Java byte []到/从String转换 [英] Java byte[] to/from String conversion

问题描述

为什么这次junit测试失败？

Why does this junit test fail?

import org.junit.Assert;
import org.junit.Test;

import java.io.UnsupportedEncodingException;

public class TestBytes {
    @Test
    public void testBytes() throws UnsupportedEncodingException {
        byte[] bytes = new byte[]{0, -121, -80, 116, -62};
        String string = new String(bytes, "UTF-8");
        byte[] bytes2 = string.getBytes("UTF-8");
        System.out.print("bytes2: [");
        for (byte b : bytes2) System.out.print(b + ", ");
        System.out.print("]\n");
        Assert.assertArrayEquals(bytes, bytes2);
    }
}

我会假设传入的字节数组等于结果但不知何故，可能由于UTF-8字符占用两个字节这一事实，结果数组在内容和长度上都与传入数组不同。

I would assume that the incoming byte array equaled the outcome, but somehow, probably due to the fact that UTF-8 characters take two bytes, the outcome array differs from the incoming array in both content and length.

请赐教。

推荐答案

原因是 0，-121，-80,116，-62 不是有效的UTF-8字节序列。 new String（bytes，UTF-8）在这种情况下不会抛出任何异常，但结果很难预测。阅读 http://en.wikipedia.org/wiki/UTF-8 无效的字节序列部分。

The reason is 0, -121, -80, 116, -62 is not a valid UTF-8 byte sequence. new String(bytes, "UTF-8") does not throw any exception in such situations but the result is difficult to predict. Read http://en.wikipedia.org/wiki/UTF-8 Invalid byte sequences section.

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