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@Setterpublic 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@Datapublic 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:

@Builderpublic 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@ToStringpublic 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！