c语言json库parson的介绍和使用

符畅

2023-12-01

简介

本文章主要介绍下parson库的使用
parson : parson是用C语言开发的一个json解析库，提供json的序列化和反序列化功能。使用时只需要在我们的工程中引入头文件parson.h和源文件parson.c即可使用。

使用parson解析json

单层json结构解析

代码

  const char* resp = "{\"code\":0, \"flag\":true, \"msg\":\"success\"}";
  bool bRet = false;
  JSON_Value *rootValue = NULL;

  do {
  	//反序列化为json对象
      rootValue = json_parse_string(resp);
      if (rootValue == NULL) {
  	    break;
      }

      JSON_Object *rootObject = json_value_get_object(rootValue);
      if (rootObject == NULL) {
  	    break;
      }

      if (!json_object_has_value(rootObject, "code")) {
  	    break;
      }

      int code = json_object_get_number(rootObject, "code");

      if (!json_object_has_value(rootObject, "flag")) {
  	    break;
      }

      bool flag = json_object_get_boolean(rootObject, "flag");

      if (!json_object_has_value(rootObject, "msg")) {
  	    break;
      }

      const char* msg = json_object_get_string(rootObject, "msg");

      printf("code = %d, flag = %d, msg = %s\n", code, flag, msg);

      bRet = true;
  } while (0);

  if (rootValue != NULL) {
      json_value_free(rootValue);
      rootValue = NULL;
  }

  return bRet;

执行结果
```
  code = 0, flag = 1, msg = success
```

多层json结构解析

代码

  const char* resp = "{\"code\":0, \"msg\":\"success\", \"data\":{\"name\":\"lucy\", \"score\":99.5}}";

  bool bRet = false;
  JSON_Value *rootValue = NULL;

  do {
  	rootValue = json_parse_string(resp);
  	if (rootValue == NULL) {
  		break;
  	}

  	JSON_Object *rootObject = json_value_get_object(rootValue);
  	if (rootObject == NULL) {
  		break;
  	}	

  	if (!json_object_has_value(rootObject, "code")) {
  		break;
  	}

  	int code = json_object_get_number(rootObject, "code");


  	if (!json_object_has_value(rootObject, "msg")) {
  		break;
  	}

  	const char* msg = json_object_get_string(rootObject, "msg");

  	if (!json_object_has_value(rootObject, "data")) {
  		break;
  	}

  	JSON_Object *dataObject = json_object_get_object(rootObject, "data");
  	if (dataObject == NULL) {
  		break;
  	}

  	if (!json_object_has_value(dataObject, "name")) {
  		break;
  	}

  	const char* name = json_object_get_string(dataObject, "name");

  	if (!json_object_has_value(dataObject, "score")) {
  		break;
  	}

  	double score = json_object_get_number(dataObject, "score");

  	printf("code = %d, msg = %s, name = %s, score = %lf\n", code, msg, name, score);

  	bRet = true;
  } while (0);

  if (rootValue != NULL) {
  	json_value_free(rootValue);
  	rootValue = NULL;
  }

  return bRet;

执行结果

  code = 0, msg = success, name = lucy, score = 99.500000

有数组的json结构解析

代码

  const char* resp = "{\"code\":0, \"msg\":\"success\", \"result\":[\"tcp\", \"udp\", \"http\", \"tls\"]}";

  bool bRet = false;
  JSON_Value *root_value = NULL;

  do {
  	root_value = json_parse_string(resp);
  	if (root_value == NULL) {
  		break;
  	}

  	JSON_Object *root_object = json_value_get_object(root_value);
  	if (root_object == NULL) {
  		break;
  	}

  	if (!json_object_has_value(root_object, "code")) {
  		break;
  	}

  	int code = json_object_get_number(root_object, "code");
  	printf("code is %d\n", code);


  	if (!json_object_has_value(root_object, "msg")) {
  		break;
  	}

  	const char* msg = json_object_get_string(root_object, "msg");
  	printf("msg is %s\n", msg);

  	if (!json_object_has_value(root_object, "result")) {
  		break;
  	}

  	JSON_Array *result_obj = json_object_get_array(root_object, "result");
  	if (result_obj == NULL) {
  		break;
  	}

  	printf("result: ");
  	for (int i = 0; i < json_array_get_count(result_obj); i++) {
  		const char *pStr = json_array_get_string(result_obj, i);
  		if (pStr != NULL) {
  			printf("%s ", pStr);
  		}
  	}
  	printf("\n");

  	bRet = true;
  } while (0);

  if (root_value != NULL) {
  	json_value_free(root_value);
  	root_value = NULL;
  }

  return bRet;

执行结果

  code is 0
  msg is success
  result: tcp udp http tls

json文件解析

文件内容 test.json

  {"code":0,"flag":true,"msg":"success"}

代码

  bool bRet = false;
  JSON_Value *rootValue = NULL;

  do {
  	// 如果json文件内容带注释可用这个函数 json_parse_file_with_comments
  	rootValue = json_parse_file("test.json");
  	if (rootValue == NULL) {
  		break;
  	}

  	JSON_Object *rootObject = json_value_get_object(rootValue);
  	if (rootObject == NULL) {
  		break;
  	}

  	if (!json_object_has_value(rootObject, "code")) {
  		break;
  	}

  	int code = json_object_get_number(rootObject, "code");

  	if (!json_object_has_value(rootObject, "flag")) {
  		break;
  	}

  	bool flag = json_object_get_boolean(rootObject, "flag");

  	if (!json_object_has_value(rootObject, "msg")) {
  		break;
  	}

  	const char* msg = json_object_get_string(rootObject, "msg");

  	printf("code = %d, flag = %d, msg = %s\n", code, flag, msg);

  	bRet = true;
  } while (0);

  if (rootValue != NULL) {
  	json_value_free(rootValue);
  	rootValue = NULL;
  }

  return bRet;

执行结果
```
  code = 0, flag = 1, msg = success
```

使用parson构建json

单层json结构构建

代码

  bool bRet = false;
  JSON_Value *root_value = NULL;

  do {
  	root_value = json_value_init_object();
  	if (root_value == NULL) {
  		break;
  	}

  	JSON_Object *root_object = json_value_get_object(root_value);
  	if (root_object == NULL) {
  		break;
  	}

  	json_object_set_number(root_object, "code", 0);
  	json_object_set_boolean(root_object, "flag", true);
  	json_object_set_string(root_object, "msg", "success");
  	json_object_set_number(root_object, "rate", 10.5);

  	char *data = json_serialize_to_string(root_value);
  	if (data == NULL) {
  		break;
  	}
  	printf("%s\n", data);
  	bRet = true;
  	json_free_serialized_string(data);
  } while (0);

  if (root_value != NULL) {
  	json_value_free(root_value);
  	root_value = NULL;
  }
  return bRet;

执行结果

  {"code":0,"flag":true,"msg":"success","rate":10.5}

多层json结构构建

代码

  bool bRet = false;
  JSON_Value *root_value = NULL;

  do {
  	root_value = json_value_init_object();
  	if (root_value == NULL) {
  		break;
  	}

  	JSON_Object *root_object = json_value_get_object(root_value);
  	if (root_object == NULL) {
  		break;
  	}

  	JSON_Value *data_value = json_value_init_object();
  	if (data_value == NULL) {
  		break;
  	}

  	JSON_Object *data_object = json_value_get_object(data_value);
  	if (data_object == NULL) {
  		break;
  	}

  	json_object_set_string(data_object, "name", "jack");
  	json_object_set_number(data_object, "age", 28);

  	json_object_set_number(root_object, "code", 0);
  	json_object_set_boolean(root_object, "flag", true);
  	json_object_set_string(root_object, "msg", "success");
  	json_object_set_value(root_object, "data", data_value);

  	char *data = json_serialize_to_string(root_value);
  	if (data == NULL) {
  		break;
  	}
  	printf("%s\n", data);
  	bRet = true;
  	json_free_serialized_string(data);
  } while (0);

  if (root_value != NULL) {
  	json_value_free(root_value);
  	root_value = NULL;
  }

  return bRet;

执行结果

  {"code":0,"flag":true,"msg":"success","data":{"name":"jack","age":28}}

带有数组的json结构构建

代码

  bool bRet = false;
  JSON_Value *root_value = NULL;

  do {
  	root_value = json_value_init_object();
  	if (root_value == NULL) {
  		break;
  	}

  	JSON_Object *root_object = json_value_get_object(root_value);
  	if (root_object == NULL) {
  		break;
  	}

  	JSON_Value *data_value = json_value_init_object();
  	if (data_value == NULL) {
  		break;
  	}

  	JSON_Object *data_object = json_value_get_object(data_value);
  	if (data_object == NULL) {
  		break;
  	}


  	JSON_Value *dataValueArray = json_value_init_array();
  	if (dataValueArray == NULL) {
  		break;
  	}

  	JSON_Array *dataObjectArray = json_value_get_array(dataValueArray);
  	if (dataObjectArray == NULL) {
  		break;
  	}

  	for (int i = 0; i < 5; i++) {
  		JSON_Value *pValue = json_value_init_object();
  		if (pValue == NULL) {
  			break;
  		}

  		JSON_Object *pObject = json_value_get_object(pValue);
  		if (pObject == NULL) {
  			break;
  		}

  		json_object_set_number(pObject, "index", i);
  		json_object_set_string(pObject, "status","success");

  		json_array_append_value(dataObjectArray, pValue);
  	}

  	json_object_set_string(data_object, "name", "jack");
  	json_object_set_number(data_object, "age", 28);

  	json_object_set_number(root_object, "code", 0);
  	json_object_set_boolean(root_object, "flag", true);
  	json_object_set_string(root_object, "msg", "success");
  	json_object_set_value(root_object, "data", dataValueArray);

  	char *data = json_serialize_to_string(root_value);
  	if (data == NULL) {
  		break;
  	}
  	printf("%s\n", data);
  	bRet = true;
  	json_free_serialized_string(data);
  } while (0);

  if (root_value != NULL) {
  	json_value_free(root_value);
  	root_value = NULL;
  }

  return bRet;

执行结果

  {"code":0,"flag":true,"msg":"success","data":[{"index":0,"status":"success"},{"index":1,"status":"success"},{"index":2,"status":"success"},{"index":3,"status":"success"},{"index":4,"status":"success"}]}

构建json并保存到文件

代码

  bool bRet = false;
  JSON_Value *root_value = NULL;

  do {
  	root_value = json_value_init_object();
  	if (root_value == NULL) {
  		break;
  	}

  	JSON_Object *root_object = json_value_get_object(root_value);
  	if (root_object == NULL) {
  		break;
  	}

  	json_object_set_number(root_object, "code", 0);
  	json_object_set_boolean(root_object, "flag", true);
  	json_object_set_string(root_object, "msg", "success");
  	json_object_set_number(root_object, "rate", 10.5);

  	JSON_Status status = json_serialize_to_file(root_value, "test.json");
  	if (status == JSONFailure) {
  		break;
  	}

  	bRet = true;
  } while (0);

  if (root_value != NULL) {
  	json_value_free(root_value);
  	root_value = NULL;
  }
  return bRet;

test.json文件内容

  {"code":0,"flag":true,"msg":"success","rate":10.5}

c语言json库parson的介绍和使用

简介

使用parson解析json

使用parson构建json

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