public static String gbToUnicode(final String gbString) {       
    char[] utfBytes = gbString.toCharArray();             
    String unicodeBytes = "";              
    for (int byteIndex = 0; byteIndex < utfBytes.length; byteIndex++) {
        String hexB = Integer.toHexString(utfBytes[byteIndex]);                     
        if
 
 (hexB.length() <= 2) {                         
            hexB = "00" + hexB;                   
            }                     
        unicodeBytes = unicodeBytes + "\\u" + hexB;                 
        }                                  
    return unicodeBytes;            
}                   
public
 
 static String unicodeToGB(final String dataStr) {              
    int start = 0;                
    int end = 0;              
    final StringBuffer buffer = new StringBuffer();                
    while (start > -1) {                   
        end = dataStr.indexOf("\\u", start + 2);                    
        String charStr = ""
 
;                    
        if (end == -1) {                        
            charStr = dataStr.substring(start + 2, dataStr.length());                   
            } else {                      
                charStr = dataStr.substring(start + 2, end);                    
                }                   
        char letter = (char) Integer.parseInt(charStr, 16); 
        buffer.append(new Character(letter).toString());                  
        start = end;                
        }                
    return buffer.toString();           
    } 

PS：

String str = "\u4e2d\u56fd";
System.out.println(str);
這樣就可以直接輸出了
列印結果： 中國