3.1 ConfigurationProperties应用形式

3.1.1. 步骤

@Component+@ConfigurationProperties(prefix="person")

person是在yml中配置的前缀: person: ...

3.1.2. 样例

(1). maven依赖
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0"         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0</modelVersion>    <groupId>com.niewj</groupId>    <artifactId>springboot-study</artifactId>    <version>1.0-SNAPSHOT</version>    <properties>        <spring-boot-version>2.3.2.RELEASE</spring-boot-version>    </properties>    <modules>        <module>springboot-01-helloworld</module>    </modules>    <!-- 示意是一个pom总的父工程 -->    <packaging>pom</packaging>    <dependencies>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-parent</artifactId>            <version>${spring-boot-version}</version>        </dependency>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-web</artifactId>            <version>${spring-boot-version}</version>        </dependency>        <!-- springboot测试用例须要的依赖 -->        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-test</artifactId>            <version>${spring-boot-version}</version>        </dependency>        <!-- ConfigurationProperties属性配置工具依赖 -->        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-configuration-processor</artifactId>            <version>${spring-boot-version}</version>        </dependency>        <!-- json依赖 -->        <dependency>            <groupId>com.google.code.gson</groupId>            <artifactId>gson</artifactId>            <version>2.8.6</version>        </dependency>        <dependency>            <groupId>org.projectlombok</groupId>            <artifactId>lombok</artifactId>            <version>1.18.12</version>        </dependency>    </dependencies>    <build>        <plugins>            <!-- 解决 ConfigurationProperties报错 -->            <plugin>                <groupId>org.springframework.boot</groupId>                <artifactId>spring-boot-maven-plugin</artifactId>                <configuration>                    <excludes>                        <exclude>                            <groupId>org.springframework.boot</groupId>                            <artifactId>spring-boot-configuration-processor</artifactId>                        </exclude>                    </excludes>                </configuration>            </plugin>        </plugins>    </build></project>

(2). 样例之:person.java

package com.niewj.springboot.model;import lombok.Data;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.stereotype.Component;import java.util.Date;import java.util.List;import java.util.Map;/** * Created by niewj on 2020/8/5 0:01 */@Data@Component@ConfigurationProperties(prefix = "person")public class Person {    private String lastName;    private Integer age;    private Boolean male;    private Date birth;    private Map<String, Object> maps;    private List<Object> lists;    private Dog dog;}

(3). Dog.java

package com.niewj.springboot.model;import lombok.Data;/** * Created by niewj on 2020/8/5 0:04 */@Datapublic class Dog {    private String name;    private Integer age;}

(4). application.yml

server:  port: 8888person:  lastName: 张三  age: 33  male: true  birth: 1985/03/03  maps: {k1: v1, k2: 20, k3: true}  lists:    - lisi    - wangwu  dog:    name: 小黑    age: 3

(5). 测试用例:

package com.niewj.springboot;import com.google.gson.Gson;import com.niewj.springboot.model.Person;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;import org.springframework.test.context.junit4.SpringRunner;/** * Created by niewj on 2020/8/5 0:19 */@RunWith(SpringRunner.class)@SpringBootTestpublic class TestProperties {    @Autowired    private Person person;    @Test    public void printPerson(){        System.out.println(new Gson().toJson(person));    }}

(6). 输入:

{    "lastName": "张三",    "age": 33,    "male": true,    "birth": "Mar 3, 1985 12:00:00 AM",    "maps": {        "k1": "v1",        "k2": 20,        "k3": true    },    "lists": ["lisi", "wangwu"],    "dog": {        "name": "小黑",        "age": 3    }}

3.2 @ConfigurationProperties 和 @Value比拟

3.2.1 @ConfiguratonProperties

  1. 适宜场景: 批量注入配置文件中的属性;

  2. 反对 Relax-Binding(送伞绑定);

    如 Person.firstName 匹配:

    person.first-name

    person.first_name

    person.firstName

    PERSON_FIRST_NAME

  3. 不反对spEL表达式;
  4. JSR303 数据校验反对;
  5. 反对简单类型: 能够取到 maps 的值;

3.2.2 @Value

  1. 适宜场景: 一个一个指定配置属性;
  2. 不反对 Relax-Binding (涣散绑定);
  3. 反对spEL;

    如 @Value("#{20*2}") // 会计算出 40赋值给字段属性

  4. 不反对JSR303数据校验;
  5. @Value取不到 maps 的值(不反对简单类型)