Basic knowledge in the project

Boolean.TRUE and true Performance comparison

• A,D > B,C

// 7.844
Boolean A(){
     
    return Boolean.TRUE;
}
// 10.109
boolean B(){
    
    return Boolean.TRUE
}
// 7.906
Boolean C(){
    
    return true;
}
// 7.828
boolean D(){
    
    return true;
}

The string is empty isEmpty and isBlank The difference between

• isEmpty Just judge the null and length as 0 character string
• isBlank The judgment is empty , The length is 0, Blank character （ Including Spaces , tabs \t, A newline \n, Page identifier \f, enter \r） Composed string

StringUtils.isEmpty(null) = true
StringUtils.isEmpty("") = true
StringUtils.isEmpty(" ") = false
StringUtils.isEmpty("aaa") = false
StringUtils.isEmpty("\t \n \r \f") = false
StringUtils.isBlank(null) = true
StringUtils.isBlank("") = true
StringUitls.isBlank(" ") = true
StringUtils.isEmpty("aaa") = false
StringUtils.isEmpty("\t \n \r \f") = true

• hutool Tools ：StrUtil

System.out.println(StrUtil.isEmpty(null)); // true
System.out.println(StrUtil.isEmpty("")); // true
System.out.println(StrUtil.isEmpty(" ")); // false
System.out.println(StrUtil.isEmpty("aaa")); // false
System.out.println(StrUtil.isEmpty("\r \t \n \f")); // false
System.out.println(StrUtil.isBlank(null)); // true
System.out.println(StrUtil.isBlank("")); // true
System.out.println(StrUtil.isBlank(" ")); // true
System.out.println(StrUtil.isBlank("aaa")); // false
System.out.println(StrUtil.isBlank("\r \n \t \f")); // true

Swagger-ApiModel and ApiModelProperty

• ApiModel annotation ： This attribute is to describe the interface related entity classes that need special description

The attribute name	Attribute types	The default value is	effect
value()	String	empty	Name of custom class
description()	String	empty	Add long text description information to the class

• ApiModelProperty annotation ： This attribute is a description of the parameters in the entity class

The attribute name	Attribute types	The default value is	effect
value()	String	empty	Define parameter description information
name()	String	empty	Define the parameter name
required()	boolean	false	Define whether parameters must be passed
hidden()	boolean	false	Define whether the parameter is hidden
allowEmptyValue()	boolean	false	Define whether the parameter can be null

@ApiModel(value = " User entity , Store user related fields ", description = " The user entity contains all business fields related to the user , If necessary, please add another ")
public class User{
    
    // do something...
}
@ApiModelProperty(value = " user Id")
private Integer id;

Swagger-ApiOperation and ApiParam

• @ApiOperation Annotations are not Spring Self contained , It is swagger Inside com.wordnik.swagger.annotations.ApiOperation;
• annotation @ApiOperation and @ApiParam It's used to build Api Document
• @ApiOperation(value=“ Interface specification ”,httpMethod=“ Interface request mode ”,response=“ Interface return parameter type ”,notes=“ Interface release notes ”), Used in the method of request , Explain the purpose of the method 、 effect
• @ApiParam(required =“ Whether the parameter ”,name=“ Parameter name ”,value=“ Parameter description ”)

Other notes ：

• @ApiImplicitParams： Used in the method of request , Represents a set of parameter descriptions
• @Api： For the requested class , Represents a description of a class
• @ApiImplicitParams： Used in the method of request , Represents a set of parameter descriptions
• @ApiResponses： Used in the method of request , Represents a set of responses
• Reference link

BeanUtils.copyProperties

• Shallow copy , If they are all single attributes , So it's not about deep copy , Suitable for use BeanUtils

• BeanUtils.copyProperties(a, b);

  • b Properties that exist in ,a There must be , however a There can be extra attributes in the ;
  • a China and b The same attributes in the are replaced , Whether it's worth it or not ;
  • a、 b The attributes in the should have the same name , Can be assigned , Otherwise, manual assignment is required ;
  • Spring Of BeanUtils Of CopyProperties The corresponding properties required by the method are getter and setter Method ;
  • If there is an inner class with exactly the same properties , But not the same inner class , That is, they belong to their own internal classes , be spring Will think that the properties are different , Can't copy;
  • spring and apache Of copy The position of the method source and destination parameters of the property is exactly the opposite , Therefore, we should pay attention to both guiding package and calling

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