lombok使用手册

lombok使用手册：

1、安装插件

1.1、idel：

elipse:下载地址https://projectlombok.org/download

运行jar文件

1.2、使用lombok还需要引用相关jar包

参考网址：https://projectlombok.org/features/all

2、注解说明

2.1、@Data

@Data
All together now: A shortcut for @ToString, @EqualsAndHashCode, @Getter on all fields, and @Setter on all non-final fields, and @RequiredArgsConstructor!
Lombok代码：

@Data
public class Lombok {
    private String name;
    private String age;
}

编译后代码：

public class Lombok {
    private String name;
    private String age;

    public Lombok() {
    }

    public String getName() {
        return this.name;
    }

    public String getAge() {
        return this.age;
    }

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

    public void setAge(String age) {
        this.age = age;
    }

    public boolean equals(Object o) {
        if(o == this) {
            return true;
        } else if(!(o instanceof Lombok)) {
            return false;
        } else {
            Lombok other = (Lombok)o;
            if(!other.canEqual(this)) {
                return false;
            } else {
                String this$name = this.getName();
                String other$name = other.getName();
                if(this$name == null) {
                    if(other$name != null) {
                        return false;
                    }
                } else if(!this$name.equals(other$name)) {
                    return false;
                }

                String this$age = this.getAge();
                String other$age = other.getAge();
                if(this$age == null) {
                    if(other$age != null) {
                        return false;
                    }
                } else if(!this$age.equals(other$age)) {
                    return false;
                }

                return true;
            }
        }
    }

    protected boolean canEqual(Object other) {
        return other instanceof Lombok;
    }

    public int hashCode() {
        boolean PRIME = true;
        byte result = 1;
        String $name = this.getName();
        int result1 = result * 59 + ($name == null?43:$name.hashCode());
        String $age = this.getAge();
        result1 = result1 * 59 + ($age == null?43:$age.hashCode());
        return result1;
    }

    public String toString() {
        return "Lombok(name=" + this.getName() + ", age=" + this.getAge() + ")";
    }
}

2.2、@val

编译前代码：

    val example = new ArrayList<String>();
    example.add("Hello, World!");
    val foo = example.get(0);
    return foo.toLowerCase();

    val map = new HashMap<Integer, String>();
    map.put(0, "zero");
    map.put(5, "five");
    for (val entry : map.entrySet()) {
      System.out.printf("%d: %s
", entry.getKey(), entry.getValue());
    }

编译后代码：

    final ArrayList<String> example = new ArrayList<String>();
    example.add("Hello, World!");
    final String foo = example.get(0);
    return foo.toLowerCase();

    final HashMap<Integer, String> map = new HashMap<Integer, String>();
    map.put(0, "zero");
    map.put(5, "five");
    for (final Map.Entry<Integer, String> entry : map.entrySet()) {
      System.out.printf("%d: %s
", entry.getKey(), entry.getValue());
    }

2.3、@var 用法参考@val

2.4、@NonNull

编译前代码：

  public NonNullExample(@NonNull Person person) {
    this.name = person.getName();
  }

编译后代码：

public NonNullExample(@NonNull Person person) {
    if (person == null) {
      throw new NullPointerException("person is marked @NonNull but is null");
    }
    this.name = person.getName();
  }

2.5、@Cleanup

编译前代码：

    @Cleanup InputStream in = new FileInputStream(args[0]);
    @Cleanup OutputStream out = new FileOutputStream(args[1]);
    byte[] b = new byte[10000];
    while (true) {
      int r = in.read(b);
      if (r == -1) break;
      out.write(b, 0, r);
    }

编译后代码：

    InputStream in = new FileInputStream(args[0]);
    try {
      OutputStream out = new FileOutputStream(args[1]);
      try {
        byte[] b = new byte[10000];
        while (true) {
          int r = in.read(b);
          if (r == -1) break;
          out.write(b, 0, r);
        }
      } finally {
        if (out != null) {
          out.close();
        }
      }
    } finally {
      if (in != null) {
        in.close();
      }
    }

 2.6、@Getter、@Setter

编译前代码：

  @Getter @Setter private int age = 10;
  @Setter private String name;

编译后代码：

  public int getAge() {
    return age;
  }
  public void setAge(int age) {
    this.age = age;
  }
  protected void setName(String name) {
    this.name = name;
  }

2.7、@ToString

编译前代码：

@ToString
public class Lombok {
    @Getter @Setter String name;
    @Getter @Setter private String age;
    @ToString.Exclude String id;
}

编译后代码：

public class Lombok {
    String name;
    private String age;
    String id;

    public Lombok() {
    }

    public String toString() {
        return "Lombok(name=" + this.getName() + ", age=" + this.getAge() + ")";
    }

    public String getName() {
        return this.name;
    }

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

    public String getAge() {
        return this.age;
    }

    public void setAge(String age) {
        this.age = age;
    }
}

2.8、@EqualsAndHashCode

编译前代码：

@EqualsAndHashCode
public class Lombok {
    @Getter @Setter String name;
    @Getter @Setter private String age;
    @EqualsAndHashCode.Exclude String id;
}

编译后代码：

public class Lombok {
    String name;
    private String age;
    String id;

    public Lombok() {
    }

    public boolean equals(Object o) {
        if(o == this) {
            return true;
        } else if(!(o instanceof Lombok)) {
            return false;
        } else {
            Lombok other = (Lombok)o;
            if(!other.canEqual(this)) {
                return false;
            } else {
                String this$name = this.getName();
                String other$name = other.getName();
                if(this$name == null) {
                    if(other$name != null) {
                        return false;
                    }
                } else if(!this$name.equals(other$name)) {
                    return false;
                }

                String this$age = this.getAge();
                String other$age = other.getAge();
                if(this$age == null) {
                    if(other$age != null) {
                        return false;
                    }
                } else if(!this$age.equals(other$age)) {
                    return false;
                }

                return true;
            }
        }
    }

    protected boolean canEqual(Object other) {
        return other instanceof Lombok;
    }

    public int hashCode() {
        boolean PRIME = true;
        byte result = 1;
        String $name = this.getName();
        int result1 = result * 59 + ($name == null?43:$name.hashCode());
        String $age = this.getAge();
        result1 = result1 * 59 + ($age == null?43:$age.hashCode());
        return result1;
    }

    public String getName() {
        return this.name;
    }

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

    public String getAge() {
        return this.age;
    }

    public void setAge(String age) {
        this.age = age;
    }
}

2.9、@NoArgsConstructor, @RequiredArgsConstructor, @AllArgsConstructor构造器

编译前代码：

@RequiredArgsConstructor(staticName = "of")
@AllArgsConstructor(access = AccessLevel.PROTECTED)
public class ConstructorExample<T> {
  private int x, y;
  @NonNull private T description;
  
  @NoArgsConstructor
  public static class NoArgsExample {
    @NonNull private String field;
  }
}

编译后代码：

 public class ConstructorExample<T> {
  private int x, y;
  @NonNull private T description;
  
  private ConstructorExample(T description) {
    if (description == null) throw new NullPointerException("description");
    this.description = description;
  }
  
  public static <T> ConstructorExample<T> of(T description) {
    return new ConstructorExample<T>(description);
  }
  
  @java.beans.ConstructorProperties({"x", "y", "description"})
  protected ConstructorExample(int x, int y, T description) {
    if (description == null) throw new NullPointerException("description");
    this.x = x;
    this.y = y;
    this.description = description;
  }
  
  public static class NoArgsExample {
    @NonNull private String field;
    
    public NoArgsExample() {
    }
  }
}

2.10、@Value用法参考@Data默认设置为final，会被其他注解显示生效

2.11、@Builder

编译前代码：

@Builder
public class BuilderExample {
    @Builder.Default private long created = System.currentTimeMillis();
    private String name;
    private int age;
    @Singular
    private Set<String> occupations;
}

编译后代码：

public class BuilderExample {
    private long created;
    private String name;
    private int age;
    private Set<String> occupations;

    private static long $default$created() {
        return System.currentTimeMillis();
    }

    BuilderExample(long created, String name, int age, Set<String> occupations) {
        this.created = created;
        this.name = name;
        this.age = age;
        this.occupations = occupations;
    }

    public static BuilderExample.BuilderExampleBuilder builder() {
        return new BuilderExample.BuilderExampleBuilder();
    }

    public static class BuilderExampleBuilder {
        private boolean created$set;
        private long created$value;
        private String name;
        private int age;
        private ArrayList<String> occupations;

        BuilderExampleBuilder() {
        }

        public BuilderExample.BuilderExampleBuilder created(long created) {
            this.created$value = created;
            this.created$set = true;
            return this;
        }

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

        public BuilderExample.BuilderExampleBuilder age(int age) {
            this.age = age;
            return this;
        }

        public BuilderExample.BuilderExampleBuilder occupation(String occupation) {
            if(this.occupations == null) {
                this.occupations = new ArrayList();
            }

            this.occupations.add(occupation);
            return this;
        }

        public BuilderExample.BuilderExampleBuilder occupations(Collection<? extends String> occupations) {
            if(this.occupations == null) {
                this.occupations = new ArrayList();
            }

            this.occupations.addAll(occupations);
            return this;
        }

        public BuilderExample.BuilderExampleBuilder clearOccupations() {
            if(this.occupations != null) {
                this.occupations.clear();
            }

            return this;
        }

        public BuilderExample build() {
            Set occupations;
            switch(this.occupations == null?0:this.occupations.size()) {
            case 0:
                occupations = Collections.emptySet();
                break;
            case 1:
                occupations = Collections.singleton(this.occupations.get(0));
                break;
            default:
                LinkedHashSet occupations1 = new LinkedHashSet(this.occupations.size() < 1073741824?1 + this.occupations.size() + (this.occupations.size() - 3) / 3:2147483647);
                occupations1.addAll(this.occupations);
                occupations = Collections.unmodifiableSet(occupations1);
            }

            long created$value = this.created$value;
            if(!this.created$set) {
                created$value = System.currentTimeMillis();
            }

            return new BuilderExample(created$value, this.name, this.age, occupations);
        }

        public String toString() {
            return "BuilderExample.BuilderExampleBuilder(created$value=" + this.created$value + ", name=" + this.name + ", age=" + this.age + ", occupations=" + this.occupations + ")";
        }
    }
}

 2.12、@SneakyThrows

编译前代码：

 @SneakyThrows(UnsupportedEncodingException.class)
  public String utf8ToString(byte[] bytes) {
    return new String(bytes, "UTF-8");
  }
  
  @SneakyThrows
  public void run() {
    throw new Throwable();
  }

编译后代码：

  public String utf8ToString(byte[] bytes) {
    try {
      return new String(bytes, "UTF-8");
    } catch (UnsupportedEncodingException e) {
      throw Lombok.sneakyThrow(e);
    }
  }
  
  public void run() {
    try {
      throw new Throwable();
    } catch (Throwable t) {
      throw Lombok.sneakyThrow(t);
    }
  }

2.13、@Synchronized

编译前代码：

public class SynchronizedExample {
  private final Object readLock = new Object();
  
  @Synchronized
  public static void hello() {
    System.out.println("world");
  }
  
  @Synchronized
  public int answerToLife() {
    return 42;
  }
  
  @Synchronized("readLock")
  public void foo() {
    System.out.println("bar");
  }
}

编译后代码：

 public class SynchronizedExample {
  private static final Object $LOCK = new Object[0];
  private final Object $lock = new Object[0];
  private final Object readLock = new Object();
  
  public static void hello() {
    synchronized($LOCK) {
      System.out.println("world");
    }
  }
  
  public int answerToLife() {
    synchronized($lock) {
      return 42;
    }
  }
  
  public void foo() {
    synchronized(readLock) {
      System.out.println("bar");
    }
  }
}

2.14、@With 必须要包含全参数构造器

编译前代码：

@AllArgsConstructor
public class Lombok {
    @With private Integer x;
    @With private Integer y;
    @With private Integer z;
}

编译后代码：

public class Lombok {
    private Integer x;
    private Integer y;
    private Integer z;

    public Lombok(Integer x, Integer y, Integer z) {
        this.x = x;
        this.y = y;
        this.z = z;
    }

    public Lombok withX(Integer x) {
        return this.x == x?this:new Lombok(x, this.y, this.z);
    }

    public Lombok withY(Integer y) {
        return this.y == y?this:new Lombok(this.x, y, this.z);
    }

    public Lombok withZ(Integer z) {
        return this.z == z?this:new Lombok(this.x, this.y, z);
    }
}

2.15、@Getter(lazy=true)缓存

编译前代码：

public class Lombok {
    @Getter(lazy=true) private final int[] cached = expensive();

    private int[] expensive() {
        int[] result = new int[1000000];
        for (int i = 0; i < result.length; i++) {
            result[i] = i;
        }
        return result;
    }
}

编译后代码：

public class Lombok {
    private final AtomicReference<Object> cached = new AtomicReference();

    public Lombok() {
    }

    private int[] expensive() {
        int[] result = new int[1000000];

        for(int i = 0; i < result.length; result[i] = i++) {
            ;
        }

        return result;
    }

    public int[] getCached() {
        Object value = this.cached.get();
        if(value == null) {
            AtomicReference var2 = this.cached;
            synchronized(this.cached) {
                value = this.cached.get();
                if(value == null) {
                    int[] actualValue = this.expensive();
                    value = actualValue == null?this.cached:actualValue;
                    this.cached.set(value);
                }
            }
        }

        return (int[])((int[])(value == this.cached?null:value));
    }
}

2.16、日志@Log (and friends)

 @CommonsLog
    Creates private static final org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(LogExample.class);
@Flogger
    Creates private static final com.google.common.flogger.FluentLogger log = com.google.common.flogger.FluentLogger.forEnclosingClass();
@JBossLog
    Creates private static final org.jboss.logging.Logger log = org.jboss.logging.Logger.getLogger(LogExample.class);
@Log
    Creates private static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(LogExample.class.getName());
@Log4j
    Creates private static final org.apache.log4j.Logger log = org.apache.log4j.Logger.getLogger(LogExample.class);
@Log4j2
    Creates private static final org.apache.logging.log4j.Logger log = org.apache.logging.log4j.LogManager.getLogger(LogExample.class);
@Slf4j
    Creates private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(LogExample.class);
@XSlf4j
    Creates private static final org.slf4j.ext.XLogger log = org.slf4j.ext.XLoggerFactory.getXLogger(LogExample.class);
@CustomLog
    Creates private static final com.foo.your.Logger log = com.foo.your.LoggerFactory.createYourLogger(LogExample.class);

@Log
public class Lombok {
    @Getter(lazy=true) private final int[] cached = expensive();

    private int[] expensive() {
        int[] result = new int[1000000];
        for (int i = 0; i < result.length; i++) {
            result[i] = i;
        }
        log.severe(result.toString());
        return result;
    }
}

2.17、额外的注解见链接https://projectlombok.org/features/all

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原文地址：https://www.cnblogs.com/miaosj/p/11760054.html