美团龙猫利用expat库实现的保存xml指定范围数据到csv的C程序

用自己代码逐个字符解析的速度较慢，尝试了libxml2也比较慢，它需要一次性读入内存，而expat库支持流式读取。就让龙猫写了一个程序，毕竟是久经考验的库，程序很快就调试通过了。要不是我一开始没信心，让他先输出10行试试，还能少走很多弯路。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <expat.h>#define MAX_CELL_CONTENT 256// 解析范围
typedef struct {int start_row;int end_row;char start_col;char end_col;
} ParseRange;// 全局结果存储
typedef struct {int row;char col;char value[MAX_CELL_CONTENT];
} CellResult;// 范围检查
int is_cell_in_range(int row, char col, ParseRange range) {return (row >= range.start_row && row <= range.end_row &&col >= range.start_col && col <= range.end_col);
}
// 全局结果存储（动态数组）
typedef struct {CellResult *data;     // 动态数组int count;            // 当前数量int capacity;         // 当前容量
} DynamicResults;DynamicResults all_results = {0}; // 全局变量// 初始化动态数组
void init_results() {all_results.capacity = 1024;  // 初始容量all_results.data = malloc(all_results.capacity * sizeof(CellResult));all_results.count = 0;
}// 扩容动态数组
void ensure_capacity(int needed) {if (all_results.count + needed >= all_results.capacity) {all_results.capacity *= 2;  // 翻倍扩容all_results.data = realloc(all_results.data, all_results.capacity * sizeof(CellResult));}
}// 添加结果（无限制版本）
void add_cell_result(int row, char col, const char *value, int is_empty) {ensure_capacity(1);  // 确保有空间all_results.data[all_results.count].row = row;all_results.data[all_results.count].col = col;strncpy(all_results.data[all_results.count].value, value, MAX_CELL_CONTENT - 1);all_results.count++;
}// 释放内存
void free_results() {free(all_results.data);all_results.data = NULL;all_results.count = all_results.capacity = 0;
}// 解析Excel范围 (如"A1:Z100")
int parse_excel_range(const char *range_str, ParseRange *range) {if (sscanf(range_str, "%c%d:%c%d", &range->start_col, &range->start_row,&range->end_col, &range->end_row) != 4) {return -1;}if (range->start_col > range->end_col) return -1;if (range->start_row > range->end_row) return -1;return 0;
}// 解析器状态
typedef struct {ParseRange range;int in_row;int current_row;char current_col;int value_started;char temp_value[MAX_CELL_CONTENT];int value_len;int rows_parsed;  // 已解析行数
} ParserState;// 开始标签回调
void XMLCALL start_element(void *user_data, const XML_Char *name, const XML_Char **attrs) {ParserState *state = (ParserState*)user_data;if (strcmp(name, "row") == 0) {state->in_row = 1;state->current_row = -1;// 解析行号属性for (int i = 0; attrs[i]; i += 2) {if (strcmp(attrs[i], "r") == 0) {state->current_row = atoi(attrs[i+1]);state->rows_parsed++;break;}}if(1==0)printf("解析行 %d\n", state->current_row);}else if (strcmp(name, "c") == 0 && state->in_row) {// 解析列属性for (int i = 0; attrs[i]; i += 2) {if (strcmp(attrs[i], "r") == 0) {state->current_col = attrs[i+1][0];break;}}}else if (strcmp(name, "v") == 0 || strcmp(name, "t") == 0) {if (state->current_row >= state->range.start_row && state->current_row <= state->range.end_row) {state->value_started = 1;state->value_len = 0;state->temp_value[0] = '\0';}}
}// 文本内容回调
void XMLCALL character_data(void *user_data, const XML_Char *s, int len) {ParserState *state = (ParserState*)user_data;if (state->value_started && state->value_len + len < MAX_CELL_CONTENT - 1) {memcpy(state->temp_value + state->value_len, s, len);state->value_len += len;state->temp_value[state->value_len] = '\0';}
}// 结束标签回调
void XMLCALL end_element(void *user_data, const XML_Char *name) {ParserState *state = (ParserState*)user_data;if (strcmp(name, "row") == 0) {state->in_row = 0;}else if ((strcmp(name, "v") == 0 || strcmp(name, "t") == 0) && state->value_started) {if (is_cell_in_range(state->current_row, state->current_col, state->range)) {if(1==0)printf("  单元格 %c%d: '%s'\n", state->current_col, state->current_row, state->temp_value);add_cell_result(state->current_row, state->current_col, state->temp_value, 0);}state->value_started = 0;}
}// 主解析函数
int parse_sheet_xml(const char *filename, ParseRange range) {XML_Parser parser = XML_ParserCreate(NULL);ParserState state = {0};state.range = range;XML_SetUserData(parser, &state);XML_SetElementHandler(parser, start_element, end_element);XML_SetCharacterDataHandler(parser, character_data);FILE *file = fopen(filename, "rb");if (!file) {printf("错误: 无法打开文件 %s\n", filename);XML_ParserFree(parser);return -1;}char buffer[8192];int done;do {size_t len = fread(buffer, 1, sizeof(buffer), file);done = (len < sizeof(buffer));if (XML_Parse(parser, buffer, len, done) == XML_STATUS_ERROR) {printf("解析错误: %s (行 %d)\n", XML_ErrorString(XML_GetErrorCode(parser)),XML_GetCurrentLineNumber(parser));break;}} while (!done);fclose(file);XML_ParserFree(parser);return 0;
}
/*** 输出CSV文件* @param filename 输出文件名*/
int save_results_to_csv(const char *filename) {FILE *csv = fopen(filename, "w");if (!csv) {printf("错误: 无法创建CSV文件 %s\n", filename);return -1;}// 计算列范围char min_col = all_results.data[0].col;char max_col = all_results.data[0].col;for (int i = 1; i < all_results.count; i++) {if (all_results.data[i].col < min_col) min_col = all_results.data[i].col;if (all_results.data[i].col > max_col) max_col = all_results.data[i].col;}// 输出标题fprintf(csv, "Row");for (char col = min_col; col <= max_col; col++) {fprintf(csv, ",%c", col);}    fprintf(csv, "\n");// 数据行int current_row = all_results.data[0].row;int row_start_idx = 0;for (int i = 0; i < all_results.count; i++) {	if (all_results.data[i].row != current_row) {// 输出当前行fprintf(csv, "%d", current_row);for (char col = min_col; col <= max_col; col++) {int found = 0;for (int j = row_start_idx; j < i; j++) {if (all_results.data[j].col == col) {fprintf(csv, ",%s", all_results.data[j].value);found = 1;break;}}if (!found) fprintf(csv, ",");}fprintf(csv, "\n");// 下一行current_row = all_results.data[i].row;row_start_idx = i;}}fclose(csv);printf("CSV已保存到 %s\n", filename);return 0;
}// 主函数
int main(int argc, char *argv[]) {if (argc != 3) {printf("用法: %s <xml文件> <范围(A1:Z100)>\n", argv[0]);return 1;}ParseRange range;if (parse_excel_range(argv[2], &range) != 0) {printf("错误: 无效范围格式，应为 A1:Z100\n");return 1;}printf("解析范围: %c%d:%c%d\n", range.start_col, range.start_row, range.end_col, range.end_row);init_results();   if (parse_sheet_xml(argv[1], range) == 0) {// 生成CSV文件名（替换.xml为.csv）char csv_filename[256];strncpy(csv_filename, argv[1], sizeof(csv_filename) - 1);char *ext = strrchr(csv_filename, '.');if (ext) strcpy(ext, ".csv");else strncat(csv_filename, ".csv", sizeof(csv_filename) - strlen(csv_filename) - 1);// 输出CSVsave_results_to_csv(csv_filename);}   free_results();   return 0;
}

编译执行

gcc -o expatxml3 expatxml3.c -lexpat -O3
time ./expatxml3 lineitem/xl/worksheets/sheet1.xml A1:Z10000
解析范围: A1:Z10000
CSV已保存到 lineitem/xl/worksheets/sheet1.csvreal    0m6.508s
user    0m2.132s
sys     0m0.392s
time ./expatxml3 lineitem/xl/worksheets/sheet1.xml A100001:Z110000
解析范围: A100001:Z110000
CSV已保存到 lineitem/xl/worksheets/sheet1.csvreal    0m6.534s
user    0m2.111s
sys     0m0.431s
time ./expatxml3 lineitem/xl/worksheets/sheet1.xml A1:Z1000000
解析范围: A1:Z1000000
CSV已保存到 lineitem/xl/worksheets/sheet1.csvreal    0m10.207s
user    0m3.046s
sys     0m1.795s
time ./expatxml3 lineitem/xl/worksheets/sheet1.xml A300000:Z660000
解析范围: A300000:Z660000
CSV已保存到 lineitem/xl/worksheets/sheet1.csvreal    0m9.378s
user    0m2.574s
sys     0m1.030s

针对60万行16列，300MB xml, 这个时间还不错，但是没有考虑sharedstrings.xml，否则会慢一些。