com.aliyun.odps.io.Text Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.aliyun.odps.io;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.MalformedInputException;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
/**
* Text 提供了字符串的 {@link Writable} 和 {@link WritableComparable} 的实现.
*
*
* Text 内部使用字节数组保存字符串，并采用 UTF-8 编码，提供了序列化、反序列化以及字节级别的字符串比较方法。
*
*
* 另外，Text 也提供了一组丰富的字符串处理函数。
*/
public class Text extends BinaryComparable implements
WritableComparable {
private static ThreadLocal ENCODER_FACTORY = new ThreadLocal() {
protected CharsetEncoder initialValue() {
return Charset.forName("UTF-8").newEncoder()
.onMalformedInput(CodingErrorAction.REPORT)
.onUnmappableCharacter(CodingErrorAction.REPORT);
}
};
private static ThreadLocal DECODER_FACTORY = new ThreadLocal() {
protected CharsetDecoder initialValue() {
return Charset.forName("UTF-8").newDecoder()
.onMalformedInput(CodingErrorAction.REPORT)
.onUnmappableCharacter(CodingErrorAction.REPORT);
}
};
private static final byte[] EMPTY_BYTES = new byte[0];
private byte[] bytes;
private int length;
/**
* 默认构造空串的 Text.
*/
public Text() {
bytes = EMPTY_BYTES;
}
/**
* 给定字符串构造一个 Text.
*
* @param string
*/
public Text(String string) {
set(string);
}
/**
* 从另一个 Text 对象构造 Text，内容会做拷贝.
*
* @param string
*/
public Text(Text utf8) {
set(utf8);
}
/**
* 给定字节数组构造 Text
*
* @param utf8
*/
public Text(byte[] utf8) {
set(utf8);
}
/**
* 返回存储字符串内容的字节数组，注意字节数组的有效内容是：0 ~ {@link #getLength()}.
*
* 注意：字节数组的有效内容是：0 ~ {@link #getLength()}
* ！直接使用整个字节数组可能会读到无效内容。
*
* @see #getLength()
*/
@Override
public byte[] getBytes() {
return bytes;
}
/**
* 获取内容长度，单位：字节
*
* @see #getBytes()
*/
@Override
public int getLength() {
return length;
}
/**
* 返回给定位置 position 的 Unicode 32位标量值（Unicode scalar value）.
*
*
* Text 内部使用字节数组保存字符串，并采用 UTF-8 编码，charAt 方法将字节数组在 position 位置的 UTF-8 字符转换为
* Unicode 32位标量值并返回
*
* @see #getBytes()
* @see #getLength()
* @return position 位置的 Unicode 32位标量值（Unicode scalar value），如果 position
* 无效（position < 0 或 position >= {@link #getLength()}），则返回-1
*/
public int charAt(int position) {
// FIXME: should >= ?
if (position > this.length)
return -1; // too long
if (position < 0)
return -1; // duh.
ByteBuffer bb = (ByteBuffer) ByteBuffer.wrap(bytes).position(position);
return bytesToCodePoint(bb.slice());
}
/**
* 查找子串出现的位置.
*
*
* 等价于 find(what, 0);
*
* @return 如果找到，返回子串第一次出现在字节数组的位置，如果为找到，返回-1
*/
public int find(String what) {
return find(what, 0);
}
/**
* 从某个起始位置开始查找子串出现的位置
*
* @return 如果找到，返回子串第一次出现在字节数组的位置，如果为找到，返回-1
*/
public int find(String what, int start) {
try {
ByteBuffer src = ByteBuffer.wrap(this.bytes, 0, this.length);
ByteBuffer tgt = encode(what);
byte b = tgt.get();
src.position(start);
while (src.hasRemaining()) {
if (b == src.get()) { // matching first byte
src.mark(); // save position in loop
tgt.mark(); // save position in target
boolean found = true;
int pos = src.position() - 1;
while (tgt.hasRemaining()) {
if (!src.hasRemaining()) { // src expired first
tgt.reset();
src.reset();
found = false;
break;
}
if (!(tgt.get() == src.get())) {
tgt.reset();
src.reset();
found = false;
break; // no match
}
}
if (found)
return pos;
}
}
return -1; // not found
} catch (CharacterCodingException e) {
// can't get here
e.printStackTrace();
return -1;
}
}
/**
* 给定 String 设置字符串内容.
*
* @param string
*/
public void set(String string) {
try {
ByteBuffer bb = encode(string, true);
bytes = bb.array();
length = bb.limit();
} catch (CharacterCodingException e) {
throw new RuntimeException("Should not have happened " + e.toString());
}
}
/**
* 给定 UTF-8 编码数组设置字符串内容.
*
* @param utf8
*/
public void set(byte[] utf8) {
set(utf8, 0, utf8.length);
}
/**
* 拷贝另个 Text 的内容.
*
* @param other
*/
public void set(Text other) {
set(other.getBytes(), 0, other.getLength());
}
/**
* 设置字符串内容.
*
* @param utf8
* 待拷贝内容的字节数组
* @param start
* 待拷贝内容的起始位置
* @param len
* 待拷贝内容的长度
*/
public void set(byte[] utf8, int start, int len) {
setCapacity(len, false);
System.arraycopy(utf8, start, bytes, 0, len);
this.length = len;
}
/**
* 追加字符串内容.
*
* @param utf8
* 待追加内容的字节数组
* @param start
* 待追加内容的起始位置
* @param len
* 待追加内容的长度
*/
public void append(byte[] utf8, int start, int len) {
setCapacity(length + len, true);
System.arraycopy(utf8, start, bytes, length, len);
length += len;
}
/**
* 清空字符串，清空后 {@link #getLength()} 返回0
*/
public void clear() {
length = 0;
}
/*
* Sets the capacity of this Text object to at least len
* bytes. If the current buffer is longer, then the capacity and existing
* content of the buffer are unchanged. If len is larger than the
* current capacity, the Text object's capacity is increased to match.
*
* @param len the number of bytes we need
*
* @param keepData should the old data be kept
*/
private void setCapacity(int len, boolean keepData) {
if (bytes == null || bytes.length < len) {
byte[] newBytes = new byte[len];
if (bytes != null && keepData) {
System.arraycopy(bytes, 0, newBytes, 0, length);
}
bytes = newBytes;
}
}
/**
* Convert text back to string
*
* @see java.lang.Object#toString()
*/
public String toString() {
try {
return decode(bytes, 0, length);
} catch (CharacterCodingException e) {
throw new RuntimeException("Should not have happened " + e.toString());
}
}
@Override
public void readFields(DataInput in) throws IOException {
int newLength = WritableUtils.readVInt(in);
setCapacity(newLength, false);
in.readFully(bytes, 0, newLength);
length = newLength;
}
public void readFields(ByteBuffer bf) {
int newLength = bf.getInt();
setCapacity(newLength, false);
bf.get(bytes, 0, newLength);
length = newLength;
}
/** Skips over one Text in the input. */
public static void skip(DataInput in) throws IOException {
int length = WritableUtils.readVInt(in);
WritableUtils.skipFully(in, length);
}
@Override
public void write(DataOutput out) throws IOException {
WritableUtils.writeVInt(out, length);
out.write(bytes, 0, length);
}
/** Returns true iff o is a Text with the same contents. */
public boolean equals(Object o) {
if (o instanceof Text)
return super.equals(o);
return false;
}
public int hashCode() {
return super.hashCode();
}
/**
* Text 对象的 {@link WritableComparator} 自然顺序实现（升序）.
*/
public static class Comparator extends WritableComparator {
public Comparator() {
this(Text.class);
}
public Comparator(Class keyClass) {
super(keyClass);
}
/**
* 基于二进制内容的 Text 对象比较函数.
*/
@Override
public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
int n1 = WritableUtils.decodeVIntSize(b1[s1]);
int n2 = WritableUtils.decodeVIntSize(b2[s2]);
return compareBytes(b1, s1 + n1, l1 - n1, b2, s2 + n2, l2 - n2);
}
}
static {
// register this comparator
WritableComparator.define(Text.class, new Comparator());
}
// / STATIC UTILITIES FROM HERE DOWN
/**
* Converts the provided byte array to a String using the UTF-8 encoding. If
* the input is malformed, replace by a default value.
*/
public static String decode(byte[] utf8) throws CharacterCodingException {
return decode(ByteBuffer.wrap(utf8), true);
}
public static String decode(byte[] utf8, int start, int length)
throws CharacterCodingException {
return decode(ByteBuffer.wrap(utf8, start, length), true);
}
/**
* Converts the provided byte array to a String using the UTF-8 encoding. If
* replace is true, then malformed input is replaced with the
* substitution character, which is U+FFFD. Otherwise the method throws a
* MalformedInputException.
*/
public static String decode(byte[] utf8, int start, int length,
boolean replace) throws CharacterCodingException {
return decode(ByteBuffer.wrap(utf8, start, length), replace);
}
private static String decode(ByteBuffer utf8, boolean replace)
throws CharacterCodingException {
CharsetDecoder decoder = DECODER_FACTORY.get();
if (replace) {
decoder.onMalformedInput(java.nio.charset.CodingErrorAction.REPLACE);
decoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
}
String str = decoder.decode(utf8).toString();
// set decoder back to its default value: REPORT
if (replace) {
decoder.onMalformedInput(CodingErrorAction.REPORT);
decoder.onUnmappableCharacter(CodingErrorAction.REPORT);
}
return str;
}
/**
* Converts the provided String to bytes using the UTF-8 encoding. If the
* input is malformed, invalid chars are replaced by a default value.
*
* @return ByteBuffer: bytes stores at ByteBuffer.array() and length is
* ByteBuffer.limit()
*/
public static ByteBuffer encode(String string)
throws CharacterCodingException {
return encode(string, true);
}
/**
* Converts the provided String to bytes using the UTF-8 encoding. If
* replace is true, then malformed input is replaced with the
* substitution character, which is U+FFFD. Otherwise the method throws a
* MalformedInputException.
*
* @return ByteBuffer: bytes stores at ByteBuffer.array() and length is
* ByteBuffer.limit()
*/
public static ByteBuffer encode(String string, boolean replace)
throws CharacterCodingException {
CharsetEncoder encoder = ENCODER_FACTORY.get();
if (replace) {
encoder.onMalformedInput(CodingErrorAction.REPLACE);
encoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
}
ByteBuffer bytes = encoder.encode(CharBuffer.wrap(string.toCharArray()));
if (replace) {
encoder.onMalformedInput(CodingErrorAction.REPORT);
encoder.onUnmappableCharacter(CodingErrorAction.REPORT);
}
return bytes;
}
/**
* Read a UTF8 encoded string from in
*/
public static String readString(DataInput in) throws IOException {
int length = WritableUtils.readVInt(in);
byte[] bytes = new byte[length];
in.readFully(bytes, 0, length);
return decode(bytes);
}
/**
* Write a UTF8 encoded string to out
*/
public static int writeString(DataOutput out, String s) throws IOException {
ByteBuffer bytes = encode(s);
int length = bytes.limit();
WritableUtils.writeVInt(out, length);
out.write(bytes.array(), 0, length);
return length;
}
// //// states for validateUTF8
private static final int LEAD_BYTE = 0;
private static final int TRAIL_BYTE_1 = 1;
private static final int TRAIL_BYTE = 2;
/**
* Check if a byte array contains valid utf-8
*
* @param utf8
* byte array
* @throws MalformedInputException
* if the byte array contains invalid utf-8
*/
public static void validateUTF8(byte[] utf8) throws MalformedInputException {
validateUTF8(utf8, 0, utf8.length);
}
/**
* Check to see if a byte array is valid utf-8
*
* @param utf8
* the array of bytes
* @param start
* the offset of the first byte in the array
* @param len
* the length of the byte sequence
* @throws MalformedInputException
* if the byte array contains invalid bytes
*/
public static void validateUTF8(byte[] utf8, int start, int len)
throws MalformedInputException {
int count = start;
int leadByte = 0;
int length = 0;
int state = LEAD_BYTE;
while (count < start + len) {
int aByte = ((int) utf8[count] & 0xFF);
switch (state) {
case LEAD_BYTE:
leadByte = aByte;
length = bytesFromUTF8[aByte];
switch (length) {
case 0: // check for ASCII
if (leadByte > 0x7F)
throw new MalformedInputException(count);
break;
case 1:
if (leadByte < 0xC2 || leadByte > 0xDF)
throw new MalformedInputException(count);
state = TRAIL_BYTE_1;
break;
case 2:
if (leadByte < 0xE0 || leadByte > 0xEF)
throw new MalformedInputException(count);
state = TRAIL_BYTE_1;
break;
case 3:
if (leadByte < 0xF0 || leadByte > 0xF4)
throw new MalformedInputException(count);
state = TRAIL_BYTE_1;
break;
default:
// too long! Longest valid UTF-8 is 4 bytes (lead + three)
// or if < 0 we got a trail byte in the lead byte position
throw new MalformedInputException(count);
} // switch (length)
break;
case TRAIL_BYTE_1:
if (leadByte == 0xF0 && aByte < 0x90)
throw new MalformedInputException(count);
if (leadByte == 0xF4 && aByte > 0x8F)
throw new MalformedInputException(count);
if (leadByte == 0xE0 && aByte < 0xA0)
throw new MalformedInputException(count);
if (leadByte == 0xED && aByte > 0x9F)
throw new MalformedInputException(count);
// falls through to regular trail-byte test!!
case TRAIL_BYTE:
if (aByte < 0x80 || aByte > 0xBF)
throw new MalformedInputException(count);
if (--length == 0) {
state = LEAD_BYTE;
} else {
state = TRAIL_BYTE;
}
break;
} // switch (state)
count++;
}
}
/**
* Magic numbers for UTF-8. These are the number of bytes that follow
* a given lead byte. Trailing bytes have the value -1. The values 4 and 5 are
* presented in this table, even though valid UTF-8 cannot include the five
* and six byte sequences.
*/
static final int[] bytesFromUTF8 = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0,
0,
0,
0,
0,
// trail bytes
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4,
4, 5, 5, 5, 5 };
/**
* Returns the next code point at the current position in the buffer. The
* buffer's position will be incremented. Any mark set on this buffer will be
* changed by this method!
*/
public static int bytesToCodePoint(ByteBuffer bytes) {
bytes.mark();
byte b = bytes.get();
bytes.reset();
int extraBytesToRead = bytesFromUTF8[(b & 0xFF)];
if (extraBytesToRead < 0)
return -1; // trailing byte!
int ch = 0;
switch (extraBytesToRead) {
case 5:
ch += (bytes.get() & 0xFF);
ch <<= 6; /* remember, illegal UTF-8 */
case 4:
ch += (bytes.get() & 0xFF);
ch <<= 6; /* remember, illegal UTF-8 */
case 3:
ch += (bytes.get() & 0xFF);
ch <<= 6;
case 2:
ch += (bytes.get() & 0xFF);
ch <<= 6;
case 1:
ch += (bytes.get() & 0xFF);
ch <<= 6;
case 0:
ch += (bytes.get() & 0xFF);
}
ch -= offsetsFromUTF8[extraBytesToRead];
return ch;
}
static final int offsetsFromUTF8[] = { 0x00000000, 0x00003080, 0x000E2080,
0x03C82080, 0xFA082080, 0x82082080 };
/**
* For the given string, returns the number of UTF-8 bytes required to encode
* the string.
*
* @param string
* text to encode
* @return number of UTF-8 bytes required to encode
*/
public static int utf8Length(String string) {
CharacterIterator iter = new StringCharacterIterator(string);
char ch = iter.first();
int size = 0;
while (ch != CharacterIterator.DONE) {
if ((ch >= 0xD800) && (ch < 0xDC00)) {
// surrogate pair?
char trail = iter.next();
if ((trail > 0xDBFF) && (trail < 0xE000)) {
// valid pair
size += 4;
} else {
// invalid pair
size += 3;
iter.previous(); // rewind one
}
} else if (ch < 0x80) {
size++;
} else if (ch < 0x800) {
size += 2;
} else {
// ch < 0x10000, that is, the largest char value
size += 3;
}
ch = iter.next();
}
return size;
}
}