org.apache.commons.lang3.text.StrSubstitutor
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java.lang.Object
public class StrSubstitutor
Substitutes variables within a string by values.
This class takes a piece of text and substitutes all the variables within it.
The default definition of a variable is ${variableName}.
The prefix and suffix can be changed via constructors and set methods.
Variable values are typically resolved from a map, but could also be resolved from system properties, or by supplying a custom variable resolver.
The simplest example is to use this class to replace Java System properties. For example:
StrSubstitutor.replaceSystemProperties(
"You are running with java.version = ${java.version} and os.name = ${os.name}.");
Typical usage of this class follows the following pattern: First an instance is created
and initialized with the map that contains the values for the available variables.
If a prefix and/or suffix for variables should be used other than the default ones,
the appropriate settings can be performed. After that the replace()
method can be called passing in the source text for interpolation. In the returned
text all variable references (as long as their values are known) will be resolved.
The following example demonstrates this:
Map valuesMap = HashMap();
valuesMap.put("animal", "quick brown fox");
valuesMap.put("target", "lazy dog");
String templateString = "The ${animal} jumped over the ${target}.";
StrSubstitutor sub = new StrSubstitutor(valuesMap);
String resolvedString = sub.replace(templateString);
yielding:
The quick brown fox jumped over the lazy dog.
In addition to this usage pattern there are some static convenience methods that cover the most common use cases. These methods can be used without the need of manually creating an instance. However if multiple replace operations are to be performed, creating and reusing an instance of this class will be more efficient.
Variable replacement works in a recursive way. Thus, if a variable value contains a variable then that variable will also be replaced. Cyclic replacements are detected and will cause an exception to be thrown.
Sometimes the interpolation's result must contain a variable prefix. As an example take the following source text:
The variable ${${name}} must be used.
Here only the variable's name referred to in the text should be replaced resulting
in the text (assuming that the value of the name variable is x):
The variable ${x} must be used.
To achieve this effect there are two possibilities: Either set a different prefix
and suffix for variables which do not conflict with the result text you want to
produce. The other possibility is to use the escape character, by default '$'.
If this character is placed before a variable reference, this reference is ignored
and won't be replaced. For example:
The variable $${${name}} must be used.
In some complex scenarios you might even want to perform substitution in the names of variables, for instance
${jre-${java.specification.version}}
StrSubstitutor supports this recursive substitution in variable
names, but it has to be enabled explicitly by setting the
enableSubstitutionInVariables
property to true.
| Field Summary | |
|---|---|
static char |
DEFAULT_ESCAPE
Constant for the default escape character. |
static StrMatcher |
DEFAULT_PREFIX
Constant for the default variable prefix. |
static StrMatcher |
DEFAULT_SUFFIX
Constant for the default variable suffix. |
| Constructor Summary | |
|---|---|
StrSubstitutor()
Creates a new instance with defaults for variable prefix and suffix and the escaping character. |
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StrSubstitutor(Map<String,V> valueMap)
Creates a new instance and initializes it. |
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StrSubstitutor(Map<String,V> valueMap,
String prefix,
String suffix)
Creates a new instance and initializes it. |
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StrSubstitutor(Map<String,V> valueMap,
String prefix,
String suffix,
char escape)
Creates a new instance and initializes it. |
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StrSubstitutor(StrLookup<?> variableResolver)
Creates a new instance and initializes it. |
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StrSubstitutor(StrLookup<?> variableResolver,
String prefix,
String suffix,
char escape)
Creates a new instance and initializes it. |
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StrSubstitutor(StrLookup<?> variableResolver,
StrMatcher prefixMatcher,
StrMatcher suffixMatcher,
char escape)
Creates a new instance and initializes it. |
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| Method Summary | ||
|---|---|---|
char |
getEscapeChar()
Returns the escape character. |
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StrMatcher |
getVariablePrefixMatcher()
Gets the variable prefix matcher currently in use. |
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StrLookup<?> |
getVariableResolver()
Gets the VariableResolver that is used to lookup variables. |
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StrMatcher |
getVariableSuffixMatcher()
Gets the variable suffix matcher currently in use. |
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boolean |
isEnableSubstitutionInVariables()
Returns a flag whether substitution is done in variable names. |
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String |
replace(char[] source)
Replaces all the occurrences of variables with their matching values from the resolver using the given source array as a template. |
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String |
replace(char[] source,
int offset,
int length)
Replaces all the occurrences of variables with their matching values from the resolver using the given source array as a template. |
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String |
replace(Object source)
Replaces all the occurrences of variables in the given source object with their matching values from the resolver. |
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static
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replace(Object source,
Map<String,V> valueMap)
Replaces all the occurrences of variables in the given source object with their matching values from the map. |
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static
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replace(Object source,
Map<String,V> valueMap,
String prefix,
String suffix)
Replaces all the occurrences of variables in the given source object with their matching values from the map. |
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static String |
replace(Object source,
Properties valueProperties)
Replaces all the occurrences of variables in the given source object with their matching values from the properties. |
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String |
replace(StrBuilder source)
Replaces all the occurrences of variables with their matching values from the resolver using the given source builder as a template. |
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String |
replace(StrBuilder source,
int offset,
int length)
Replaces all the occurrences of variables with their matching values from the resolver using the given source builder as a template. |
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String |
replace(String source)
Replaces all the occurrences of variables with their matching values from the resolver using the given source string as a template. |
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String |
replace(StringBuffer source)
Replaces all the occurrences of variables with their matching values from the resolver using the given source buffer as a template. |
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String |
replace(StringBuffer source,
int offset,
int length)
Replaces all the occurrences of variables with their matching values from the resolver using the given source buffer as a template. |
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String |
replace(String source,
int offset,
int length)
Replaces all the occurrences of variables with their matching values from the resolver using the given source string as a template. |
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boolean |
replaceIn(StrBuilder source)
Replaces all the occurrences of variables within the given source builder with their matching values from the resolver. |
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boolean |
replaceIn(StrBuilder source,
int offset,
int length)
Replaces all the occurrences of variables within the given source builder with their matching values from the resolver. |
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boolean |
replaceIn(StringBuffer source)
Replaces all the occurrences of variables within the given source buffer with their matching values from the resolver. |
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boolean |
replaceIn(StringBuffer source,
int offset,
int length)
Replaces all the occurrences of variables within the given source buffer with their matching values from the resolver. |
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static String |
replaceSystemProperties(Object source)
Replaces all the occurrences of variables in the given source object with their matching values from the system properties. |
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protected String |
resolveVariable(String variableName,
StrBuilder buf,
int startPos,
int endPos)
Internal method that resolves the value of a variable. |
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void |
setEnableSubstitutionInVariables(boolean enableSubstitutionInVariables)
Sets a flag whether substitution is done in variable names. |
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void |
setEscapeChar(char escapeCharacter)
Sets the escape character. |
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StrSubstitutor |
setVariablePrefix(char prefix)
Sets the variable prefix to use. |
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StrSubstitutor |
setVariablePrefix(String prefix)
Sets the variable prefix to use. |
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StrSubstitutor |
setVariablePrefixMatcher(StrMatcher prefixMatcher)
Sets the variable prefix matcher currently in use. |
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void |
setVariableResolver(StrLookup<?> variableResolver)
Sets the VariableResolver that is used to lookup variables. |
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StrSubstitutor |
setVariableSuffix(char suffix)
Sets the variable suffix to use. |
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StrSubstitutor |
setVariableSuffix(String suffix)
Sets the variable suffix to use. |
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StrSubstitutor |
setVariableSuffixMatcher(StrMatcher suffixMatcher)
Sets the variable suffix matcher currently in use. |
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protected boolean |
substitute(StrBuilder buf,
int offset,
int length)
Internal method that substitutes the variables. |
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| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
|---|
public static final char DEFAULT_ESCAPE
public static final StrMatcher DEFAULT_PREFIX
public static final StrMatcher DEFAULT_SUFFIX
| Constructor Detail |
|---|
public StrSubstitutor()
public StrSubstitutor(Map<String,V> valueMap)
V - the type of the values in the mapvalueMap - the map with the variables' values, may be null
public StrSubstitutor(Map<String,V> valueMap,
String prefix,
String suffix)
V - the type of the values in the mapvalueMap - the map with the variables' values, may be nullprefix - the prefix for variables, not nullsuffix - the suffix for variables, not null
IllegalArgumentException - if the prefix or suffix is null
public StrSubstitutor(Map<String,V> valueMap,
String prefix,
String suffix,
char escape)
V - the type of the values in the mapvalueMap - the map with the variables' values, may be nullprefix - the prefix for variables, not nullsuffix - the suffix for variables, not nullescape - the escape character
IllegalArgumentException - if the prefix or suffix is nullpublic StrSubstitutor(StrLookup<?> variableResolver)
variableResolver - the variable resolver, may be null
public StrSubstitutor(StrLookup<?> variableResolver,
String prefix,
String suffix,
char escape)
variableResolver - the variable resolver, may be nullprefix - the prefix for variables, not nullsuffix - the suffix for variables, not nullescape - the escape character
IllegalArgumentException - if the prefix or suffix is null
public StrSubstitutor(StrLookup<?> variableResolver,
StrMatcher prefixMatcher,
StrMatcher suffixMatcher,
char escape)
variableResolver - the variable resolver, may be nullprefixMatcher - the prefix for variables, not nullsuffixMatcher - the suffix for variables, not nullescape - the escape character
IllegalArgumentException - if the prefix or suffix is null| Method Detail |
|---|
public static <V> String replace(Object source,
Map<String,V> valueMap)
V - the type of the values in the mapsource - the source text containing the variables to substitute, null returns nullvalueMap - the map with the values, may be null
public static <V> String replace(Object source,
Map<String,V> valueMap,
String prefix,
String suffix)
V - the type of the values in the mapsource - the source text containing the variables to substitute, null returns nullvalueMap - the map with the values, may be nullprefix - the prefix of variables, not nullsuffix - the suffix of variables, not null
IllegalArgumentException - if the prefix or suffix is null
public static String replace(Object source,
Properties valueProperties)
source - the source text containing the variables to substitute, null returns nullvalueProperties - the properties with values, may be null
public static String replaceSystemProperties(Object source)
source - the source text containing the variables to substitute, null returns null
public String replace(String source)
source - the string to replace in, null returns null
public String replace(String source,
int offset,
int length)
Only the specified portion of the string will be processed. The rest of the string is not processed, and is not returned.
source - the string to replace in, null returns nulloffset - the start offset within the array, must be validlength - the length within the array to be processed, must be valid
public String replace(char[] source)
source - the character array to replace in, not altered, null returns null
public String replace(char[] source,
int offset,
int length)
Only the specified portion of the array will be processed. The rest of the array is not processed, and is not returned.
source - the character array to replace in, not altered, null returns nulloffset - the start offset within the array, must be validlength - the length within the array to be processed, must be valid
public String replace(StringBuffer source)
source - the buffer to use as a template, not changed, null returns null
public String replace(StringBuffer source,
int offset,
int length)
Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not returned.
source - the buffer to use as a template, not changed, null returns nulloffset - the start offset within the array, must be validlength - the length within the array to be processed, must be valid
public String replace(StrBuilder source)
source - the builder to use as a template, not changed, null returns null
public String replace(StrBuilder source,
int offset,
int length)
Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not returned.
source - the builder to use as a template, not changed, null returns nulloffset - the start offset within the array, must be validlength - the length within the array to be processed, must be valid
public String replace(Object source)
toString and is not altered.
source - the source to replace in, null returns null
public boolean replaceIn(StringBuffer source)
source - the buffer to replace in, updated, null returns zero
public boolean replaceIn(StringBuffer source,
int offset,
int length)
Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is not deleted.
source - the buffer to replace in, updated, null returns zerooffset - the start offset within the array, must be validlength - the length within the buffer to be processed, must be valid
public boolean replaceIn(StrBuilder source)
source - the builder to replace in, updated, null returns zero
public boolean replaceIn(StrBuilder source,
int offset,
int length)
Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is not deleted.
source - the builder to replace in, null returns zerooffset - the start offset within the array, must be validlength - the length within the builder to be processed, must be valid
protected boolean substitute(StrBuilder buf,
int offset,
int length)
Most users of this class do not need to call this method. This method will be called automatically by another (public) method.
Writers of subclasses can override this method if they need access to the substitution process at the start or end.
buf - the string builder to substitute into, not nulloffset - the start offset within the builder, must be validlength - the length within the builder to be processed, must be valid
protected String resolveVariable(String variableName,
StrBuilder buf,
int startPos,
int endPos)
Most users of this class do not need to call this method. This method is called automatically by the substitution process.
Writers of subclasses can override this method if they need to alter
how each substitution occurs. The method is passed the variable's name
and must return the corresponding value. This implementation uses the
getVariableResolver() with the variable's name as the key.
variableName - the name of the variable, not nullbuf - the buffer where the substitution is occurring, not nullstartPos - the start position of the variable including the prefix, validendPos - the end position of the variable including the suffix, valid
public char getEscapeChar()
public void setEscapeChar(char escapeCharacter)
escapeCharacter - the escape character (0 for disabling escaping)public StrMatcher getVariablePrefixMatcher()
The variable prefix is the characer or characters that identify the start of a variable. This prefix is expressed in terms of a matcher allowing advanced prefix matches.
public StrSubstitutor setVariablePrefixMatcher(StrMatcher prefixMatcher)
The variable prefix is the characer or characters that identify the start of a variable. This prefix is expressed in terms of a matcher allowing advanced prefix matches.
prefixMatcher - the prefix matcher to use, null ignored
IllegalArgumentException - if the prefix matcher is nullpublic StrSubstitutor setVariablePrefix(char prefix)
The variable prefix is the character or characters that identify the start of a variable. This method allows a single character prefix to be easily set.
prefix - the prefix character to use
public StrSubstitutor setVariablePrefix(String prefix)
The variable prefix is the characer or characters that identify the start of a variable. This method allows a string prefix to be easily set.
prefix - the prefix for variables, not null
IllegalArgumentException - if the prefix is nullpublic StrMatcher getVariableSuffixMatcher()
The variable suffix is the characer or characters that identify the end of a variable. This suffix is expressed in terms of a matcher allowing advanced suffix matches.
public StrSubstitutor setVariableSuffixMatcher(StrMatcher suffixMatcher)
The variable suffix is the characer or characters that identify the end of a variable. This suffix is expressed in terms of a matcher allowing advanced suffix matches.
suffixMatcher - the suffix matcher to use, null ignored
IllegalArgumentException - if the suffix matcher is nullpublic StrSubstitutor setVariableSuffix(char suffix)
The variable suffix is the characer or characters that identify the end of a variable. This method allows a single character suffix to be easily set.
suffix - the suffix character to use
public StrSubstitutor setVariableSuffix(String suffix)
The variable suffix is the character or characters that identify the end of a variable. This method allows a string suffix to be easily set.
suffix - the suffix for variables, not null
IllegalArgumentException - if the suffix is nullpublic StrLookup<?> getVariableResolver()
public void setVariableResolver(StrLookup<?> variableResolver)
variableResolver - the VariableResolverpublic boolean isEnableSubstitutionInVariables()
public void setEnableSubstitutionInVariables(boolean enableSubstitutionInVariables)
${jre-${java.version}}. The default value is false.
enableSubstitutionInVariables - the new value of the flag
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