person:
        name: qinjiang${random.uuid} # 随机uuid
        age: ${random.int}  # 随机int
        happy: false
        birth: 2000/01/01
        maps: {k1: v1,k2: v2}
        lists:
          - code
          - girl
          - music
        dog:
          name: ${person.hello:other}_旺财
          age: 1

# 四、对比小结 #

@Value这个使用起来并不友好！我们需要为每个属性单独注解赋值，比较麻烦；我们来看个功能对比图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 4][]

1、@ConfigurationProperties只需要写一次即可 ， @Value则需要每个字段都添加；
    
    2、松散绑定：这个什么意思呢? 比如我的yml中写的last-name，这个和lastName是一样的， - 后面跟着的字母默认是大写的。这就是松散绑定。可以测试一下；
    
    3、JSR303数据校验 ， 这个就是我们可以在字段是增加一层过滤器验证 ， 可以保证数据的合法性；
    
    4、复杂类型封装，yml中可以封装对象 ， 使用value就不支持；

### 结论： ###

配置yml和配置properties都可以获取到值 ， 强烈推荐 yml；

如果我们在某个业务中，只需要获取配置文件中的某个值，可以使用一下 @value；

如果说，我们专门编写了一个JavaBean来和配置文件进行一一映射，就直接@configurationProperties，不要犹豫！

**yaml 和 yml 是一个意思。**

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