public class Order {

    public String system_id;

    public String finger_id;

    public String merchant_id;

    public Double tx_money;

    public String pay_date;

    public String payment_status;

    public Date settle_date;

    public Long goods_count;

}

public class startMapping {

    private static Log log = LogFactory.getLog(startMapping.class);

    private static TransportClient client = null;

    private static IndicesAdminClient adminClient;  

    private static TransportClient getClient() throws UnknownHostException {

        Settings settings = Settings.settingsBuilder().put("cluster.name", Constant.CLUSTER).build();

        TransportClient client = TransportClient.builder().settings(settings).build();

        client.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName(Constant.ESHOST), Constant.ESPORT));

        return client;

    }

    static{

        try {

            client = getClient();

        } catch (UnknownHostException e) {

            e.printStackTrace();

        }

    }

    public static void main(String[] args) {

        //elasticsearch-mapping build

        DoMapping();

    }

    /**

     * 判断ElasticSearch中的索引是否存在

     */

    private static boolean exists(String index){

        adminClient = client.admin().indices();

        IndicesExistsRequest request = new IndicesExistsRequest(index);

        IndicesExistsResponse response = adminClient.exists(request).actionGet();

        if (response.isExists()) {

            return true;

        }

        return false;

    }  

    private static void DoMapping() {

        if(exists(Constant.INDEX)){

            System.out.println(Constant.INDEX+"索引已经存在！");

            log.info(Constant.INDEX+"索引已经存在！");

            return;

        }

        String template = "{\n"

                            +"\t\""+Constant.INDEX+"\":{\n"

                                +"\t\t\"properties\":{\n"

                                        + "\t\t{#}\n"

                                + "\t\t\t\t}\n"

                                + "\t\t}\n"

                            +"}";

        String fieldString =  getClassMapping();

        template = template.replace("{#}",fieldString);

        client.admin().indices().prepareCreate(Constant.INDEX).addMapping(Constant.INDEX, template).get();

        System.out.println(template);

        System.out.println("创建ElasticSearch Mapping完成！！！");

        log.info("创建ElasticSearch Mapping完成！！！");

    }

    /**

     * 从类的字段映射处elasticsearch中的字段

     * @return

     */

    public static String getClassMapping() {

        StringBuilder fieldstring = new StringBuilder();

        Field[] fields = Order.class.getDeclaredFields();

        for (int i = 0; i < fields.length; i++) {

             fieldstring.append("\t\t\t\t\"" + fields[i].getName().toLowerCase() + "\": {\n");

             fieldstring.append("\t\t\t\t\t\t\"type\": \""

                        + GetElasticSearchMappingType(fields[i].getType().getSimpleName()) + "\n");

             if (i == fields.length-1) {

                    fieldstring.append("\t\t\t\t\t}\n");

                } else {

                    fieldstring.append("\t\t\t\t\t},\n");

                }

        }

        return fieldstring.toString();

    }

    private static String GetElasticSearchMappingType(String varType) {

        String es = "String";

        switch (varType) {

        case "Date":

            es = "date\"\n"+"\t\t\t\t\t\t,\"format\":\"yyyy-MM-dd HH:mm:ss\"\n"+"\t\t\t\t\t\t,\"null_value\":\"1900-01-01 00:00:01\"";

            break;

        case "Double":

            es = "double\"\n"+"\t\t\t\t\t\t,\"null_value\":\"NaN\"";

            break;

        case "Long":

            es = "long\"";

            break;

        default:

            es = "string\"";

            break;

        }

        return es;

    }  

}