js.io

Class VariablesWriter

java.lang.Object

java.io.Writer

js.io.VariablesWriter

All Implemented Interfaces:

Closeable, Flushable, Appendable, AutoCloseable

public class VariablesWriter
extends Writer

Character stream writer with variable injection. This is a standard characters stream but with variables using standard ${...} notation. Values are injected on the fly, while the character stream is written to target writer. This class gets a variables map from where retrieve values by name. If a variable from stream has a name not existing into variables map, stream variable remains unresolved.

 +----------+   (1)   +-----------------------+   (2)   +---------------+
 | template +---------> VariablesWriter.write +---------> target writer |
 +----------+         +-----------------------+         +---------------+
 
 1 - variables stream
 2 - stream with values injected
 

Variables writer is in fact a decorator. It adds variable injection functionality to an ordinary writer. If none provided on constructor uses an internal StringWriter.

 // variables writer with string target writer
 VariablesWriter writer = new VariablesWriter(variables);
 // copy template and inject values on the fly
 Files.copy(new StringReader(template), writer);
 // string with values resolved
 String string = writer.toString();
 

Version:

final

Author:

Iulian Rotaru

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	VariablesWriter.State Internal state machine for variables writer parser.

Field Summary

Fields

Modifier and Type	Field and Description
private VariablesWriter.State	state Current state of the finite states machine used by variables parser.
private Writer	targetWriter Target writer is where stream with variables injected is actually being write.
private StringBuilder	variableBuilder String builder for variable name discovered on variables writer.
private Map<String,String>	variables Variable values map.

Fields inherited from class java.io.Writer

lock

Constructor Summary

Constructors

Constructor and Description
VariablesWriter(Map<String,String> variables) Construct a variables writer instance targeting an internal string writer.
VariablesWriter(Writer targetWriter, Map<String,String> variables) Construct a variables writer decorator for given target writer.

Method Summary

Modifier and Type	Method and Description
void	close() Close target writer.
void	flush() Flush target writer.
String	toString() Return target writer string value.
void	write(char[] cbuf, int off, int len) Inject values into given variables stream and write the result to target writer.

Methods inherited from class java.io.Writer

append, append, append, write, write, write, write

Methods inherited from class java.lang.Object

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

Field Detail

targetWriter

private Writer targetWriter

Target writer is where stream with variables injected is actually being write.

variables

private Map<String,String> variables

Variable values map.

variableBuilder

private StringBuilder variableBuilder

String builder for variable name discovered on variables writer.

state

private VariablesWriter.State state

Current state of the finite states machine used by variables parser.

Constructor Detail

VariablesWriter

public VariablesWriter(Map<String,String> variables)

Construct a variables writer instance targeting an internal string writer. Its value can be retrieved via this class toString().

Parameters:

variables - variables map.

VariablesWriter

public VariablesWriter(Writer targetWriter,
                       Map<String,String> variables)

Construct a variables writer decorator for given target writer.

Parameters:

targetWriter - target writer,

variables - variables map.

Method Detail

write

public void write(char[] cbuf,
                  int off,
                  int len)
           throws IOException

Inject values into given variables stream and write the result to target writer.

Specified by:

write in class Writer

Parameters:

cbuf - characters from variables stream,

off - buffer offset,

len - buffer length.

Throws:

IOException

flush

public void flush()
           throws IOException

Flush target writer.

Specified by:

flush in interface Flushable

Specified by:

flush in class Writer

Throws:

IOException

close

public void close()
           throws IOException

Close target writer.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in class Writer

Throws:

IOException

toString

public String toString()

Return target writer string value. Useful if target writer is a string writer.

Overrides:

toString in class Object