支付宝，点击支付功能：

例：

加依赖：

下载导入jar包，点击编译

点击打开链接

加权限：

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

主方法类：

public class MainActivity extends AppCompatActivity  {

    // 商户PID
    public static final String PARTNER = "2088221871911835";
    // 商户收款账号
    public static final String SELLER = "[email protected]";
    // 商户私钥(你配置的东西)，pkcs8格式,注意复制到这里的公私钥信息要掐头去尾,没有回车,空格,就一行.
    public static final String RSA_PRIVATE ="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";


    
    // 支付宝公钥,不是你本地生成
    public static final String RSA_PUBLIC = "";
    private static final int SDK_PAY_FLAG = 1;

    @SuppressLint("HandlerLeak")
    private Handler mHandler = new Handler() {
        @SuppressWarnings("unused")
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case SDK_PAY_FLAG: {
                    PayResult payResult = new PayResult((String) msg.obj);
                    /**
                     * 同步返回的结果必须放置到服务端进行验证（验证的规则请看https://doc.open.alipay.com/doc2/
                     * detail.htm?spm=0.0.0.0.xdvAU6&treeId=59&articleId=103665&
                     * docType=1) 建议商户依赖异步通知
                     */
                    String resultInfo = payResult.getResult();// 同步返回需要验证的信息

                    String resultStatus = payResult.getResultStatus();
                    // 判断resultStatus 为“9000”则代表支付成功，具体状态码代表含义可参考接口文档
                    if (TextUtils.equals(resultStatus, "9000")) {
                        Toast.makeText(MainActivity.this, "支付成功", Toast.LENGTH_SHORT).show();
                    } else {
                        // 判断resultStatus 为非"9000"则代表可能支付失败
                        // "8000"代表支付结果因为支付渠道原因或者系统原因还在等待支付结果确认，最终交易是否成功以服务端异步通知为准（小概率状态）
                        if (TextUtils.equals(resultStatus, "8000")) {
                            Toast.makeText(MainActivity.this, "支付结果确认中", Toast.LENGTH_SHORT).show();
                        } else {
                            // 其他值就可以判断为支付失败，包括用户主动取消支付，或者系统返回的错误
                            Toast.makeText(MainActivity.this, "支付失败", Toast.LENGTH_SHORT).show();
                        }
                    }
                    break;
                }
                default:
                    break;
            }
        };
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }
    /**
     * call alipay sdk pay. 调用SDK支付
     * 最核心的一段代码.pay();
     */
    public void pay(View v) {
        //对公私进行非空判断.
        if (TextUtils.isEmpty(PARTNER) || TextUtils.isEmpty(RSA_PRIVATE) || TextUtils.isEmpty(SELLER)) {
            //对话框
            new AlertDialog.Builder(this).setTitle("警告").setMessage("需要配置PARTNER | RSA_PRIVATE| SELLER")
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialoginterface, int i) {
                            finish();
                        }
                    }).show();
            return;
        }

        //生成订单信息,拼接字符串,订单号,公司立马服务器接口(url)
        String orderInfo = getOrderInfo("测试的商品", "该测试商品的详细描述", "0.01");

        /**
         * 特别注意，这里的签名逻辑需要放在服务端，切勿将私钥泄露在代码中！对订单信息用我们上面的私钥加密.
         */
        String sign = sign(orderInfo);
        try {
            /**
             * 仅需对sign 做UTF-8编码,我们发送内容符合支付宝要求,无论是否是UTF编码,我们都转一下.
             */
            sign = URLEncoder.encode(sign, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        /**
         * 完整的符合支付宝参数规范的订单信息,完全就是为了符合支付宝的要求
         */
        final String payInfo = orderInfo + "&sign=\"" + sign + "\"&" + getSignType();

        //在一个子线程中,进行处理,是一个同步操作.网络请求,由客户端,把数据直接传送给支付宝服务器
        Runnable payRunnable = new Runnable() {
            @Override
            public void run() {
                // 构造PayTask 对象
                PayTask alipay = new PayTask(MainActivity.this);
                // 调用支付接口，获取支付结果,你要知道传的参数是什么,给你结果是什么,你拿去用就行.
                String result = alipay.pay(payInfo, true);

                //用handler把支付的结果更新到UI界面上.
                Message msg = new Message();
                msg.what = SDK_PAY_FLAG;
                msg.obj = result;
                mHandler.sendMessage(msg);
            }
        };
        // 必须异步调用
        Thread payThread = new Thread(payRunnable);
        payThread.start();
    }

    /**
     * create the order info. 创建订单信息,实际就是拼接一个大的字符串.
     */
    private String getOrderInfo(String subject, String body, String price) {

        // 签约合作者身份ID
        String orderInfo = "partner=" + "\"" + PARTNER + "\"";

        // 签约卖家支付宝账号
        orderInfo += "&seller_id=" + "\"" + SELLER + "\"";

        // 商户网站唯一订单号,支付宝使用方法模拟了一个订单编号,实际开发中服务器会给我们一个订单编号,时间具备了唯一性
        orderInfo += "&out_trade_no=" + "\"" + getOutTradeNo() + "\"";

        // 商品名称
        orderInfo += "&subject=" + "\"" + subject + "\"";

        // 商品详情
        orderInfo += "&body=" + "\"" + body + "\"";

        // 商品金额
        orderInfo += "&total_fee=" + "\"" + price + "\"";

        // 服务器异步通知页面路径(就是自己服务器如果想知道支付到底有没有成功,当支付宝服务器支付完成后,会调用此链接进行通知,此链接由服务器开发人员设置)
        // 这个接口网址可以改成自己服务器的,不过我们没有,所以就不改了
        orderInfo += "&notify_url=" + "\"" + "http://notify.msp.hk/notify.htm" + "\"";

        // 服务接口名称， 固定值
        orderInfo += "&service=\"mobile.securitypay.pay\"";

        // 支付类型， 固定值
        orderInfo += "&payment_type=\"1\"";

        // 参数编码， 固定值
        orderInfo += "&_input_charset=\"utf-8\"";

        // 设置未付款交易的超时时间
        // 默认30分钟，一旦超时，该笔交易就会自动被关闭。
        // 取值范围：1m～15d。
        // m-分钟，h-小时，d-天，1c-当天（无论交易何时创建，都在0点关闭）。
        // 该参数数值不接受小数点，如1.5h，可转换为90m。
        orderInfo += "&it_b_pay=\"30m\"";

        // extern_token为经过快登授权获取到的alipay_open_id,带上此参数用户将使用授权的账户进行支付
        // orderInfo += "&extern_token=" + "\"" + extern_token + "\"";

        // 支付宝处理完请求后，当前页面跳转到商户指定页面的路径，可空
        orderInfo += "&return_url=\"m.alipay.com\"";

        // 调用银行卡支付，需配置此参数，参与签名， 固定值 （需要签约《无线银行卡快捷支付》才能使用）
        // orderInfo += "&paymethod=\"expressGateway\"";

        return orderInfo;
    }
    /**
     * sign the order info. 对订单信息进行签名
     *
     * @param content
     *            待签名订单信息
     */
    private String sign(String content) {
        //参数1.内容订单信息    参数2.私钥
        return SignUtils.sign(content, RSA_PRIVATE);
    }

    /**
     * get the sign type we use. 获取签名方式
     *
     */
    private String getSignType() {
        return "sign_type=\"RSA\"";
    }

    /**
     * get the out_trade_no for an order. 生成商户订单号，该值在商户端应保持唯一（可自定义格式规范）
     * 使用到了时间戳,和产生随机数的类.来保证订单唯一性(时间戳+随机数),不是我们做的
     */
    private String getOutTradeNo() {
        SimpleDateFormat format = new SimpleDateFormat("MMddHHmmss", Locale.getDefault());
        Date date = new Date();
        String key = format.format(date);

        Random r = new Random();
        key = key + r.nextInt();
        key = key.substring(0, 15);
        return key;
    }

}

activity_main

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="75dp"
        android:onClick="pay"
        android:text="pay点击支付" />
</RelativeLayout>

PayResult类：

public class PayResult {
   private String resultStatus;
   private String result;
   private String memo;
   public PayResult(String rawResult) {

      if (TextUtils.isEmpty(rawResult))
         return;
      String[] resultParams = rawResult.split(";");
      for (String resultParam : resultParams) {
         if (resultParam.startsWith("resultStatus")) {
            resultStatus = gatValue(resultParam, "resultStatus");
         }
         if (resultParam.startsWith("result")) {
            result = gatValue(resultParam, "result");
         }
         if (resultParam.startsWith("memo")) {
            memo = gatValue(resultParam, "memo");
         }
      }
   }
   @Override
   public String toString() {
      return "resultStatus={" + resultStatus + "};memo={" + memo
            + "};result={" + result + "}";
   }
   private String gatValue(String content, String key) {
      String prefix = key + "={";
      return content.substring(content.indexOf(prefix) + prefix.length(),
            content.lastIndexOf("}"));
   }
   /**
    * @return the resultStatus
    */
   public String getResultStatus() {
      return resultStatus;
   }
   /**
    * @return the memo
    */
   public String getMemo() {
      return memo;
   }
   /**
    * @return the result
    */
   public String getResult() {
      return result;
   }
}

SignUtils 类：

//实际就是对一些订单信息进行一个RSA及base64加密,主要是保证用户的安全,让黑客即使拿到数据,也看不懂.
public class SignUtils {

   private static final String ALGORITHM = "RSA";

   private static final String SIGN_ALGORITHMS = "SHA1WithRSA";

   private static final String DEFAULT_CHARSET = "UTF-8";

   public static String sign(String content, String privateKey) {
      try {
         PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(
               Base64.decode(privateKey));
         KeyFactory keyf = KeyFactory.getInstance(ALGORITHM);
         PrivateKey priKey = keyf.generatePrivate(priPKCS8);

         java.security.Signature signature = java.security.Signature
               .getInstance(SIGN_ALGORITHMS);

         signature.initSign(priKey);
         signature.update(content.getBytes(DEFAULT_CHARSET));

         byte[] signed = signature.sign();

         return Base64.encode(signed);
      } catch (Exception e) {
         e.printStackTrace();
      }

      return null;
   }

}

Base64 类

public final class Base64 {

   private static final int BASELENGTH = 128;
   private static final int LOOKUPLENGTH = 64;
   private static final int TWENTYFOURBITGROUP = 24;
   private static final int EIGHTBIT = 8;
   private static final int SIXTEENBIT = 16;
   private static final int FOURBYTE = 4;
   private static final int SIGN = -128;
   private static char PAD = '=';
   private static byte[] base64Alphabet = new byte[BASELENGTH];
   private static char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];

   static {
      for (int i = 0; i < BASELENGTH; ++i) {
         base64Alphabet[i] = -1;
      }
      for (int i = 'Z'; i >= 'A'; i--) {
         base64Alphabet[i] = (byte) (i - 'A');
      }
      for (int i = 'z'; i >= 'a'; i--) {
         base64Alphabet[i] = (byte) (i - 'a' + 26);
      }

      for (int i = '9'; i >= '0'; i--) {
         base64Alphabet[i] = (byte) (i - '0' + 52);
      }

      base64Alphabet['+'] = 62;
      base64Alphabet['/'] = 63;

      for (int i = 0; i <= 25; i++) {
         lookUpBase64Alphabet[i] = (char) ('A' + i);
      }

      for (int i = 26, j = 0; i <= 51; i++, j++) {
         lookUpBase64Alphabet[i] = (char) ('a' + j);
      }
      for (int i = 52, j = 0; i <= 61; i++, j++) {
         lookUpBase64Alphabet[i] = (char) ('0' + j);
      }
      lookUpBase64Alphabet[62] = (char) '+';
      lookUpBase64Alphabet[63] = (char) '/';

   }

   private static boolean isWhiteSpace(char octect) {
      return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
   }

   private static boolean isPad(char octect) {
      return (octect == PAD);
   }

   private static boolean isData(char octect) {
      return (octect < BASELENGTH && base64Alphabet[octect] != -1);
   }

   /**
    * Encodes hex octects into Base64
    * 
    * @param binaryData
    *            Array containing binaryData
    * @return Encoded Base64 array
    */
   public static String encode(byte[] binaryData) {

      if (binaryData == null) {
         return null;
      }

      int lengthDataBits = binaryData.length * EIGHTBIT;
      if (lengthDataBits == 0) {
         return "";
      }

      int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
      int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
      int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1
            : numberTriplets;
      char encodedData[] = null;

      encodedData = new char[numberQuartet * 4];

      byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;

      int encodedIndex = 0;
      int dataIndex = 0;

      for (int i = 0; i < numberTriplets; i++) {
         b1 = binaryData[dataIndex++];
         b2 = binaryData[dataIndex++];
         b3 = binaryData[dataIndex++];

         l = (byte) (b2 & 0x0f);
         k = (byte) (b1 & 0x03);

         byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
               : (byte) ((b1) >> 2 ^ 0xc0);
         byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4)
               : (byte) ((b2) >> 4 ^ 0xf0);
         byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6)
               : (byte) ((b3) >> 6 ^ 0xfc);

         encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
         encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
         encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
         encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
      }

      // form integral number of 6-bit groups
      if (fewerThan24bits == EIGHTBIT) {
         b1 = binaryData[dataIndex];
         k = (byte) (b1 & 0x03);
         
         byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
               : (byte) ((b1) >> 2 ^ 0xc0);
         encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
         encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
         encodedData[encodedIndex++] = PAD;
         encodedData[encodedIndex++] = PAD;
      } else if (fewerThan24bits == SIXTEENBIT) {
         b1 = binaryData[dataIndex];
         b2 = binaryData[dataIndex + 1];
         l = (byte) (b2 & 0x0f);
         k = (byte) (b1 & 0x03);

         byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2)
               : (byte) ((b1) >> 2 ^ 0xc0);
         byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4)
               : (byte) ((b2) >> 4 ^ 0xf0);

         encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
         encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
         encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
         encodedData[encodedIndex++] = PAD;
      }

      return new String(encodedData);
   }

   /**
    * Decodes Base64 data into octects
    * 
    * @param encoded
    *            string containing Base64 data
    * @return Array containind decoded data.
    */
   public static byte[] decode(String encoded) {

      if (encoded == null) {
         return null;
      }

      char[] base64Data = encoded.toCharArray();
      // remove white spaces
      int len = removeWhiteSpace(base64Data);

      if (len % FOURBYTE != 0) {
         return null;// should be divisible by four
      }

      int numberQuadruple = (len / FOURBYTE);

      if (numberQuadruple == 0) {
         return new byte[0];
      }

      byte decodedData[] = null;
      byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
      char d1 = 0, d2 = 0, d3 = 0, d4 = 0;

      int i = 0;
      int encodedIndex = 0;
      int dataIndex = 0;
      decodedData = new byte[(numberQuadruple) * 3];

      for (; i < numberQuadruple - 1; i++) {

         if (!isData((d1 = base64Data[dataIndex++]))
               || !isData((d2 = base64Data[dataIndex++]))
               || !isData((d3 = base64Data[dataIndex++]))
               || !isData((d4 = base64Data[dataIndex++]))) {
            return null;
         }// if found "no data" just return null

         b1 = base64Alphabet[d1];
         b2 = base64Alphabet[d2];
         b3 = base64Alphabet[d3];
         b4 = base64Alphabet[d4];

         decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
         decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
         decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
      }

      if (!isData((d1 = base64Data[dataIndex++]))
            || !isData((d2 = base64Data[dataIndex++]))) {
         return null;// if found "no data" just return null
      }

      b1 = base64Alphabet[d1];
      b2 = base64Alphabet[d2];

      d3 = base64Data[dataIndex++];
      d4 = base64Data[dataIndex++];
      if (!isData((d3)) || !isData((d4))) {// Check if they are PAD characters
         if (isPad(d3) && isPad(d4)) {
            if ((b2 & 0xf) != 0)// last 4 bits should be zero
            {
               return null;
            }
            byte[] tmp = new byte[i * 3 + 1];
            System.arraycopy(decodedData, 0, tmp, 0, i * 3);
            tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
            return tmp;
         } else if (!isPad(d3) && isPad(d4)) {
            b3 = base64Alphabet[d3];
            if ((b3 & 0x3) != 0)// last 2 bits should be zero
            {
               return null;
            }
            byte[] tmp = new byte[i * 3 + 2];
            System.arraycopy(decodedData, 0, tmp, 0, i * 3);
            tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
            tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            return tmp;
         } else {
            return null;
         }
      } else { // No PAD e.g 3cQl
         b3 = base64Alphabet[d3];
         b4 = base64Alphabet[d4];
         decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
         decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
         decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);

      }

      return decodedData;
   }

   /**
    * remove WhiteSpace from MIME containing encoded Base64 data.
    * 
    * @param data
    *            the byte array of base64 data (with WS)
    * @return the new length
    */
   private static int removeWhiteSpace(char[] data) {
      if (data == null) {
         return 0;
      }

      // count characters that's not whitespace
      int newSize = 0;
      int len = data.length;
      for (int i = 0; i < len; i++) {
         if (!isWhiteSpace(data[i])) {
            data[newSize++] = data[i];
         }
      }
      return newSize;
   }
}

这样就完成了，简单易懂，不过要记得手机上一定要有支付宝App，

好了最后附上支付宝官方demo工程源码：

支付宝官方demo

下载之后，你自己导入工程中，粘贴你自己需要的方法。