使用Ognl对象图导航语言,获取JSON多层嵌套数据

在公司金融云中台项目中，需要对接不同的资金方和资产方，对接的接口JSON报文形式也是各式各样。经常需要获取某个json字段，不得不层层获取json对象，非常不方便。
后来发现Ognl（Object Graph Navigation Language 对象导航图语言）能够通过EL表达式获取对象的属性值。根据这一特性，经过封装，轻松实现获取JSON多层嵌套数据。

工具特点
1、方便获取JSON多层嵌套数据，无需层层获取json对象
2、当json字段值为空字符串时，返回空字符串
3、当json字段不存在时，返回NULL

POM引入

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.22</version>
 </dependency>
 <dependency>
            <groupId>ognl</groupId>
            <artifactId>ognl</artifactId>
            <version>2.3.2</version>
 </dependency>

封装OGNL工具类

import com.alibaba.fastjson.JSONObject;
import ognl.Ognl;
import ognl.OgnlContext;
import ognl.OgnlException;
import org.junit.Test;

/**
 * @program: java-deep
 * @description 工具类：使用Ognl对象图导航语言,获取JSON多层嵌套数据
 * @author: DONGSHILEI
 * @create: 2020/5/20 16:26
 **/
public class OgnlUtil {
    private OgnlContext context;

    public OgnlUtil context(OgnlContext context) {
        this.context = context;
        return this;
    }

    public static OgnlUtil build() {
        return new OgnlUtil();
    }

    public OgnlUtil add(JSONObject source) {
        return this.add(null, source);
    }

    public OgnlUtil add(String key, JSONObject source) {
        if (this.context == null) {
            this.context = new OgnlContext();
        }
        if (key == null) {
            this.context.setRoot(source);
        } else {
            this.context.put(key, source);
        }
        return this;
    }

    public static Object getValue(OgnlContext context, String dsl) throws OgnlException {
        Object mapValue = Ognl.getValue(dsl, context, context.getRoot());
        return mapValue;
    }

    public Object getValue(String dsl) throws OgnlException {
        Object mapValue = Ognl.getValue(dsl, this.context, this.context.getRoot());
        return mapValue;
    }
}

测试
JSON示例

{
    "body": {
        "accountInfo": {
            "loanBankCode": "0308",
            "repayBankProvince": "",
            "loanBankProvince": "",
            "loanPrivatePublicAccount": "01",
            "loanTrusteeType": "B134003"
        },
        "contactInfo": [{
            "relativeName": "王一",
            "relativeCompanyAddress": "来广营",
            "relativeCode": "F1004",
            "relativeMobile": "18612994747"
        }, {
            "relativeName": "王二",
            "relativeCode": "F1004",
            "relativeMobile": "18612994848"
        }],
        "professionInfo": {
            "incomeLevelCode": "B20202",
            "professionCode": "F12326",
            "incomeSourceCode": "B20305",
            "duty": "B2910",
            "yearIncome": 48000,
            "industryCode": "B1036"
        }
    }
}

 public static void main(String[] args) {
        String jsonStr = "{\"body\":{\"accountInfo\":{\"loanBankCode\":\"0308\",\"repayBankProvince\":\"\",\"loanBankProvince\":\"\",\"loanPrivatePublicAccount\":\"01\",\"loanTrusteeType\":\"B134003\"},\"contactInfo\":[{\"relativeName\":\"王一\",\"relativeCompanyAddress\":\"来广营\",\"relativeCode\":\"F1004\",\"relativeMobile\":\"18612994747\"},{\"relativeName\":\"王二\",\"relativeCode\":\"F1004\",\"relativeMobile\":\"18612994848\"}],\"professionInfo\":{\"incomeLevelCode\":\"B20202\",\"professionCode\":\"F12326\",\"incomeSourceCode\":\"B20305\",\"duty\":\"B2910\",\"yearIncome\":48000,\"industryCode\":\"B1036\"}}}";
        JSONObject source = JSONObject.parseObject(jsonStr);
        try {
            //将json数据放到context中，并获取特定的值
            OgnlContext context = new OgnlContext();
            OgnlUtil ognlUtil = OgnlUtil.build().context(context).add("body", source);
            Object value = ognlUtil.getValue("#body.body.accountInfo.loanBankCode");
            System.out.println("#body.body.accountInfo.loanBankCode:"+value);
            // 获取JsonArray中值
            Object value1 = ognlUtil.getValue("#body.body.contactInfo[0].relativeName");
            System.out.println("#body.body.contactInfo[0].relativeName:"+value1);
            //获取的value值为空字符串，则正常打印空字符串
            Object value3 = ognlUtil.getValue("#body.body.accountInfo.repayBankProvince");
            System.out.println(value3);
            //获取的json key不存在，则打印null
            Object value4 = ognlUtil.getValue("#body.body.accountInfo.repayBankProvince1");
            System.out.println(value4);
            //获取json对象
            String expression = "body.contactInfo";
            Object value2 = Ognl.getValue(expression, new OgnlContext(), source);
            System.out.println("body.contactInfo:"+value2);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

测试结果

#body.body.accountInfo.loanBankCode:0308
#body.body.contactInfo[0].relativeName:王一
#body.body.accountInfo.repayBankProvince:
#body.body.accountInfo.repayBankProvince1:null
body.contactInfo:[{"relativeName":"王一","relativeCompanyAddress":"来广营","relativeCode":"F1004","relativeMobile":"18612994747"},{"relativeName":"王二","relativeCode":"F1004","relativeMobile":"18612994848"}]