封装具体的算法。复制代码

//算法接口   public interface CompressionStrategy {    public OutputStream compress(OutputStream data) throws IOException;} 复制代码

//算法的具体实现public class GzipCompressionStrategy implements CompressionStrategy {    @Override    public OutputStream compress(OutputStream data) throws IOException{        return new GZIPOutputStream(data);    }}复制代码

//策略对象    public class Compressor {    private final CompressionStrategy strategy;    public Compressor(CompressionStrategy strategy){        this.strategy=strategy;    }    public void compress(Path infile,File outfile) throws IOException {        try (OutputStream out = new FileOutputStream(outfile)) {            Files.copy(infile,strategy.compress(out));        }    }  }复制代码

//使用   // old way       Compressor gzip=new Compressor(new GzipCompressionStrategy());       gzip.compress(infile,outfile);       //lambda way       Compressor zip=new Compressor(ZipOutputStream::new);       zip.compress(infile,outfile);复制代码