JAVA如何判断字符串编码

public static String getEncoding(String str) {

String encode = "GB2312";

try {

if (str.equals(new String(str.getBytes(encode), encode))) {

String s = encode;

return s;

}

} catch (Exception exception) {

}

encode = "ISO-8859-1";

try {

if (str.equals(new String(str.getBytes(encode), encode))) {

String s1 = encode;

return s1;

}

} catch (Exception exception1) {

}

encode = "UTF-8";

try {

if (str.equals(new String(str.getBytes(encode), encode))) {

String s2 = encode;

return s2;

}

} catch (Exception exception2) {

}

encode = "GBK";

try {

if (str.equals(new String(str.getBytes(encode), encode))) {

String s3 = encode;

return s3;

}

} catch (Exception exception3) {

}

return "";

}