如何在 Java 中将字符串与 UTF8 字节数组相互转换
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How to convert Strings to and from UTF8 byte arrays in Java
提问by mcherm
In Java, I have a String and I want to encode it as a byte array (in UTF8, or some other encoding). Alternately, I have a byte array (in some known encoding) and I want to convert it into a Java String. How do I do these conversions?
在 Java 中，我有一个 String，我想将它编码为一个字节数组（UTF8 或其他一些编码）。或者，我有一个字节数组（采用某种已知编码），我想将其转换为 Java 字符串。我如何进行这些转换？
采纳答案by mcherm
Convert from String to byte[]:
从字符串转换为字节[]：
String s = "some text here";
byte[] b = s.getBytes(StandardCharsets.UTF_8);
Convert from byte[] to String:
从字节 [] 转换为字符串：
byte[] b = {(byte) 99, (byte)97, (byte)116};
String s = new String(b, StandardCharsets.US_ASCII);
You should, of course, use the correct encoding name. My examples used US-ASCII and UTF-8, the two most common encodings.
当然，您应该使用正确的编码名称。我的示例使用了 US-ASCII 和 UTF-8，这两种最常见的编码。
回答by Jorge Ferreira
String original = "hello world";
byte[] utf8Bytes = original.getBytes("UTF-8");
回答by McDowell
You can convert directly via the String(byte[], String)constructor and getBytes(String) method. Java exposes available character sets via the Charsetclass. The JDK documentation lists supported encodings.
您可以直接通过String(byte[], String)构造函数和 getBytes(String) 方法进行转换。Java 通过Charset类公开可用的字符集。JDK 文档列出了支持的编码。
90% of the time, such conversions are performed on streams, so you'd use the Reader/Writerclasses. You would not incrementally decode using the String methods on arbitrary byte streams - you would leave yourself open to bugs involving multibyte characters.
90% 的情况下，此类转换是在流上执行的，因此您将使用Reader/ Writer类。您不会在任意字节流上使用 String 方法进行增量解码 - 您可能会遇到涉及多字节字符的错误。
回答by savio
terribly late but i just encountered this issue and this is my fix:
太晚了，但我刚刚遇到了这个问题，这是我的解决方法：
private static String removeNonUtf8CompliantCharacters( final String inString ) {
if (null == inString ) return null;
byte[] byteArr = inString.getBytes();
for ( int i=0; i < byteArr.length; i++ ) {
byte ch= byteArr[i];
// remove any characters outside the valid UTF-8 range as well as all control characters
// except tabs and new lines
if ( !( (ch > 31 && ch < 253 ) || ch == '\t' || ch == '\n' || ch == '\r') ) {
byteArr[i]=' ';
}
}
return new String( byteArr );
}
回答by M. Leonhard
Here's a solution that avoids performing the Charset lookup for every conversion:
这是一个避免为每次转换执行 Charset 查找的解决方案：
import java.nio.charset.Charset;
private final Charset UTF8_CHARSET = Charset.forName("UTF-8");
String decodeUTF8(byte[] bytes) {
return new String(bytes, UTF8_CHARSET);
}
byte[] encodeUTF8(String string) {
return string.getBytes(UTF8_CHARSET);
}
回答by Pacerier
If you are using 7-bit ASCII or ISO-8859-1 (an amazingly common format) then you don't have to create a new java.lang.Stringat all. It's much much more performant to simply cast the byte into char:
如果您使用的是 7 位 ASCII 或 ISO-8859-1（一种非常常见的格式），那么您根本不必创建新的java.lang.String。简单地将字节转换为字符的性能要高得多：
Full working example:
完整的工作示例：
for (byte b : new byte[] { 43, 45, (byte) 215, (byte) 247 }) {
char c = (char) b;
System.out.print(c);
}
If you are notusing extended-characterslike ?, ?, ?, ?, ?, ê andcan be sure that the only transmitted values are of the first 128 Unicode characters, then this code will also work for UTF-8 and extended ASCII (like cp-1252).
如果您不使用扩展字符，如 ?, ?, ?, ?, ?, ê并且可以确定唯一传输的值是前 128 个 Unicode 字符，那么此代码也适用于 UTF-8 和扩展 ASCII （如cp-1252）。
回答by Ran Adler
//query is your json
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost postRequest = new HttpPost("http://my.site/test/v1/product/search?qy=");
StringEntity input = new StringEntity(query, "UTF-8");
input.setContentType("application/json");
postRequest.setEntity(input);
HttpResponse response=response = httpClient.execute(postRequest);
回答by paiego
My tomcat7 implementation is accepting strings as ISO-8859-1; despite the content-type of the HTTP request. The following solution worked for me when trying to correctly interpret characters like 'é' .
我的 tomcat7 实现接受字符串为 ISO-8859-1；尽管 HTTP 请求的内容类型。在尝试正确解释像 'é' 这样的字符时，以下解决方案对我有用。
byte[] b1 = szP1.getBytes("ISO-8859-1");
System.out.println(b1.toString());
String szUT8 = new String(b1, "UTF-8");
System.out.println(szUT8);
When trying to interpret the string as US-ASCII, the byte info wasn't correctly interpreted.
尝试将字符串解释为 US-ASCII 时，字节信息未正确解释。
b1 = szP1.getBytes("US-ASCII");
System.out.println(b1.toString());
回答by vtor
As an alternative, StringUtilsfrom Apache Commons can be used.
作为替代方案，可以使用来自 Apache Commons 的StringUtils。
byte[] bytes = {(byte) 1};
String convertedString = StringUtils.newStringUtf8(bytes);
or
或者
String myString = "example";
byte[] convertedBytes = StringUtils.getBytesUtf8(myString);
If you have non-standard charset, you can use getBytesUnchecked()or newString()accordingly.
如果您有非标准字符集，则可以相应地使用getBytesUnchecked()或newString()。
回答by Макс Даниленко
Reader reader = new BufferedReader(
new InputStreamReader(
new ByteArrayInputStream(
string.getBytes(StandardCharsets.UTF_8)), StandardCharsets.UTF_8));
