(java)签名算法的使用以及正则表达式的简单使用

直接上代码吧：

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Base64;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.sound.sampled.AudioFormat.Encoding;

public class TestPattern {

public static void main(String[] args) {
// TODO Auto-generated method stub
String s="we are people"
+ "hahh";
System.out.println("正则表达式去除空格换行: "+p(s));
System.out.println("RSA签名： "+md5(s));
}
public static String p(String pa){
Pattern p=Pattern.compile("\t|\r|\n| ");
Matcher m=p.matcher(pa);
return m.replaceAll("");
}
public static String md5(String s){
byte[] signdata = null;
try{
KeyPairGenerator myKeyGen= KeyPairGenerator.getInstance("RSA");
myKeyGen.initialize(1024);
KeyPair myKeyPair = myKeyGen.generateKeyPair();
Signature sg=Signature.getInstance("MD5withRSA");
sg.initSign(myKeyPair.getPrivate());
sg.update(s.getBytes());
signdata=sg.sign();
}catch(Exception e){
e.printStackTrace();
}
return Base64.getEncoder().encodeToString(signdata);
}

}