Groovy 简单的`@ToString`注解

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白石

修改于 2019-09-09 06:40:55

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从Groovy 1.8开始，我们可以使用@ToString注释来轻松创建toString()方法。我们只需要在类定义中添加注释，我们就可以获得类的属性的格式良好的输出。

我们甚至可以自定义我们想要在输出中看到的内容。如果我们添加属性includeNames=true，我们可以在toString()输出中看到我们类的属性的名称。默认情况下，只将属性添加到输出中，但我们也可以包含字段以及注释属性includeFields=true。要排除属性，我们使用属性excludes，并在输出中用逗号分隔我们不想要的属性的名称。

最后，我们可以包含一个超类的属性，其注释属性为includeSuper=true。

让我们看一下@ToString中的几个样本：

// Most simple implementation of toString.
import groovy.transform.ToString

@ToString
class Person {
    String name
    List likes
    private boolean active = false
}

def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

assert person.toString() == 'Person(mrhaki, [Groovy, Java])'
// includeNames to output the names of the properties.
import groovy.transform.ToString

@ToString(includeNames=true)
class Person {
    String name
    List likes
    private boolean active = false
}

def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

assert person.toString() == 'Person(name:mrhaki, likes:[Groovy, Java])'
// includeFields to not only output properties, but also field values.
import groovy.transform.ToString

@ToString(includeNames=true, includeFields=true)
class Person {
    String name
    List likes
    private boolean active = false
}

def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

assert person.toString() == 'Person(name:mrhaki, likes:[Groovy, Java], active:false)'
// Use includeSuper to include properties from super class in output.
import groovy.transform.ToString

@ToString(includeNames=true)
class Person {
    String name
    List likes
    private boolean active = false
}

@ToString(includeSuper=true, includeNames=true)
class Student extends Person {
    List courses
}

def student = new Student(name: 'mrhaki', likes: ['Groovy', 'Java'], courses: ['IT', 'Business'])

assert student.toString() == 'Student(courses:[IT, Business], super:Person(name:mrhaki, likes:[Groovy, Java]))'
// excludes active field and likes property from output
import groovy.transform.ToString

@ToString(includeNames=true, includeFields=true, excludes='active,likes')
class Person {
    String name
    List likes
    private boolean active = false
}

def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

assert person.toString() == 'Person(name:mrhaki)'