使用java枚举实现一个bitfield [英] Implementing a bitfield using java enums
问题描述
static int DOCUMENT_STATUS_NO_STATE = 0
static int DOCUMENT_STATUS_OK = 1
static int DOCUMENT_STATUS_NO_TIF_FILE = 2
static int DOCUMENT_STATUS_NO_PDF_FILE = 4
这使它很漂亮通过设置相应的标志,很容易指示文档所在的状态。例如:
status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE;
由于使用静态常量的方法是不好的做法,因为我想改进代码,正在寻找使用枚举来实现相同的。有一些要求,其中之一是需要将数据库的状态保存为数字类型。因此,需要将枚举常量转换为数值。以下是我的第一个方法,我想知道这是否是正确的方法?
class DocumentStatus {
public enum StatusFlag {
DOCUMENT_STATUS_NOT_DEFINED(1< ;
DOCUMENT_STATUS_OK(1 <1),
DOCUMENT_STATUS_MISSING_TID_DIR(1< 2),
DOCUMENT_STATUS_MISSING_TIF_FILE(1< 3),
DOCUMENT_STATUS_MISSING_PDF_FILE (1< 4),
DOCUMENT_STATUS_MISSING_OCR_FILE(1< 5),
DOCUMENT_STATUS_PAGE_COUNT_TIF(1< 6),
DOCUMENT_STATUS_PAGE_COUNT_PDF(1< 7) b DOCUMENT_STATUS_UNAVAILABLE(1< <8);
private final long statusFlagValue;
StatusFlag(long statusFlagValue){
this.statusFlagValue = statusFlagValue;
}
public long getStatusFlagValue(){
return statusFlagValue;
}
}
/ **
*将数字状态代码转换为一组StatusFlag枚举
* @param numeric statusValue
* @return表示文档状态的枚举集
* /
public EnumSet< StatusFlag> getStatusFlags(long statusValue){
EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class);
StatusFlag.each {statusFlag - >
long flagValue = statusFlag.statusFlagValue
if((flagValue& statusValue)== flagValue){
statusFlags.add(statusFlag);
}
}
return statusFlags;
}
/ **
*将一组StatusFlag枚举转换为数字状态代码
* @param设置if statusFlags
* @返回文档状态的数值表示
* /
public long getStatusValue(Set< StatusFlag> flags){
long value = 0;
flags.each {statusFlag - >
value | = statusFlag.getStatusFlagValue()
}
返回值;
}
public static void main(String [] args){
DocumentStatus ds = new DocumentStatus();
设置statusFlags = EnumSet.of(
StatusFlag.DOCUMENT_STATUS_OK,
StatusFlag.DOCUMENT_STATUS_UNAVAILABLE);
assert ds.getStatusValue(statusFlags)== 258 // 0000.0001 | 0000.0010
long numericStatusCode = 56;
statusFlags = ds.getStatusFlags(numericStatusCode);
assert!statusFlags.contains(StatusFlag.DOCUMENT_STATUS_OK);
assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_TIF_FILE);
assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_PDF_FILE);
assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_OCR_FILE);
}
}
你的方法是完美的方式。
I maintain a large document archive and I often use bit fields to record the status of my documents during processing or when validating them. My legacy code simply uses static int constants such as:
static int DOCUMENT_STATUS_NO_STATE = 0
static int DOCUMENT_STATUS_OK = 1
static int DOCUMENT_STATUS_NO_TIF_FILE = 2
static int DOCUMENT_STATUS_NO_PDF_FILE = 4
This makes it pretty easy to indicate the state a document is in, by setting the appropriate flags. For example:
status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE;
Since the approach of using static constants is bad practice and because I would like to improve the code, I was looking to use Enums to achieve the same. There are a few requirements, one of them being the need to save the status into a database as a numeric type. So there is a need to transform the enumeration constants to a numeric value. Below is my first approach and I wonder if this is the correct way to go about this?
class DocumentStatus{
public enum StatusFlag {
DOCUMENT_STATUS_NOT_DEFINED(1<<0),
DOCUMENT_STATUS_OK(1<<1),
DOCUMENT_STATUS_MISSING_TID_DIR(1<<2),
DOCUMENT_STATUS_MISSING_TIF_FILE(1<<3),
DOCUMENT_STATUS_MISSING_PDF_FILE(1<<4),
DOCUMENT_STATUS_MISSING_OCR_FILE(1<<5),
DOCUMENT_STATUS_PAGE_COUNT_TIF(1<<6),
DOCUMENT_STATUS_PAGE_COUNT_PDF(1<<7),
DOCUMENT_STATUS_UNAVAILABLE(1<<8);
private final long statusFlagValue;
StatusFlag(long statusFlagValue) {
this.statusFlagValue = statusFlagValue;
}
public long getStatusFlagValue(){
return statusFlagValue;
}
}
/**
* Translates a numeric status code into a Set of StatusFlag enums
* @param numeric statusValue
* @return EnumSet representing a documents status
*/
public EnumSet<StatusFlag> getStatusFlags(long statusValue) {
EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class);
StatusFlag.each { statusFlag ->
long flagValue = statusFlag.statusFlagValue
if ( (flagValue&statusValue ) == flagValue ) {
statusFlags.add(statusFlag);
}
}
return statusFlags;
}
/**
* Translates a set of StatusFlag enums into a numeric status code
* @param Set if statusFlags
* @return numeric representation of the document status
*/
public long getStatusValue(Set<StatusFlag> flags) {
long value=0;
flags.each { statusFlag ->
value|=statusFlag.getStatusFlagValue()
}
return value;
}
public static void main(String[] args) {
DocumentStatus ds = new DocumentStatus();
Set statusFlags = EnumSet.of(
StatusFlag.DOCUMENT_STATUS_OK,
StatusFlag.DOCUMENT_STATUS_UNAVAILABLE);
assert ds.getStatusValue( statusFlags )==258 // 0000.0001|0000.0010
long numericStatusCode = 56;
statusFlags = ds.getStatusFlags(numericStatusCode);
assert !statusFlags.contains(StatusFlag.DOCUMENT_STATUS_OK);
assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_TIF_FILE);
assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_PDF_FILE);
assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_OCR_FILE);
}
}
your approach is exactly the way to do it.
这篇关于使用java枚举实现一个bitfield的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!