Java同样的汉字在服务器和本地的电脑上URLencode 出来的结果不一致-白红宇

Java同样的汉字在服务器和本地的电脑上URLencode 出来的结果不一致

在CSDN问答中看到这个问题，通常这类问题都是由于字符串的编码导致的。

代码如下：

String oldStr = new String("中文字符");  //我的环境默认UTF-8        System.out.println(URLEncoder.encode(oldStr));        try {            String newStr = new String(oldStr.getBytes(), "gb2312");            System.out.println(URLEncoder.encode(newStr));        } catch (UnsupportedEncodingException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

输出：

%E4%B8%AD%E6%96%87%E5%AD%97%E7%AC%A6

%E6%B6%93%EF%BF%BD%EF%BF%BD%EF%BF%BD%E7%80%9B%EF%BF%BD%E7%BB%97%EF%BF%BD

UTF-8的才是正确的。

URLEncoder.encode(String s) 过时了，使用下面的方法：

String oldStr = new String("中文字符");        try {            System.out.println(URLEncoder.encode(oldStr, "utf-8"));            System.out.println(URLEncoder.encode(oldStr, "gb2312"));        } catch (UnsupportedEncodingException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

输出：

%E4%B8%AD%E6%96%87%E5%AD%97%E7%AC%A6

%D6%D0%CE%C4%D7%D6%B7%FB

查看默认编码：

System.out.println(Charset.defaultCharset()); //查看默认编码

问题又来了，两次输出的 GB2312 编码的不一样！一次那么长，一次却很短！

查看的实现源码吧！

package java.net;import java.io.CharArrayWriter;import java.io.UnsupportedEncodingException;import java.nio.charset.Charset;import java.nio.charset.IllegalCharsetNameException;import java.nio.charset.UnsupportedCharsetException;import java.security.AccessController;import java.util.BitSet;import sun.security.action.GetPropertyAction;public class URLEncoder{  static BitSet dontNeedEncoding;  static final int caseDiff = 32;  static String dfltEncName = null;  @Deprecated  public static String encode(String paramString)  {    String str = null;    try    {      str = encode(paramString, dfltEncName);    }    catch (UnsupportedEncodingException localUnsupportedEncodingException)    {    }    return str;  }  public static String encode(String paramString1, String paramString2)    throws UnsupportedEncodingException  {    int i = 0;    StringBuffer localStringBuffer = new StringBuffer(paramString1.length());    CharArrayWriter localCharArrayWriter = new CharArrayWriter();    if (paramString2 == null)      throw new NullPointerException("charsetName");    Charset localCharset;    try    {      localCharset = Charset.forName(paramString2);    }    catch (IllegalCharsetNameException localIllegalCharsetNameException)    {      throw new UnsupportedEncodingException(paramString2);    }    catch (UnsupportedCharsetException localUnsupportedCharsetException)    {      throw new UnsupportedEncodingException(paramString2);    }    int j = 0;    while (j < paramString1.length())    {      int k = paramString1.charAt(j);      if (dontNeedEncoding.get(k))      {        if (k == 32)        {          k = 43;          i = 1;        }        localStringBuffer.append((char)k);        ++j;      }      else      {        do        {          localCharArrayWriter.write(k);          if ((k < 55296) || (k > 56319) || (j + 1 >= paramString1.length()))            continue;          int l = paramString1.charAt(j + 1);          if ((l < 56320) || (l > 57343))            continue;          localCharArrayWriter.write(l);          ++j;        }        while ((++j < paramString1.length()) && (!dontNeedEncoding.get(k = paramString1.charAt(j))));        localCharArrayWriter.flush();        String str = new String(localCharArrayWriter.toCharArray());        byte[] arrayOfByte = str.getBytes(localCharset);        for (int i1 = 0; i1 < arrayOfByte.length; ++i1)        {          localStringBuffer.append('%');          char c = Character.forDigit(arrayOfByte[i1] >> 4 & 0xF, 16);          if (Character.isLetter(c))            c = (char)(c - ' ');          localStringBuffer.append(c);          c = Character.forDigit(arrayOfByte[i1] & 0xF, 16);          if (Character.isLetter(c))            c = (char)(c - ' ');          localStringBuffer.append(c);        }        localCharArrayWriter.reset();        i = 1;      }    }    return (i != 0) ? localStringBuffer.toString() : paramString1;  }  static  {    dontNeedEncoding = new BitSet(256);    for (int i = 97; i <= 122; ++i)      dontNeedEncoding.set(i);    for (i = 65; i <= 90; ++i)      dontNeedEncoding.set(i);    for (i = 48; i <= 57; ++i)      dontNeedEncoding.set(i);    dontNeedEncoding.set(32);    dontNeedEncoding.set(45);    dontNeedEncoding.set(95);    dontNeedEncoding.set(46);    dontNeedEncoding.set(42);    dfltEncName = (String)AccessController.doPrivileged(new GetPropertyAction("file.encoding"));  }}

通过查看源码我们可以明白，传入的第二个参数是输出的编码，而不是指将传入的第一个参数转换为什么类型的编码；

默认它应该是读取的容器（如：Tomcat）的默认编码；

我们可以通过执行以下代码查看：

dfltEncName = (String)AccessController.doPrivileged(new GetPropertyAction("file.encoding"));	    	    System.out.println(dfltEncName);

需要在项目中添加一个类：GetPropertyAction.java

package sun.security.action;import java.security.PrivilegedAction;public class GetPropertyAction  implements PrivilegedAction
    
     {  private String theProp;  private String defaultVal;  public GetPropertyAction(String paramString)  {    this.theProp = paramString;  }  public GetPropertyAction(String paramString1, String paramString2)  {    this.theProp = paramString1;    this.defaultVal = paramString2;  }  public String run()  {    String str = System.getProperty(this.theProp);    return (str == null) ? this.defaultVal : str;  }}

所以正确的姿势是先判断你的默认编码是不是“UTF-8”,使用：Charset.defaultCharset()；

如果不是，就将其转换为“UTF-8”，使用：String newStr = new String(oldStr.getBytes(), "utf-8");

然后再编码：URLEncoder.encode(newStr, "utf-8");

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