lombok使用及常用注解

简介

大部分项目中都必不可少的包含数据库实体(Entity)、数据载体(dto,dataObject),而这两部分都包含着大量的没有业务逻辑的setter、getter、空参构造，同时我们一般要复写类的toString(),equals(),hashCode()方法(贫血模型)。这些工作都是重复性的工作，作为程序员，懒是必备素质之一，这些工作肯定已经有大牛封装好了处理方法,这就是lombok。

idea 安装插件，支持lombok

lombok是在编译阶段才生成相应的代码体，所以在项目中直接调用setter，getter,constructor会报错，这时候可以在IDE安装相应的插件支持lombok。这里介绍idea插件安装，eclipse请自行百度。

安装方法

1. 进入设置页面(windows:setting,Mac:Preferences)
2. 点击Plugin
3. Browse repositories
4. 搜索lombok
5. 点击Install
6. 安装完毕后开启注解权限才能正常使用: 
   
   • –>setting
   • –>Build,Execution,Deployment
   • –>Compiler
   • –>Annontation Processors
   • –>勾选Enable annotation processing
   • –> Apply
7. 重启Idea

引入方法

gradle

1. // https://mvnrepository.com/artifact/org.projectlombok/lombok
2. compile group: 'org.projectlombok', name: 'lombok', version: '1.16.16'

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maven

1. <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
2. <dependency>
3. <groupId>org.projectlombok</groupId>
4. <artifactId>lombok</artifactId>
5. <version>1.16.16</version>
6. </dependency>

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常用方法

@Setter

生成setter方法,final变量不包含

1. //原始类
2. @Setter
3. public class TestEntity {
5. private String name;
7. private Integer age;
9. private final String type = "type";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. private Integer age;
15. private final String type = "person";
17. public TestEntity() {
18. }
20. public void setName(String name) {
21. this.name = name;
22. }
24. public void setAge(Integer age) {
25. this.age = age;
26. }
27. }

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@Getter

生成getter方法,final变量不包含

1. //原始类
2. @Getter
3. public class TestEntity {
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. private Integer age;
15. private final String type = "person";
17. public TestEntity() {
18. }
20. public String getName() {
21. return this.name;
22. }
24. public Integer getAge() {
25. return this.age;
26. }
28. public String getType() {
29. this.getClass();
30. return "person";
31. }
32. }

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@NoArgsConstructor

生成空参构造

1. //原始类
2. @NoArgsConstructor
3. public class TestEntity {
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. private Integer age;
15. private final String type = "person";
17. public TestEntity() {
18. }
19. }

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@AllArgsConstructor

生成全部参数构造

1. //原始类
2. @AllArgsConstructor
3. public class TestEntity {
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. private Integer age;
15. private final String type = "person";
17. @ConstructorProperties({"name", "age"})
18. public TestEntity(String name, Integer age) {
19. this.name = name;
20. this.age = age;
21. }
22. }

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@RequiredArgsConstructor

将标记为@NoNull的属性生成一个构造器

如果运行中标记为@NoNull的属性为null,会抛出空指针异常。

1. //原始类
2. @RequiredArgsConstructor
3. public class TestEntity {
5. private String name;
6. @NonNull
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. @NonNull
15. private Integer age;
16. private final String type = "person";
18. @ConstructorProperties({"age"})
19. public TestEntity(@NonNull Integer age) {
20. if(age == null) {
21. throw new NullPointerException("age");
22. } else {
23. this.age = age;
24. }
25. }
26. }

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@ToString

生成所有属性的toString()方法

1. //原始类
2. @ToString
3. public class TestEntity {
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. private Integer age;
15. private final String type = "person";
17. public TestEntity() {
18. }
20. public String toString() {
21. StringBuilder var10000 = (new StringBuilder()).append("TestEntity(name=").append(this.name).append(", age=").append(this.age).append(", type=");
22. this.getClass();
23. return var10000.append("person").append(")").toString();
24. }
25. }

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@EqualsAndHashCode

生成equals()方法和hashCode方法

1. //原始类
2. @EqualsAndHashCode
3. public class TestEntity {
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. private Integer age;
15. private final String type = "person";
17. public TestEntity() {
18. }
20. public boolean equals(Object o) {
21. if(o == this) {
22. return true;
23. } else if(!(o instanceof TestEntity)) {
24. return false;
25. } else {
26. TestEntity other = (TestEntity)o;
27. if(!other.canEqual(this)) {
28. return false;
29. } else {
30. label47: {
31. String this$name = this.name;
32. String other$name = other.name;
33. if(this$name == null) {
34. if(other$name == null) {
35. break label47;
36. }
37. } else if(this$name.equals(other$name)) {
38. break label47;
39. }
41. return false;
42. }
44. Integer this$age = this.age;
45. Integer other$age = other.age;
46. if(this$age == null) {
47. if(other$age != null) {
48. return false;
49. }
50. } else if(!this$age.equals(other$age)) {
51. return false;
52. }
54. this.getClass();
55. String this$type = "person";
56. other.getClass();
57. String other$type = "person";
58. if(this$type == null) {
59. if(other$type != null) {
60. return false;
61. }
62. } else if(!this$type.equals(other$type)) {
63. return false;
64. }
66. return true;
67. }
68. }
69. }
71. protected boolean canEqual(Object other) {
72. return other instanceof TestEntity;
73. }
75. public int hashCode() {
76. boolean PRIME = true;
77. byte result = 1;
78. String $name = this.name;
79. int result1 = result * 59 + ($name == null?43:$name.hashCode());
80. Integer $age = this.age;
81. result1 = result1 * 59 + ($age == null?43:$age.hashCode());
82. this.getClass();
83. String $type = "person";
84. result1 = result1 * 59 + ($type == null?43:$type.hashCode());
85. return result1;
86. }
87. }

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@Data(常用)

@Data直接修饰POJO or beans， getter所有的变量，setter所有不为final的变量。如果你不需要默认的生成方式，直接填写你需要的annotation的就可以了。默认生成的所有的annotation都是public的，如果需要不同权限修饰符可以使用AccessLevel.NONE选项。当然@Data 也可以使用staticConstructor选项生成一个静态方法。

[email protected][email protected][email protected][email protected]

1. //原始类
2. @Data
3. public class TestEntity {
4. @Setter(AccessLevel.PRIVATE)
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
13. public class TestEntity {
14. private String name;
15. private Integer age;
16. private final String type = "person";
18. public TestEntity() {
19. }
21. public String getName() {
22. return this.name;
23. }
25. public Integer getAge() {
26. return this.age;
27. }
29. public String getType() {
30. this.getClass();
31. return "person";
32. }
34. public void setAge(Integer age) {
35. this.age = age;
36. }
38. public boolean equals(Object o) {
39. if(o == this) {
40. return true;
41. } else if(!(o instanceof TestEntity)) {
42. return false;
43. } else {
44. TestEntity other = (TestEntity)o;
45. if(!other.canEqual(this)) {
46. return false;
47. } else {
48. label47: {
49. String this$name = this.getName();
50. String other$name = other.getName();
51. if(this$name == null) {
52. if(other$name == null) {
53. break label47;
54. }
55. } else if(this$name.equals(other$name)) {
56. break label47;
57. }
59. return false;
60. }
62. Integer this$age = this.getAge();
63. Integer other$age = other.getAge();
64. if(this$age == null) {
65. if(other$age != null) {
66. return false;
67. }
68. } else if(!this$age.equals(other$age)) {
69. return false;
70. }
72. String this$type = this.getType();
73. String other$type = other.getType();
74. if(this$type == null) {
75. if(other$type != null) {
76. return false;
77. }
78. } else if(!this$type.equals(other$type)) {
79. return false;
80. }
82. return true;
83. }
84. }
85. }
87. protected boolean canEqual(Object other) {
88. return other instanceof TestEntity;
89. }
91. public int hashCode() {
92. boolean PRIME = true;
93. byte result = 1;
94. String $name = this.getName();
95. int result1 = result * 59 + ($name == null?43:$name.hashCode());
96. Integer $age = this.getAge();
97. result1 = result1 * 59 + ($age == null?43:$age.hashCode());
98. String $type = this.getType();
99. result1 = result1 * 59 + ($type == null?43:$type.hashCode());
100. return result1;
101. }
103. public String toString() {
104. return "TestEntity(name=" + this.getName() + ", age=" + this.getAge() + ", type=" + this.getType() + ")";
105. }
107. private void setName(String name) {
108. this.name = name;
109. }
110. }

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@Builder

构造Builder模式的结构。通过内部类Builder()进行构建对象。

1. //原始类
2. @Builder
3. public class TestEntity {
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public class TestEntity {
13. private String name;
14. private Integer age;
15. private final String type = "person";
17. @ConstructorProperties({"name", "age"})
18. TestEntity(String name, Integer age) {
19. this.name = name;
20. this.age = age;
21. }
23. public static TestEntity.TestEntityBuilder builder() {
24. return new TestEntity.TestEntityBuilder();
25. }
27. public static class TestEntityBuilder {
28. private String name;
29. private Integer age;
31. TestEntityBuilder() {
32. }
34. public TestEntity.TestEntityBuilder name(String name) {
35. this.name = name;
36. return this;
37. }
39. public TestEntity.TestEntityBuilder age(Integer age) {
40. this.age = age;
41. return this;
42. }
44. public TestEntity build() {
45. return new TestEntity(this.name, this.age);
46. }
48. public String toString() {
49. return "TestEntity.TestEntityBuilder(name=" + this.name + ", age=" + this.age + ")";
50. }
51. }
52. }
54. //Builder模式使用方法
55. @Test
56. public void test(){
57. TestEntity testEntity = TestEntity.builder()
58. .name("java")
59. .age(18)
60. .build();
61. }

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@Value

与@Data相对应的@Value， 两个annotation的主要区别就是如果变量不加@NonFinal ，@Value会给所有的弄成final的。当然如果是final的话，就没有set方法了。

1. //原始类
2. @Value
3. public class TestEntity {
4. @Setter(AccessLevel.PRIVATE)
5. private String name;
7. private Integer age;
9. private final String type = "person";
10. }
11. //反编译的类
12. public final class TestEntity {
13. private final String name;
14. private final Integer age;
15. private final String type = "person";
17. @ConstructorProperties({"name", "age"})
18. public TestEntity(String name, Integer age) {
19. this.name = name;
20. this.age = age;
21. }
23. public String getName() {
24. return this.name;
25. }
27. public Integer getAge() {
28. return this.age;
29. }
31. public String getType() {
32. this.getClass();
33. return "person";
34. }
36. public boolean equals(Object o) {
37. if(o == this) {
38. return true;
39. } else if(!(o instanceof TestEntity)) {
40. return false;
41. } else {
42. TestEntity other;
43. label44: {
44. other = (TestEntity)o;
45. String this$name = this.getName();
46. String other$name = other.getName();
47. if(this$name == null) {
48. if(other$name == null) {
49. break label44;
50. }
51. } else if(this$name.equals(other$name)) {
52. break label44;
53. }
55. return false;
56. }
58. Integer this$age = this.getAge();
59. Integer other$age = other.getAge();
60. if(this$age == null) {
61. if(other$age != null) {
62. return false;
63. }
64. } else if(!this$age.equals(other$age)) {
65. return false;
66. }
68. String this$type = this.getType();
69. String other$type = other.getType();
70. if(this$type == null) {
71. if(other$type != null) {
72. return false;
73. }
74. } else if(!this$type.equals(other$type)) {
75. return false;
76. }
78. return true;
79. }
80. }
82. public int hashCode() {
83. boolean PRIME = true;
84. byte result = 1;
85. String $name = this.getName();
86. int result1 = result * 59 + ($name == null?43:$name.hashCode());
87. Integer $age = this.getAge();
88. result1 = result1 * 59 + ($age == null?43:$age.hashCode());
89. String $type = this.getType();
90. result1 = result1 * 59 + ($type == null?43:$type.hashCode());
91. return result1;
92. }
94. public String toString() {
95. return "TestEntity(name=" + this.getName() + ", age=" + this.getAge() + ", type=" + this.getType() + ")";
96. }
97. }

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@Synchronized

同步方法

1. //原始类
2. public class TestEntity {
3. private String name;
5. private Integer age;
7. private final String type = "person";
8. @Synchronized
9. public void write(){
10. //do something
11. }
12. }
13. //反编译的类
14. public class TestEntity {
15. private final Object $lock = new Object[0];
16. private String name;
17. private Integer age;
18. private final String type = "person";
20. public TestEntity() {
21. }
23. public void write() {
24. Object var1 = this.$lock;
25. synchronized(this.$lock) {
26. ;
27. }
28. }
29. }

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@Cleanup @@SneakyThrows

自动调用close方法关闭资源。

1. //原始类
2. public class TestEntity {
3. private String name;
5. private Integer age;
7. private final String type = "person";
9. @SneakyThrows
10. public void outputStream(){
11. @Cleanup OutputStream outputStream = new FileOutputStream(new File("/Users/hello"));
12. }
13. }
14. //反编译的类
15. public class TestEntity {
16. private String name;
17. private Integer age;
18. private final String type = "person";
20. public TestEntity() {
21. }
23. public void outputStream() {
24. try {
25. FileOutputStream $ex = new FileOutputStream(new File("/Users/hello"));
26. if(Collections.singletonList($ex).get(0) != null) {
27. $ex.close();
28. }
30. } catch (Throwable var2) {
31. throw var2;
32. }
33. }