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);

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