springboot 自定义格式化器（Formatter）

朴灿烈づ我的快乐病毒、 2023-02-25 10:07 277阅读 0赞

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### springboot 自定义格式化器（Formatter） ###

**应用：自定义格式化注解解析字符串**

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**相关类与接口**

**Formatter**

public interface Formatter<T> extends Printer<T>, Parser<T> {
    
    }

**Parser：解析指定格式的字符串，转换为对象T**

@FunctionalInterface
    public interface Parser<T> {
    
    	T parse(String text, Locale locale) throws ParseException;
    
    }

**Printer：转换后的对象T输出为字符串**

@FunctionalInterface
    public interface Printer<T> {
    
    	String print(T object, Locale locale);
    
    }

**AnnotationFormatterFactory**

public interface AnnotationFormatterFactory<A extends Annotation> {
    
    	Set<Class<?>> getFieldTypes();  //注解可以标注的字段类型
    
    	Printer<?> getPrinter(A annotation, Class<?> fieldType);
    	Parser<?> getParser(A annotation, Class<?> fieldType);
    
    }

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**示例**

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**formatter 层**

**BooleanFormat**

@Documented
    @Retention(RetentionPolicy.RUNTIME)
    @Target({ElementType.FIELD,ElementType.METHOD,ElementType.PARAMETER})
    public @interface BooleanFormat {
    
    }

**BooleanFormatter**

@Component
    public class BooleanFormatter implements Formatter<Boolean> {
    
        private final String[] values={"是","1","ok","true"};
    
        @Override
        public Boolean parse(String text, Locale locale) throws ParseException {
            return Arrays.asList(values).contains(text.toLowerCase());
        }
    
        @Override
        public String print(Boolean object, Locale locale) {
            return object?"true":"false";
        }
    }

**CustomBooleanFormatAnnotationFactory**

@Component
    public class CustomBooleanFormatAnnotationFactory implements AnnotationFormatterFactory<BooleanFormat> {
    
        @Resource
        private BooleanFormatter booleanFormatter;
    
        @Override
        public Set<Class<?>> getFieldTypes() {
            Set<Class<?>> set=new HashSet<>();
            set.add(Boolean.class);
    
            return set;
        }
    
        @Override
        public Parser<?> getParser(BooleanFormat annotation, Class<?> fieldType) {
            return booleanFormatter;
        }
    
        @Override
        public Printer<?> getPrinter(BooleanFormat annotation, Class<?> fieldType) {
            return booleanFormatter;
        }
    }

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**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @RequestMapping("/hello")
        public String hello(@BooleanFormat Boolean value){
            System.out.println(value);
    
            return value.toString();
        }
    }

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**使用测试**

**localhost:8080/hello?value=ok**

2020-07-12 10:56:50.812  INFO 5376 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2020-07-12 10:56:50.823  INFO 5376 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 11 ms
    true

**localhost:8080/hello?value=是**

true