如何通过json来解析配置文件？

快来打我* 2022-12-02 00:54 337阅读 0赞

## 用json解析的有点： ##

1.解析速度比较快  
2.配置比较合理  
3.配置文件比较通用

## json配置文件的一般格式： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTMwOTkxNg_size_16_color_FFFFFF_t_70_pic_center]

## json解析库 ##

### cJSON.h ###

/* Copyright (c) 2009-2017 Dave Gamble and cJSON contributors Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
    
    #ifndef cJSON__h
    #define cJSON__h
    
    #ifdef __cplusplus
    extern "C"
    { 
    #endif
    
    /* project version */
    #define CJSON_VERSION_MAJOR 1
    #define CJSON_VERSION_MINOR 6
    #define CJSON_VERSION_PATCH 0
    
    #include <stddef.h>
    
    /* cJSON Types: */
    #define cJSON_Invalid (0)
    #define cJSON_False (1 << 0)
    #define cJSON_True (1 << 1)
    #define cJSON_NULL (1 << 2)
    #define cJSON_Number (1 << 3)
    #define cJSON_String (1 << 4)
    #define cJSON_Array (1 << 5)
    #define cJSON_Object (1 << 6)
    #define cJSON_Raw (1 << 7) /* raw json */
    
    #define cJSON_IsReference 256
    #define cJSON_StringIsConst 512
    
    /* The cJSON structure: */
    typedef struct cJSON
    { 
        /* next/prev allow you to walk array/object chains. Alternatively, use GetArraySize/GetArrayItem/GetObjectItem */
        struct cJSON *next;
        struct cJSON *prev;
        /* An array or object item will have a child pointer pointing to a chain of the items in the array/object. */
        struct cJSON *child;
    
        /* The type of the item, as above. */
        int type;
    
        /* The item's string, if type==cJSON_String and type == cJSON_Raw */
        char *valuestring;
        /* writing to valueint is DEPRECATED, use cJSON_SetNumberValue instead */
        int valueint;
        /* The item's number, if type==cJSON_Number */
        double valuedouble;
    
        /* The item's name string, if this item is the child of, or is in the list of subitems of an object. */
        char *string;
    } cJSON;
    
    typedef struct cJSON_Hooks
    { 
          void *(*malloc_fn)(size_t sz);
          void (*free_fn)(void *ptr);
    } cJSON_Hooks;
    
    typedef int cJSON_bool;
    
    #if !defined(__WINDOWS__) && (defined(WIN32) || defined(WIN64) || defined(_MSC_VER) || defined(_WIN32))
    #define __WINDOWS__
    #endif
    #ifdef __WINDOWS__
    
    /* When compiling for windows, we specify a specific calling convention to avoid issues where we are being called from a project with a different default calling convention. For windows you have 2 define options: CJSON_HIDE_SYMBOLS - Define this in the case where you don't want to ever dllexport symbols CJSON_EXPORT_SYMBOLS - Define this on library build when you want to dllexport symbols (default) CJSON_IMPORT_SYMBOLS - Define this if you want to dllimport symbol For *nix builds that support visibility attribute, you can define similar behavior by setting default visibility to hidden by adding -fvisibility=hidden (for gcc) or -xldscope=hidden (for sun cc) to CFLAGS then using the CJSON_API_VISIBILITY flag to "export" the same symbols the way CJSON_EXPORT_SYMBOLS does */
    
    /* export symbols by default, this is necessary for copy pasting the C and header file */
    #if !defined(CJSON_HIDE_SYMBOLS) && !defined(CJSON_IMPORT_SYMBOLS) && !defined(CJSON_EXPORT_SYMBOLS)
    #define CJSON_EXPORT_SYMBOLS
    #endif
    
    #if defined(CJSON_HIDE_SYMBOLS)
    #define CJSON_PUBLIC(type) type __stdcall
    #elif defined(CJSON_EXPORT_SYMBOLS)
    #define CJSON_PUBLIC(type) __declspec(dllexport) type __stdcall
    #elif defined(CJSON_IMPORT_SYMBOLS)
    #define CJSON_PUBLIC(type) __declspec(dllimport) type __stdcall
    #endif
    #else /* !WIN32 */
    #if (defined(__GNUC__) || defined(__SUNPRO_CC) || defined (__SUNPRO_C)) && defined(CJSON_API_VISIBILITY)
    #define CJSON_PUBLIC(type) __attribute__((visibility("default"))) type
    #else
    #define CJSON_PUBLIC(type) type
    #endif
    #endif
    
    /* Limits how deeply nested arrays/objects can be before cJSON rejects to parse them. * This is to prevent stack overflows. */
    #ifndef CJSON_NESTING_LIMIT
    #define CJSON_NESTING_LIMIT 1000
    #endif
    
    /* returns the version of cJSON as a string */
    CJSON_PUBLIC(const char*) cJSON_Version(void);
    
    /* Supply malloc, realloc and free functions to cJSON */
    CJSON_PUBLIC(void) cJSON_InitHooks(cJSON_Hooks* hooks);
    
    /* Memory Management: the caller is always responsible to free the results from all variants of cJSON_Parse (with cJSON_Delete) and cJSON_Print (with stdlib free, cJSON_Hooks.free_fn, or cJSON_free as appropriate). The exception is cJSON_PrintPreallocated, where the caller has full responsibility of the buffer. */
    /* Supply a block of JSON, and this returns a cJSON object you can interrogate. */
    CJSON_PUBLIC(cJSON *) cJSON_Parse(const char *value);
    /* ParseWithOpts allows you to require (and check) that the JSON is null terminated, and to retrieve the pointer to the final byte parsed. */
    /* If you supply a ptr in return_parse_end and parsing fails, then return_parse_end will contain a pointer to the error so will match cJSON_GetErrorPtr(). */
    CJSON_PUBLIC(cJSON *) cJSON_ParseWithOpts(const char *value, const char **return_parse_end, cJSON_bool require_null_terminated);
    
    /* Render a cJSON entity to text for transfer/storage. */
    CJSON_PUBLIC(char *) cJSON_Print(const cJSON *item);
    /* Render a cJSON entity to text for transfer/storage without any formatting. */
    CJSON_PUBLIC(char *) cJSON_PrintUnformatted(const cJSON *item);
    /* Render a cJSON entity to text using a buffered strategy. prebuffer is a guess at the final size. guessing well reduces reallocation. fmt=0 gives unformatted, =1 gives formatted */
    CJSON_PUBLIC(char *) cJSON_PrintBuffered(const cJSON *item, int prebuffer, cJSON_bool fmt);
    /* Render a cJSON entity to text using a buffer already allocated in memory with given length. Returns 1 on success and 0 on failure. */
    /* NOTE: cJSON is not always 100% accurate in estimating how much memory it will use, so to be safe allocate 5 bytes more than you actually need */
    CJSON_PUBLIC(cJSON_bool) cJSON_PrintPreallocated(cJSON *item, char *buffer, const int length, const cJSON_bool format);
    /* Delete a cJSON entity and all subentities. */
    CJSON_PUBLIC(void) cJSON_Delete(cJSON *c);
    
    /* Returns the number of items in an array (or object). */
    CJSON_PUBLIC(int) cJSON_GetArraySize(const cJSON *array);
    /* Retrieve item number "item" from array "array". Returns NULL if unsuccessful. */
    CJSON_PUBLIC(cJSON *) cJSON_GetArrayItem(const cJSON *array, int index);
    /* Get item "string" from object. Case insensitive. */
    CJSON_PUBLIC(cJSON *) cJSON_GetObjectItem(const cJSON * const object, const char * const string);
    CJSON_PUBLIC(cJSON *) cJSON_GetObjectItemCaseSensitive(const cJSON * const object, const char * const string);
    CJSON_PUBLIC(cJSON_bool) cJSON_HasObjectItem(const cJSON *object, const char *string);
    /* For analysing failed parses. This returns a pointer to the parse error. You'll probably need to look a few chars back to make sense of it. Defined when cJSON_Parse() returns 0. 0 when cJSON_Parse() succeeds. */
    CJSON_PUBLIC(const char *) cJSON_GetErrorPtr(void);
    
    /* These functions check the type of an item */
    CJSON_PUBLIC(cJSON_bool) cJSON_IsInvalid(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsFalse(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsTrue(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsBool(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsNull(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsNumber(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsString(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsArray(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsObject(const cJSON * const item);
    CJSON_PUBLIC(cJSON_bool) cJSON_IsRaw(const cJSON * const item);
    
    /* These calls create a cJSON item of the appropriate type. */
    CJSON_PUBLIC(cJSON *) cJSON_CreateNull(void);
    CJSON_PUBLIC(cJSON *) cJSON_CreateTrue(void);
    CJSON_PUBLIC(cJSON *) cJSON_CreateFalse(void);
    CJSON_PUBLIC(cJSON *) cJSON_CreateBool(cJSON_bool boolean);
    CJSON_PUBLIC(cJSON *) cJSON_CreateNumber(double num);
    CJSON_PUBLIC(cJSON *) cJSON_CreateString(const char *string);
    /* raw json */
    CJSON_PUBLIC(cJSON *) cJSON_CreateRaw(const char *raw);
    CJSON_PUBLIC(cJSON *) cJSON_CreateArray(void);
    CJSON_PUBLIC(cJSON *) cJSON_CreateObject(void);
    
    /* These utilities create an Array of count items. */
    CJSON_PUBLIC(cJSON *) cJSON_CreateIntArray(const int *numbers, int count);
    CJSON_PUBLIC(cJSON *) cJSON_CreateFloatArray(const float *numbers, int count);
    CJSON_PUBLIC(cJSON *) cJSON_CreateDoubleArray(const double *numbers, int count);
    CJSON_PUBLIC(cJSON *) cJSON_CreateStringArray(const char **strings, int count);
    
    /* Append item to the specified array/object. */
    CJSON_PUBLIC(void) cJSON_AddItemToArray(cJSON *array, cJSON *item);
    CJSON_PUBLIC(void) cJSON_AddItemToObject(cJSON *object, const char *string, cJSON *item);
    /* Use this when string is definitely const (i.e. a literal, or as good as), and will definitely survive the cJSON object. * WARNING: When this function was used, make sure to always check that (item->type & cJSON_StringIsConst) is zero before * writing to `item->string` */
    CJSON_PUBLIC(void) cJSON_AddItemToObjectCS(cJSON *object, const char *string, cJSON *item);
    /* Append reference to item to the specified array/object. Use this when you want to add an existing cJSON to a new cJSON, but don't want to corrupt your existing cJSON. */
    CJSON_PUBLIC(void) cJSON_AddItemReferenceToArray(cJSON *array, cJSON *item);
    CJSON_PUBLIC(void) cJSON_AddItemReferenceToObject(cJSON *object, const char *string, cJSON *item);
    
    /* Remove/Detatch items from Arrays/Objects. */
    CJSON_PUBLIC(cJSON *) cJSON_DetachItemViaPointer(cJSON *parent, cJSON * const item);
    CJSON_PUBLIC(cJSON *) cJSON_DetachItemFromArray(cJSON *array, int which);
    CJSON_PUBLIC(void) cJSON_DeleteItemFromArray(cJSON *array, int which);
    CJSON_PUBLIC(cJSON *) cJSON_DetachItemFromObject(cJSON *object, const char *string);
    CJSON_PUBLIC(cJSON *) cJSON_DetachItemFromObjectCaseSensitive(cJSON *object, const char *string);
    CJSON_PUBLIC(void) cJSON_DeleteItemFromObject(cJSON *object, const char *string);
    CJSON_PUBLIC(void) cJSON_DeleteItemFromObjectCaseSensitive(cJSON *object, const char *string);
    
    /* Update array items. */
    CJSON_PUBLIC(void) cJSON_InsertItemInArray(cJSON *array, int which, cJSON *newitem); /* Shifts pre-existing items to the right. */
    CJSON_PUBLIC(cJSON_bool) cJSON_ReplaceItemViaPointer(cJSON * const parent, cJSON * const item, cJSON * replacement);
    CJSON_PUBLIC(void) cJSON_ReplaceItemInArray(cJSON *array, int which, cJSON *newitem);
    CJSON_PUBLIC(void) cJSON_ReplaceItemInObject(cJSON *object,const char *string,cJSON *newitem);
    CJSON_PUBLIC(void) cJSON_ReplaceItemInObjectCaseSensitive(cJSON *object,const char *string,cJSON *newitem);
    
    /* Duplicate a cJSON item */
    CJSON_PUBLIC(cJSON *) cJSON_Duplicate(const cJSON *item, cJSON_bool recurse);
    /* Duplicate will create a new, identical cJSON item to the one you pass, in new memory that will need to be released. With recurse!=0, it will duplicate any children connected to the item. The item->next and ->prev pointers are always zero on return from Duplicate. */
    /* Recursively compare two cJSON items for equality. If either a or b is NULL or invalid, they will be considered unequal. * case_sensitive determines if object keys are treated case sensitive (1) or case insensitive (0) */
    CJSON_PUBLIC(cJSON_bool) cJSON_Compare(const cJSON * const a, const cJSON * const b, const cJSON_bool case_sensitive);
    
    
    CJSON_PUBLIC(void) cJSON_Minify(char *json);
    
    /* Macros for creating things quickly. */
    #define cJSON_AddNullToObject(object,name) cJSON_AddItemToObject(object, name, cJSON_CreateNull())
    #define cJSON_AddTrueToObject(object,name) cJSON_AddItemToObject(object, name, cJSON_CreateTrue())
    #define cJSON_AddFalseToObject(object,name) cJSON_AddItemToObject(object, name, cJSON_CreateFalse())
    #define cJSON_AddBoolToObject(object,name,b) cJSON_AddItemToObject(object, name, cJSON_CreateBool(b))
    #define cJSON_AddNumberToObject(object,name,n) cJSON_AddItemToObject(object, name, cJSON_CreateNumber(n))
    #define cJSON_AddStringToObject(object,name,s) cJSON_AddItemToObject(object, name, cJSON_CreateString(s))
    #define cJSON_AddRawToObject(object,name,s) cJSON_AddItemToObject(object, name, cJSON_CreateRaw(s))
    
    /* When assigning an integer value, it needs to be propagated to valuedouble too. */
    #define cJSON_SetIntValue(object, number) ((object) ? (object)->valueint = (object)->valuedouble = (number) : (number))
    /* helper for the cJSON_SetNumberValue macro */
    CJSON_PUBLIC(double) cJSON_SetNumberHelper(cJSON *object, double number);
    #define cJSON_SetNumberValue(object, number) ((object != NULL) ? cJSON_SetNumberHelper(object, (double)number) : (number))
    
    /* Macro for iterating over an array or object */
    #define cJSON_ArrayForEach(element, array) for(element = (array != NULL) ? (array)->child : NULL; element != NULL; element = element->next)
    
    /* malloc/free objects using the malloc/free functions that have been set with cJSON_InitHooks */
    CJSON_PUBLIC(void *) cJSON_malloc(size_t size);
    CJSON_PUBLIC(void) cJSON_free(void *object);
    
    #ifdef __cplusplus
    }
    #endif
    
    #endif

### JSON处理方式 ###

```c
    #include "stdlib.h"
    #include "stdio.h"
    #include "./cJSON.h"
     
    #define FIELD_TYPE_DOUBLE 0 //DOUBLE有符号整形
    #define FIELD_TYPE_DOUBLE_U 1 //DOUBLE无符号整形
    #define FIELD_TYPE_FLOAT 2 //FLOAT有符号整形
    #define FIELD_TYPE_FLOAT_U 3 //FLOAT无符号整形
    #define FIELD_TYPE_INT 4 //有符号整形(4字节)
    #define FIELD_TYPE_INT_U 5 //无符号整形(4字节)
    #define FIELD_TYPE_SHORT 6 //有符号短整形(2字节)
    #define FIELD_TYPE_SHORT_U 7 //无符号短整形(2字节)
    #define FIELD_TYPE_CHAR 8 //有符号字符(2字节)
    #define FIELD_TYPE_CHAR_U 9 //无符号字符(2字节)
    #define FIELD_TYPE_STRING 10 //字符串
    #define FTILD_TYPE_TIME 11 //时间
     
    //描述：js格式解析，只处理一层的js格式
    struct TJS{ 
    	char *Field;  //客户定义的字段
    	int FieldType; //字段的格式类型，如整形，字符串
    	cJSON *pJON; //json解析之后的字符串数据，实际使用时需将字符串转化成对应字段Field的数据
    };
     
    //根据客户定义的js字段填充如下结构体
    struct TJS g_TJsCfg[] = { 
    	{ "startTime", FTILD_TYPE_TIME},
    	{ "endTime", FTILD_TYPE_TIME},
    	{ "UUID", FIELD_TYPE_STRING},
    	{ "subDeviceID", FTILD_TYPE_TIME},
    	{ "UserType", FIELD_TYPE_INT},
    	{ "CredenceType", FIELD_TYPE_INT},
    	{ "credenceNo", FIELD_TYPE_STRING},
    	{ "userName", FIELD_TYPE_STRING},
    	{ "userID", FIELD_TYPE_STRING},
    	{ "opTime", FTILD_TYPE_TIME},
    	{ "placeNo", FIELD_TYPE_STRING},
    	{ "placeLockNo", FIELD_TYPE_STRING},
    };
     
    int g_iJsCfgNum = sizeof(g_TJsCfg)/sizeof(g_TJsCfg[0]);
     
    //描述：以下根据具体的需求提取数据，这里只是纯粹的用于验证JSON解析的数据是否正确
    void printf_js(cJSON *pJSON, int FieldType)
    { 
    	switch(FieldType)
    	{ 
    	case FIELD_TYPE_DOUBLE:
    	case FIELD_TYPE_DOUBLE_U:	
    		printf("Name: %s, Data:%s\n", pJSON->string, pJSON->valuestring);
    		break;
    	case FIELD_TYPE_FLOAT:
    		break;
    	case FIELD_TYPE_FLOAT_U:
    		break;
    	case FIELD_TYPE_INT:
    	case FIELD_TYPE_INT_U:
    		printf("Name: %s, Data:%s\n", pJSON->string, pJSON->valuestring);
    		break;
    	case FIELD_TYPE_SHORT:
    		break;
    	case FIELD_TYPE_SHORT_U:
    		break;
    	case FIELD_TYPE_CHAR:
    		break;
    	case FIELD_TYPE_CHAR_U:
    		break;
    	case FIELD_TYPE_STRING:
    	case FTILD_TYPE_TIME:
    		printf("Name: %s, Data:%s\n", pJSON->string, pJSON->valuestring);
    		break;
    	default:
    		printf("Unsupport fmt:%d\n", FieldType);
    	}
    }
     
    void parse_js(void)
    { 
    	//假设接收到客户的js字段数据为
    	char *pRevJson = "{\"startTime\":\"2017-11-10 08:00:01\",\ \"endTime\":\"2020-11-10 08:00:01\",\ \"UUID\":\"ca23bc4456de223de11a3a7a8ac1d2e3\",\ \"subDeviceID\":\"2020-11-10 08:00:01\",\ \"UserType\":\"1\",\ \"CredenceType\":\"5\",\ \"credenceNo\":\"粤A123456\",\ \"userName\":\"张三\",\ \"userID\":\"1002\",\ \"opTime\":\"2017-11-10 08:00:01\",\ \"placeNo\":\"CA12001\",\ \"placeLockNo\":\"1234566\"\ }";
    	
    	int idx;
     
    	
    	//1. 初始化接收到的客户端json数据
    	cJSON *root = cJSON_Parse(pRevJson); 
    	if(!root) { 
    		printf("get root faild !\n");
    		return;
    	}
    	//2. 解析客户的数据
    	for (idx=0; idx<g_iJsCfgNum; idx++)
    		g_TJsCfg[idx].pJON = cJSON_GetObjectItem(root, g_TJsCfg[idx].Field);
    	
    	//3. 提取客户的数据
    	for (idx=0; idx<g_iJsCfgNum; idx++)
    	{ 
    		if (g_TJsCfg[idx].pJON)
    			printf_js(g_TJsCfg[idx].pJON, g_TJsCfg[idx].FieldType);
    		else
    			printf("Name:%s, No data!\n", g_TJsCfg[idx].pJON->string);
    	}
    	
    	//4. 释放内存，防止内存泄露！！！
    	if (root)
    		cJSON_Delete(root);
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NTMwOTkxNg_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/f1e9cf84417e4038993ba060bc933a9c.png