程序包 cn.taketoday.util

类 PlaceholderParser

java.lang.Object

cn.taketoday.util.PlaceholderParser

final class PlaceholderParser
extends Object

Parser for Strings that have placeholder values in them. In its simplest form, a placeholder takes the form of ${name}, where name is the key that can be resolved using a PlaceholderResolver, ${ the prefix, and } the suffix.

A placeholder can also have a default value if its key does not represent a known property. The default value is separated from the key using a separator. For instance ${name:John} resolves to John if the placeholder resolver does not provide a value for the name property.

Placeholders can also have a more complex structure, and the resolution of a given key can involve the resolution of nested placeholders. Default values can also have placeholders.

For situations where the syntax of a valid placeholder matches a String that must be rendered as is, the placeholder can be escaped using an escape character. For instance \${name} resolves as ${name}.

The prefix, suffix, separator, and escape characters are configurable. Only the prefix and suffix are mandatory, and the support for default values or escaping is conditional on providing non-null values for them.

This parser makes sure to resolves placeholders as lazily as possible.

从以下版本开始:

4.0

作者:

Stephane Nicoll, Harry Yang

嵌套类概要

嵌套类

修饰符和类型	类	说明
(专用程序包) static final record	PlaceholderParser.NestedPlaceholderPart	A PlaceholderParser.Part implementation that represents a single placeholder containing nested placeholders.
(专用程序包) static final record	PlaceholderParser.ParsedValue	A representation of the parsing of an input string.
(专用程序包) static interface	PlaceholderParser.Part	A part is a section of a String containing placeholders to replace.
(专用程序包) static class	PlaceholderParser.PartResolutionContext	Provide the necessary context to handle and resolve underlying placeholders.
(专用程序包) static final record	PlaceholderParser.SimplePlaceholderPart	A PlaceholderParser.Part implementation that represents a single placeholder with a hard-coded fallback.
(专用程序包) static final record	PlaceholderParser.TextPart	A PlaceholderParser.Part implementation that does not contain a valid placeholder.

字段概要

字段

修饰符和类型	字段	说明
private final Character	escape
private final boolean	ignoreUnresolvablePlaceholders
private static final Logger	logger
private final int	placeholderPrefixLength
private final int	placeholderSuffixLength
private final String	prefix
private final String	separator
private final String	simplePrefix
private final String	suffix
private static final Map<String,String>	wellKnownSimplePrefixes

构造器概要

构造器

构造器	说明
PlaceholderParser(String prefix, String suffix, String separator, Character escape, boolean ignoreUnresolvablePlaceholders)	Create an instance using the specified input for the parser.

方法概要

修饰符和类型	方法	说明
private static void	addText(String value, int start, int end, LinkedList<PlaceholderParser.Part> parts)
private PlaceholderParser.NestedPlaceholderPart	createNestedPlaceholderPart(String text, List<PlaceholderParser.Part> parts)
private PlaceholderParser.SimplePlaceholderPart	createSimplePlaceholderPart(String text)
private boolean	isEscaped(String value, int index)
private int	nextStartPrefix(String value, int index)
private int	nextValidEndPrefix(String value, int startIndex)
PlaceholderParser.ParsedValue	parse(String value)	Parse the specified value.
private List<PlaceholderParser.Part>	parse(String value, boolean inPlaceholder)
String	replacePlaceholders(String value, PlaceholderResolver placeholderResolver)	Replace all placeholders of format ${name} with the value returned from the supplied PlaceholderResolver.
private String[]	splitKeyAndDefault(String value)

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

字段详细资料

logger

private static final Logger logger

wellKnownSimplePrefixes

private static final Map<String,String> wellKnownSimplePrefixes

prefix

private final String prefix

suffix

private final String suffix

simplePrefix

private final String simplePrefix

separator

@Nullable
private final String separator

ignoreUnresolvablePlaceholders

private final boolean ignoreUnresolvablePlaceholders

escape

@Nullable
private final Character escape

placeholderPrefixLength

private final int placeholderPrefixLength

placeholderSuffixLength

private final int placeholderSuffixLength

构造器详细资料

PlaceholderParser

PlaceholderParser(String prefix,
 String suffix,
 @Nullable
 String separator,
 @Nullable
 Character escape,
 boolean ignoreUnresolvablePlaceholders)

Create an instance using the specified input for the parser.

参数:

prefix - the prefix that denotes the start of a placeholder

suffix - the suffix that denotes the end of a placeholder

separator - the separating character between the placeholder variable and the associated default value, if any

escape - the character to use at the beginning of a placeholder prefix or separator to escape it and render it as is

ignoreUnresolvablePlaceholders - whether unresolvable placeholders should be ignored (true) or cause an exception (false)

方法详细资料

replacePlaceholders

public String replacePlaceholders(String value,
 PlaceholderResolver placeholderResolver)

Replace all placeholders of format ${name} with the value returned from the supplied PlaceholderResolver.

参数:

value - the value containing the placeholders to be replaced

placeholderResolver - the PlaceholderResolver to use for replacement

返回:

the supplied value with placeholders replaced inline

parse

public PlaceholderParser.ParsedValue parse(String value)

Parse the specified value.

参数:

value - the value containing the placeholders to be replaced

返回:

the different parts that have been identified

parse

private List<PlaceholderParser.Part> parse(String value,
 boolean inPlaceholder)

createSimplePlaceholderPart

private PlaceholderParser.SimplePlaceholderPart createSimplePlaceholderPart(String text)

createNestedPlaceholderPart

private PlaceholderParser.NestedPlaceholderPart createNestedPlaceholderPart(String text,
 List<PlaceholderParser.Part> parts)

splitKeyAndDefault

@Nullable
private String[] splitKeyAndDefault(String value)

addText

private static void addText(String value,
 int start,
 int end,
 LinkedList<PlaceholderParser.Part> parts)

nextStartPrefix

private int nextStartPrefix(String value,
 int index)

nextValidEndPrefix

private int nextValidEndPrefix(String value,
 int startIndex)

isEscaped

private boolean isEscaped(String value,
 int index)