Lombok(1.14.8)的简单示例

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 @Setterprivate int studNo;@Getter @Setterprivate String studName;@Getter @Setterprivate 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;@EqualsAndHashCodepublic class Student {@Getter @Setterprivate int studNo;@Getter @Setterprivate String studName;@Getter @Setterprivate 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：

-1678491668-1678491668true

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;@ToStringpublic class Student {@Getter @Setterprivate int studNo;@Getter @Setterprivate String studName;@Getter @Setterprivate 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;@Datapublic 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：

0trueStudent(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@Datapublic 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@Datapublic 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 {@Overridepublic void run() {sayHello();}@Synchronizedpublic 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 2014hello, 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 {@SneakyThrowspublic 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);@CleanupFileReader 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);@CleanupFileReader 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;@Logpublic 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);