add method

hutool-core/src/main/java/cn/hutool/core/io/copy/IoCopier.java

@@ -25,6 +25,11 @@ public abstract class IoCopier<S, T> {
 	 */
 	protected StreamProgress progress;
 
+	/**
+	 * 是否每次写出一个buffer内容就执行flush
+	 */
+	protected boolean flushEveryBuffer;
+
 	/**
 	 * 构造
 	 *
@@ -56,4 +61,16 @@ public abstract class IoCopier<S, T> {
 	protected int bufferSize(long count) {
 		return (int) Math.min(this.bufferSize, count);
 	}
+
+	/**
+	 * 设置是否每次写出一个buffer内容就执行flush
+	 *
+	 * @param flushEveryBuffer 是否每次写出一个buffer内容就执行flush
+	 * @return this
+	 * @since 5.7.18
+	 */
+	public IoCopier<S, T> setFlushEveryBuffer(boolean flushEveryBuffer){
+		this.flushEveryBuffer = flushEveryBuffer;
+		return this;
+	}
 }

hutool-core/src/main/java/cn/hutool/core/io/copy/ReaderWriterCopier.java

@@ -101,6 +101,9 @@ public class ReaderWriterCopier extends IoCopier<Reader, Writer> {
 				break;
 			}
 			target.write(buffer, 0, read);
+			if(flushEveryBuffer){
+				target.flush();
+			}
 
 			numToRead -= read;
 			total += read;

hutool-core/src/main/java/cn/hutool/core/io/copy/StreamCopier.java

@@ -100,6 +100,9 @@ public class StreamCopier extends IoCopier<InputStream, OutputStream> {
 				break;
 			}
 			target.write(buffer, 0, read);
+			if(flushEveryBuffer){
+				target.flush();
+			}
 
 			numToRead -= read;
 			total += read;