How to understand the "Simple CSV" framework technical principle in the Java class library
"Simple CSV" framework technical principle in the Java class library
Introduction:
Simple CSV is a framework technology used in the Java class library to process CSV (comma separation value) file.CSV is a common data storage and exchange format, which is usually used to import and export form data.The Simple CSV framework provides a simple and powerful way to read, write and process CSV files.This article will introduce the technical principles of the Simple CSV framework, and explain the complete program code and related configuration under the necessary situation.
1. Overview of the Simple CSV framework
The Simple CSV framework is an open source project that can be used to process data in the CSV file.It provides a simple API, making it easy to read and write CSV files.The Simple CSV framework realizes data conversion and processing by parsing the CSV file as a Java object, or serializing the Java object to CSV files.
2. The core category of the Simple CSV framework
The core categories of the Simple CSV framework are CSVReader and CSVWriter.CSVReader is used to read data from CSV files, while CSVWriter is used to write data into CSV files.Both categories provide rich methods and options to process data in CSV files.
3. Use the Simple CSV framework to read the CSV file
The following is an example of reading CSV files using the Simple CSV framework:
import com.github.cliftonlabs.json_simple.*;
public class CSVReaderExample {
public static void main(String[] args) {
try {
CSVReader reader = new CSVReaderBuilder(new FileReader("data.csv"))
.withSkipLines(1)
.build();
String[] nextLine;
while ((nextLine = reader.readNext()) != null) {
for (String value : nextLine) {
System.out.println(value);
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above code, we created a CSVReader object and specified the CSV file to be read.By calling the method of calling `withskiplines (1), we tell the framework to ignore the first line of the CSV file.Then, we read the CSV file with the `WHILE` cycle and print out the values of each line.
4. Use the Simple CSV framework to write to the CSV file
Below is an example of using the Simple CSV framework to write to the CSV file:
import com.github.cliftonlabs.json_simple.*;
public class CSVWriterExample {
public static void main(String[] args) {
try {
CSVWriter writer = new CSVWriter(new FileWriter("data.csv"));
String[] header = {"Name", "Age", "Email"};
writer.writeNext(header);
String[] data1 = {"John Doe", "30", "john.doe@example.com"};
writer.writeNext(data1);
String[] data2 = {"Jane Smith", "25", "jane.smith@example.com"};
writer.writeNext(data2);
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above code, we created a CSVWriter object and specified the CSV file to be written.First, we wrote the title line of the CSV file, and then wrote the data one by one.Finally, we call the `Close ()" method to close the writer to ensure that the written data is saved in the CSV file.
5. Configuration of the Simple CSV framework
The Simple CSV framework provides various configuration options to meet different needs.For example, we can set field separation symbols, quotes characters, and lines.Below is an example of setting field separation symbols:
import com.github.cliftonlabs.json_simple.*;
public class CSVConfigurationExample {
public static void main(String[] args) {
try {
CSVReader reader = new CSVReaderBuilder(new FileReader("data.csv"))
.withCSVParser(new CSVParserBuilder()
.withSeparator(',')
.build())
.build();
// Read and process CSV files
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above code, we set the field separation symbols to comma through the method of `withcsvparser ()`.
Summarize:
The Simple CSV framework is a powerful tool for processing CSV files.It provides an easy -to -use API to make it very convenient to read, write and process the CSV files.By understanding the technical principles and use examples of the Simple CSV framework, we can make full use of this framework to process data in the CSV file.
