在Java中使用zlib壓縮數據可以通過Java標準庫中的Deflater和Inflater類來實現。以下是一個示例代碼：

import java.util.zip.Deflater;
import java.util.zip.Inflater;

public class ZlibCompression {
    
    public static byte[] compressData(byte[] data) {
        Deflater deflater = new Deflater();
        deflater.setInput(data);
        deflater.finish();

        byte[] buffer = new byte[1024];
        int compressedDataLength = deflater.deflate(buffer);

        byte[] compressedData = new byte[compressedDataLength];
        System.arraycopy(buffer, 0, compressedData, 0, compressedDataLength);

        deflater.end();

        return compressedData;
    }

    public static byte[] decompressData(byte[] compressedData) {
        Inflater inflater = new Inflater();
        inflater.setInput(compressedData);

        byte[] buffer = new byte[1024];
        int decompressedDataLength = inflater.inflate(buffer);

        byte[] decompressedData = new byte[decompressedDataLength];
        System.arraycopy(buffer, 0, decompressedData, 0, decompressedDataLength);

        inflater.end();

        return decompressedData;
    }

    public static void main(String[] args) {
        String input = "Hello, world!";
        byte[] inputData = input.getBytes();

        byte[] compressedData = compressData(inputData);
        byte[] decompressedData = decompressData(compressedData);

        String output = new String(decompressedData);
        System.out.println(output);
    }
}

在上面的示例中，我們定義了compressData和decompressData方法來分別壓縮和解壓數據。在main方法中，我們先將字符串"Hello, world!"轉換為字節數組，然后進行壓縮和解壓操作，最后打印解壓后的字符串。