blocks|key|712838|text|使用getBytes方法，为其提供适当的Charset+(或Charset名称)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|712839|示例：|712840|String+s+=+"Hello,+there.";
byte[]+b+=+s.getBytes(StandardCharsets.US_ASCII);|code-block|syntax|javascript|712841|(在Java7之前：byte[]+b+=+s.getBytes("US-ASCII");)|712842|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/6/docs/api/java/lang/String.html#getBytes(java.lang.String)|1|http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html^0|2|8|K|7|U|7|2|8|0|K|7|1|0|0|0|A|Y|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]|$9|18|A|19|1|1A]]|E|$]]|$1|F|3|G|5|6|7|1B|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1C|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1D|8|@$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]]]

Using the <a href="http://download.oracle.com/javase/6/docs/api/java/lang/String.html#getBytes(java.lang.String)" rel="noreferrer"><code>getBytes</code></a> method, giving it the appropriate <a href="http://download.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html" rel="noreferrer"><code>Charset</code></a> (or <code>Charset</code> name).

Example:

<pre><code>String s = "Hello, there.";
byte[] b = s.getBytes(StandardCharsets.US_ASCII);
</code></pre>

(Before Java 7: <code>byte[] b = s.getBytes("US-ASCII");</code>)

blocks|key|713138|text|如果您是guava用户，有一个方便的Charsets类：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|713139|String+s+=+"Hello,+world!";
byte[]+b+=+s.getBytes(Charsets.US_ASCII);|code-block|syntax|javascript|713140|除了不在源代码中硬编码任意字符集名称之外，它还有一个更大的优势：Charsets.US_ASCII是Charset类型(而不是String)，因此您可以避免仅从String.getBytes(String)抛出检查的UnsupportedEncodingException，而不是从String.getBytes(Charset)抛出。|713141|在Java7中，有等效的StandardCharsets类。|713142|entityMap|0|LINK|mutability|MUTABLE|url|/questions/tagged/guava|1|https://google.github.io/guava/releases/19.0/api/docs/com/google/common/base/Charsets.html|2|http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/base/Charsets.html#US_ASCII|3|http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes(java.lang.String))|4|http://docs.oracle.com/javase/7/docs/api/java/io/UnsupportedEncodingException.html|5|http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes(java.nio.charset.Charset))|6|http://docs.oracle.com/javase/7/docs/api/java/nio/charset/StandardCharsets.html^0|I|8|4|5|0|I|8|1|0|0|W|H|1E|7|1R|6|28|N|30|S|3X|O|W|H|2|28|N|3|30|S|4|3X|O|5|0|C|G|C|G|6|0^^$0|@$1|2|3|4|5|6|7|18|8|@$9|19|A|1A|B|C]]|D|@$9|1B|A|1C|1|1D]|$9|1E|A|1F|1|1G]]|E|$]]|$1|F|3|G|5|H|7|1H|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1I|8|@$9|1J|A|1K|B|C]|$9|1L|A|1M|B|C]|$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]|$9|1R|A|1S|B|C]|$9|1T|A|1U|B|C]]|D|@$9|1V|A|1W|1|1X]|$9|1Y|A|1Z|1|20]|$9|21|A|22|1|23]|$9|24|A|25|1|26]]|E|$]]|$1|M|3|N|5|6|7|27|8|@$9|28|A|29|B|C]]|D|@$9|2A|A|2B|1|2C]]|E|$]]|$1|O|3|-4|5|6|7|2D|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]|Y|$5|R|S|T|E|$U|Z]]|10|$5|R|S|T|E|$U|11]]|12|$5|R|S|T|E|$U|13]]|14|$5|R|S|T|E|$U|15]]|16|$5|R|S|T|E|$U|17]]]]

If you are a <a href="/questions/tagged/guava" class="post-tag" title="show questions tagged &#39;guava&#39;" rel="tag">guava</a> user there is a handy <a href="https://google.github.io/guava/releases/19.0/api/docs/com/google/common/base/Charsets.html" rel="nofollow noreferrer"><code>Charsets</code></a> class:

<pre><code>String s = "Hello, world!";
byte[] b = s.getBytes(Charsets.US_ASCII);
</code></pre>

Apart from not hard-coding arbitrary charset name in your source code it has a much bigger advantage: <a href="http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/base/Charsets.html#US_ASCII" rel="nofollow noreferrer"><code>Charsets.US_ASCII</code></a> is of <code>Charset</code> type (not <code>String</code>) so you avoid checked <a href="http://docs.oracle.com/javase/7/docs/api/java/io/UnsupportedEncodingException.html" rel="nofollow noreferrer"><code>UnsupportedEncodingException</code></a> thrown only from <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes(java.lang.String)" rel="nofollow noreferrer"><code>String.getBytes(String)</code></a>, but not from <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes(java.nio.charset.Charset)" rel="nofollow noreferrer"><code>String.getBytes(Charset)</code></a>.

In Java 7 there is equivalent <a href="http://docs.oracle.com/javase/7/docs/api/java/nio/charset/StandardCharsets.html" rel="nofollow noreferrer"><code>StandardCharsets</code></a> class.

blocks|key|929000|text|您尝试的代码中只有一个字符是错误的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|929001|Charset+characterSet+=+Charset.forName("US-ASCII");
String+string+=+"Wazzup";
byte[]+bytes+=+String.getBytes(characterSet);
+++++++++++++++%5E|code-block|syntax|javascript|929002|请注意大写的"String“。这将尝试在string类上调用一个不存在的静态方法。相反，您需要调用string实例上的方法：|929003|byte[]+bytes+=+string.getBytes(characterSet);|929004|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

There is only one character wrong in the code you tried:

<pre><code>Charset characterSet = Charset.forName("US-ASCII");
String string = "Wazzup";
byte[] bytes = String.getBytes(characterSet);
 ^
</code></pre>

Notice the upper case "String". This tries to invoke a static method on the string class, which does not exist. Instead you need to invoke the method on your string instance:

<pre><code>byte[] bytes = string.getBytes(characterSet);
</code></pre>

blocks|key|929073|text|其他建议的解决方案的问题是，它们要么删除不能直接映射到ASCII的字符，要么用像?这样的标记字符替换它们。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|929074|例如，您可能希望将带重音的字符转换为不带重音的相同字符。有几个技巧可以做到这一点(包括自己构建静态映射表或利用为unicode定义的现有“规范化”)，但这些方法远未完成。|929075|您最好的选择是使用junidecode库，该库也不完整，但以最合理的方式将Unicode音译为ASCII码，包含了许多经验。|929076|entityMap|0|LINK|mutability|MUTABLE|url|http://www.ippatsuman.com/projects/junidecode/index.html^0|14|1|0|0|9|A|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@]|D|@$9|W|A|X|1|Y]]|E|$]]|$1|J|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

The problem with other proposed solutions is that they will either drop characters that cannot be directly mapped to ASCII, or replace them with a marker character like <code>?</code>. 

You might desire to have for example accented characters converted to that same character without the accent. There are a couple of tricks to do this (including building a static mapping table yourself or leveraging existing 'normalization' defined for unicode), but those methods are far from complete.

Your best bet is using the <a href="http://www.ippatsuman.com/projects/junidecode/index.html" rel="noreferrer">junidecode</a> library, which cannot be complete either but incorporates a lot of experience in the most sane way of transliterating Unicode to ASCII.

blocks|key|928950|text|String+s+=+"ASCII+Text";
byte[]+bytes+=+s.getBytes("US-ASCII");|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|928951|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>String s = "ASCII Text";
byte[] bytes = s.getBytes("US-ASCII");
</code></pre>

blocks|key|713081|text|如果你碰巧在安卓中需要这个，并且想让它在任何比FroYo更老的系统上工作，你也可以使用EncodingUtils.getAsciiBytes()|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|713082|byte[]+bytes+=+EncodingUtils.getAsciiBytes("ASCII+Text");|code-block|syntax|javascript|713083|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/reference/org/apache/http/util/EncodingUtils.html#getAsciiBytes%2528java.lang.String%2529^0|17|T|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

If you happen to need this in Android and want to make it work with anything older than FroYo, you can also use <a href="http://developer.android.com/reference/org/apache/http/util/EncodingUtils.html#getAsciiBytes%28java.lang.String%29" rel="nofollow">EncodingUtils.getAsciiBytes()</a>:

<pre><code>byte[] bytes = EncodingUtils.getAsciiBytes("ASCII Text");
</code></pre>

blocks|key|713207|text|在我的字符串中，有泰语字符(TIS620编码)和德语元音。来自agiles的答案让我走上了正确的道路。我现在使用的不是.getBytes()|type|unstyled|depth|inlineStyleRanges|entityRanges|data|713208|++int+len+=+mString.length();+//+Length+of+the+string
++byte[]+dataset+=+new+byte[len];
++for+(int+i+=+0;+i+<+len;+%2B%2Bi)+{
+++++char+c+=+mString.charAt(i);
+++++dataset[i]=+(byte)+c;
++}|code-block|syntax|javascript|713209|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In my string I have Thai characters (TIS620 encoded) and German umlauts. The answer from agiles put me on the right path. Instead of .getBytes() I use now

<pre><code> int len = mString.length(); // Length of the string
 byte[] dataset = new byte[len];
 for (int i = 0; i &lt; len; ++i) {
 char c = mString.charAt(i);
 dataset[i]= (byte) c;
 }
</code></pre>

blocks|key|929028|text|将字符串转换为ascii值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|929029|+++String+test+=+"ABCD";

+++for+(+int+i+=+0;+i+<+test.length();+%2B%2Bi+)+{
+++char+c+=+test.charAt(+i+);
+++int+j+=+(int)+c;
+++System.out.println(j);
+++}|code-block|syntax|javascript|929030|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Convert string to ascii values.

<pre><code> String test = "ABCD";

 for ( int i = 0; i &lt; test.length(); ++i ) {
 char c = test.charAt( i );
 int j = (int) c;
 System.out.println(j);
 }
</code></pre>

blocks|key|713252|text|我找到了解决方案。实际上，Base64类在安卓中是不可用的。有关更多信息，请参见下面的链接。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|713253|byte[]+byteArray;++++++++++++++++++++++++++++++++++++++++++++++++++
+++++byteArray=+json.getBytes(StandardCharsets.US_ASCII);
++++String+encoded=Base64.encodeBytes(byteArray);
++++userLogin(encoded);|code-block|syntax|javascript|713254|这是Base64类的链接：http://androidcodemonkey.blogspot.com/2010/03/how-to-base64-encode-decode-android.html|offset|length|713255|entityMap|0|LINK|mutability|MUTABLE|url|http://androidcodemonkey.blogspot.com/2010/03/how-to-base64-encode-decode-android.html^0|0|0|D|2E|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

I found the solution. Actually Base64 class is not available in Android. Link is given below for more information.

<pre><code>byte[] byteArray; 
 byteArray= json.getBytes(StandardCharsets.US_ASCII);
 String encoded=Base64.encodeBytes(byteArray);
 userLogin(encoded);
</code></pre>

Here is the link for Base64 class: <a href="http://androidcodemonkey.blogspot.com/2010/03/how-to-base64-encode-decode-android.html" rel="nofollow noreferrer">http://androidcodemonkey.blogspot.com/2010/03/how-to-base64-encode-decode-android.html</a>

blocks|key|713273|text|要将字符串转换为ASCII字节数组：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|713274|String+s1+=+"Hello+World!";
byte[]+byteArray+=+s1.getBytes(StandardCharsets.US_ASCII);
//+Now+byteArray+is+[72,+101,+108,+108,+111,+32,+87,+111,+114,+108,+100,+33]|code-block|syntax|javascript|713275|要将ASCII字节数组转换为字符串，请执行以下操作：|713276|String+s2+=+new+String(byteArray,+StandardCharsets.US_ASCII));|713277|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

To convert String to ASCII byte array:
<pre><code>String s1 = &quot;Hello World!&quot;;
byte[] byteArray = s1.getBytes(StandardCharsets.US_ASCII);
// Now byteArray is [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100, 33]
</code></pre>
To convert ASCII byte array to String:
<pre><code>String s2 = new String(byteArray, StandardCharsets.US_ASCII));
</code></pre>

blocks|key|713168|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|713169|/**
+*+@(#)demo1.java
+*
+*
+*+@author+
+*+@version+1.00+2012/8/30
+*/

import+java.util.*;

public+class+demo1+
{
++++Scanner+s=new+Scanner(System.in);

++++String+str;
++++int+key;

++++void+getdata()
++++{
++++++++System.out.println+("plase+enter+a+string");
++++++++str=s.next();
++++++++System.out.println+("plase+enter+a+key");
++++++++key=s.nextInt();
++++}

++++void+display()
++++{
++++++++char+a;
++++++++int+j;
++++++++for+(+int+i+=+0;+i+<+str.length();+%2B%2Bi+)
++++++++{

++++++++++++char+c+=+str.charAt(+i+);
++++++++++++j+=+(int)+c+%2B+key;
++++++++++++a=+(char)+j;

++++++++++++System.out.print(a);++
++++++++}

++++++++public+static+void+main(String[]+args)
++++++++{
++++++++++++demo1+obj=new+demo1();
++++++++++++obj.getdata();
++++++++++++obj.display();
++++++++}
++++}
}|code-block|syntax|javascript|713170|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this:

<pre><code>/**
 * @(#)demo1.java
 *
 *
 * @author 
 * @version 1.00 2012/8/30
 */

import java.util.*;

public class demo1 
{
 Scanner s=new Scanner(System.in);

 String str;
 int key;

 void getdata()
 {
 System.out.println ("plase enter a string");
 str=s.next();
 System.out.println ("plase enter a key");
 key=s.nextInt();
 }

 void display()
 {
 char a;
 int j;
 for ( int i = 0; i &lt; str.length(); ++i )
 {

 char c = str.charAt( i );
 j = (int) c + key;
 a= (char) j;

 System.out.print(a); 
 }

 public static void main(String[] args)
 {
 demo1 obj=new demo1();
 obj.getdata();
 obj.display();
 }
 }
}
</code></pre>

How to convert a Java String to an ASCII byte array?

How to convert a Java String to an ASCII byte array?

Java

如何将Java字符串转换为ASCII字节数组？

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