Analysis of the core technical principles of the Commons CSV (SANDBOX) framework in the Java class library
The Commons CSV (Sandbox) framework is a Java class library for processing CSV (comma separation value) file.It provides a simple and powerful API that can read and write CSV files, as well as analysis and generating CSV records.In this article, we will analyze the core technical principles of the COMMONS CSV framework in the Java class library, and help understand it by providing some Java code examples.
1. Introduction to CSV file:
CSV is a common text file format for storing and exchange simple table data.Each record is usually composed of a line, and the comma is separated between the fields.CSV files can be edited using pure text editors, or they can be created and edited by electronic table software (such as Microsoft Excel and Google Sheets).
2. COMMONS CSV Framework Overview:
Commons CSV is an open source project developed by Apache Software Foundation to provide a simple and reliable way to read and write CSV files.It introduces some key concepts and classes in the Java library to easily operate CSV data.
3. Core technology:
The core technical principles of the Commons CSV framework mainly include the following aspects:
-CSVFormat class: This is the main class used in the CSV file format in the Commons CSV framework.It defines information such as commas, quotation characters, changes, etc., and provides a set of static methods to create different CSV format instances.For example, you can use CSVFormat.Default to create the default format instance.
-CSVPARSER class: This class is used to analyze CSV files and convert it into a set of CSV records.By reading the CSV file and using the format defined by CSVFormat, CSVPARSER can analyze each line into a CSV record object.For example, you can use the CSVPARSER.PARSE method to analyze the CSV file as ITERABLE <CSVRecord>, and then traverse the fields of each CSVRecord object to access the records.
-CSVPrinter class: This type is used to write CSV records into CSV files.Using CSVFormat definition formats and the CSVPrinter instance provided, you can use CSVPrinter.printReCord method to write the recorded fields into the line of the CSV file.For example, a set of records can be written into the CSV file with CSVPrinter.prinTRECORDS method.
4. Java code example:
The following is a simple Java code example, which demonstrates how to use the Commons CSV framework to read and write the CSV file:
Read the CSV file:
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
public class CSVReaderExample {
public static void main(String[] args) {
try {
Reader Reader = New FILEREADER ("Data.csv"); // Read csv file
CSVPARSER PARSER = CSVFormat.default.parse (Reader); // Create a CSV parser
For (CSVRECORD Record: Parser) {// Traversing CSV records
String name = record.get (0); // Get the first field value
String age = record.get (1); // Get the second field value
System.out.println("Name: " + name + ", Age: " + age);
}
Reader.close (); // Close the reader
} catch (IOException e) {
e.printStackTrace();
}
}
}
Write to CSV file:
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.Arrays;
import java.util.List;
public class CSVWriterExample {
public static void main(String[] args) {
try {
Writer writer = new filewriter ("data.csv"); // Create a CSV writer
CSVPrinter Printer = New CSVPrinter (Writer, CSVFormat.Default); // Create CSV printers
List <string> Record1 = Arrays.aslist ("John Smith", "25"); // Create a record 1
List <string> Record2 = Arrays.aslist ("Jane Doe", "30"); // Create Record 2
Printer.printRecord (record1); // Write to record 1
printer.printRecord (record2); // Write to record records 2
writer.close (); // Turn off the writer
} catch (IOException e) {
e.printStackTrace();
}
}
}
The above example shows the basic usage of the Commons CSV framework. It can easily process data in the CSV file through the CSVPARSER class and the CSVPrinter class.You can use the API provided by the Commons CSV framework to read and write the CSV file flexibly according to the specific needs.
