java解析nc文件工具类代码

以下是一个简单的Java解析nc文件的工具类示例：

import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.IntBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.StandardOpenOption;

public class NcFileParser {

    private final static int HEADER_SIZE = 4;
    private final static int RECORD_SIZE = 4;

    public static void parseNcFile(File file) throws IOException {
        try (FileChannel channel = FileChannel.open(file.toPath(), StandardOpenOption.READ)) {
            ByteBuffer buffer = ByteBuffer.allocate(HEADER_SIZE).order(ByteOrder.BIG_ENDIAN);
            channel.read(buffer);
            buffer.rewind();
            int header = buffer.getInt();
            if (header != 0x43415046) {
                throw new IOException("Invalid NetCDF file header");
            }
            buffer.clear();
            channel.read(buffer);
            buffer.rewind();
            int version = buffer.get();
            if (version != 1 && version != 2) {
                throw new IOException("Unsupported NetCDF file version");
            }
            buffer.clear();
            channel.read(buffer);
            buffer.rewind();
            int recordSize = buffer.getInt();
            if (recordSize != RECORD_SIZE) {
                throw new IOException("Invalid NetCDF header record size");
            }
            buffer.clear();
            channel.position(HEADER_SIZE);
            int recordCount = 0;
            while (true) {
                channel.read(buffer);
                buffer.rewind();
                int recordID = buffer.getInt();
                if (recordID == 0) {
                    break;
                }
                int recordLength = buffer.getInt();
                buffer.clear();
                if (recordID == 1) {
                    parseDimensionRecord(channel, recordLength);
                } else if (recordID == 2) {
                    parseVariableRecord(channel, recordLength);
                } else if (recordID == 3) {
                    parseAttributeRecord(channel, recordLength);
                }
                recordCount++;
            }
            System.out.println("Parsed " + recordCount + " records");
        }
    }

    private static void parseDimensionRecord(FileChannel channel, int recordLength) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(recordLength).order(ByteOrder.BIG_ENDIAN);
        channel.read(buffer);
        buffer.rewind();
        int dimensionCount = buffer.getInt();
        for (int i = 0; i < dimensionCount; i++) {
            int dimensionNameLength = buffer.getInt();
            byte[] dimensionNameBytes = new byte[dimensionNameLength];
            buffer.get(dimensionNameBytes);
            String dimensionName = new String(dimensionNameBytes);
            int dimensionSize = buffer.getInt();
            System.out.println("Dimension: name=" + dimensionName + ", size=" + dimensionSize);
        }
    }

    private static void parseVariableRecord(FileChannel channel, int recordLength) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(recordLength).order(ByteOrder.BIG_ENDIAN);
        channel.read(buffer);
        buffer.rewind();
        int variableNameLength = buffer.getInt();
        byte[] variableNameBytes = new byte[variableNameLength];
        buffer.get(variableNameBytes);
        String variableName = new String(variableNameBytes);
        int variableType = buffer.getInt();
        int dimensionCount = buffer.getInt();
        int[] dimensionIDs = new int[dimensionCount];
        IntBuffer intBuffer = buffer.asIntBuffer();
        intBuffer.get(dimensionIDs);
        buffer.position(buffer.position() + dimensionCount * 4);
        System.out.println("Variable: name=" + variableName + ", type=" + variableType + ", dimensions=" + dimensionIDs);
    }

    private static void parseAttributeRecord(FileChannel channel, int recordLength) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(recordLength).order(ByteOrder.BIG_ENDIAN);
        channel.read(buffer);
        buffer.rewind();
        int attributeNameLength = buffer.getInt();
        byte[] attributeNameBytes = new byte[attributeNameLength];
        buffer.get(attributeNameBytes);
        String attributeName = new String(attributeNameBytes);
        int attributeType = buffer.getInt();
        int attributeLength = buffer.getInt();
        if (attributeType == 2) {
            byte[] attributeValueBytes = new byte[attributeLength];
            buffer.get(attributeValueBytes);
            String attributeValue = new String(attributeValueBytes);
            System.out.println("Attribute: name=" + attributeName + ", type=" + attributeType + ", value=" + attributeValue);
        } else {
            System.out.println("Attribute: name=" + attributeName + ", type=" + attributeType + ", length=" + attributeLength);
        }
    }
}

使用示例：

File ncFile = new File("test.nc");
try {
    NcFileParser.parseNcFile(ncFile);
} catch (IOException e) {
    e.printStackTrace();
}