JAVA利用反射清除实体类对应字段

# 使用场景

该工具类适用于某些接口中一些参数不需要设置为null，通常我们都是在代码中调用对应字段的set方法显示的去进行设置为null。而该工具类则是通过反射来进行设置，凡是标注了对应注解的字段都会进行清空

# 工具类

1.自定义忽略字段注解IgnoreField

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface IgnoreField {
}

1
2
3
4
5

2.工具类

import com.weiyiji.annotation.IgnoreField;

import java.lang.reflect.Field;
import java.util.Collection;

public class BusinessFieldRemoveUtil {

    static String JAVA_LANG_STRING = "java.lang.String";

    public static void removeFields(Object object) throws Exception {
        try {
            removeField(object);
        } catch (Exception e) {
            throw new Exception("不需要的业务字段移除失败" + e.getMessage());
        }
    }

    private static void removeField(Object removeObject) throws IllegalAccessException {
        Class<?> infoClass = removeObject.getClass();
        Field[] infoFieldArray = infoClass.getDeclaredFields();
        for (Field field : infoFieldArray) {
            if (field.isAnnotationPresent(IgnoreField.class)) {

                if (field.getType().getTypeName().equals(JAVA_LANG_STRING)) {
                    field.setAccessible(true);
                    field.set(removeObject, null);
                } else {
                    field.setAccessible(true);
                    Object obj = field.get(removeObject);
                    if (obj == null) {
                        continue;
                    }
                    if (obj instanceof Collection) {
                        Collection collection = (Collection) obj;
                        for (Object o : collection) {
                            if (o != null) {
                                removeField(o);
                            }
                        }
                    } else {
                        removeField(obj);
                    }
                }
            }
        }
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

# 测试

实体类：

@Data
@Builder
public class User {
  private String name;
  private String address;
  @IgnoreField
  private String email;
  @IgnoreField
  private String qq;

}

1
2
3
4
5
6
7
8
9
10
11
12

测试类：

  public static void main(String[] args) {
    User build =
        User.builder()
            .name("程序员子龙")
            .qq("123456")
            .address("北京")
            .wx("xxxx")
            .email("qq.com")
            .build();
    System.out.println(build);
    try {
      BusinessFieldRemoveUtil.removeFields(build);
      System.out.println(build);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

输出结果：

User(name=程序员子龙, address=北京, email=qq.com, qq=123456, wx=xxxx) User(name=程序员子龙, address=北京, email=null, qq=null, wx=null)

上次更新: 2024/03/18, 15:55:19

← java中double类型数据加减乘除操作精度丢失问题及解决方法 JSON转换问题最全详解（json转List，json转对象，json转JSONObject）→