lombok使用-简介

lombok使用

lombok的使用简介

lombok其实就是在我们进行编译事加一层处理的机制，具体百度。
* https://projectlombok.org/features/index.html
* http://lrwinx.github.io/2017/03/04/%E7%BB%86%E6%80%9D%E6%9E%81%E6%81%90-%E4%BD%A0%E7%9C%9F%E7%9A%84%E4%BC%9A%E5%86%99java%E5%90%97/ 这个小哥写的不错
* http://tech.meituan.com/clean-code.html cleancode
* http://www.zuidaima.com/share/1949333085654016.htm lombok使用

常用注解

@Data ：注解在类上；提供类所有属性的 getting 和 setting 方法，此外还提供了equals、canEqual、hashCode、toString 方法
@Setter：注解在属性上；为属性提供 setting 方法
@Getter：注解在属性上；为属性提供 getting 方法
@Log4j ：注解在类上；为类提供一个 属性名为log 的 log4j 日志对象
@Slf4j : 注解在类上；为类提供一个 属性名为log 的 log4j 日志对象
@NoArgsConstructor：注解在类上；为类提供一个无参的构造方法
@AllArgsConstructor：注解在类上；为类提供一个全参的构造方法
@Accessors(chain = true) 支持链式调用的:
@Builder 建筑者模式

实战

Getter，Setter

import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
@Slf4j
@Getter
@Setter
public class Person {
    private String name;
    private String old;

    public static void main(String[] args) {

        Person px =new Person();
        px.setName("xx");
        px.setOld("xx");
        log.info(px.getName());
    }
}

编译后的代码：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Person {
    private static final Logger log = LoggerFactory.getLogger(Person.class);
    private String name;
    private String old;

    public Person() {
    }

    public static void main(String[] args) {
        Person px = new Person();
        px.setName("xx");
        px.setOld("xx");
        log.info(px.getName());
    }

    public String getName() {
        return this.name;
    }

    public String getOld() {
        return this.old;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setOld(String old) {
        this.old = old;
    }
}

@Data

编译前：

import lombok.Data;
import lombok.extern.slf4j.Slf4j;

/**
 * Created by wangji on 2017/3/20.
 */

@Slf4j
@Data
public class Person {
    private String name;
    private String old;

    public static void main(String[] args) {

        Person px =new Person();
        px.setName("xx");
        px.setOld("xx");
        log.info(px.getName());
    }
}

编译后的结果,可以看到给予了许多的get,set and toString等等

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Person {
    private static final Logger log = LoggerFactory.getLogger(Person.class);
    private String name;
    private String old;

    public static void main(String[] args) {
        Person px = new Person();
        px.setName("xx");
        px.setOld("xx");
        log.info(px.getName());
    }

    public Person() {
    }

    public String getName() {
        return this.name;
    }

    public String getOld() {
        return this.old;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setOld(String old) {
        this.old = old;
    }

    public boolean equals(Object o) {
        if(o == this) {
            return true;
        } else if(!(o instanceof Person)) {
            return false;
        } else {
            Person other = (Person)o;
            if(!other.canEqual(this)) {
                return false;
            } else {
                String this$name = this.getName();
                String other$name = other.getName();
                if(this$name == null) {
                    if(other$name != null) {
                        return false;
                    }
                } else if(!this$name.equals(other$name)) {
                    return false;
                }

                String this$old = this.getOld();
                String other$old = other.getOld();
                if(this$old == null) {
                    if(other$old != null) {
                        return false;
                    }
                } else if(!this$old.equals(other$old)) {
                    return false;
                }

                return true;
            }
        }
    }

    protected boolean canEqual(Object other) {
        return other instanceof Person;
    }

    public int hashCode() {
        boolean PRIME = true;
        byte result = 1;
        String $name = this.getName();
        int result1 = result * 59 + ($name == null?43:$name.hashCode());
        String $old = this.getOld();
        result1 = result1 * 59 + ($old == null?43:$old.hashCode());
        return result1;
    }

    public String toString() {
        return "Person(name=" + this.getName() + ", old=" + this.getOld() + ")";
    }
}

支持链式调用 @Data @Accessors(chain = true) 配合使用

类似这种类型：

Student student = new Student()
        .setAge(24)
        .setName("zs");

编译前：

import lombok.Data;
import lombok.experimental.Accessors;
import lombok.extern.slf4j.Slf4j;

/**
 * Created by wangji on 2017/3/20.
 */

@Slf4j
@Data
@Accessors(chain = true)
public class Person {
    private String name;
    private String old;

    public static void main(String[] args) {

        Person px =new Person().setOld("xxx").setName("xxx");
        log.info(px.getName());
    }
}

编译后的代码：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Person {
    private static final Logger log = LoggerFactory.getLogger(Person.class);
    private String name;
    private String old;

    public static void main(String[] args) {
        Person px = (new Person()).setOld("xxx").setName("xxx");
        log.info(px.getName());
    }

    public Person() {
    }

    public String getName() {
        return this.name;
    }

    public String getOld() {
        return this.old;
    }

    public Person setName(String name) {
        this.name = name;
        return this;
    }

    public Person setOld(String old) {
        this.old = old;
        return this;
    }

    public boolean equals(Object o) {
        if(o == this) {
            return true;
        } else if(!(o instanceof Person)) {
            return false;
        } else {
            Person other = (Person)o;
            if(!other.canEqual(this)) {
                return false;
            } else {
                String this$name = this.getName();
                String other$name = other.getName();
                if(this$name == null) {
                    if(other$name != null) {
                        return false;
                    }
                } else if(!this$name.equals(other$name)) {
                    return false;
                }

                String this$old = this.getOld();
                String other$old = other.getOld();
                if(this$old == null) {
                    if(other$old != null) {
                        return false;
                    }
                } else if(!this$old.equals(other$old)) {
                    return false;
                }

                return true;
            }
        }
    }

    protected boolean canEqual(Object other) {
        return other instanceof Person;
    }

    public int hashCode() {
        boolean PRIME = true;
        byte result = 1;
        String $name = this.getName();
        int result1 = result * 59 + ($name == null?43:$name.hashCode());
        String $old = this.getOld();
        result1 = result1 * 59 + ($old == null?43:$old.hashCode());
        return result1;
    }

    public String toString() {
        return "Person(name=" + this.getName() + ", old=" + this.getOld() + ")";
    }
}

@builder

Builder模式,可以看一下《Head First》(设计模式) 的建造者模式。
一种变种的builder模式，那就是构建bean的builder模式，其实主要的思想是带着大家一起看一下lombok给我们带来了什么。
看一下Student这个类的原始builder状态:

public class Student {
    private String name;
    private int age;

    public String getName() {
            return name;
    }

    public void setName(String name) {
            this.name = name;
    }

    public int getAge() {
            return age;
    }

    public void setAge(int age) {
            this.age = age;
    }

    public static Builder builder(){
            return new Builder();
    }
    public static class Builder{
            private String name;
            private int age;
            public Builder name(String name){
                    this.name = name;
                    return this;
            }

            public Builder age(int age){
                    this.age = age;
                    return this;
            }

            public Student build(){
                    Student student = new Student();
                    student.setAge(age);
                    student.setName(name);
                    return student;
            }
    }

}

调用的方法：

Student student = Student.builder().name("zs").age(24).build();

这样的builder代码，让我是在恶心难受，于是我打算用lombok重构这段代码:

@Builder
public class Student {
    private String name;
    private int age;
}
Student student = Student.builder().name("zs").age(24).build();

上面的是参考的，下面是自己实现的

import lombok.Builder;
import lombok.ToString;
import lombok.extern.slf4j.Slf4j;

/**
 * Created by wangji on 2017/3/20.
 */

@Slf4j
@Builder
@ToString
public class Person {
    private String name;
    private String old;

    public static void main(String[] args) {

      Person person =Person.builder().name("xxx").old("xx").build();
      log.info(person.toString());
    }
}

编译后的代码：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Person {
    private static final Logger log = LoggerFactory.getLogger(Person.class);
    private String name;
    private String old;

    public static void main(String[] args) {
        Person person = builder().name("xxx").old("xx").build();
        log.info(person.toString());
    }

    Person(String name, String old) {
        this.name = name;
        this.old = old;
    }

    public static Person.PersonBuilder builder() {
        return new Person.PersonBuilder();
    }

    public String toString() {
        return "Person(name=" + this.name + ", old=" + this.old + ")";
    }

    public static class PersonBuilder {
        private String name;
        private String old;

        PersonBuilder() {
        }

        public Person.PersonBuilder name(String name) {
            this.name = name;
            return this;
        }

        public Person.PersonBuilder old(String old) {
            this.old = old;
            return this;
        }

        public Person build() {
            return new Person(this.name, this.old);
        }

        public String toString() {
            return "Person.PersonBuilder(name=" + this.name + ", old=" + this.old + ")";
        }
    }
}

@NoArgsConstructor：注解在类上；为类提供一个无参的构造方法 @AllArgsConstructor：注解在类上；为类提供一个全参的构造方法

这个没啥好说的！

每天都是学习！哈哈！