Json取值工具类

喜欢总结一些工作中写的代码，将部分代码抽离出来，形成一个小的工具类或者jar包，方便在各个项目中使用，这样时间久了、总结的多了就形成了自己的代码库，这些都是自己的资源。本篇将总结一个从Json字符串中直接取指定key值的工具类，详细代码如下：

import com.alibaba.fastjson.JSONArray; import com.alibaba.fastjson.JSONObject; import com.google.common.base.Strings; import org.junit.Test; public class JsonValueTool { @Test public void test() { String originString = "{\n" + " \"student\": [\n" + " {\n" + " \"name\": \"jack\", \n" + " \"age\": 25, \n" + " \"education\": {\n" + " \"education1\": \"Harvard University\", \n" + " \"education2\": \"University of Cambridge\", \n" + " \"education3\": \"Massachusetts Institue of Technology\"\n" + " }\n" + " }\n" + " ]\n" + "}"; JSONObject originObject = JSONObject.parseObject(originString); System.out.println(JsonValueTool.getValueByKeyExpression(originObject, "student", "student#education#education2")); } public static Object getValueByKeyExpression(Object originObject, String startKey, String targetKeyExpression) { if (Strings.isNullOrEmpty(startKey)) { return originObject; } if (originObject instanceof JSONObject) { return getValueFromJSONObjectByKeyExpression((JSONObject) originObject, startKey, targetKeyExpression); } if (originObject instanceof JSONArray) { return getValueFromJSONArrayByKeyExpression((JSONArray) originObject, startKey, targetKeyExpression); } return null; } private static String getNextKey(String startKey, String targetKeyExpression) { if (Strings.isNullOrEmpty(targetKeyExpression)) { return null; } String[] keys = targetKeyExpression.split("#"); for (int i = 0; i < keys.length; i++) { if (keys[i].equals(startKey) && (i < keys.length - 1)) { return keys[i + 1]; } } return null; } private static Object getValueFromJSONArrayByKeyExpression(JSONArray originObject, String startKey, String targetKeyExpression) { for (int j = 0; j < originObject.size(); j++) { JSONObject jsonObject = originObject.getJSONObject(j); Object targetObject = getValueFromJSONObjectByKeyExpression(jsonObject, startKey, targetKeyExpression); if (targetObject != null) { return targetObject; } } return null; } private static Object getValueFromJSONObjectByKeyExpression(JSONObject originObject, String startKey, String targetKeyExpression) { Object object = originObject.get(startKey); return object != null ? getValueByKeyExpression(object, getNextKey(startKey, targetKeyExpression), targetKeyExpression) : null; } }

示例单元测试将输出：University of Cambridge