Lombok(1.14.8)的简单示例

分享自： http://blog.csdn.net/huey2672/article/details/42240985

Lombok是一种Java™实用工具，可用来帮助开发人员消除Java的冗长，尤其是对于简单的Java对象（POJO）。它通过注释实现这一目的。通过在开发环境中实现Lombok，开发人员可以节省构建诸如hashCode()和equals()这样的方法以及以往用来分类各种accessor和mutator的大量时间。

 

下载安装Lombok

1. 下载lombok.jar，http://projectlombok.org/

2. 找到MyEclipse的安装目录下的myeclipse.ini文件，在文件末尾添加以下两行：

-Xbootclasspath/a:lombok.jar
-javaagent:lombok.jar

3. 重启MyEclipse。

Lombok使用的简单示例

1. @Getter和@Setter，实现了Getter和Setter方法：

package com.huey.dream.beans;

import java.util.Date;

import lombok.Getter;
import lombok.Setter;

public class Student {

    @Getter @Setter
    private int studNo;
    @Getter @Setter
    private String studName;
    @Getter @Setter
    private Date birthday;


    public static void main(String[] args) {
        Student stud = new Student();
        stud.setStudName("huey");
        System.out.println(stud.getStudName());
    }
}

结果输出：

huey

2. @EqualsAndHashCode，实现了equals()和hashCode()方法：

package com.huey.dream.beans;

import java.util.Date;

import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.Setter;

@EqualsAndHashCode
public class Student {

    @Getter @Setter
    private int studNo;
    @Getter @Setter
    private String studName;
    @Getter @Setter
    private Date birthday;

    public static void main(String[] args) {
        Date today = new Date();

        Student stud1 = new Student();
        stud1.setStudNo(10001);
        stud1.setStudName("huey");
        stud1.setBirthday(today);

        Student stud2 = new Student();
        stud2.setStudNo(10001);
        stud2.setStudName("huey");
        stud2.setBirthday(today);

        System.out.println(stud1.hashCode());
        System.out.println(stud2.hashCode());
        System.out.println(stud1.equals(stud2));
    }
}

结果输出：

-1678491668
-1678491668
true

3. @ToString，实现了toString()方法：

package com.huey.dream.beans;

import java.util.Date;

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

@ToString
public class Student {

    @Getter @Setter
    private int studNo;
    @Getter @Setter
    private String studName;
    @Getter @Setter
    private Date birthday;


    public static void main(String[] args) {
        Date today = new Date();

        Student stud = new Student();
        stud.setStudNo(10001);
        stud.setStudName("huey");
        stud.setBirthday(today);

        System.out.println(stud);
    }
}

结果输出：

Student(studNo=10001, studName=huey, birthday=Mon Dec 29 21:04:17 CST 2014)

4. @Data， 相当上述三个annotation：

package com.huey.dream.beans;

import java.util.Date;

import lombok.Data;

@Data
public class Student {

    private int studNo;
    private String studName;
    private Date birthday;


    public static void main(String[] args) {
        Date today = new Date();

        Student stud1 = new Student();
        stud1.setStudNo(10001);
        stud1.setStudName("huey");
        stud1.setBirthday(today);

        Student stud2 = new Student();
        stud2.setStudNo(10001);
        stud2.setStudName("huey");
        stud2.setBirthday(today);

        System.out.println(stud1.hashCode() - stud2.hashCode());
        System.out.println(stud1.equals(stud2));
        System.out.println(stud1);
    }
}

结果输出：

0
true
Student(studNo=10001, studName=huey, birthday=Mon Dec 29 21:05:32 CST 2014)

5. @NoArgsConstructor，提供一个无参的构造方法：

package com.huey.dream.beans;

import java.util.Date;

import lombok.Data;
import lombok.NoArgsConstructor;

@NoArgsConstructor
@Data
public class Student {

    private int studNo;
    private String studName;
    private Date birthday;

    public Student(int studNo, String studName, Date birthday) {
        super();
        this.studNo = studNo;
        this.studName = studName;
        this.birthday = birthday;
    }

    public static void main(String[] args) {
        Date today = new Date();
        Student stud = new Student();
        stud.setStudNo(10001);
        stud.setStudName("huey");
        stud.setBirthday(today);
        System.out.println(stud);
    }
}

结果输出：

Student(studNo=10001, studName=huey, birthday=Mon Dec 29 21:15:00 CST 2014)

6. @AllArgsConstructor，提供一个全参的构造方法：

package com.huey.dream.beans;

import java.util.Date;

import lombok.AllArgsConstructor;
import lombok.Data;

@AllArgsConstructor
@Data
public class Student {

    private int studNo;
    private String studName;
    private Date birthday;


    public static void main(String[] args) {
        Date today = new Date();
        Student stud = new Student(10001, "huey", today);
        System.out.println(stud);
    }
}

结果输出：

Student(studNo=10001, studName=huey, birthday=Mon Dec 29 21:10:37 CST 2014)

7.  @Synchronized，实现同步

package com.huey.dream.foo;

import java.util.Date;

import lombok.Synchronized;

public class Foo implements Runnable {

    @Override
    public void run() {
        sayHello();
    }

    @Synchronized
    public void sayHello() {
        System.out.println("hello, " + Thread.currentThread().getName() +"! Now is " + new Date());
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Foo foo = new Foo();
        new Thread(foo).start();
        new Thread(foo).start();
    }
}

结果输出：

hello, Thread-0! Now is Mon Dec 29 21:38:26 CST 2014
hello, Thread-1! Now is Mon Dec 29 21:38:29 CST 2014

8. @SneakyThrows，抛出异常

package com.huey.dream.foo;

import java.util.Date;

import lombok.SneakyThrows;

public class Foo {


    @SneakyThrows
    public void sayHello() {
        System.out.println("hello, " + Thread.currentThread().getName() +"! Now is " + new Date());
        Thread.sleep(3000);
    }

    public static void main(String[] args) {
        new Foo().sayHello();
    }
}

9. @Cleanup，关闭流，如果最后清理资源的方法不是close()，可以指定，@Cleanup("clean")：

package com.huey.dream.foo;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

import lombok.Cleanup;

public class Foo {

    public void bar(String path) throws IOException {
        File file = new File(path);
        @Cleanup
        FileReader fr = new FileReader(file);
        BufferedReader br = new BufferedReader(fr);
        // ...
    }
}

10. @NonNull，生成一个非空检查：

package com.huey.dream.foo;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

import lombok.Cleanup;
import lombok.NonNull;

public class Foo {

    public void bar(@NonNull String path) throws IOException {
        File file = new File(path);
        @Cleanup
        FileReader fr = new FileReader(file);
        BufferedReader br = new BufferedReader(fr);
        // ...
    }
}

11. @Logs，生成一个日志对象：

package com.huey.dream.foo;

import lombok.extern.java.Log;

@Log
public class Foo {

    public static void main(String[] args) {
        log.info("This is an info message.");
    }
}

除了，Log还有其他annotation来封装一些主流的日志类库：

@CommonsLog
Creates private static final org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(Foo.class);
@Log
Creates private static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(Foo.class.getName());
@Log4j
Creates private static final org.apache.log4j.Logger log = org.apache.log4j.Logger.getLogger(Foo.class);
@Log4j2
Creates private static final org.apache.logging.log4j.Logger log = org.apache.logging.log4j.LogManager.getLogger(Foo.class);
@Slf4j
Creates private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(Foo.class);
@XSlf4j
Creates private static final org.slf4j.ext.XLogger log = org.slf4j.ext.XLoggerFactory.getXLogger(Foo.class);