我正在尝试找到将InputStream传输到OutputStream的最佳方法。 我没有使用任何其他库，如Apache IO，的选项。 以下是代码片段和输出。
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.channels.FileChannel;
public class Pipe {
public static void main(String[] args) throws Exception {
for(PipeTestCase testCase : testCases) {
System.out.println(testCase.getApproach());
InputStream is = new FileInputStream("D:\\in\\lft_.txt");
OutputStream os = new FileOutputStream("D:\\in\\out.txt");
long start = System.currentTimeMillis();
testCase.pipe(is, os);
long end = System.currentTimeMillis();
System.out.println("Execution Time = " + (end - start) + " millis");
System.out.println("============================================");
is.close();
os.close();
}
}
private static PipeTestCase[] testCases = {
new PipeTestCase("Fixed Buffer Read") {
@Override
public void pipe(InputStream is, OutputStream os) throws IOException {
byte[] buffer = new byte[1024];
while(is.read(buffer) > -1) {
os.write(buffer);
}
}
},
new PipeTestCase("dynamic Buffer Read") {
@Override
public void pipe(InputStream is, OutputStream os) throws IOException {
byte[] buffer = new byte[is.available()];
while(is.read(buffer) > -1) {
os.write(buffer);
buffer = new byte[is.available() + 1];
}
}
},
new PipeTestCase("Byte Read") {
@Override
public void pipe(InputStream is, OutputStream os) throws IOException {
int c;
while((c = is.read()) > -1) {
os.write(c);
}
}
},
new PipeTestCase("NIO Read") {
@Override
public void pipe(InputStream is, OutputStream os) throws IOException {
FileChannel source = ((FileInputStream) is).getChannel();
FileChannel destnation = ((FileOutputStream) os).getChannel();
destnation.transferFrom(source, 0, source.size());
}
},
};
}
abstract class PipeTestCase {
private String approach;
public PipeTestCase( final String approach) {
this.approach = approach;
}
public String getApproach() {
return approach;
}
public abstract void pipe(InputStream is, OutputStream os) throws IOException;
}
输出（~4MB输入文件）：
Fixed Buffer Read
Execution Time = 71 millis
============================================
dynamic Buffer Read
Execution Time = 167 millis
============================================
Byte Read
Execution Time = 29124 millis
============================================
NIO Read
Execution Time = 125 millis
============================================
'动态缓冲读取'使用available()方法。但根据Java文档，它不可靠。
从该方法返回值来分配一个旨在容纳此流中所有数据的缓冲区是不正确的。
'字节读取'似乎非常缓慢。
那么在管道中，“固定缓冲区读取”是最佳选项吗？有什么想法？