记lombok@Data和@Builder一起用无法添加无参构造方法的坑

 

今天和小伙伴讨论一个mybatis-plus的一个诡异问题，最后定位到原因竟然是lombok@Data和@Builder一起用无法添加无参构造方法引起的,非常隐蔽。

很多框架都是同反射等调用无参数构造方法来创建实例的，需要注意。

 

单独使用@Data注解，编译后的类文件会生成无参数构造方法（这并不是@Data提供的特性，而是Java自带的特性）。

  // IntelliJ API Decompiler stub source generated from a class file
  // Implementation of methods is not available

package com.chujianyun.util;

public class Dog {
    private java.lang.String name;
    private java.lang.Integer age;
    private java.lang.String nickName;
    private java.lang.String test;

    public Dog() { /* compiled code */ }

    public java.lang.String getName() { /* compiled code */ }

    public java.lang.Integer getAge() { /* compiled code */ }

    public java.lang.String getNickName() { /* compiled code */ }

    public java.lang.String getTest() { /* compiled code */ }

    public void setName(java.lang.String name) { /* compiled code */ }

    public void setAge(java.lang.Integer age) { /* compiled code */ }

    public void setNickName(java.lang.String nickName) { /* compiled code */ }

    public void setTest(java.lang.String test) { /* compiled code */ }

    public boolean equals(java.lang.Object o) { /* compiled code */ }

    protected boolean canEqual(java.lang.Object other) { /* compiled code */ }

    public int hashCode() { /* compiled code */ }

    public java.lang.String toString() { /* compiled code */ }
}

 

单独使用@Builder注解，发现生成了全属性的构造方法。

package com.chujianyun.util;

public class Dog {
    private java.lang.String name;
    private java.lang.Integer age;
    private java.lang.String nickName;
    private java.lang.String test;

    Dog(java.lang.String name, java.lang.Integer age, java.lang.String nickName, java.lang.String test) { /* compiled code */ }

    public static com.chujianyun.util.Dog.DogBuilder builder() { /* compiled code */ }

    public static class DogBuilder {
        private java.lang.String name;
        private java.lang.Integer age;
        private java.lang.String nickName;
        private java.lang.String test;

        DogBuilder() { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder name(java.lang.String name) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder age(java.lang.Integer age) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder nickName(java.lang.String nickName) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder test(java.lang.String test) { /* compiled code */ }

        public com.chujianyun.util.Dog build() { /* compiled code */ }

        public java.lang.String toString() { /* compiled code */ }
    }
}

@Data和@Builder一起用

@Data
@Builder
public class Dog {

    private String name;

    private Integer age;

    private String nickName;

    private String test;

}

效果

  // IntelliJ API Decompiler stub source generated from a class file
  // Implementation of methods is not available

package com.chujianyun.util;

public class Dog {
    private java.lang.String name;
    private java.lang.Integer age;
    private java.lang.String nickName;
    private java.lang.String test;

    Dog(java.lang.String name, java.lang.Integer age, java.lang.String nickName, java.lang.String test) { /* compiled code */ }

    public static com.chujianyun.util.Dog.DogBuilder builder() { /* compiled code */ }

    public java.lang.String getName() { /* compiled code */ }

    public java.lang.Integer getAge() { /* compiled code */ }

    public java.lang.String getNickName() { /* compiled code */ }

    public java.lang.String getTest() { /* compiled code */ }

    public void setName(java.lang.String name) { /* compiled code */ }

    public void setAge(java.lang.Integer age) { /* compiled code */ }

    public void setNickName(java.lang.String nickName) { /* compiled code */ }

    public void setTest(java.lang.String test) { /* compiled code */ }

    public boolean equals(java.lang.Object o) { /* compiled code */ }

    protected boolean canEqual(java.lang.Object other) { /* compiled code */ }

    public int hashCode() { /* compiled code */ }

    public java.lang.String toString() { /* compiled code */ }

    public static class DogBuilder {
        private java.lang.String name;
        private java.lang.Integer age;
        private java.lang.String nickName;
        private java.lang.String test;

        DogBuilder() { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder name(java.lang.String name) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder age(java.lang.Integer age) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder nickName(java.lang.String nickName) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder test(java.lang.String test) { /* compiled code */ }

        public com.chujianyun.util.Dog build() { /* compiled code */ }

        public java.lang.String toString() { /* compiled code */ }
    }
}

我们发现外层的Dog类没有了默认的构造方法。

 

如果手动添加无参数构造方法或者用@NoArgsConstructor注解都会报错！

@Builder
@Data
@NoArgsConstructor
public class Dog {

    private String name;

    private Integer age;

    private String nickName;

    private String test;

}

正确写法如下：

@Builder
@Data
public class Dog {

    private String name;

    private Integer age;

    private String nickName;

    private String test;

    @Tolerate
    Dog() {}
}

 

解释如下

 

添加函数或者构造方法，让lombok假装它不存在（不感知）。

 

效果如下：

package com.chujianyun.util;

public class Dog {
    private java.lang.String name;
    private java.lang.Integer age;
    private java.lang.String nickName;
    private java.lang.String test;

    Dog() { /* compiled code */ }

    Dog(java.lang.String name, java.lang.Integer age, java.lang.String nickName, java.lang.String test) { /* compiled code */ }

    public static com.chujianyun.util.Dog.DogBuilder builder() { /* compiled code */ }

    public java.lang.String getName() { /* compiled code */ }

    public java.lang.Integer getAge() { /* compiled code */ }

    public java.lang.String getNickName() { /* compiled code */ }

    public java.lang.String getTest() { /* compiled code */ }

    public void setName(java.lang.String name) { /* compiled code */ }

    public void setAge(java.lang.Integer age) { /* compiled code */ }

    public void setNickName(java.lang.String nickName) { /* compiled code */ }

    public void setTest(java.lang.String test) { /* compiled code */ }

    public boolean equals(java.lang.Object o) { /* compiled code */ }

    protected boolean canEqual(java.lang.Object other) { /* compiled code */ }

    public int hashCode() { /* compiled code */ }

    public java.lang.String toString() { /* compiled code */ }

    public static class DogBuilder {
        private java.lang.String name;
        private java.lang.Integer age;
        private java.lang.String nickName;
        private java.lang.String test;

        DogBuilder() { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder name(java.lang.String name) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder age(java.lang.Integer age) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder nickName(java.lang.String nickName) { /* compiled code */ }

        public com.chujianyun.util.Dog.DogBuilder test(java.lang.String test) { /* compiled code */ }

        public com.chujianyun.util.Dog build() { /* compiled code */ }

        public java.lang.String toString() { /* compiled code */ }
    }
}

完美，手工。。。