怎么从SHA256withRSA nonce=de193801-ff43-44a0-91ec-a2fc5723dc58,timestamp=1686017309416,sign=UI9leRDCWwxVOrSBWTMpdnif7eUZACVZRdMGdfb5jjZyZCMaGuxjqNFYnbuptJKycR9+QxanN2FmX4iUkwODuB3Z3MPcOZAoEfpEqAsElpwrk5W9OzLdVXCriaZd+ax8fzkBqv8IMdGJnjEShKIzaN5LEwGPV69Jm8DK1PXpkzy+iLtQYmabt+JNJzQgBFO0PsXeHeGoIYHmMJYBOCmXpmDT5AiykFifQjrw4lLCBRJCjmmYvFnWvU6oKXLzanz8VomuyY/Vjx1JXV9FrXbM//Wpw3MWbtU7sCRirbHIn33WTUiPrFBS1tUdAo+55CP8Rs74mMhyfDSaCqnCK4/StQ==这串数据中获取nonce这个字段的值

你可以使用字符串处理函数来获取nonce的值。首先，根据逗号分隔这个字符串，然后再根据等号分隔每个字段，最后找到nonce字段的值即可。具体代码实现可以参考以下示例：

String data = "SHA256withRSA nonce=de193801-ff43-44a0-91ec-a2fc5723dc58,timestamp=1686017309416,sign=UI9leRDCWwxVOrSBWTMpdnif7eUZACVZRdMGdfb5jjZyZCMaGuxjqNFYnbuptJKycR9+QxanN2FmX4iUkwODuB3Z3MPcOZAoEfpEqAsElpwrk5W9OzLdVXCriaZd+ax8fzkBqv8IMdGJnjEShKIzaN5LEwGPV69Jm8DK1PXpkzy+iLtQYmabt+JNJzQgBFO0PsXeHeGoIYHmMJYBOCmXpmDT5AiykFifQjrw4lLCBRJCjmmYvFnWvU6oKXLzanz8VomuyY/Vjx1JXV9FrXbM//Wpw3MWbtU7sCRirbHIn33WTUiPrFBS1tUdAo+55CP8Rs74mMhyfDSaCqnCK4/StQ==";
String[] fields = data.split(",");
String nonce = null;
for (String field : fields) {
    String[] pair = field.split("=");
    if (pair[0].trim().equals("nonce")) {
        nonce = pair[1].trim();
        break;
    }
}
System.out.println("nonce: " + nonce); // 输出 nonce: de193801-ff43-44a0-91ec-a2fc5723dc58