@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface ControllerAdvice {

	@AliasFor("basePackages")
	String[] value() default {};

	@AliasFor("value")
	String[] basePackages() default {};

	Class<?>[] basePackageClasses() default {};

	Class<?>[] assignableTypes() default {};

	Class<? extends Annotation>[] annotations() default {};

}

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(IllegalArgumentException.class)
    public ModelAndView handleException(IllegalArgumentException e){
        ModelAndView modelAndView = new ModelAndView("error");
        modelAndView.addObject("errorMessage", "參數(shù)不符合規(guī)范!");
        return modelAndView;
    }
}

/**
 * Annotation that binds a method parameter or method return value
 * to a named model attribute, exposed to a web view. Supported
 * for controller classes with {@link RequestMapping @RequestMapping}
 * methods.
 * 此注解用于綁定一個方法參數(shù)或者返回值到一個被命名的model屬性中，暴露給web視圖。支持在
 * 在Controller類中注有@RequestMapping的方法使用（這里有點拗口，不過結(jié)合下面的使用介紹
 * 你就會明白的)
 */
@Target({ElementType.PARAMETER, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ModelAttribute {

	@AliasFor("name")
	String value() default "";

	@AliasFor("value")
	String name() default "";

	boolean binding() default true;

}

@ControllerAdvice
public class MyGlobalHandler {
    @ModelAttribute
    public void presetParam(Model model){
        model.addAttribute("globalAttr","this is a global attribute");
    }
}

@ControllerAdvice
public class MyGlobalHandler {

    @ModelAttribute()
    public Map<String, String> presetParam(){
        Map<String, String> map = new HashMap<String, String>();
        map.put("key1", "value1");
        map.put("key2", "value2");
        map.put("key3", "value3");
        return map;
    }

}

@RestController
public class AdviceController {

    @GetMapping("methodOne")
    public String methodOne(Model model){ 
        Map<String, Object> modelMap = model.asMap();
        return (String)modelMap.get("globalAttr");
    }

  
    @GetMapping("methodTwo")
    public String methodTwo(@ModelAttribute("globalAttr") String globalAttr){
        return globalAttr;
    }


    @GetMapping("methodThree")
    public String methodThree(ModelMap modelMap) {
        return (String) modelMap.get("globalAttr");
    }
    
}

/**
 * Annotation that identifies methods which initialize the
 * {@link org.springframework.web.bind.WebDataBinder} which
 * will be used for populating command and form object arguments
 * of annotated handler methods.
 * 粗略翻譯：此注解用于標(biāo)記那些 (初始化[用于組裝命令和表單對象參數(shù)的]WebDataBinder)的方法。
 * 原諒我的英語水平，翻譯起來太拗口了，從句太多就用‘()、[]'分割一下便于閱讀
 *
 * Init-binder methods must not have a return value; they are usually
 * declared as {@code void}.
 * 粗略翻譯：初始化綁定的方法禁止有返回值，他們通常聲明為 'void'
 *
 * <p>Typical arguments are {@link org.springframework.web.bind.WebDataBinder}
 * in combination with {@link org.springframework.web.context.request.WebRequest}
 * or {@link java.util.Locale}, allowing to register context-specific editors.
 * 粗略翻譯：典型的參數(shù)是`WebDataBinder`，結(jié)合`WebRequest`或`Locale`使用，允許注冊特定于上下文的編輯 
 * 器。
 * 
 * 總結(jié)如下：
 *  1. @InitBinder 標(biāo)識的方法的參數(shù)通常是 WebDataBinder。
 *  2. @InitBinder 標(biāo)識的方法,可以對 WebDataBinder 進(jìn)行初始化。WebDataBinder 是 DataBinder 的一
 * 		           個子類,用于完成由表單字段到 JavaBean 屬性的綁定。
 *  3. @InitBinder 標(biāo)識的方法不能有返回值,必須聲明為void。
 */
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface InitBinder {
	/**
	 * The names of command/form attributes and/or request parameters
	 * that this init-binder method is supposed to apply to.
	 * <p>Default is to apply to all command/form attributes and all request parameters
	 * processed by the annotated handler class. Specifying model attribute names or
	 * request parameter names here restricts the init-binder method to those specific
	 * attributes/parameters, with different init-binder methods typically applying to
	 * different groups of attributes or parameters.
	 * 粗略翻譯：此init-binder方法應(yīng)該應(yīng)用于的命令/表單屬性和/或請求參數(shù)的名稱。默認(rèn)是應(yīng)用于所有命	   		* 令/表單屬性和所有由帶注釋的處理類處理的請求參數(shù)。這里指定模型屬性名或請求參數(shù)名將init-binder		 * 方法限制為那些特定的屬性/參數(shù)，不同的init-binder方法通常應(yīng)用于不同的屬性或參數(shù)組。
	 * 我至己都理解不太理解這說的是啥呀，我們還是看例子吧
	 */
	String[] value() default {};
}

@ControllerAdvice
public class MyGlobalHandler {

    @InitBinder
    public void processParam(WebDataBinder dataBinder){

        /*
         * 創(chuàng)建一個字符串微調(diào)編輯器
         * 參數(shù){boolean emptyAsNull}: 是否把空字符串("")視為 null
         */
        StringTrimmerEditor trimmerEditor = new StringTrimmerEditor(true);

        /*
         * 注冊自定義編輯器
         * 接受兩個參數(shù){Class<?> requiredType, PropertyEditor propertyEditor}
         * requiredType：所需處理的類型
         * propertyEditor：屬性編輯器，StringTrimmerEditor就是 propertyEditor的一個子類
         */
        dataBinder.registerCustomEditor(String.class, trimmerEditor);
        
        //同上，這里就不再一步一步講解了
        binder.registerCustomEditor(Date.class,
                new CustomDateEditor(new SimpleDateFormat("yyyy-MM-dd"), false));
    }
}

@RestController
public class BinderTestController {

    @GetMapping("processParam")
    public Map<String, Object> test(String str, Date date) throws Exception {
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("str", str);
        map.put("data", date);
        return  map;
    }
}

class Person {

    private String name;
    private Integer age;
    // omitted getters and setters.
}

class Book {

    private String name;
    private Double price;
    // omitted getters and setters.
}

@RestController
public class BinderTestController {

    @PostMapping("bindParam")
    public void test(Person person, Book book) throws Exception {
        System.out.println(person);
        System.out.println(book);
    }
}

@ControllerAdvice
public class MyGlobalHandler {

	/*
     * @InitBinder("person") 對應(yīng)找到@RequstMapping標(biāo)識的方法參數(shù)中
     * 找參數(shù)名為person的參數(shù)。
     * 在進(jìn)行參數(shù)綁定的時候，以‘p.'開頭的都綁定到名為person的參數(shù)中。
     */
    @InitBinder("person")
    public void BindPerson(WebDataBinder dataBinder){
        dataBinder.setFieldDefaultPrefix("p.");
    }

    @InitBinder("book")
    public void BindBook(WebDataBinder dataBinder){
        dataBinder.setFieldDefaultPrefix("b.");
    }
}