@Introduction and three usages of controlleradvice

​

Study @ControllerAdvice

 First ,@ControllerAdvice It's essentially a @Component, So it will also be used as a build scan .

added @ControllerAdvice Classes of are declared for those （@ExceptionHandler、@InitBinder or @ModelAttribute annotated ） Method
Professional @Component , For more than one Controller Shared by classes .
To put it bluntly , Namely aop A realization of thought , You told me you need interception rules , I'll help you stop them , Specifically, you want to do more detailed interception screening and processing after interception ,
By yourself @ExceptionHandler、@InitBinder or @ModelAttribute These three annotations and the methods annotated by them are self-defined .

• @ExceptionHandler How to annotate ： Used to capture Controller Different types of exceptions thrown in , So as to achieve the purpose of global exception processing ;
• @InitBinder How to annotate ： Resolution for registering custom parameters in the request , So as to achieve the purpose of customizing the request parameter format ;
• @ModelAttribute How to annotate ： Indicates that this method will execute the target Controller Method is executed before

!!! These three annotations can be used in ordinary Controller Class using the ,ControllerAdvice Only the scope can be customized ( Default all )

1. Scope of action

​ ControllerAdvice Various designations are provided Advice How rules are defined , By default, nothing is written , It is Advice all Controller, Of course, you can also specify rules in the following ways
such as :

• Specified package

 matching org.my.pkg All under the package and its sub packages Controller
@ControllerAdvice(basePackages="org.my.pkg")
 Of course, it can also be specified in the form of an array , Such as ：
@ControllerAdvice(basePackages={
    "org.my.pkg", "org.my.other.pkg"}),

• Specify the annotation

  You can also specify annotations to match , For example, I made one myself  @CustomAnnotation  annotation , I want to match all that are decorated by this annotation  Controller,  It can be written like this ：@ControllerAdvice（annotations={
    CustomAnnotation.class})

2. Preset global data @ModelAttribute

​ Use @ModelAttribute Can be in controller Store data before request

	// 1. No return value method , Put in Model, Customize  key ,value
    @ModelAttribute()
    public void presetParam(Model model) {
    
        model.addAttribute("globalAttr", " I am a global parameter ");
    }

    // 2. No designation name, Return value method , The return value is map,int etc. ,key Namely map,int etc. ,,value Is the return value 
    @ModelAttribute()
    public Map<String, String> presetParam2() {
    
        Map<String, String> map1 = new HashMap<String, String>();
        map1.put("key1", "value1");
        return map1;
    }

    // 3. Appoint name, Return value method ,key Namely name,value Is the return value 
    @ModelAttribute(name = "map2")
    public Map<String, String> presetParam3() {
    
        Map<String, String> map = new HashMap<String, String>();
        map.put("key2", "value2");
        return map;
    }

	// 4. Request parameters can be accepted 
    @ModelAttribute()
    public void presetParam4(@RequestParam("name") String name,Model model) {
    
        model.addAttribute("name", name);
    }

​ Use

	 //1. Use Model Take out 
    @GetMapping("model")
    public String methodOne(Model model) {
    
        Map<String, Object> modelMap = model.asMap();
        System.out.println(modelMap.get("name").toString()); //  Pass in name Value  
        return modelMap.get("globalAttr").toString();
    }

    //2. Use ModelMap Take out 
    @GetMapping("modelMap")
    public String methodThree(ModelMap modelMap) {
    
        return modelMap.get("map").toString();
    }

    //[email protected]() Appoint key, Take it out directly 
    @GetMapping("modelAttribute")
    public String methodTwo(@ModelAttribute("map2") Map map2) {
    
        return map2.toString();
    }
	

3. Handling global exceptions @ExceptionHandler

	
	// @Validated Parameter checking  , analysis BindingResult And return 
    @ExceptionHandler(BindException.class)
    @ResponseBody
    public JsonResult exceptionHandler(BindException e, BindingResult result) {
    
        List<FieldError> fieldErrors = result.getFieldErrors();
        String collect = fieldErrors.stream().map(f -> f.getField()+":"+f.getDefaultMessage()).collect(Collectors.joining(","));
        return new JsonResult(JsonResult.Validated_ERROR, collect);
    }

	// Here is the general exception handler , All unexpected Exception Exceptions are handled here 
    @ExceptionHandler(Exception.class)
    @ResponseBody
    public JsonResult exceptionHandler(Exception e) {
    
        return new JsonResult(JsonResult.SYSTEM_ERROR, e.getMessage());
    }

    

4. Request parameter preprocessing @InitBinder

Use the default attribute editor

 @InitBinder
    public void initBinder(WebDataBinder dataBinder){
    
        /* *  Create a string trimming editor  *  Parameters {boolean emptyAsNull}:  Empty string ("") As  null */
        StringTrimmerEditor trimmerEditor = new StringTrimmerEditor(true);
        /* *  Register custom editor  *  Take two parameters {Class<?> requiredType, PropertyEditor propertyEditor} * requiredType： The type of processing required  * propertyEditor： Property editor ,StringTrimmerEditor Namely  propertyEditor A subclass of  */
        dataBinder.registerCustomEditor(String.class, trimmerEditor);
        // Convert a string in date format to Date object 
       dataBinder.registerCustomEditor(Date.class, new CustomDateEditor(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"), false));
        
   dataBinder.addValidators(paramVOValidator);

}

Custom property editor

 /** * @description:  prevent xss Inject  * @params: String Type conversion , Pass in all String Conduct HTML code , prevent XSS attack  * @return: */
    //@InitBinder
    protected void initBinder2(WebDataBinder binder) {
    

        System.out.println("22222222222222");

       // Custom property editor  PropertyEditorSupport
        binder.registerCustomEditor(String.class, new PropertyEditorSupport() {
    
            @Override
            public void setAsText(String text) {
    
                setValue(text == null ? null : StringEscapeUtils.escapeHtml4(text.trim()));
            }
            @Override
            public String getAsText() {
    
                Object value = getValue();
                return value != null ? value.toString() : "";
            }
        });
    }

Custom parameter verification @Validated!!!

@Data
public class ParamVO implements Serializable {
    

    @ApiModelProperty("age")
    private Integer age;
    
    @ApiModelProperty("name")
    private String name;
}

@Component
public class ParamVOValidator implements Validator {
    

	/** * @description:  Only when the conditions are met  * @params: * @return: */
    @Override
    public boolean supports(Class<?> clazz) {
    
        //  Only support ParamVO Verification of type objects 
        return ParamVO.class.equals(clazz);
    }

    /** * @description:  Custom validation rules  * @params: * @return: */
    @Override
    public void validate(Object target, Errors errors) {
    
        ParamVO paramVO = (ParamVO) target;
        String userName = paramVO.getName();
        if (StringUtils.isEmpty(userName) || userName.length() < 8) {
    
            errors.rejectValue("name", "valid.userNameLen", new Object[]{
    "minLength", 8}, " User name cannot be less than 8 position ");
        }

    }
}

	@Autowired
    private ParamVOValidator paramVOValidator;
     @InitBinder
    public void initBinder(WebDataBinder dataBinder) {
    
        dataBinder.addValidators(paramVOValidator);
    
    }

Be careful !!!

These three annotations can be used in ordinary Controller Class using the ,ControllerAdvice Only the scope can be customized ( Default all )