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Hutool是一个小而全的Java工具类库,通过静态方法封装,降低相关API的学习成本,提高工作效率,使Java拥有函数式语言般的优雅,让Java语言也可以“甜甜的”。
package cn.hutool.core.io.copy;
import cn.hutool.core.io.IORuntimeException;
import cn.hutool.core.io.IoUtil;
import cn.hutool.core.io.StreamProgress;
import cn.hutool.core.lang.Assert;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* {@link InputStream} 向 {@link OutputStream} 拷贝
*
* @author looly
* @since 5.7.8
*/
public class StreamCopier extends IoCopier {
/**
* 构造
*/
public StreamCopier() {
this(IoUtil.DEFAULT_BUFFER_SIZE);
}
/**
* 构造
*
* @param bufferSize 缓存大小
*/
public StreamCopier(int bufferSize) {
this(bufferSize, -1);
}
/**
* 构造
*
* @param bufferSize 缓存大小
* @param count 拷贝总数
*/
public StreamCopier(int bufferSize, long count) {
this(bufferSize, count, null);
}
/**
* 构造
*
* @param bufferSize 缓存大小
* @param count 拷贝总数
* @param progress 进度条
*/
public StreamCopier(int bufferSize, long count, StreamProgress progress) {
super(bufferSize, count, progress);
}
@Override
public long copy(InputStream source, OutputStream target) {
Assert.notNull(source, "InputStream is null !");
Assert.notNull(target, "OutputStream is null !");
final StreamProgress progress = this.progress;
if (null != progress) {
progress.start();
}
final long size;
try {
size = doCopy(source, target, new byte[bufferSize(this.count)], progress);
target.flush();
} catch (IOException e) {
throw new IORuntimeException(e);
}
if (null != progress) {
progress.finish();
}
return size;
}
/**
* 执行拷贝,如果限制最大长度,则按照最大长度读取,否则一直读取直到遇到-1
*
* @param source {@link InputStream}
* @param target {@link OutputStream}
* @param buffer 缓存
* @param progress 进度条
* @return 拷贝总长度
* @throws IOException IO异常
*/
private long doCopy(InputStream source, OutputStream target, byte[] buffer, StreamProgress progress) throws IOException {
long numToRead = this.count > 0 ? this.count : Long.MAX_VALUE;
long total = 0;
int read;
while (numToRead > 0) {
read = source.read(buffer, 0, bufferSize(numToRead));
if (read < 0) {
// 提前读取到末尾
break;
}
target.write(buffer, 0, read);
if(flushEveryBuffer){
target.flush();
}
numToRead -= read;
total += read;
if (null != progress) {
progress.progress(this.count, total);
}
}
return total;
}
}
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