Lombok简化java开发 - Getter/Setter注解,让你不用再多getter/setter写方法

这个内容在之前的帖子中已经有人讨论过,今天再做一更进一步的了解.

 

本篇会涉及如下三个注解:

 

• @Getter/@Setter: 帮助我们对应的 getter/setter方法
  • (Come on, 这个没什么意思, Hibernate Tools会生成,　Eclipse 佷智能的好不拉!　是的,　从这个角度出发的确没太大吸引力,　各位看管姑且看之, 　@Data会更有用,　总是会有需要手写pojo的情况)
• @NonNull: 在setter方法中做非null判断,遇到null参数,会抛出NullPointerException

 

如果你还不知道Lombok是什么,　先看看这篇:

Lombok简化Java代码　-　code less do more

 

关于这部分主题,官方文档在这里(E文强力的朋友也看这里)

http://projectlombok.org/features/GetterSetter.html

 

代码演示:

 

package lv.sample.lombok;

import lombok.AccessLevel;
import lombok.Getter;
import lombok.NonNull;
import lombok.Setter;
import lombok.ToString;

@ToString
public class GetterSetterUser {
	
	@Getter @Setter private int age = 25;
	
	@Setter(AccessLevel.PROTECTED) private String address = "shanghai";
	
	/*
	 * add a notnull constraint.
	 */
	@Getter @Setter @NonNull
	private String email = null;
	
	/**
	 * if the setName method has been declared,
	 * the Lombok does not generate it.
	 */
	@Setter @Getter
	private Object name = null;
	
	/**
	 * code by myself
	 * @param name
	 */
	public void setName(String name) {
		this.name = name + " from my code";
	}
	
	public static void main(String[] args) {
		// we test the getter/setter annotation
		GetterSetterUser bean = new GetterSetterUser();
		bean.setAge(20);
		bean.setAddress("xi'an");
		bean.setName("wity_lv,");
		
		/* 
		 * the toString() method has been instead of the Lombok @ToString
		 * annotation
		 */
		System.out.println(bean.toString());
		
		/*
		 * set a null value to email
		 */
		try {
			bean.setEmail(null);
		} catch(NullPointerException e) {
			System.out.println("phone could not be null value");
		}
		
	}
}

 

console out 写道

GetterSetterUser(age=20, address=xi'an, email=null, name=wity_lv, from my code)
email could not be null value

 

使用 delombok工具反向生成代码,　看看使用注解能省多少代码:

注意: lombok的注解是可以直接用的,　delombok工具只是用来查看生成的代码,　不需要将delombok生成的代码复制回工程

 

delombok 写道

java -jar -cp lib/log4j-1.2.8.jar lib/lombok.jar delombok src -d ./src-delomboked

 

 

// Generated by delombok at Fri Aug 26 10:57:14 CST 2011
package lv.sample.lombok;

import lombok.NonNull;

public class GetterSetterUser {
	
	private int age = 25;
	private String address = "shanghai";
	/*
	 * add a notnull constraint.
	 */
	@NonNull
	private String email = null;
	/**
	 * if the setName method has been declared,
	 * the Lombok does not generate it.
	 */
	private Object name = null;
	/**
	 * code by myself
	 * @param name
	 */
	public void setName(String name) {
		this.name = name + " from my code";
	}
	
	public static void main(String[] args) {
		// we test the getter/setter annotation
		GetterSetterUser bean = new GetterSetterUser();
		bean.setAge(20);
		bean.setAddress("xi\'an");
		bean.setName("wity_lv,");
		/* 
		 * the toString() method has been instead of the Lombok @ToString
		 * annotation
		 */
		System.out.println(bean.toString());
		/*
		 * set a null value to email
		 */
		try {
			bean.setEmail(null);
		} catch (NullPointerException e) {
			System.out.println("phone could not be null value");
		}
	}
	
	@java.lang.Override
	@java.lang.SuppressWarnings("all")
	public java.lang.String toString() {
		return "GetterSetterUser(age=" + this.getAge() + ", address=" + this.address + ", email=" + this.getEmail() + ", name=" + this.getName() + ")";
	}
	
	@java.lang.SuppressWarnings("all")
	public int getAge() {
		return this.age;
	}
	
	@java.lang.SuppressWarnings("all")
	public void setAge(final int age) {
		this.age = age;
	}
	
	@java.lang.SuppressWarnings("all")
	protected void setAddress(final String address) {
		this.address = address;
	}
	
	@NonNull
	@java.lang.SuppressWarnings("all")
	public String getEmail() {
		return this.email;
	}
	
	@java.lang.SuppressWarnings("all")
	public void setEmail(@NonNull final String email) {
		if (email == null) throw new java.lang.NullPointerException("email");
		this.email = email;
	}
	
	@java.lang.SuppressWarnings("all")
	public Object getName() {
		return this.name;
	}
}

 

 

话说,为每个字段写@Getter @Setter有些麻烦, 这里有个@Data会省不少事:

 

 

@Data
@NoArgsConstructor
@AllArgsConstructor
@Log4j
public class LombokUser {
	
	private String id = null;
	private String name = null;
	
	@NonNull
	private String email = null;
	
	public static void main(String[] args) {
		log.info("test the lombok bean");
		
		LombokUser u = new LombokUser("001", "wity_lv", "wity_lv@sample.com");
		log.info(u.toString());
		
		LombokUser u2 = new LombokUser("001", "wity_lv", "wity_lv@sample.com");
		log.info(u.equals(u2));
		
		try {
			u.setEmail(null);
		} catch(NullPointerException ex) {
			log.info("email could not be null: " + ex.getMessage());
		}
	}
}

 

 

console out 写道

2011-08-26 11:10:40 test the lombok bean
2011-08-26 11:10:40 LombokUser(id=001, name=wity_lv, email=wity_lv@sample.com)
2011-08-26 11:10:40 true
2011-08-26 11:10:40 email could not be null: email