Lombok注解

2020-01-11 本文已影响0人西三旗靓仔

注解

@AllArgsConstructor

生成包含所有字段的构造器

staticName : 不为空的话，生成一个静态方法返回实例，并把构造器设置为private

@AllArgsConstructor(staticName = "create")
public class Example {

   private int foo;
   private final String bar;
}

生成：

public class Example {
   private int foo;
   private final String bar;

   private Example(int foo, String bar) {
       this.foo = foo;
       this.bar = bar;
   }

   public static Example create(int foo, String bar) {
       return new Example(foo, bar);
   }
}

access : 构造器访问权限修饰符，默认public

@Builder

生成构建者(Builder)模式

@Builder
public class Example {

   private int foo;
   private final String bar;
}

生成：

public class Example {
   private int foo;
   private final String bar;

   Example(int foo, String bar) {
       this.foo = foo;
       this.bar = bar;
   }

   public static Example.ExampleBuilder builder() {
       return new Example.ExampleBuilder();
   }

   public static class ExampleBuilder {
       private int foo;
       private String bar;

       ExampleBuilder() {
       }

       public Example.ExampleBuilder foo(int foo) {
           this.foo = foo;
           return this;
       }

       public Example.ExampleBuilder bar(String bar) {
           this.bar = bar;
           return this;
       }

       public Example build() {
           return new Example(this.foo, this.bar);
       }

       public String toString() {
           return "Example.ExampleBuilder(foo=" + this.foo + ", bar=" + this.bar + ")";
       }
   }
}

参数

builderMethodName : 创建构建器实例的方法名称
buildMethodName：构建器类中创建构造器实例的方法名称
builderClassName：构造器类名
toBuilder：生成toBuilder方法

例子

public Example.ExampleBuilder toBuilder() {
   return (new Example.ExampleBuilder()).foo(this.foo).bar(this.bar);
}

@Cleanup

在变量上声明@Cleanup，生成的代码会把变量用try{}包围，并在finallly块中调用close()

public class Example {

   public void copyFile(String in, String out) throws IOException {
       @Cleanup FileInputStream inStream = new FileInputStream(in);
       @Cleanup FileOutputStream outStream = new FileOutputStream(out);
       byte[] b = new byte[65536];
       while (true) {
           int r = inStream.read(b);
           if (r == -1) break;
           outStream.write(b, 0, r);
       }
   }
}

生成后：

public class Example {
   public Example() {
   }

   public void copyFile(String in, String out) throws IOException {
       FileInputStream inStream = new FileInputStream(in);

       try {
           FileOutputStream outStream = new FileOutputStream(out);

           try {
               byte[] b = new byte[65536];

               while(true) {
                   int r = inStream.read(b);
                   if (r == -1) {
                       return;
                   }

                   outStream.write(b, 0, r);
               }
           } finally {
               if (Collections.singletonList(outStream).get(0) != null) {
                   outStream.close();
               }

           }
       } finally {
           if (Collections.singletonList(inStream).get(0) != null) {
               inStream.close();
           }

       }
   }
}

value：被在finally块中调用的方法名，方法体不能带有参数，默认为close

@Data

生成所有字段的getter、toString()、hashCode()、equals()、所有非final字段的setter、构造器，相当于设置了 @Getter @Setter @RequiredArgsConstructor @ToString @EqualsAndHashCode

@Data
public class Example {

   private int foo;
   private final String bar;
}

生成：

public class Example {
   private int foo;
   private final String bar;

   public Example(String bar) {
       this.bar = bar;
   }

   public int getFoo() {
       return this.foo;
   }

   public String getBar() {
       return this.bar;
   }

   public void setFoo(int foo) {
       this.foo = foo;
   }

   public boolean equals(Object o) {
       if (o == this) {
           return true;
       } else if (!(o instanceof Example)) {
           return false;
       } else {
           Example other = (Example)o;
           if (!other.canEqual(this)) {
               return false;
           } else if (this.getFoo() != other.getFoo()) {
               return false;
           } else {
               Object this$bar = this.getBar();
               Object other$bar = other.getBar();
               if (this$bar == null) {
                   if (other$bar != null) {
                       return false;
                   }
               } else if (!this$bar.equals(other$bar)) {
                   return false;
               }

               return true;
           }
       }
   }

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

   public int hashCode() {
       int PRIME = true;
       int result = 1;
       int result = result * 59 + this.getFoo();
       Object $bar = this.getBar();
       result = result * 59 + ($bar == null ? 43 : $bar.hashCode());
       return result;
   }

   public String toString() {
       return "Example(foo=" + this.getFoo() + ", bar=" + this.getBar() + ")";
   }
}

@Delegate

@EqualsAndHashCode

生成hashCode()、equals()，效果见@Data

callSuper：是否调用父类的hashCode()，默认：false
doNotUseGetters：是否不调用字段的getter，默认如果有getter会调用。设置为true，直接访问字段，不调用getter
exclude：此处列出的任何字段都不会在生成的equals和hashCode中使用。
of：与exclude相反，设置of，exclude失效
onParam：添加注解，参考@Getter#onMethod

@Getter

生成getter、写在类上会生成该类下所有字段的getter。写在某个字段上就作用与该字段

onMethod：把需要添加的注解写在这

public class Example {

   @Getter(onMethod_={@Deprecated}) // JDK7写法 @Getter(onMethod=@__({@Deprecated}))
   private int foo;
   private final String bar  = "";
}

生成：

public class Example {
   private int foo;
   private final String bar = "";

   public Example() {
   }

   /** @deprecated */
   @Deprecated
   public int getFoo() {
       return this.foo;
   }
}

value：访问权限修饰符

@NoArgsConstructor

生成无参数构造器

access：访问权限修饰符
force：为true时，强制生成构造器，final字段初始化为null
onConstructor：添加注解，参考@Getter#onMethod

@NonNull

空检查

public class Example {

   @NonNull
   @Getter
   @Setter
   private Integer foo;
}

生成后：

public class Example {
   @NonNull
   private Integer foo;

   public Example() {
   }

   @NonNull
   public Integer getFoo() {
       return this.foo;
   }

   public void setFoo(@NonNull Integer foo) {
       if (foo == null) {
           throw new NullPointerException("foo is marked @NonNull but is null");
       } else {
           this.foo = foo;
       }
   }
}

@RequiredArgsConstructor

生成必须初始化字段的构造器，比如带final、@NonNull

@RequiredArgsConstructor
public class Example {

   @NonNull
   private Integer foo;
   private final String bar;
}

生成后：

public class Example {
   @NonNull
   private Integer foo;
   private final String bar;

   public Example(@NonNull Integer foo, String bar) {
       if (foo == null) {
           throw new NullPointerException("foo is marked @NonNull but is null");
       } else {
           this.foo = foo;
           this.bar = bar;
       }
   }
}

@Setter

生成Setter

onMethod：在方法上添加中注解，见@Getter#onMethod
onParam：在方法的参数上添加注解，见@Getter#onMethod
value：访问权限修饰符

@Singular

这个注解和@Builder一起使用，为Builder生成字段是集合类型的add方法，字段名不能是单数形式，否则需要指定value值

@Builder
public class Example {

   @Singular
   @Setter
   private List<Integer> foos;
}

生成：

public class Example {
   private List<Integer> foos;

   Example(List<Integer> foos) {
       this.foos = foos;
   }

   public static Example.ExampleBuilder builder() {
       return new Example.ExampleBuilder();
   }

   public void setFoos(List<Integer> foos) {
       this.foos = foos;
   }

   public static class ExampleBuilder {
       private ArrayList<Integer> foos;

       ExampleBuilder() {
       }
      
       // 这方法是@Singular作用生成的
       public Example.ExampleBuilder foo(Integer foo) {
           if (this.foos == null) {
               this.foos = new ArrayList();
           }

           this.foos.add(foo);
           return this;
       }

       public Example.ExampleBuilder foos(Collection<? extends Integer> foos) {
           if (this.foos == null) {
               this.foos = new ArrayList();
           }

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

       public Example.ExampleBuilder clearFoos() {
           if (this.foos != null) {
               this.foos.clear();
           }

           return this;
       }

       public Example build() {
           List foos;
           switch(this.foos == null ? 0 : this.foos.size()) {
           case 0:
               foos = Collections.emptyList();
               break;
           case 1:
               foos = Collections.singletonList(this.foos.get(0));
               break;
           default:
               foos = Collections.unmodifiableList(new ArrayList(this.foos));
           }

           return new Example(foos);
       }

       public String toString() {
           return "Example.ExampleBuilder(foos=" + this.foos + ")";
       }
   }
}

@SneakyThrows

用try{}catch{}捕捉异常

public class Example {

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

生成后：

public class Example {
   public Example() {
   }

   public String utf8ToString(byte[] bytes) {
       try {
           return new String(bytes, "UTF-8");
       } catch (UnsupportedEncodingException var3) {
           throw var3;
       }
   }
}

@Synchronized

生成Synchronized(){}包围代码

public class Example {

   @Synchronized
   public String utf8ToString(byte[] bytes) {
       return new String(bytes, Charset.defaultCharset());
   }
}

生成后：

public class Example {
   private final Object $lock = new Object[0];

   public Example() {
   }

   public String utf8ToString(byte[] bytes) {
       Object var2 = this.$lock;
       synchronized(this.$lock) {
           return new String(bytes, Charset.defaultCharset());
       }
   }
}

@ToString

生成toString()方法

@val

变量声明类型推断

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

   public void example2() {
       val map = new HashMap<Integer, String>();
       map.put(0, "zero");
       map.put(5, "five");
       for (val entry : map.entrySet()) {
           System.out.printf("%d: %s\n", entry.getKey(), entry.getValue());
       }
   }
}

生成后：

public class ValExample {
   public ValExample() {
   }

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

   public void example2() {
       HashMap<Integer, String> map = new HashMap();
       map.put(0, "zero");
       map.put(5, "five");
       Iterator var2 = map.entrySet().iterator();

       while(var2.hasNext()) {
           Entry<Integer, String> entry = (Entry)var2.next();
           System.out.printf("%d: %s\n", entry.getKey(), entry.getValue());
       }

   }
}

@Value

把类声明为final，并添加toString()、hashCode()等方法，相当于 @Getter @FieldDefaults(makeFinal=true, level=AccessLevel.PRIVATE) @AllArgsConstructor @ToString @EqualsAndHashCode.

例子

@Value
public class Example {

   private Integer foo;
}

生成后：

public final class Example {
   private final Integer foo;

   public Example(Integer foo) {
       this.foo = foo;
   }

   public Integer getFoo() {
       return this.foo;
   }

   public boolean equals(Object o) {
       if (o == this) {
           return true;
       } else if (!(o instanceof Example)) {
           return false;
       } else {
           Example other = (Example)o;
           Object this$foo = this.getFoo();
           Object other$foo = other.getFoo();
           if (this$foo == null) {
               if (other$foo != null) {
                   return false;
               }
           } else if (!this$foo.equals(other$foo)) {
               return false;
           }

           return true;
       }
   }

   public int hashCode() {
       int PRIME = true;
       int result = 1;
       Object $foo = this.getFoo();
       int result = result * 59 + ($foo == null ? 43 : $foo.hashCode());
       return result;
   }

   public String toString() {
       return "Example(foo=" + this.getFoo() + ")";
   }
}

@var

和val一样，官方文档中说区别就是var不加final修饰，但测试的效果是一样的

Experimental注解

在lombok.experimental包下

@Accessors

默认情况下，没什么作用，需要设置参数

chain：为true时，setter链式返回，即setter的返回值为this
fluent：为true时，默认设置chain为true，setter的方法名修改为字段名

@Delegate

代理模式，把字段的方法代理给类，默认代理所有方法

types：指定代理的方法
excludes：和types相反

public class Example {

   private interface Add {
       boolean add(String x);
       boolean addAll(Collection<? extends String> x);
   }

   private @Delegate(types = Add.class) List<String> strings;
}

生成后：

public class Example {
   private List<String> strings;

   public Example() {
   }

   public boolean add(String x) {
       return this.strings.add(x);
   }

   public boolean addAll(Collection<? extends String> x) {
       return this.strings.addAll(x);
   }

   private interface Add {
       boolean add(String var1);

       boolean addAll(Collection<? extends String> var1);
   }
}

@ExtensionMethod

拓展方法，向现有类型“添加”方法，而无需创建新的派生类型。有点像kotlin的扩展函数。

@ExtensionMethod({Arrays.class, Extensions.class})
public class Example {

   public static void main(String[] args) {
       int[] intArray = {5, 3, 8, 2};
       intArray.sort();
       int num = 1;
       num = num.increase();

       Arrays.stream(intArray).forEach(System.out::println);
       System.out.println("num = " + num);
   }
}

class Extensions {
   public static int increase(int num) {
       return ++num;
   }
}

生成后：

public class Example {
   public Example() {
   }

   public static void main(String[] args) {
       int[] intArray = new int[]{5, 3, 8, 2};
       Arrays.sort(intArray);
       int num = 1;
       int num = Extensions.increase(num);
       IntStream var10000 = Arrays.stream(intArray);
       PrintStream var10001 = System.out;
       System.out.getClass();
       var10000.forEach(var10001::println);
       System.out.println("num = " + num);
   }
}

输出：

2
3
5
8
num = 2

@FieldDefaults

定义类、字段的修饰符

AccessLevel：访问权限修饰符
makeFinal：是否加final

@FieldNameConstants

默认生成一个常量，名称为大写字段名，值为字段名

prefix：前缀
suffix：后缀

例子

public class Example {

   @FieldNameConstants(prefix = "PREFIX_", suffix = "_SUFFIX")
   private String foo;
}

生成后：

public class Example {
   public static final String PREFIX_FOO_SUFFIX = "foo";
   private String foo;

   public Example() {
   }
}

@Helper

方法内部的类方法暴露给方法使用

测试时，maven编译不通过。

@NonFinal

设置不为Final，@FieldDefaults和@Value也有这功能

@PackagePrivate

作用

设置为private，@FieldDefaults和@Value也有这功能

@SuperBuilder

@Tolerate

@UtilityClass

@Wither

生成withXXX方法，返回类实例

@RequiredArgsConstructor
public class Example {
   private @Wither final int foo;
}

生成后：

public class Example {
   private final int foo;

   public Example(int foo) {
       this.foo = foo;
   }

   public Example withFoo(int foo) {
       return this.foo == foo ? this : new Example(foo);
   }
}

Lombok注解

注解

@AllArgsConstructor

@Builder

@Cleanup

@Data

@Delegate

@EqualsAndHashCode

@Getter

@NoArgsConstructor

@NonNull

@RequiredArgsConstructor

@Setter

@Singular

@SneakyThrows

@Synchronized

@ToString

@val

@Value

@var

Experimental注解

@Accessors

@Delegate

@ExtensionMethod

@FieldDefaults

@FieldNameConstants

@Helper

@NonFinal

@PackagePrivate

@SuperBuilder

@Tolerate

@UtilityClass

@Wither

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