我从供应商那里得到一个文件，每行有 115 个固定宽度的字段。如何将该文件解析为 115 个字段，以便在我的代码中使用它们？
我的第一个想法就是为每个字段创建常量，例如NAME_START_POSITIONandNAME_LENGTH和 using substring。这看起来很丑，所以我很好奇更好的方法。谷歌搜索的几个图书馆似乎也没有一个更好。
问问题
56503 次
10 回答
7
我用fixedformat4j玩过arround，非常好。易于配置转换器等。
于 2009-10-22T21:02:34.537 回答
7
uniVocity-parsers带有一个FixedWidthParser并且FixedWidthWriter可以支持棘手的固定宽度格式，包括具有不同字段、填充等的行。
// creates the sequence of field lengths in the file to be parsed
FixedWidthFields fields = new FixedWidthFields(4, 5, 40, 40, 8);
// creates the default settings for a fixed width parser
FixedWidthParserSettings settings = new FixedWidthParserSettings(fields); // many settings here, check the tutorial.
//sets the character used for padding unwritten spaces in the file
settings.getFormat().setPadding('_');
// creates a fixed-width parser with the given settings
FixedWidthParser parser = new FixedWidthParser(settings);
// parses all rows in one go.
List<String[]> allRows = parser.parseAll(new File("path/to/fixed.txt")));
以下是解析各种固定宽度输入的几个示例。
这里有一些其他的一般写作示例和其他特定于固定宽度格式的固定宽度示例。
披露：我是这个库的作者，它是开源和免费的（Apache 2.0 许可证）
于 2016-05-02T03:49:38.510 回答
1
这是我使用的一个基本实现：
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
public class FlatFileParser {
public static void main(String[] args) {
File inputFile = new File("data.in");
File outputFile = new File("data.out");
int columnLengths[] = {7, 4, 10, 1};
String charset = "ISO-8859-1";
String delimiter = "~";
System.out.println(
convertFixedWidthFile(inputFile, outputFile, columnLengths, delimiter, charset)
+ " lines written to " + outputFile.getAbsolutePath());
}
/**
* Converts a fixed width file to a delimited file.
* <p>
* This method ignores (consumes) newline and carriage return
* characters. Lines returned is based strictly on the aggregated
* lengths of the columns.
*
* A RuntimeException is thrown if run-off characters are detected
* at eof.
*
* @param inputFile the fixed width file
* @param outputFile the generated delimited file
* @param columnLengths the array of column lengths
* @param delimiter the delimiter used to split the columns
* @param charsetName the charset name of the supplied files
* @return the number of completed lines
*/
public static final long convertFixedWidthFile(
File inputFile,
File outputFile,
int columnLengths[],
String delimiter,
String charsetName) {
InputStream inputStream = null;
Reader inputStreamReader = null;
OutputStream outputStream = null;
Writer outputStreamWriter = null;
String newline = System.getProperty("line.separator");
String separator;
int data;
int currentIndex = 0;
int currentLength = columnLengths[currentIndex];
int currentPosition = 0;
long lines = 0;
try {
inputStream = new FileInputStream(inputFile);
inputStreamReader = new InputStreamReader(inputStream, charsetName);
outputStream = new FileOutputStream(outputFile);
outputStreamWriter = new OutputStreamWriter(outputStream, charsetName);
while((data = inputStreamReader.read()) != -1) {
if(data != 13 && data != 10) {
outputStreamWriter.write(data);
if(++currentPosition > (currentLength - 1)) {
currentIndex++;
separator = delimiter;
if(currentIndex > columnLengths.length - 1) {
currentIndex = 0;
separator = newline;
lines++;
}
outputStreamWriter.write(separator);
currentLength = columnLengths[currentIndex];
currentPosition = 0;
}
}
}
if(currentIndex > 0 || currentPosition > 0) {
String line = "Line " + ((int)lines + 1);
String column = ", Column " + ((int)currentIndex + 1);
String position = ", Position " + ((int)currentPosition);
throw new RuntimeException("Incomplete record detected. " + line + column + position);
}
return lines;
}
catch (Throwable e) {
throw new RuntimeException(e);
}
finally {
try {
inputStreamReader.close();
outputStreamWriter.close();
}
catch (Throwable e) {
throw new RuntimeException(e);
}
}
}
}
于 2016-06-11T11:44:19.680 回答
1
最适合 Scala，但可能你可以在 Java 中使用它
我已经厌倦了这样一个事实，即没有我自己创建的固定长度格式的适当库。你可以在这里查看：https ://github.com/atais/Fixed-Length
一个基本用法是您创建一个案例类，并将其描述为HList（无形）：
case class Employee(name: String, number: Option[Int], manager: Boolean)
object Employee {
import com.github.atais.util.Read._
import cats.implicits._
import com.github.atais.util.Write._
import Codec._
implicit val employeeCodec: Codec[Employee] = {
fixed[String](0, 10) <<:
fixed[Option[Int]](10, 13, Alignment.Right) <<:
fixed[Boolean](13, 18)
}.as[Employee]
}
您现在可以轻松地解码您的线条或编码您的对象：
import Employee._
Parser.decode[Employee](exampleString)
Parser.encode(exampleObject)
于 2017-07-12T10:18:00.687 回答
1
如果您的字符串被调用inStr，请将其转换为 char 数组并使用
String(char[], start, length)构造函数
char[] intStrChar = inStr.toCharArray();
String charfirst10 = new String(intStrChar,0,9);
String char10to20 = new String(intStrChar,10,19);
于 2018-06-01T13:07:23.107 回答
0
Apache Commons CSV项目可以处理固定文件。
看起来固定宽度功能无法在沙盒中进行推广。
于 2009-10-22T21:33:04.007 回答
0
这是读取固定宽度文件的纯 java 代码：
import java.io.File;
import java.io.FileNotFoundException;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
public class FixedWidth {
public static void main(String[] args) throws FileNotFoundException, IOException {
// String S1="NHJAMES TURNER M123-45-67890004224345";
String FixedLengths = "2,15,15,1,11,10";
List<String> items = Arrays.asList(FixedLengths.split("\\s*,\\s*"));
File file = new File("src/sample.txt");
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
String line1;
while ((line1 = br.readLine()) != null) {
// process the line.
int n = 0;
String line = "";
for (String i : items) {
// System.out.println("Before"+n);
if (i == items.get(items.size() - 1)) {
line = line + line1.substring(n, n + Integer.parseInt(i)).trim();
} else {
line = line + line1.substring(n, n + Integer.parseInt(i)).trim() + ",";
}
// System.out.println(
// S1.substring(n,n+Integer.parseInt(i)));
n = n + Integer.parseInt(i);
// System.out.println("After"+n);
}
System.out.println(line);
}
}
}
}
于 2015-09-17T16:41:31.737 回答
0
/*The method takes three parameters, fixed length record , length of record which will come from schema , say 10 columns and third parameter is delimiter*/
public class Testing {
public static void main(String as[]) throws InterruptedException {
fixedLengthRecordProcessor("1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10", 10, ",");
}
public static void fixedLengthRecordProcessor(String input, int reclength, String dilimiter) {
String[] values = input.split(dilimiter);
String record = "";
int recCounter = 0;
for (Object O : values) {
if (recCounter == reclength) {
System.out.println(record.substring(0, record.length() - 1));// process
// your
// record
record = "";
record = record + O.toString() + ",";
recCounter = 1;
} else {
record = record + O.toString() + ",";
recCounter++;
}
}
System.out.println(record.substring(0, record.length() - 1)); // process
// your
// record
}
}
于 2016-07-10T13:13:22.660 回答
0
另一个可用于解析固定宽度文本源的库： https ://github.com/org-tigris-jsapar/jsapar
允许您在 xml 或代码中定义模式并将固定宽度的文本解析为 Java bean 或从内部格式获取值。
披露：我是 jsapar 库的作者。如果它不能满足您的需求，您可以在此页面上找到其他解析库的完整列表。它们中的大多数仅用于分隔文件，但有些也可以解析固定宽度。
于 2019-06-10T14:33:26.113 回答