[英]Regex Issue With Multiple Groups
我正在尝试创建一个正则表达式模式以匹配以下格式的行:
field[bii] = float4:.4f_degree // Galactic Latitude
field[class] = int2 (index) // Browse Object Classification
field[dec] = float8:.4f_degree (key) // Declination
field[name] = char20 (index) // Object Designation
field[dircos1] = float8 // 1st Directional Cosine
我想出了这种模式,该模式似乎有效,然后突然似乎不起作用:
field\[(.*)\] = (float|int|char)([0-9]|[1-9][0-9]).*(:(\.([0-9])))
这是我要使用的代码(编辑:提供完整方法而不是摘录):
private static Map<String, String> createColumnMap(String filename) {
// create a linked hashmap mapping field names to their column types. Use LHM because I'm picky and
// would prefer to preserve the order
Map<String, String> columnMap = new LinkedHashMap<String, String>();
// define the regex patterns
Pattern columnNamePattern = Pattern.compile(columnNameRegexPattern);
try {
Scanner scanner = new Scanner(new FileInputStream(filename));
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
if (line.indexOf("field[") != -1) {
// get the field name
Matcher fieldNameMatcher = columnNamePattern.matcher(line);
String fieldName = null;
if (fieldNameMatcher.find()) {
fieldName = fieldNameMatcher.group(1);
}
String columnName = null;
String columnType = null;
String columnPrecision = null;
String columnScale = null;
//Pattern columnTypePattern = Pattern.compile(".*(float|int|char)([0-9]|[1-9][0-9])");
Pattern columnTypePattern = Pattern.compile("field\\[(.*)\\] = (float|int|char).*([0-9]|[1-9][0-9]).*(:(\\.([0-9])))");
Matcher columnTypeMatcher = columnTypePattern.matcher(line);
System.out.println(columnTypeMatcher.lookingAt());
if (columnTypeMatcher.lookingAt()) {
System.out.println(fieldName + ": " + columnTypeMatcher.groupCount());
int count = columnTypeMatcher.groupCount();
if (count > 1) {
columnName = columnTypeMatcher.group(1);
columnType = columnTypeMatcher.group(2);
}
if (count > 2) {
columnScale = columnTypeMatcher.group(3);
}
if (count >= 6) {
columnPrecision = columnTypeMatcher.group(6);
}
}
int precision = Integer.parseInt(columnPrecision);
int scale = Integer.parseInt(columnScale);
if (columnType.equals("int")) {
if (precision <= 4) {
columnMap.put(fieldName, "INTEGER");
} else {
columnMap.put(fieldName, "BIGINT");
}
} else if (columnType.equals("float")) {
if (columnPrecision==null) {
columnMap.put(fieldName,"DECIMAL(8,4)");
} else {
columnMap.put(fieldName,"DECIMAL(" + columnPrecision + "," + columnScale + ")");
}
} else {
columnMap.put(fieldName,"VARCHAR("+columnPrecision+")");
}
}
if (line.indexOf("<DATA>") != -1) {
scanner.close();
break;
}
}
scanner.close();
} catch (FileNotFoundException e) {
}
return columnMap;
}
当我从Matcher对象获得groupCount时,它说有6个组。 但是,它们与文本不匹配,因此我绝对可以使用一些帮助...任何人都可以提供帮助?
我不清楚您要做什么,但我想出了以下模式,它接受了您所有的输入示例:
field\\[(.*)\\] = (float|int|char)([1-9][0-9]?)?(:\\.([0-9]))?
使用此代码:
String columnName = null;
String columnType = null;
String columnPrecision = null;
String columnScale = null;
// Pattern columnTypePattern =
// Pattern.compile(".*(float|int|char)([0-9]|[1-9][0-9])");
// field\[(.*)\] = (float|int|char)([0-9]|[1-9][0-9]).*(:(\.([0-9])))
Pattern columnTypePattern = Pattern
.compile("field\\[(.*)\\] = (float|int|char)([1-9][0-9]?)?(:\\.([0-9]))?");
Matcher columnTypeMatcher = columnTypePattern.matcher(line);
boolean match = columnTypeMatcher.lookingAt();
System.out.println("Match: " + match);
if (match) {
int count = columnTypeMatcher.groupCount();
if (count > 1) {
columnName = columnTypeMatcher.group(1);
columnType = columnTypeMatcher.group(2);
}
if (count > 2) {
columnScale = columnTypeMatcher.group(3);
}
if (count > 4) {
columnPrecision = columnTypeMatcher.group(5);
}
System.out.println("Name=" + columnName + "; Type=" + columnType + "; Scale=" + columnScale + "; Precision=" + columnPrecision);
}
我认为您的正则表达式的问题是需要使比例和精度为可选。
field\\[(.*)\\] = (float|int|char)([0-9]|[1-9][0-9]).*(:(\\.([0-9])))
在.*
过于宽泛,而且有很多冗余的([0-9]|[1-9][0-9])
我认为开头的括号组:
和之前的.*
应可选的。
消除所有歧义后,我得到
field\[([^\]]*)\] = (float|int|char)(0|[1-9][0-9]+)(?:[^:]*(:(\.([0-9]+))))?
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