我正在尝试使用以下代码将字节数组转换为Java中的字符串:
byte[] myArray = {25, -50, -86, 81, 47, 44, 97, -5, 69, -4, 87, -114, -47, 62, -113, -64, 58, -32, -121, -102, 53, -89, -122, 12, -2, -23, -127, 111, -100, 53, -87, -23, -44, -28, 4, -21, -42, 75, 87, -112, -38, 118, 54, 92, -116, 4, -118, 110, -87, 7, -13, 3, -72, -63, -69, 123, 92, 94, 56, 61, 120, -52, 98, -17, 5, 41, 101, -3, 121, 81, -90, 12, -35, -21, -24, 112, -94, 123, 62, 8, 27, 54, 107, -77, 64, 8, -102, -99, -1, 119, 127, 43, 12, -31, -1, 51, -15, 83, -4, -68, -30, 91, -104, 84, 18, -122, -120, 66, 116, -17, -101, -24, 105, -112, -116, -64, -108, 112, -35, 61, 66, 100, 5, -24, -26, -44, 81, -84}; // Bytes from Byte.MIN_VALUE to Byte.MAX_VALUE
String result = new String(myArray, StandardCharsets.UTF_8);
问题是,如果我在Windows(JVM 1.8.0_112)中运行代码,而不是在我的Android设备中运行它(在Android 5.1和6.0中测试),我会得到不同的结果。我正在测试一个长度为128的字节数组,在android中我得到一个长度为120的字符串,而在Windows中我得到一个长度为125的字符串。我猜它与某些字节无效有关-8个字符,但根据平台得到不同的结果仍然很奇怪。
如果我将编码更改为US-ASCII,我会在两个平台上得到与预期相同的结果:
String result = new String(myArray, StandardCharsets.US_ASCII);
编辑:对此感到抱歉。我不是每次都随机生成它。我只是说字节没有有意义的UTF-8值。这是我用来测试的字节数组:
System.out.println(Arrays.toString(myArray)): [25, -50, -86, 81, 47, 44, 97, -5, 69, -4, 87, -114, -47, 62, -113, -64, 58, -32, -121, -102, 53, -89, -122, 12, -2, -23, -127, 111, -100, 53, -87, -23, -44, -28, 4, -21, -42, 75, 87, -112, -38, 118, 54, 92, -116, 4, -118, 110, -87, 7, -13, 3, -72, -63, -69, 123, 92, 94, 56, 61, 120, -52, 98, -17, 5, 41, 101, -3, 121, 81, -90, 12, -35, -21, -24, 112, -94, 123, 62, 8, 27, 54, 107, -77, 64, 8, -102, -99, -1, 119, 127, 43, 12, -31, -1, 51, -15, 83, -4, -68, -30, 91, -104, 84, 18, -122, -120, 66, 116, -17, -101, -24, 105, -112, -116, -64, -108, 112, -35, 61, 66, 100, 5, -24, -26, -44, 81, -84]
编辑2: 窗口结果:
System.out.println(String(myArray, StandardCharsets.UTF_8)).length: 125
System.out.println(String(myArray, StandardCharsets.UTF_8)): ΪQ/,a�E�W��>��:���5����o�5������KW��v6\��n�����{\^8=x�b�)e�yQ����p�{6k����w+��3�S���[�T��Bt��i����p�=Bd���Q�
System.out.println(toUnicode(String(myArray, StandardCharsets.UTF_8))): \u0019\u03aa\u0051\u002f\u002c\u0061\ufffd\u0045\ufffd\u0057\ufffd\ufffd\u003e\ufffd\ufffd\u003a\ufffd\ufffd\ufffd\u0035\ufffd\ufffd\u000c\ufffd\ufffd\u006f\ufffd\u0035\ufffd\ufffd\ufffd\ufffd\u0004\ufffd\ufffd\u004b\u0057\ufffd\ufffd\u0076\u0036\u005c\ufffd\u0004\ufffd\u006e\ufffd\u0007\ufffd\u0003\ufffd\ufffd\ufffd\u007b\u005c\u005e\u0038\u003d\u0078\ufffd\u0062\ufffd\u0005\u0029\u0065\ufffd\u0079\u0051\ufffd\u000c\ufffd\ufffd\ufffd\u0070\ufffd\u007b\u003e\u0008\u001b\u0036\u006b\ufffd\u0040\u0008\ufffd\ufffd\ufffd\u0077\u007f\u002b\u000c\ufffd\ufffd\u0033\ufffd\u0053\ufffd\ufffd\ufffd\u005b\ufffd\u0054\u0012\ufffd\ufffd\u0042\u0074\ufffd\ufffd\u0069\ufffd\ufffd\ufffd\ufffd\u0070\ufffd\u003d\u0042\u0064\u0005\ufffd\ufffd\ufffd\u0051\ufffd
android结果:
System.out.println(String(myArray, StandardCharsets.UTF_8)).length: 120
System.out.println(String(myArray, StandardCharsets.UTF_8)): ΪQ/,a�E�W��>��:ǚ5����o�5������KW��v6\��n���{{\^8=x�b�)e�yQ����p�{>6k�@���w+�
System.out.println(toUnicode(String(myArray, StandardCharsets.UTF_8))): \u0019\u03aa\u0051\u002f\u002c\u0061\ufffd\u0045\ufffd\u0057\ufffd\ufffd\u003e\ufffd\ufffd\u003a\u01da\u0035\ufffd\ufffd\u000c\ufffd\ufffd\u006f\ufffd\u0035\ufffd\ufffd\ufffd\ufffd\u0004\ufffd\ufffd\u004b\u0057\ufffd\ufffd\u0076\u0036\u005c\ufffd\u0004\ufffd\u006e\ufffd\u0007\ufffd\u0003\ufffd\u007b\u007b\u005c\u005e\u0038\u003d\u0078\ufffd\u0062\ufffd\u0005\u0029\u0065\ufffd\u0079\u0051\ufffd\u000c\ufffd\ufffd\ufffd\u0070\ufffd\u007b\u003e\u0008\u001b\u0036\u006b\ufffd\u0040\u0008\ufffd\ufffd\ufffd\u0077\u007f\u002b\u000c\ufffd\ufffd\u0033\ufffd\u0053\ufffd\ufffd\u005b\ufffd\u0054\u0012\ufffd\ufffd\u0042\u0074\ufffd\ufffd\u0069\ufffd\ufffd\u0014\u0070\ufffd\u003d\u0042\u0064\u0005\ufffd\ufffd\ufffd\u0051\ufffd
编辑3:添加了正确的UTF-16字符串
编辑4:将代码更改为工作示例
答案 0 :(得分:4)
看来,Android在解释UTF-8序列时有点草率。标准的相关部分位于chapter 3, “Conformance”中的D92
:
在Unicode标准3.1版之前,有问题的“非最短形式” UTF-8中的字节序列是可以表示BMP字符的字节序列 不止一种方式。这些序列是不正确的,因为它们是 表3-7 不允许。
您的输入具有“非最短形式”序列,例如-32, -121, -102
和-63, -69
。当Android将每个序列解释为单个字符时,Java会正确拒绝这些序列,并将格式错误的输入的每个字节转换为单个替换字符,从而产生更长的字符串。
您可以使用解释“Modified UTF-8”的解析器在Java中演示它:
byte[][] samples = {
{ -32, -121, -102 },
{ -63, -69 }
};
for(byte[] array: samples) {
System.out.println("source: "+Arrays.toString(array));
String string = new String(array, StandardCharsets.UTF_8);
System.out.println("strictly interpreted: "+string);
System.out.println("length: "+string.length());
ByteBuffer bb = ByteBuffer.allocate(array.length+2);
bb.putShort((short)array.length).put(array);
ByteArrayInputStream bis = new ByteArrayInputStream(bb.array());
DataInputStream dis = new DataInputStream(bis);
string = dis.readUTF();
System.out.println("sloppily interpreted: "+string);
System.out.println("length: "+string.length());
byte[] actual = string.getBytes(StandardCharsets.UTF_8);
System.out.println("correct sequence: "+Arrays.toString(actual));
System.out.println();
}
将打印
source: [-32, -121, -102]
strictly interpreted: ���
length: 3
sloppily interpreted: ǚ
length: 1
correct sequence: [-57, -102]
source: [-63, -69]
strictly interpreted: ��
length: 2
sloppily interpreted: {
length: 1
correct sequence: [123]
它还显示了正确的“最短形式”字符序列。
答案 1 :(得分:2)
输出字符串有一些差异。第一个对应于输入字节序列0xE0 0x87 0x9A。正确的解码是异常或替换字符。 (它应该是one, two, or three替换字符吗?我会争辩两个,这就是我机器上的.NET解码器所给出的。但是,在大多数情况下,我更喜欢例外情况。)
你的Andriod JVM正在将其解释为U+01DA。可能"正确"数学上在对无效序列执行不充分检查的算法中。