Java8 中Optional类的使用

1、利用Optional 提取Json中的某个字段的值, 本例子程序提取 sku 的值

import com.jd.fastjson.JSONArray;
import com.jd.fastjson.JSONObject;
import org.junit.Test;

import java.util.Optional;

/**
 * @author: wangyingjie1
 * @version: 1.0
 * @createdate: 2017-09-19 16:31
 */
public class OptionalTest {

    @Test
    public void testOptionalGetValue() {
        //利用Optional 提取Json中的某个字段的值, 本例子程序提取 sku 的值
        String json = "{\n" +
                "    \"code\": \"0\",\n" +
                "    \"result\": \"Success\",\n" +
                "    \"data\": {\n" +
                "        \"totalCount\": 10,\n" +
                "        \"resultData\": [\n" +
                "            {\n" +
                "                \"sku\": 13346254358,\n" +
                "                \"name\": \"博世（BOSCH）机油滤清器 机油格 机滤 机油滤芯 新领驭 1.8T (09-10款)\",\n" +
                "                \"accyModelId\": 28489,\n" +
                "                \"cid1\": 6728,\n" +
                "                \"cid2\": 6742,\n" +
                "                \"cid3\": 11852,\n" +
                "                \"venderId\": 111655,\n" +
                "                \"brandId\": 5125,\n" +
                "                \"venderName\": \"上海硕泽实业有限公司\",                \n" +
                "                \"modelIds\": null,\n" +
                "                \"carButlerCatIds\": [\n" +
                "                    2\n" +
                "                ]\n" +
                "            }\n" +
                "        ]\n" +
                "    },\n" +
                "    \"foot\": {\n" +
                "        \"operationTime\": \"2017-09-20 11:18:10\",\n" +
                "        \"version\": \"1.0.0\",\n" +
                "        \"clientVersion\": null,\n" +
                "        \"client\": null,\n" +
                "        \"osVersion\": null\n" +
                "    }\n" +
                "}";

        Long sku = Optional.ofNullable(json)
                .map(JSONObject::parseObject)
                .map(jsonObject -> jsonObject.getJSONObject("data"))
                .map(jsonObject -> jsonObject.getJSONArray("resultData"))
                .flatMap(jsonArr -> convertJsonStrToJsonObjectStream(jsonArr))
                .get();
        System.out.println("sku============" + sku);
    }

    private Optional convertJsonStrToJsonObjectStream(JSONArray jsonArr) {
        return jsonArr.stream()
                .map(obj -> (JSONObject) obj)
                .findFirst()
                .map(obj -> obj.getLong("sku"))
                ;
    }

}