SpringBoot获取配置中的数据

不念不忘少年蓝@ 2024-03-31 17:50 33阅读 0赞

## SpringBoot获取配置中的数据 ##

简介:本文通过案例讲解SpringBoot如何`yaml`,`yml`,`properties`中的数据。

### 方法 ###

1.`@Value`  
2. `Environment`  
3. `@ConfigurationProperties`

### 环境准备 ###

![在这里插入图片描述][0f8e0d0f35c84bb99998ed38dc0e2dbb.png]

name: abc
    
    # 对象
    person:
      name: LIHUA
      age: 20
    
    # 对象行内写法
    person1: {name: zhangsan, age: 20}
      
    # 数组
    address:
      - beijing
      - shanghai
    
    # 数组的行内写法
    address1: [wodetian, fangdefa]
      
    # 纯量
    msg1: 'hello \n lihua'
    msg2: "hello \n lihua"

### @Value ###

**学习代码**

package com.example.springbootstudy;
    
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class HelloController {
        
        @Value("${name}")
        private String name;
    
        @Value("${person.name")
        private String name2;
    
        @Value("${person.age}")
        private int age;
    
        @Value("$address[0]")
        private String address1;
    
        @Value("${msg1}")
        private String msg1;
        @Value("${msg2}")
        private String msg2;
        @RequestMapping("/hello2")
        public String hello2(){
        
            System.out.println(name);
            System.out.println(name2);
            System.out.println(age);
            System.out.println(address1);
            System.out.println(address1);
            System.out.println(msg1);
            System.out.println(msg2);
            return "hello Spring Boot";
        }
        @RequestMapping("/hello")
        public String hello(){
        
            return "Hello World";
        }
    }

**运行结果**  
![在这里插入图片描述][5be62d48cb4a48c7b5c8537e02605844.png]  
![在这里插入图片描述][c080f12b18ea4944a16f7bc16ec8a418.png]

![在这里插入图片描述][55a862174a9f4b8696e0d94363ec5d46.png]

### Environment ###

**学习代码**

package com.example.springbootstudy;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.core.env.Environment;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class HelloController {
        
    
        @Autowired
        private Environment env;
    
        @RequestMapping("/hello2")
        public String hello2(){
        
            System.out.println(env.getProperty("name"));
            System.out.println(env.getProperty("person.name"));
            System.out.println(env.getProperty("address[0]"));
            return "hello Spring Boot";
        }
        @RequestMapping("/hello")
        public String hello(){
        
            return "Hello World";
        }
    }

**运行结果**  
![在这里插入图片描述][612165ff317b48e08d683cf80195cacd.png]  
![在这里插入图片描述][ca3a87cd10f64d7a86fbace25704f094.png]

### @ConfigurationProperties ###

**文件结构**  
![在这里插入图片描述][8d00e8a939a643f4844f154da19c3e01.png]

**学习代码**

#### Person ####

package com.example.springbootstudy;
    
    import org.springframework.boot.context.properties.ConfigurationProperties;
    import org.springframework.stereotype.Component;
    
    import java.util.Arrays;
    
    @Component
    @ConfigurationProperties(prefix = "person") // 这种方式需要定义前缀 然后才能在yml中找到正确的位置
    // 这种方式是 自动化配对所以需要yml中的数据与Person类中的一致
    public class Person {
        
        private String name;
        private int age;
        private String [] address;
    
        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;
        }
    
        public String[] getAddress() {
        
            return address;
        }
    
        public void setAddress(String[] address) {
        
            this.address = address;
        }
    
        @Override
        public String toString() {
        
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    ", address=" + Arrays.toString(address) +
                    '}';
        }
    }

#### HelloController ####

package com.example.springbootstudy;
    
        import org.springframework.beans.factory.annotation.Autowired;
        import org.springframework.beans.factory.annotation.Value;
        import org.springframework.core.env.Environment;
        import org.springframework.web.bind.annotation.RequestMapping;
        import org.springframework.web.bind.annotation.RestController;
    
        @RestController
        public class HelloController {
        
    
            @Autowired
            private Person person;
            @RequestMapping("/hello2")
            public String hello2(){
        
    
                System.out.println(person);
                System.out.println(person.getName());
                System.out.println(person.getAge());
                return "hello Spring Boot";
            }
            @RequestMapping("/hello")
            public String hello(){
        
                return "Hello World";
            }
        }

**运行结果**  
![在这里插入图片描述][6bd878c8908a446e911b540f3da19e9f.png]  
![在这里插入图片描述][18fbe54b867541ea976a9ed261d73266.png]

## 合并集合 ##

一共有 n 个数，编号是 1∼n，最开始每个数各自在一个集合中。

现在要进行 m 个操作，操作共有两种：

M a b，将编号为 a 和 b 的两个数所在的集合合并，如果两个数已经在同一个集合中，则忽略这个操作；  
Q a b，询问编号为 a 和 b 的两个数是否在同一个集合中；  
输入格式  
第一行输入整数 n 和 m。

接下来 m 行，每行包含一个操作指令，指令为 M a b 或 Q a b 中的一种。

输出格式  
对于每个询问指令 Q a b，都要输出一个结果，如果 a 和 b 在同一集合内，则输出 Yes，否则输出 No。

每个结果占一行。

数据范围  
1≤n,m≤105  
输入样例：  
4 5  
M 1 2  
M 3 4  
Q 1 2  
Q 1 3  
Q 3 4  
输出样例：  
Yes  
No  
Yes

**提交代码**

#include<iostream>
    using namespace std;
    
    const int N = 100010;
    int n, m;
    int p[N];
    
    int find(int x)                 // 找到x的祖先节点
    {
        
        if (p[x] != x) p[x] = find(p[x]);
        return p[x];
    }
    
    int main()
    {
        
        scanf("%d %d", &n, &m);
        for (int i = 1; i <= n; ++i) p[i] = i;
        
        while (m--)
        {
        
            char op;
            int a, b;
            scanf (" %c%d%d", &op, &a, &b);
            if (op == 'M') p[p[find(a)]] = find(b);        // 让a的祖先节点指向b的祖先节点
            else
            {
        
                if (find(a) == find(b)) puts("Yes");
                else puts("No");
            }
        }
        return 0;
    }

import java.io.*;
    
    public class Main
    {
        
        static int N = 100010;
        static int n, m;
        static int [] p = new int [N];
        
        static int find(int x)
        {
        
            if (p[x] != x) p[x] = find(p[x]);
            return p[x];
        }
        
        public static void main(String[] args) throws IOException
        {
        
            BufferedReader reader = new BufferedReader(new InputStreamReader (System.in));   
            String [] str = reader.readLine().split(" ");
            n = Integer.parseInt(str[0]);
            m = Integer.parseInt(str[1]);
            
            for (int i = 1; i <= n; ++ i) p[i] = i;
            while (m -- > 0)
            {
        
                String op;
                int a, b;
                str = reader.readLine().split(" ");
                op = str[0];
                a = Integer.parseInt(str[1]);
                b = Integer.parseInt(str[2]);
                if (op.equals("M")) p[find(a)] = find(b);
                else 
                {
        
                    if (find(a) == find(b)) System.out.println("Yes");
                    else System.out.println("No");
                }
            }
        }
    }

[0f8e0d0f35c84bb99998ed38dc0e2dbb.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/617114be6a954772ba9b6a2b6b7f7f9b.png
[5be62d48cb4a48c7b5c8537e02605844.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/ea4cf3b701eb49a5bf14692efb7b02c9.png
[c080f12b18ea4944a16f7bc16ec8a418.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/8c8946a82f9c47ab8499d0371fadf6e4.png
[55a862174a9f4b8696e0d94363ec5d46.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/3340339255c34ff997df963ff54c998b.png
[612165ff317b48e08d683cf80195cacd.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/38b17f826cd64c72b4c9293aeb3bf434.png
[ca3a87cd10f64d7a86fbace25704f094.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/0d2ddf30f256476a9910155950d1a78e.png
[8d00e8a939a643f4844f154da19c3e01.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/57f9a74101b447ac96ae77c6a8452dc6.png
[6bd878c8908a446e911b540f3da19e9f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/bbeb25239db34445a94c08e865d8ece8.png
[18fbe54b867541ea976a9ed261d73266.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/e46206fb7289443d98d2e1ed35421e65.png