springboot 自定义属性文件拓展名（PropertySourceLoader）

￡神魔★判官ぃ 2022-09-12 02:49 227阅读 0赞

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## springboot 自定义属性文件拓展名（PropertySourceLoader） ##

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**相关类与接口**

**PropertySourceLoader**

public interface PropertySourceLoader {
        String[] getFileExtensions();
    
        List<PropertySource<?>> load(String name, Resource resource) throws IOException;
    }

**PropertiesPropertySourceLoader**

public class PropertiesPropertySourceLoader implements PropertySourceLoader {
        private static final String XML_FILE_EXTENSION = ".xml";
    
        public PropertiesPropertySourceLoader() {
        }
    
        public String[] getFileExtensions() {
            return new String[]{"properties", "xml"};
        }  //加载properties、xml后缀的属性文件
    
        public List<PropertySource<?>> load(String name, Resource resource) throws IOException {
            List<Map<String, ?>> properties = this.loadProperties(resource);
                                              //加载属性文件
            if (properties.isEmpty()) {
                return Collections.emptyList();
            } else {
                List<PropertySource<?>> propertySources = new ArrayList(properties.size());
    
                for(int i = 0; i < properties.size(); ++i) {
                    String documentNumber = properties.size() != 1 ? " (document #" + i + ")" : "";
                    propertySources.add(new OriginTrackedMapPropertySource(name + documentNumber, Collections.unmodifiableMap((Map)properties.get(i)), true));
                }  //转换为List<PropertySource<?>>
    
                return propertySources;
            }
        }
    
        private List<Map<String, ?>> loadProperties(Resource resource) throws IOException {
            String filename = resource.getFilename();
            List<Map<String, ?>> result = new ArrayList();
            if (filename != null && filename.endsWith(".xml")) {
                result.add(PropertiesLoaderUtils.loadProperties(resource));
            } else {
                List<Document> documents = (new OriginTrackedPropertiesLoader(resource)).load();
                documents.forEach((document) -> {
                    result.add(document.asMap());
                });
            }
    
            return result;
        }
    }

**YamlPropertySourceLoader**

public class YamlPropertySourceLoader implements PropertySourceLoader {
        public YamlPropertySourceLoader() {
        }
    
        public String[] getFileExtensions() {
            return new String[]{"yml", "yaml"};
        }  //加载yml、yaml后缀的属性文件
    
        public List<PropertySource<?>> load(String name, Resource resource) throws IOException {
            if (!ClassUtils.isPresent("org.yaml.snakeyaml.Yaml", this.getClass().getClassLoader())) {
                throw new IllegalStateException("Attempted to load " + name + " but snakeyaml was not found on the classpath");
            } else {
                List<Map<String, Object>> loaded = (new OriginTrackedYamlLoader(resource)).load();
                                                   //加载属性文件
                if (loaded.isEmpty()) {
                    return Collections.emptyList();
                } else {
                    List<PropertySource<?>> propertySources = new ArrayList(loaded.size());
    
                    for(int i = 0; i < loaded.size(); ++i) {
                        String documentNumber = loaded.size() != 1 ? " (document #" + i + ")" : "";
                        propertySources.add(new OriginTrackedMapPropertySource(name + documentNumber, Collections.unmodifiableMap((Map)loaded.get(i)), true));
                    }  //转换为List<PropertySource<?>>
    
                    return propertySources;
                }
            }
        }
    }

**PropertySource**

public abstract class PropertySource<T> {
        protected final Log logger;
        protected final String name;
        protected final T source;
    
        public PropertySource(String name, T source) {
            this.logger = LogFactory.getLog(this.getClass());
            Assert.hasText(name, "Property source name must contain at least one character");
            Assert.notNull(source, "Property source must not be null");
            this.name = name;
            this.source = source;
        }
    
        public PropertySource(String name) {
            this(name, new Object());
        }
    
        public String getName() {
        public T getSource() {
    
        public boolean containsProperty(String name) {
            return this.getProperty(name) != null;
        }
    
        @Nullable
        public abstract Object getProperty(String var1);
    
        public boolean equals(@Nullable Object other) {
        public int hashCode() {
        public String toString() {
    
        public static PropertySource<?> named(String name) {
            return new PropertySource.ComparisonPropertySource(name);
        }
    
    **********
    内部类：ComparisonPropertySource
    
        static class ComparisonPropertySource extends PropertySource.StubPropertySource {
            private static final String USAGE_ERROR = "ComparisonPropertySource instances are for use with collection comparison only";
    
            public ComparisonPropertySource(String name) {
                super(name);
            }
    
            public Object getSource() {
                throw new UnsupportedOperationException("ComparisonPropertySource instances are for use with collection comparison only");
            }
    
            public boolean containsProperty(String name) {
                throw new UnsupportedOperationException("ComparisonPropertySource instances are for use with collection comparison only");
            }
    
            @Nullable
            public String getProperty(String name) {
                throw new UnsupportedOperationException("ComparisonPropertySource instances are for use with collection comparison only");
            }
        }
    
    
    **********
    内部类：StubPropertySource
    
        public static class StubPropertySource extends PropertySource<Object> {
            public StubPropertySource(String name) {
                super(name, new Object());
            }
    
            @Nullable
            public String getProperty(String name) {
                return null;
            }
        }
    }

**OriginTrackedMapPropertySource**

public final class OriginTrackedMapPropertySource extends MapPropertySource implements OriginLookup<String> {
        private final boolean immutable;  //默认为false
    
        public OriginTrackedMapPropertySource(String name, Map source) {
            this(name, source, false);
        }
    
        public OriginTrackedMapPropertySource(String name, Map source, boolean immutable) {
            super(name, source);
            this.immutable = immutable;
        }
    
        public Object getProperty(String name) {
        public Origin getOrigin(String name) {
    
        public boolean isImmutable() {

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**示例：自定义加载json后缀的属性文件加载器**

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**配置文件**

**application.json**

{
      "person.name": "瓜田李下",
      "person.age": 20
    }

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**pojo 层**

**Person**

@Data
    @Component
    @ConfigurationProperties("person")
    public class Person {
    
        private String name;
        private Integer age;
    }

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**config 层**

**CustomPropertySource**

public class CustomPropertySourceLoader implements PropertySourceLoader {
    
        @Override
        public String[] getFileExtensions() {
            return new String[]{"json"};
        }
    
        @Override
        public List<PropertySource<?>> load(String name, Resource resource) throws IOException {
            Map<String,Object> map=JSONObject.parseObject(IOUtils.toString(resource.getInputStream(), Charset.defaultCharset())).getInnerMap();
            if (map==null||map.size()==0){
                return Collections.emptyList();
            }else {
                return Collections.singletonList(new OriginTrackedMapPropertySource(name,map));
            }
        }
    }

**src/main/resources**下新建目录**/META-INF，创建文件spring.factories**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAb1_nk5znlLDmnY7kuItfbw_size_9_color_FFFFFF_t_70_g_se_x_16][]

**spring.factories**

org.springframework.boot.env.PropertySourceLoader=\
      com.example.demo.config.CustomPropertySourceLoader

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**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private Person person;
    
        @RequestMapping("/hello")
        public Person hello(){
            System.out.println(person);
    
            return person;
        }
    }

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**使用测试**

**localhost:8080/hello，控制台输出**

2021-09-19 15:48:22.423  INFO 7952 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2021-09-19 15:48:22.434  INFO 7952 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 11 ms
    Person(name=瓜田李下, age=20)

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