<span role="heading" aria-level="2">Lombok中@Builder注解实现原理</span>

常用Lombok的都知道里面有一个@Builder注解很好用，但是这个注解的原理是什么呢，这里简单模拟一下。

这里使用了设计模式中的建造者模式。

package com.example.demoboot;

import java.io.Serializable;

/**
 * 数据源实例
 *
 * @author starsray
 * @date 2021/11/20
 */
public class DatasourceInstance implements Serializable {

    private String type;
    private String name;
    private String username;
    private String password;
    private String url;
    private String driver;

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getName() {
        return name;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getDriver() {
        return driver;
    }

    public void setDriver(String driver) {
        this.driver = driver;
    }

    private DatasourceInstance(Builder builder) {
        this.type = builder.type;
        this.name = builder.name;
        this.username = builder.username;
        this.password = builder.password;
        this.url = builder.url;
        this.driver = builder.driver;
    }

    public static Builder builder() {
        return new Builder();
    }

    public static class Builder {
        private String type;
        private String name;
        private String username;
        private String password;
        private String url;
        private String driver;

        public Builder type(String type) {
            this.type = type;
            return this;
        }

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

        public Builder username(String username) {
            this.username = username;
            return this;
        }

        public Builder password(String password) {
            this.password = password;
            return this;
        }

        public Builder url(String url) {
            this.url = url;
            return this;
        }

        public Builder driver(String driver) {
            this.driver = driver;
            return this;
        }

        public DatasourceInstance build() {
            return new DatasourceInstance(this);
        }
    }
}