优雅地在Java应用中实现全局枚举处理的方法

// 静态方法方式

public enum genderenum {

   // 代码略

   public static genderenum get( int value) {

    for (genderenum item : genderenum.values()) {

    if (value == item.getvalue()) {

      return item;

     }

    }

    return null ;

   }

}

// 工具类方式

public class enumutil {

  public static <e extends enumerable> e of( @nonnull class <e> classtype, int value) {

   for (e enumconstant : classtype.getenumconstants()) {

    if (value == enumconstant.getvalue()) {

     return enumconstant;

    }

   }

   return null ;

  }

}

genderenum gender = enumutil.of(genderenum. class , 1 );

public interface enumerable<e extends enumerable> {

  /**

   * 获取在i18n文件中对应的 key

   * @return key

   */

  @nonnull

  string getkey();

  /**

   * 获取最终保存到数据库的值

   * @return 值

   */

  @nonnull

  int getvalue();

  /**

   * 获取 key 对应的文本信息

   * @return 文本信息

   */

  @nonnull

  default string gettext() {

   return i18nmessageutil.getmessage( this .getkey(), null );

  }

}

public enum genderenum implements enumerable {

  /** 男 */

  male( 1 , "male" ),

  /** 女 */

  female( 2 , "female" );

  private int value;

  private string key;

  genderenum( int value, string key) {

   this .value = value;

   this .key = key;

  }

  @override

  public string getkey() {

   return this .key;

  }

  @override

  public int getvalue() {

   return this .value;

  }

}

@configuration

public class mvcconfiguration implements webmvcconfigurer, webbindinginitializer {

  /**

   * [get]请求中，将int值转换成枚举类

   * @param registry

   */

  @override

  public void addformatters(formatterregistry registry) {

   registry.addconverterfactory( new enumconverterfactory());

  }

}

public class enumconverterfactory implements converterfactory<string, enumerable> {

  private final map< class , converter> convertercache = new weakhashmap<>();

  @override

  @suppresswarnings ({ "rawtypes" , "unchecked" })

  public <t extends enumerable> converter<string, t> getconverter( @nonnull class <t> targettype) {

   return convertercache测试数据puteifabsent(targettype,

     k -> convertercache.put(k, new enumconverter(k))

   );

  }

  protected class enumconverter<t extends enumerable> implements converter<integer, t> {

   private final class <t> enumtype;

   public enumconverter( @nonnull class <t> enumtype) {

    this .enumtype = enumtype;

   }

   @override

   public t convert( @nonnull integer value) {

    return enumutil.of( this .enumtype, value);

   }

  }

}

@configuration

@slf4j

public class jacksonconfiguration {

  /**

   * jackson的转换器

   * @return

   */

  @bean

  @primary

  @suppresswarnings ({ "rawtypes" , "unchecked" })

  public mappingjackson2httpmessageconverter mappingjacksonhttpmessageconverter() {

   final mappingjackson2httpmessageconverter converter = new mappingjackson2httpmessageconverter();

   objectmapper objectmapper = converter.getobjectmapper();

   // include.non_empty 属性为 空（""） 或者为 null 都不序列化，则返回的json是没有这个字段的。这样对移动端会更省流量

   objectmapper.setserializationinclusion(jsoninclude.include.non_empty);

   // 反序列化时候，遇到多余的字段不失败，忽略

   objectmapper.configure(deserializationfeature.fail_on_unknown_properties, false );

   // 允许出现特殊字符和转义符

   objectmapper.configure(jsonparser.feature.allow_unquoted_control_chars, true );

   // 允许出现单引号

   objectmapper.configure(jsonparser.feature.allow_single_quotes, true );

   simplemodule customermodule = new simplemodule();

   customermodule.adddeserializer(string. class , new stringtrimdeserializer(string. class ));

   customermodule.adddeserializer(enumerable. class , new enumdeserializer(enumerable. class ));

   customermodule.addserializer(enumerable. class , new enumserializer(enumerable. class ));

   objectmapper.registermodule(customermodule);

   converter.setsupportedmediatypes(immutablelist.of(mediatype.text_html, mediatype.application_json));

   return converter;

  }

}

public class enumdeserializer<e extends enumerable> extends stddeserializer<e> {

  private class <e> enumtype;

  public enumdeserializer( @nonnull class <e> enumtype) {

   super (enumtype);

   this .enumtype = enumtype;

  }

  @override

  public e deserialize(jsonparser jsonparser, deserializationcontext deserializationcontext) throws ioexception {

   return enumutil.of( this .enumtype, jsonparser.getintvalue());

  }

}

// 注册枚举类序列化处理类

customermodule.addserializer(enumerable. class , new enumserializer(enumerable. class ));

public class enumserializer extends stdserializer<enumerable> {

  public enumserializer( @nonnull class <enumerable> type) {

   super (type);

  }

  @override

  public void serialize(enumerable enumerable, jsongenerator jsongenerator, serializerprovider serializerprovider) throws ioexception {

   jsongenerator.writestartobject();

   jsongenerator.writenumberfield( "value" , enumerable.getvalue());

   jsongenerator.writestringfield( "text" , enumerable.gettext());

   jsongenerator.writeendobject();

  }

}

application.yml

--

mybatis:

  configuration:

   default - enum -type-handler: github.shiyajian.pretty.config.enums.enumtypehandler

public class enumtypehandler<e extends enumerable> extends basetypehandler<e> {

   private class <e> enumtype;

   public enumtypehandler() { /* instance */ }

   public enumtypehandler( @nonnull class <e> enumtype) {

     this .enumtype = enumtype;

   }

   @override

   public void setnonnullparameter(preparedstatement preparedstatement, int i, e e, jdbctype jdbctype) throws sqlexception {

     preparedstatement.setint(i, e.getvalue());

   }

   @override

   public e getnullableresult(resultset rs, string columnname) throws sqlexception {

     int value = rs.getint(columnname);

     return rs.wasnull() ? null : enumutil.of( this .enumtype, value);

   }

   @override

   public e getnullableresult(resultset rs, int columnindex) throws sqlexception {

     int value = rs.getint(columnindex);

     return rs.wasnull() ? null : enumutil.of( this .enumtype, value);

   }

   @override

   public e getnullableresult(callablestatement cs, int columnindex) throws sqlexception {

     int value = cs.getint(columnindex);

     return cs.wasnull() ? null : enumutil.of( this .enumtype, value);

   }

}