证书的生成有很多种选择，小编了解到的有openssl、keytool这两种。
并且小编一直都在用keytool生成的证书配合Tomcat做https的协议配置，但是有的项目中需要Tomcat前端挂载一个Nginx来实现负载均衡以及反向代理等等功能，那么就需要同时打开Nginx的443端口并配置相关的证书，话不多说，上内容：

1.利用keytool工具生成.keystore证书（Tomcat可直接使用）
keytool -genkey -alias LubeLspm160608 -keyalg RSA -keystore d:\lubelspm.keystore -validity 99999
注：别名可随意，密码随意，-validity为有效期，-alias为别名

2.将.keystore证书导出.cer证书
keytool -export -alias LubeLspm160608 -file d:\lubelspm.cer -keystore d:\lubelspm.keystore

3.生成.pem证书
openssl x509 -inform der -in lubelspm.cer -out lubelspm.pem

4.使用代码将lubelspm.keystore转换成lubelspm.pfx文件
代码我会粘贴到下方

5.openssl pkcs12 -in lubelspm.pfx -nocerts -nodes -out lubelspm.key
Nginx所需要的证书就是.pem和.key证书文件
Nginx相关配置：

将之前的注释打开即可，并添加自己所需要的配置。
第四步转换所需要的代码：

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.Key;
import java.security.KeyStore;
import java.security.cert.Certificate;
import java.util.Enumeration;

public class ConventPFX {
    public static final String PKCS12 = "PKCS12";
    public static final String JKS = "JKS";
    public static final String PFX_KEYSTORE_FILE = "server.p12";
    public static final String KEYSTORE_PASSWORD = "123456";
    public static final String JKS_KEYSTORE_FILE = "server.jks";

    public static void coverTokeyStore() {
        try {
            KeyStore inputKeyStore = KeyStore.getInstance("PKCS12");
            FileInputStream fis = new FileInputStream(PFX_KEYSTORE_FILE);
            char[] nPassword = null;

            if ((KEYSTORE_PASSWORD == null)
                    || KEYSTORE_PASSWORD.trim().equals("")) {
                nPassword = null;
            } else {
                nPassword = KEYSTORE_PASSWORD.toCharArray();
            }

            inputKeyStore.load(fis, nPassword);
            fis.close();

            KeyStore outputKeyStore = KeyStore.getInstance("JKS");

            outputKeyStore.load(null, KEYSTORE_PASSWORD.toCharArray());

            Enumeration enums = inputKeyStore.aliases();

            while (enums.hasMoreElements()) { //   we   are   readin   just   one   certificate.  

                String keyAlias = (String) enums.nextElement();

                System.out.println("alias=[" + keyAlias + "]");

                if (inputKeyStore.isKeyEntry(keyAlias)) {
                    Key key = inputKeyStore.getKey(keyAlias, nPassword);
                    Certificate[] certChain = inputKeyStore
                            .getCertificateChain(keyAlias);

                    outputKeyStore.setKeyEntry(keyAlias, key, KEYSTORE_PASSWORD
                            .toCharArray(), certChain);
                }
            }

            FileOutputStream out = new FileOutputStream(JKS_KEYSTORE_FILE);

            outputKeyStore.store(out, nPassword);
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void coverToPfx() {
        try {
            KeyStore inputKeyStore = KeyStore.getInstance("JKS");
            FileInputStream fis = new FileInputStream(JKS_KEYSTORE_FILE);
            char[] nPassword = null;

            if ((KEYSTORE_PASSWORD == null)
                    || KEYSTORE_PASSWORD.trim().equals("")) {
                nPassword = null;
            } else {
                nPassword = KEYSTORE_PASSWORD.toCharArray();
            }

            inputKeyStore.load(fis, nPassword);
            fis.close();

            KeyStore outputKeyStore = KeyStore.getInstance("PKCS12");

            outputKeyStore.load(null, KEYSTORE_PASSWORD.toCharArray());

            Enumeration enums = inputKeyStore.aliases();

            while (enums.hasMoreElements()) { //   we   are   readin   just   one   certificate.  

                String keyAlias = (String) enums.nextElement();

                System.out.println("alias=[" + keyAlias + "]");

                if (inputKeyStore.isKeyEntry(keyAlias)) {
                    Key key = inputKeyStore.getKey(keyAlias, nPassword);
                    Certificate[] certChain = inputKeyStore
                            .getCertificateChain(keyAlias);

                    outputKeyStore.setKeyEntry(keyAlias, key, KEYSTORE_PASSWORD
                            .toCharArray(), certChain);
                }
            }

            FileOutputStream out = new FileOutputStream(PFX_KEYSTORE_FILE);

            outputKeyStore.store(out, nPassword);
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        coverToPfx();
    }
}

更改自己的图中圈出来，自己创建的证书的信息：

Paste_Image.png