java.lang.Object org.apache.hadoop.conf.Configuration
public class Configuration
Provides access to configuration parameters.
ResourcesConfigurations are specified by resources. A resource contains a set of name/value pairs as XML data. Each resource is named by either a String or by a Path. If named by a String, then the classpath is examined for a file with that name. If named by a Path, then the local filesystem is examined directly, without referring to the classpath.
Unless explicitly turned off, Hadoop by default specifies two resources, loaded in-order from the classpath:
Configuration parameters may be declared final. Once a resource declares a value final, no subsequently-loaded resource can alter that value. For example, one might define a final parameter with:
<property>
<name>dfs.client.buffer.dir</name>
<value>/tmp/hadoop/dfs/client</value>
<final>true</final>
</property> Administrators typically define parameters as final in core-site.xml for values that user applications may not alter. Variable Expansion
Value strings are first processed for variable expansion. The available properties are:
System.getProperties().For example, if a configuration resource contains the following property definitions:
<property>
<name>basedir</name>
<value>/user/${user.name}</value>
</property>
<property>
<name>tempdir</name>
<value>${basedir}/tmp</value>
</property> When conf.get("tempdir") is called, then ${basedir} will be resolved to another property in this Configuration, while ${user.name} would then ordinarily be resolved to the value of the System property with that name. Constructor Summary Configuration()
Configuration(boolean loadDefaults)
Configuration(Configuration other)
static void addDefaultResource(String name)
void addResource(InputStream in)
void addResource(Path file)
void addResource(String name)
void addResource(URL url)
void clear()
static void dumpConfiguration(Configuration config, Writer out)
Writer The format of the output would be { "properties" : [ {key1,value1,key1.isFinal,key1.resource}, {key2,value2, key2.isFinal,key2.resource}... String get(String name)
name property, null if no such property exists. String get(String name, String defaultValue)
name property. boolean getBoolean(String name, boolean defaultValue)
name property as a boolean. Class<?> getClass(String name, Class<?> defaultValue)
name property as a Class. <U> Class<? extends U> getClass(String name, Class<? extends U> defaultValue, Class<U> xface)
name property as a Class implementing the interface specified by xface. Class<?> getClassByName(String name)
Class<?>[] getClasses(String name, Class<?>... defaultValue)
name property as an array of Class. ClassLoader getClassLoader()
ClassLoader for this job. InputStream getConfResourceAsInputStream(String name)
name. Reader getConfResourceAsReader(String name)
Reader attached to the configuration resource with the given name. <T extends Enum<T>>
T getEnum(String name, T defaultValue)
File getFile(String dirsProp, String path)
float getFloat(String name, float defaultValue)
name property as a float. <U> List<U> getInstances(String name, Class<U> xface)
name property as a List of objects implementing the interface specified by xface. int getInt(String name, int defaultValue)
name property as an int. Path getLocalPath(String dirsProp, String path)
long getLong(String name, long defaultValue)
name property as a long. Configuration.IntegerRanges getRange(String name, String defaultValue)
String getRaw(String name)
name property, without doing variable expansion. URL getResource(String name)
URL for the named resource. Collection<String> getStringCollection(String name)
name property as a collection of Strings. String[] getStrings(String name)
name property as an array of Strings. String[] getStrings(String name, String... defaultValue)
name property as an array of Strings. Map<String,String> getValByRegex(String regex)
Iterator<Map.Entry<String,String>> iterator()
Iterator to go through the list of String key-value pairs in the configuration. static void main(String[] args)
void readFields(DataInput in)
in. void reloadConfiguration()
void set(String name, String value)
value of the name property. void setBoolean(String name, boolean value)
name property to a boolean. void setBooleanIfUnset(String name, boolean value)
void setClass(String name, Class<?> theClass, Class<?> xface)
name property to the name of a theClass implementing the given interface xface. void setClassLoader(ClassLoader classLoader)
<T extends Enum<T>>
void setEnum(String name, T value)
name property to the given type. void setFloat(String name, float value)
name property to a float. void setIfUnset(String name, String value)
void setInt(String name, int value)
name property to an int. void setLong(String name, long value)
name property to a long. void setQuietMode(boolean quietmode)
void setStrings(String name, String... values)
name property as as comma delimited values. int size()
String toString()
void unset(String name)
void write(DataOutput out)
out. void writeXml(OutputStream out)
OutputStream. void writeXml(Writer out)
Writer. Configuration
public Configuration()
public Configuration(boolean loadDefaults)
loadDefaults is false, the new instance will not load resources from the default files.
loadDefaults - specifies whether to load from the default files
public Configuration(Configuration other)
other - the configuration from which to clone settings.
public static void addDefaultResource(String name)
name - file name. File should be present in the classpath.
public void addResource(String name)
name - resource to be added, the classpath is examined for a file with that name.
public void addResource(URL url)
url - url of the resource to be added, the local filesystem is examined directly to find the resource, without referring to the classpath.
public void addResource(Path file)
file - file-path of resource to be added, the local filesystem is examined directly to find the resource, without referring to the classpath.
public void addResource(InputStream in)
in - InputStream to deserialize the object from.
public void reloadConfiguration()
public String get(String name)
name property, null if no such property exists. Values are processed for variable expansion before being returned.
name - the property name.
name property, or null if no such property exists.
public String getRaw(String name)
name property, without doing variable expansion.
name - the property name.
name property, or null if no such property exists.
public void set(String name,
String value)
value of the name property.
name - property name.
value - property value.
public void unset(String name)
public void setIfUnset(String name,
String value)
name - the property name
value - the new value
public String get(String name,
String defaultValue)
name property. If no such property exists, then defaultValue is returned.
name - property name.
defaultValue - default value.
defaultValue if the property doesn't exist.
public int getInt(String name,
int defaultValue)
name property as an int. If no such property exists, or if the specified value is not a valid int, then defaultValue is returned.
name - property name.
defaultValue - default value.
int, or defaultValue.
public void setInt(String name,
int value)
name property to an int.
name - property name.
value - int value of the property.
public long getLong(String name,
long defaultValue)
name property as a long. If no such property is specified, or if the specified value is not a valid long, then defaultValue is returned.
name - property name.
defaultValue - default value.
long, or defaultValue.
public void setLong(String name,
long value)
name property to a long.
name - property name.
value - long value of the property.
public float getFloat(String name,
float defaultValue)
name property as a float. If no such property is specified, or if the specified value is not a valid float, then defaultValue is returned.
name - property name.
defaultValue - default value.
float, or defaultValue.
public void setFloat(String name,
float value)
name property to a float.
name - property name.
value - property value.
public boolean getBoolean(String name,
boolean defaultValue)
name property as a boolean. If no such property is specified, or if the specified value is not a valid boolean, then defaultValue is returned.
name - property name.
defaultValue - default value.
boolean, or defaultValue.
public void setBoolean(String name,
boolean value)
name property to a boolean.
name - property name.
value - boolean value of the property.
public void setBooleanIfUnset(String name,
boolean value)
name - property name
value - new value
public <T extends Enum<T>> void setEnum(String name,
T value)
name property to the given type. This is equivalent to set(<name>, value.toString()).
name - property name
value - new value
public <T extends Enum<T>> T getEnum(String name,
T defaultValue)
name - Property name
defaultValue - Value returned if no mapping exists
IllegalArgumentException - If mapping is illegal for the type provided
public Configuration.IntegerRanges getRange(String name,
String defaultValue)
name - the attribute name
defaultValue - the default value if it is not set
public Collection<String> getStringCollection(String name)
name property as a collection of Strings. If no such property is specified then empty collection is returned.
This is an optimized version of getStrings(String)
name - property name.
Strings.
public String[] getStrings(String name)
name property as an array of Strings. If no such property is specified then null is returned.
name - property name.
Strings, or null.
public String[] getStrings(String name,
String... defaultValue)
name property as an array of Strings. If no such property is specified then default value is returned.
name - property name.
defaultValue - The default value
Strings, or default value.
public void setStrings(String name,
String... values)
name property as as comma delimited values.
name - property name.
values - The values
public Class<?> getClassByName(String name)
throws ClassNotFoundException
name - the class name.
ClassNotFoundException - if the class is not found.
public Class<?>[] getClasses(String name,
Class<?>... defaultValue)
name property as an array of Class. The value of the property specifies a list of comma separated class names. If no such property is specified, then defaultValue is returned.
name - the property name.
defaultValue - default value.
Class[], or defaultValue.
public Class<?> getClass(String name,
Class<?> defaultValue)
name property as a Class. If no such property is specified, then defaultValue is returned.
name - the class name.
defaultValue - default value.
Class, or defaultValue.
public <U> Class<? extends U> getClass(String name,
Class<? extends U> defaultValue,
Class<U> xface)
name property as a Class implementing the interface specified by xface. If no such property is specified, then defaultValue is returned. An exception is thrown if the returned class does not implement the named interface.
name - the class name.
defaultValue - default value.
xface - the interface implemented by the named class.
Class, or defaultValue.
public <U> List<U> getInstances(String name,
Class<U> xface)
name property as a List of objects implementing the interface specified by xface. An exception is thrown if any of the classes does not exist, or if it does not implement the named interface.
name - the property name.
xface - the interface implemented by the classes named by name.
List of objects implementing xface.
public void setClass(String name,
Class<?> theClass,
Class<?> xface)
name property to the name of a theClass implementing the given interface xface. An exception is thrown if theClass does not implement the interface xface.
name - property name.
theClass - property value.
xface - the interface implemented by the named class.
public Path getLocalPath(String dirsProp,
String path)
throws IOException
dirsProp - directory in which to locate the file.
path - file-path.
IOException
public File getFile(String dirsProp,
String path)
throws IOException
dirsProp - directory in which to locate the file.
path - file-path.
IOException
public URL getResource(String name)
URL for the named resource.
name - resource name.
public InputStream getConfResourceAsInputStream(String name)
name.
name - configuration resource name.
public Reader getConfResourceAsReader(String name)
Reader attached to the configuration resource with the given name.
name - configuration resource name.
public int size()
public void clear()
public Iterator<Map.Entry<String,String>> iterator()
Iterator to go through the list of String key-value pairs in the configuration.
iterator in interface Iterable<Map.Entry<String,String>>
public void writeXml(OutputStream out)
throws IOException
OutputStream.
out - the output stream to write to.
IOException
public void writeXml(Writer out)
throws IOException
Writer.
out - the writer to write to.
IOException
public static void dumpConfiguration(Configuration config,
Writer out)
throws IOException
Writer The format of the output would be { "properties" : [ {key1,value1,key1.isFinal,key1.resource}, {key2,value2, key2.isFinal,key2.resource}... ] } It does not output the parameters of the configuration object which is loaded from an input stream.
out - the Writer to write to
IOException
public ClassLoader getClassLoader()
ClassLoader for this job.
public void setClassLoader(ClassLoader classLoader)
classLoader - the new class loader.
public String toString()
toString in class Object
public void setQuietMode(boolean quietmode)
quietmode - true to set quiet-mode on, false to turn it off.
public static void main(String[] args)
throws Exception
Exception
public void readFields(DataInput in)
throws IOException
Writable
in.
For efficiency, implementations should attempt to re-use storage in the existing object where possible.
readFields in interface Writable
in - DataInput to deseriablize this object from.
IOException
public void write(DataOutput out)
throws IOException
Writable
out.
write in interface Writable
out - DataOuput to serialize this object into.
IOException
public Map<String,String> getValByRegex(String regex)
regex -
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