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package com.zoomlion.cloud.common.codec;
import java.io.*;
import com.zoomlion.cloud.common.crypto.ByteSource;
/**
* Base abstract class that provides useful encoding and decoding operations, especially for character data.
*
* @since 0.9
*/
public abstract class CodecSupport {
/**
* Shiro's default preferred character encoding, equal to UTF-8.
*/
public static final String PREFERRED_ENCODING = "UTF-8";
/**
* Converts the specified character array to a byte array using the Shiro's preferred encoding (UTF-8).
*
* This is a convenience method equivalent to calling the {@link #toBytes(String,String)} method with a
* a wrapping String and {@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING}, i.e.
*
* toBytes( new String(chars), {@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING} );
*
* @param chars the character array to be converted to a byte array.
* @return the byte array of the UTF-8 encoded character array.
*/
public static byte[] toBytes(char[] chars) {
return toBytes(new String(chars), PREFERRED_ENCODING);
}
/**
* Converts the specified character array into a byte array using the specified character encoding.
*
* This is a convenience method equivalent to calling the {@link #toBytes(String,String)} method with a
* a wrapping String and the specified encoding, i.e.
*
* toBytes( new String(chars), encoding );
*
* @param chars the character array to be converted to a byte array
* @param encoding the character encoding to use to when converting to bytes.
* @return the bytes of the specified character array under the specified encoding.
* @throws CodecException if the JVM does not support the specified encoding.
*/
public static byte[] toBytes(char[] chars, String encoding) throws CodecException {
return toBytes(new String(chars), encoding);
}
/**
* Converts the specified source argument to a byte array with Shiro's
* {@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING}.
*
* @param source the string to convert to a byte array.
* @return the bytes representing the specified string under the {@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING}.
* @see #toBytes(String, String)
*/
public static byte[] toBytes(String source) {
return toBytes(source, PREFERRED_ENCODING);
}
/**
* Converts the specified source to a byte array via the specified encoding, throwing a
* {@link CodecException CodecException} if the encoding fails.
*
* @param source the source string to convert to a byte array.
* @param encoding the encoding to use to use.
* @return the byte array of the specified source with the given encoding.
* @throws CodecException if the JVM does not support the specified encoding.
*/
public static byte[] toBytes(String source, String encoding) throws CodecException {
try {
return source.getBytes(encoding);
} catch (UnsupportedEncodingException e) {
String msg = "Unable to convert source [" + source + "] to byte array using " +
"encoding '" + encoding + "'";
throw new CodecException(msg, e);
}
}
/**
* Converts the specified byte array to a String using the {@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING}.
*
* @param bytes the byte array to turn into a String.
* @return the specified byte array as an encoded String ({@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING}).
* @see #toString(byte[], String)
*/
public static String toString(byte[] bytes) {
return toString(bytes, PREFERRED_ENCODING);
}
/**
* Converts the specified byte array to a String using the specified character encoding. This implementation
* does the same thing as new {@link String#String(byte[], String) String(byte[], encoding)}, but will
* wrap any {@link UnsupportedEncodingException} with a nicer runtime {@link CodecException}, allowing you to
* decide whether or not you want to catch the exception or let it propagate.
*
* @param bytes the byte array to convert to a String
* @param encoding the character encoding used to encode the String.
* @return the specified byte array as an encoded String
* @throws CodecException if the JVM does not support the specified encoding.
*/
public static String toString(byte[] bytes, String encoding) throws CodecException {
try {
return new String(bytes, encoding);
} catch (UnsupportedEncodingException e) {
String msg = "Unable to convert byte array to String with encoding '" + encoding + "'.";
throw new CodecException(msg, e);
}
}
/**
* Returns the specified byte array as a character array using the
* {@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING}.
*
* @param bytes the byte array to convert to a char array
* @return the specified byte array encoded as a character array ({@link CodecSupport#PREFERRED_ENCODING PREFERRED_ENCODING}).
* @see #toChars(byte[], String)
*/
public static char[] toChars(byte[] bytes) {
return toChars(bytes, PREFERRED_ENCODING);
}
/**
* Converts the specified byte array to a character array using the specified character encoding.
*
* Effectively calls {@link #toString(byte[], String) toString(bytes,encoding)}.{@link String#toCharArray() toCharArray()};
*
* @param bytes the byte array to convert to a String
* @param encoding the character encoding used to encode the bytes.
* @return the specified byte array as an encoded char array
* @throws CodecException if the JVM does not support the specified encoding.
*/
public static char[] toChars(byte[] bytes, String encoding) throws CodecException {
return toString(bytes, encoding).toCharArray();
}
/**
* Returns {@code true} if the specified object can be easily converted to bytes by instances of this class,
* {@code false} otherwise.
*
* The default implementation returns {@code true} IFF the specified object is an instance of one of the following
* types:
*
* - {@code byte[]}
* - {@code char[]}
* - {@link ByteSource}
* - {@link String}
* - {@link File}
* - {@link InputStream}
*
*
* @param o the object to test to see if it can be easily converted to a byte array
* @return {@code true} if the specified object can be easily converted to bytes by instances of this class,
* {@code false} otherwise.
* @since 1.0
*/
protected boolean isByteSource(Object o) {
return o instanceof byte[] || o instanceof char[] || o instanceof String ||
o instanceof ByteSource || o instanceof File || o instanceof InputStream;
}
/**
* Converts the specified Object into a byte array.
*
* If the argument is a {@code byte[]}, {@code char[]}, {@link ByteSource}, {@link String}, {@link File}, or
* {@link InputStream}, it will be converted automatically and returned.}
*
* If the argument is anything other than these types, it is passed to the
* {@link #objectToBytes(Object) objectToBytes} method which must be overridden by subclasses.
*
* @param o the Object to convert into a byte array
* @return a byte array representation of the Object argument.
*/
protected byte[] toBytes(Object o) {
if (o == null) {
String msg = "Argument for byte conversion cannot be null.";
throw new IllegalArgumentException(msg);
}
if (o instanceof byte[]) {
return (byte[]) o;
} else if (o instanceof ByteSource) {
return ((ByteSource) o).getBytes();
} else if (o instanceof char[]) {
return toBytes((char[]) o);
} else if (o instanceof String) {
return toBytes((String) o);
} else if (o instanceof File) {
return toBytes((File) o);
} else if (o instanceof InputStream) {
return toBytes((InputStream) o);
} else {
return objectToBytes(o);
}
}
/**
* Converts the specified Object into a String.
*
* If the argument is a {@code byte[]} or {@code char[]} it will be converted to a String using the
* {@link #PREFERRED_ENCODING}. If a String, it will be returned as is.
*
* If the argument is anything other than these three types, it is passed to the
* {@link #objectToString(Object) objectToString} method.
*
* @param o the Object to convert into a byte array
* @return a byte array representation of the Object argument.
*/
protected String toString(Object o) {
if (o == null) {
String msg = "Argument for String conversion cannot be null.";
throw new IllegalArgumentException(msg);
}
if (o instanceof byte[]) {
return toString((byte[]) o);
} else if (o instanceof char[]) {
return new String((char[]) o);
} else if (o instanceof String) {
return (String) o;
} else {
return objectToString(o);
}
}
protected byte[] toBytes(File file) {
if (file == null) {
throw new IllegalArgumentException("File argument cannot be null.");
}
try {
return toBytes(new FileInputStream(file));
} catch (FileNotFoundException e) {
String msg = "Unable to acquire InputStream for file [" + file + "]";
throw new CodecException(msg, e);
}
}
/**
* Converts the specified {@link InputStream InputStream} into a byte array.
*
* @param in the InputStream to convert to a byte array
* @return the bytes of the input stream
* @throws IllegalArgumentException if the {@code InputStream} argument is {@code null}.
* @throws CodecException if there is any problem reading from the {@link InputStream}.
* @since 1.0
*/
protected byte[] toBytes(InputStream in) {
if (in == null) {
throw new IllegalArgumentException("InputStream argument cannot be null.");
}
final int BUFFER_SIZE = 512;
ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE);
byte[] buffer = new byte[BUFFER_SIZE];
int bytesRead;
try {
while ((bytesRead = in.read(buffer)) != -1) {
out.write(buffer, 0, bytesRead);
}
return out.toByteArray();
} catch (IOException ioe) {
throw new CodecException(ioe);
} finally {
try {
in.close();
} catch (IOException ignored) {
}
try {
out.close();
} catch (IOException ignored) {
}
}
}
/**
* Default implementation throws a CodecException immediately since it can't infer how to convert the Object
* to a byte array. This method must be overridden by subclasses if anything other than the three default
* types (listed in the {@link #toBytes(Object) toBytes(Object)} JavaDoc) are to be converted to a byte array.
*
* @param o the Object to convert to a byte array.
* @return a byte array representation of the Object argument.
*/
protected byte[] objectToBytes(Object o) {
String msg = "The " + getClass().getName() + " implementation only supports conversion to " +
"byte[] if the source is of type byte[], char[], String, " + ByteSource.class.getName() +
" File or InputStream. The instance provided as a method " +
"argument is of type [" + o.getClass().getName() + "]. If you would like to convert " +
"this argument type to a byte[], you can 1) convert the argument to one of the supported types " +
"yourself and then use that as the method argument or 2) subclass " + getClass().getName() +
"and override the objectToBytes(Object o) method.";
throw new CodecException(msg);
}
/**
* Default implementation merely returns objectArgument.toString(). Subclasses can override this
* method for different mechanisms of converting an object to a String.
*
* @param o the Object to convert to a byte array.
* @return a String representation of the Object argument.
*/
protected String objectToString(Object o) {
return o.toString();
}
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