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

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：

[java] view
pl

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！

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"));
}

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

[java] view
plain copy

package sun.security.action;  

  

import java.security.PrivilegedAction;  

  

public class GetPropertyAction  

  implements PrivilegedAction<String>  

{  

  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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