CharBuffer与char []

Question

有没有理由在下面选择a CharBuffer到a char[]:

CharBuffer buf = CharBuffer.allocate(DEFAULT_BUFFER_SIZE);
while( in.read(buf) >= 0 ) {
  out.append( buf.flip() );
  buf.clear();
}

与

char[] buf = new char[DEFAULT_BUFFER_SIZE];
int n;
while( (n = in.read(buf)) >= 0 ) {
  out.write( buf, 0, n );
}

(ina Reader和outa 在哪里Writer)？

Answer 1

不,CharBuffer在这种情况下,没有理由更喜欢.

但是,一般而言,CharBuffer(和ByteBuffer)可以真正简化API并鼓励正确处理.如果您正在设计公共API,那么绝对值得考虑面向缓冲区的API.

Answer 2

我想对这种比较进行微型基准测试.

以下是我写的课程.

事情是我无法相信CharBuffer表现如此糟糕.我有什么问题？

编辑:由于下面的第11条评论我已经编辑了代码和输出时间,所以在各方面都有更好的表现,但在时间上仍然存在显着差异.我还尝试了注释中提到的out2.append((CharBuffer)buff.flip())选项,但它比下面代码中使用的write选项慢得多.

结果:(以ms为单位)
char []:3411
CharBuffer:5653

public class CharBufferScratchBox
{
    public static void main(String[] args) throws Exception
    {
        // Some Setup Stuff
        String smallString =
                "1111111111222222222233333333334444444444555555555566666666667777777777888888888899999999990000000000";

        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < 1000; i++)
        {
            stringBuilder.append(smallString);
        }
        String string = stringBuilder.toString();
        int DEFAULT_BUFFER_SIZE = 1000;
        int ITTERATIONS = 10000;

        // char[]
        StringReader in1 = null;
        StringWriter out1 = null;
        Date start = new Date();
        for (int i = 0; i < ITTERATIONS; i++)
        {
            in1 = new StringReader(string);
            out1 = new StringWriter(string.length());

            char[] buf = new char[DEFAULT_BUFFER_SIZE];
            int n;
            while ((n = in1.read(buf)) >= 0)
            {
                out1.write(
                        buf,
                        0,
                        n);
            }
        }
        Date done = new Date();
        System.out.println("char[]    : " + (done.getTime() - start.getTime()));

        // CharBuffer
        StringReader in2 = null;
        StringWriter out2 = null;
        start = new Date();
        CharBuffer buff = CharBuffer.allocate(DEFAULT_BUFFER_SIZE);
        for (int i = 0; i < ITTERATIONS; i++)
        {
            in2 = new StringReader(string);
            out2 = new StringWriter(string.length());
            int n;
            while ((n = in2.read(buff)) >= 0)
            {
                out2.write(
                        buff.array(),
                        0,
                        n);
                buff.clear();
            }
        }
        done = new Date();
        System.out.println("CharBuffer: " + (done.getTime() - start.getTime()));
    }
}