@NotNull和@NotEmpty和@NotBlank区别

(""," ","   ")

(" ","  ")

("test")    即：必须有实际字符

@NotNull: The CharSequence, Collection, Map or Array object is not null,
but can be empty.

@NotEmpty: The CharSequence, Collection, Map or Array object is not null
and size > 0.

@NotBlank: The string is not null and the trimmed length is greater than
zero.

1.String name = null;

@NotNull: false
@NotEmpty:false
@NotBlank:false

2.String name = "";

@NotNull:true
@NotEmpty: false
@NotBlank: false

3.String name = " ";

@NotNull: true
@NotEmpty: true
@NotBlank: false

4.String name = "Great answer!";

@NotNull: true
@NotEmpty:true
@NotBlank:true