java 根据值获取枚举对象

Posted 2021-03-14 遥远2

关键方法：

/**
 * 值映射为枚举
 *
 * @param enumClass 枚举类
 * @param value     枚举值
 * @param method    取值方法
 * @param <E>       对应枚举
 * @return
 */
public static <E extends Enum<?>> E valueOf(Class<E> enumClass, Object value, Method method) {
    E[] es = enumClass.getEnumConstants();
    for (E e : es) {
        Object evalue;
        try {
            method.setAccessible(true);
            evalue = method.invoke(e);
        } catch (IllegalAccessException | InvocationTargetException e1) {
            throw ExceptionUtils.mpe("Error: NoSuchMethod in {}.  Cause:", e, enumClass.getName());
        }
        if (value instanceof Number && evalue instanceof Number
                && new BigDecimal(String.valueOf(value)).compareTo(new BigDecimal(String.valueOf(evalue))) == 0) {
            return e;
        }
        if (Objects.equals(evalue, value)) {
            return e;
        }
    }
    return null;
}

测试枚举类：

@Getter
    @NoArgsConstructor
    @AllArgsConstructor
    public enum StrEnum {
        TEST1("000","成功"), TEST2("999","失败"), TEST3("888","处理中");
        private String value;
        private String text;
    }
    @Getter
    @NoArgsConstructor
    @AllArgsConstructor
    public enum IntEnum {
        TEST1(0,"成功"), TEST2(1,"失败"), TEST3(2,"处理中");
        private int value;
        private String text;
    }
    @Getter
    @NoArgsConstructor
    @AllArgsConstructor
    public enum LongEnum {
        TEST1(0L,"成功"), TEST2(1L,"失败"), TEST3(2L,"处理中");
        private Long value;
        private String text;
    }
    @Getter
    @NoArgsConstructor
    @AllArgsConstructor
    public enum ReEnum {
        //成功SUCCESS
        SUCCESS("000", "成功", "000000", ""),
        // 新增项目
        FAIL700101("7001", "验证失败", "700101", "没有收到报文"),
        FAIL700102("7001", "验证失败", "700102", "传入参数不合法");

        private String code;
        private String text;
        private String subCode;
        private String subText;
    }

调用：

@Test
public void valueOf() throws NoSuchMethodException {
    IntEnum intEnum = EnumUtils.valueOf(IntEnum.class,2,IntEnum.class.getMethod("getValue"));
    System.out.println(intEnum);

    StrEnum strEnum = EnumUtils.valueOf(StrEnum.class,"999",StrEnum.class.getMethod("getValue"));
    System.out.println(strEnum.getText());

    LongEnum longEnum = EnumUtils.valueOf(LongEnum.class,2,LongEnum.class.getMethod("getValue"));
    System.out.println(longEnum);

    ReEnum reEnum = EnumUtils.valueOf(ReEnum.class,"700102",ReEnum.class.getMethod("getSubCode"));
    System.out.println(reEnum.getSubText());
}

附完整：

1、EnumUtils.java

package com.gomepay.gb.utils.enums;

import com.gomepay.gb.utils.ExceptionUtils;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.util.Objects;

/**
 * @author www.gomepay.com
 * @date 2020/1/19
 */
public class EnumUtils {
    /**
     * 值映射为枚举
     *
     * @param enumClass 枚举类
     * @param value     枚举值
     * @param method    取值方法
     * @param <E>       对应枚举
     * @return
     */
    public static <E extends Enum<?>> E valueOf(Class<E> enumClass, Object value, Method method) {
        E[] es = enumClass.getEnumConstants();
        for (E e : es) {
            Object evalue;
            try {
                method.setAccessible(true);
                evalue = method.invoke(e);
            } catch (IllegalAccessException | InvocationTargetException e1) {
                throw ExceptionUtils.mpe("Error: NoSuchMethod in {}.  Cause:", e, enumClass.getName());
            }
            if (value instanceof Number && evalue instanceof Number
                    && new BigDecimal(String.valueOf(value)).compareTo(new BigDecimal(String.valueOf(evalue))) == 0) {
                return e;
            }
            if (Objects.equals(evalue, value)) {
                return e;
            }
        }
        return null;
    }
    /**
     * 根据value值获取enum对象
     * @param enumClass
     * @param value
     * @param <E>
     * @return
     */
    public static <E extends Enum<E>> E getEnumByValue(final Class<E> enumClass,Object value) {
        try {
            return valueOf(enumClass,value,enumClass.getMethod("getValue"));
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
        return null;
    }
    /**
     * 根据value值获取text
     * @param enumClass
     * @param value
     * @param <E>
     * @return
     */
    public static <E extends Enum<E>> String getTextByValue(final Class<E> enumClass,Object value) {
        E e = getEnumByValue(enumClass,value);
        Object evalue;
        Method method = null;
        try {
            method = enumClass.getMethod("getText");
            method.setAccessible(true);
            evalue = method.invoke(e);
        } catch (NoSuchMethodException |IllegalAccessException | InvocationTargetException e1) {
            throw ExceptionUtils.mpe("Error: NoSuchMethod in {}.  Cause:", e, enumClass.getName());
        }
        if (evalue != null) {
            return String.valueOf(evalue);
        }
        return null;
    }
    /**
     * 根据code值获取enum对象，如果code值相同，则获取第一个enum对象
     * @param enumClass
     * @param value
     * @param <E>
     * @return
     */
    public static <E extends Enum<E>> E getEnumByCode(final Class<E> enumClass,Object value) {
        try {
            return valueOf(enumClass,value,enumClass.getMethod("getCode"));
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
        return null;
    }
    /**
     * 根据code值获取text，如果code值相同，则获取第一个enum对象的text
     * @param enumClass
     * @param value
     * @param <E>
     * @return
     */
    public static <E extends Enum<E>> String getTextByCode(final Class<E> enumClass,Object value) {
        E e = getEnumByCode(enumClass,value);
        Object evalue;
        Method method = null;
        try {
            method = enumClass.getMethod("getText");
            method.setAccessible(true);
            evalue = method.invoke(e);
        } catch (NoSuchMethodException |IllegalAccessException | InvocationTargetException e1) {
            throw ExceptionUtils.mpe("Error: NoSuchMethod in {}.  Cause:", e, enumClass.getName());
        }
        if (evalue != null) {
            return String.valueOf(evalue);
        }
        return null;
    }
    /**
     * 根据code值获取enum对象
     * @param enumClass
     * @param value
     * @param <E>
     * @return
     */
    public static <E extends Enum<E>> E getEnumBySubCode(final Class<E> enumClass,Object value) {
        try {
            return valueOf(enumClass,value,enumClass.getMethod("getSubCode"));
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
        return null;
    }
    /**
     * 根据code值获取text，如果code值相同，则获取第一个enum对象的text
     * @param enumClass
     * @param value
     * @param <E>
     * @return
     */
    public static <E extends Enum<E>> String getSubTextBySubCode(final Class<E> enumClass,Object value) {
        E e = getEnumBySubCode(enumClass,value);
        Object evalue;
        Method method = null;
        try {
            method = enumClass.getMethod("getSubText");
            method.setAccessible(true);
            evalue = method.invoke(e);
        } catch (NoSuchMethodException |IllegalAccessException | InvocationTargetException e1) {
            throw ExceptionUtils.mpe("Error: NoSuchMethod in {}.  Cause:", e, enumClass.getName());
        }
        if (evalue != null) {
            return String.valueOf(evalue);
        }
        return null;
    }
}

View Code

2、TestEnum3.java

View Code

---------------------------------------完毕。另附：hutoool操作枚举工具方法

package com.gomepay.enums;

import cn.hutool.core.lang.Console;
import cn.hutool.core.util.EnumUtil;
import org.junit.Test;

import java.util.List;
import java.util.Map;

/**
 * @author www.gomepay.com
 * @date 2020/1/19
 */
public class TestEnum1 {
    //定义枚举
    public enum TestEnum{
        TEST1("type1"), TEST2("type2"), TEST3("type3");
        private TestEnum(String type) {
            this.type = type;
        }
        private String type;
        public String getType() {
            return this.type;
        }
    }

    /**
     * 获取枚举类中所有枚举对象的name列表
     */
    @Test
    public void test1() {
        List<String> names = EnumUtil.getNames(TestEnum.class);
        //输出：[TEST1, TEST2, TEST3]
        Console.log(names);
    }

    /**
     * 获得枚举类中各枚举对象下指定字段的值
     */
    @Test
    public void test2() {
        List<Object> types = EnumUtil.getFieldValues(TestEnum.class, "type");
        //输出：[type1, type2, type3]
        Console.log(types);
    }

    /**
     * 获取枚举字符串值和枚举对象的Map对应，使用LinkedHashMap保证有序，结果中键为枚举名，值为枚举对象
     */
    @Test
    public void test3() {
        Map<String,TestEnum> enumMap = EnumUtil.getEnumMap(TestEnum.class);
        TestEnum t = enumMap.get("TEST1");
        //输出：TEST1对象
        Console.log(t);
    }

    /**
     * 获得枚举名对应指定字段值的Map，键为枚举名，值为字段值
     */
    @Test
    public void test4() {
        Map<String, Object> enumMap = EnumUtil.getNameFieldMap(TestEnum.class, "type");
        String type = (String)enumMap.get("TEST2");
        //输出：type2
        Console.log(type);
    }
}

View Code