com.jchanghong.core.text.csv.CsvParser Maven / Gradle / Ivy
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package com.jchanghong.core.text.csv;
import com.jchanghong.core.io.IORuntimeException;
import com.jchanghong.core.io.IoUtil;
import com.jchanghong.core.text.StrBuilder;
import com.jchanghong.core.util.CharUtil;
import com.jchanghong.core.util.ObjectUtil;
import com.jchanghong.core.util.StrUtil;
import java.io.Closeable;
import java.io.IOException;
import java.io.Reader;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
/**
* CSV行解析器，参考：FastCSV
*
* @author Looly
*/
public final class CsvParser implements Closeable, Serializable {
private static final long serialVersionUID = 1L;
private static final int DEFAULT_ROW_CAPACITY = 10;
private final Reader reader;
private final CsvReadConfig config;
private final char[] buf = new char[IoUtil.DEFAULT_LARGE_BUFFER_SIZE];
/** 当前位置 */
private int bufPos;
/** 读取一段后数据长度 */
private int bufLen;
/** 拷贝开始的位置，一般为上一行的结束位置 */
private int copyStart;
/** 前一个特殊分界字符 */
private int preChar = -1;
/** 是否在引号包装内 */
private boolean inQuotes;
/** 当前读取字段 */
private final StrBuilder currentField = new StrBuilder(512);
/** 标题行 */
private CsvRow header;
/** 当前行号 */
private long lineNo;
/** 第一行字段数，用于检查每行字段数是否一致 */
private int firstLineFieldCount = -1;
/** 最大字段数量 */
private int maxFieldCount;
/** 是否读取结束 */
private boolean finished;
/**
* CSV解析器
*
* @param reader Reader
* @param config 配置，null则为默认配置
*/
public CsvParser(final Reader reader, CsvReadConfig config) {
this.reader = Objects.requireNonNull(reader, "reader must not be null");
this.config = ObjectUtil.defaultIfNull(config, CsvReadConfig.defaultConfig());
}
/**
* 获取头部字段列表，如果containsHeader设置为false则抛出异常
*
* @return 头部列表
* @throws IllegalStateException 如果不解析头部或者没有调用nextRow()方法
*/
public List getHeader() {
if (false == config.containsHeader) {
throw new IllegalStateException("No header available - header parsing is disabled");
}
if (lineNo == 0) {
throw new IllegalStateException("No header available - call nextRow() first");
}
return header.fields;
}
/**
*读取下一行数据
*
* @return CsvRow
* @throws IORuntimeException IO读取异常
*/
public CsvRow nextRow() throws IORuntimeException {
long startingLineNo;
List currentFields;
int fieldCount;
while (false == finished) {
startingLineNo = ++lineNo;
currentFields = readLine();
fieldCount = currentFields.size();
if(fieldCount < 1){
break;
}
// 跳过空行
if (config.skipEmptyRows && fieldCount == 1 && currentFields.get(0).isEmpty()) {
continue;
}
// 检查每行的字段数是否一致
if (config.errorOnDifferentFieldCount) {
if (firstLineFieldCount == -1) {
firstLineFieldCount = fieldCount;
} else if (fieldCount != firstLineFieldCount) {
throw new IORuntimeException(String.format("Line %d has %d fields, but first line has %d fields", lineNo, fieldCount, firstLineFieldCount));
}
}
// 记录最大字段数
if (fieldCount > maxFieldCount) {
maxFieldCount = fieldCount;
}
//初始化标题
if (config.containsHeader && null == header) {
initHeader(currentFields);
// 作为标题行后，此行跳过，下一行做为第一行
continue;
}
return new CsvRow(startingLineNo, null == header ? null : header.headerMap, currentFields);
}
return null;
}
/**
* 当前行做为标题行
*
* @param currentFields 当前行字段列表
*/
private void initHeader(final List currentFields) {
final Map localHeaderMap = new LinkedHashMap<>(currentFields.size());
for (int i = 0; i < currentFields.size(); i++) {
final String field = currentFields.get(i);
if (StrUtil.isNotEmpty(field) && false ==localHeaderMap.containsKey(field)) {
localHeaderMap.put(field, i);
}
}
header = new CsvRow(this.lineNo, Collections.unmodifiableMap(localHeaderMap), Collections.unmodifiableList(currentFields));
}
/**
* 读取一行数据
*
* @return 一行数据
* @throws IORuntimeException IO异常
*/
private List readLine() throws IORuntimeException {
final List currentFields = new ArrayList<>(maxFieldCount > 0 ? maxFieldCount : DEFAULT_ROW_CAPACITY);
final StrBuilder localCurrentField = currentField;
final char[] localBuf = this.buf;
int localBufPos = bufPos;//当前位置
int localPreChar = preChar;//前一个特殊分界字符
int localCopyStart = copyStart;//拷贝起始位置
int copyLen = 0; //拷贝长度
while (true) {
if (bufLen == localBufPos) {
// 此Buffer读取结束，开始读取下一段
if (copyLen > 0) {
localCurrentField.append(localBuf, localCopyStart, copyLen);
}
try {
bufLen = reader.read(localBuf);
} catch (IOException e) {
throw new IORuntimeException(e);
}
if (bufLen < 0) {
// CSV读取结束
finished = true;
if (localPreChar == config.fieldSeparator || localCurrentField.hasContent()) {
//剩余部分作为一个字段
currentFields.add(StrUtil.unWrap(localCurrentField.toStringAndReset(), config.textDelimiter));
}
break;
}
//重置
localCopyStart = localBufPos = copyLen = 0;
}
final char c = localBuf[localBufPos++];
if (inQuotes) {
//引号内，做为内容，直到引号结束
if (c == config.textDelimiter) {
// End of quoted text
inQuotes = false;
} else {
if ((c == CharUtil.CR || c == CharUtil.LF) && localPreChar != CharUtil.CR) {
lineNo++;
}
}
copyLen++;
} else {
if (c == config.fieldSeparator) {
//一个字段结束
if (copyLen > 0) {
localCurrentField.append(localBuf, localCopyStart, copyLen);
copyLen = 0;
}
currentFields.add(StrUtil.unWrap(localCurrentField.toStringAndReset(), config.textDelimiter));
localCopyStart = localBufPos;
} else if (c == config.textDelimiter) {
// 引号开始
inQuotes = true;
copyLen++;
} else if (c == CharUtil.CR) {
if (copyLen > 0) {
localCurrentField.append(localBuf, localCopyStart, copyLen);
}
currentFields.add(StrUtil.unWrap(localCurrentField.toStringAndReset(), config.textDelimiter));
localPreChar = c;
localCopyStart = localBufPos;
break;
} else if (c == CharUtil.LF) {
if (localPreChar != CharUtil.CR) {
if (copyLen > 0) {
localCurrentField.append(localBuf, localCopyStart, copyLen);
}
currentFields.add(StrUtil.unWrap(localCurrentField.toStringAndReset(), config.textDelimiter));
localPreChar = c;
localCopyStart = localBufPos;
break;
}
localCopyStart = localBufPos;
} else {
copyLen++;
}
}
localPreChar = c;
}
// restore fields
bufPos = localBufPos;
preChar = localPreChar;
copyStart = localCopyStart;
return currentFields;
}
@Override
public void close() throws IOException {
reader.close();
}
}