初始化项目

data/src/main/ets/io/JsonCodec.ets

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+/**
+ * JSON 导入导出（1.8.5）。
+ *
+ * 导出行对象数组：[{"id":"1","name":"alice"}, …]。
+ * 导入要求为对象数组；缺列按空值补齐，并检查列集合一致性（不一致记为警告）。
+ * 解析失败返回错误而非抛异常。
+ */
+export interface JsonParseResult {
+  header: string[];
+  rows: string[][];
+  errors: string[];
+  warnings: string[];
+}
+
+export class JsonCodec {
+  static serialize(header: string[], rows: string[][]): string {
+    const objects: Map<string, string>[] = [];
+    for (let i = 0; i < rows.length; i++) {
+      const obj: Map<string, string> = new Map<string, string>();
+      for (let j = 0; j < header.length; j++) {
+        const value: string | undefined = rows[i][j];
+        obj.set(header[j], value === undefined ? '' : value);
+      }
+      objects.push(obj);
+    }
+    const plain: Record<string, string>[] = [];
+    for (let i = 0; i < objects.length; i++) {
+      const record: Record<string, string> = {};
+      objects[i].forEach((value: string, key: string) => {
+        record[key] = value;
+      });
+      plain.push(record);
+    }
+    return JSON.stringify(plain, null, 2);
+  }
+
+  static parse(text: string): JsonParseResult {
+    const errors: string[] = [];
+    const warnings: string[] = [];
+    let parsed: Object | null = null;
+    try {
+      parsed = JSON.parse(text) as Object;
+    } catch (e) {
+      const message: string = e instanceof Error ? e.message : String(e);
+      return { header: [], rows: [], errors: ['invalid JSON: ' + message], warnings: [] };
+    }
+    if (!Array.isArray(parsed)) {
+      return { header: [], rows: [], errors: ['top-level JSON value must be an array'], warnings: [] };
+    }
+    const array: Object[] = parsed as Object[];
+    if (array.length === 0) {
+      return { header: [], rows: [], errors: [], warnings: ['empty array'] };
+    }
+    const header: string[] = [];
+    const first: Object = array[0];
+    if (first === null || Array.isArray(first) || typeof first !== 'object') {
+      return { header: [], rows: [], errors: ['array items must be objects'], warnings: [] };
+    }
+    const firstRecord: Record<string, Object> = first as Record<string, Object>;
+    for (const key in firstRecord) {
+      header.push(key);
+    }
+    const rows: string[][] = [];
+    for (let i = 0; i < array.length; i++) {
+      const item: Object = array[i];
+      if (item === null || Array.isArray(item) || typeof item !== 'object') {
+        errors.push('item ' + i + ' is not an object');
+        continue;
+      }
+      const record: Record<string, Object> = item as Record<string, Object>;
+      const row: string[] = [];
+      for (let j = 0; j < header.length; j++) {
+        const value: Object = record[header[j]];
+        if (value === undefined) {
+          warnings.push('item ' + i + ' missing key ' + header[j]);
+          row.push('');
+        } else {
+          row.push(JsonCodec.stringifyValue(value));
+        }
+      }
+      for (const key in record) {
+        if (header.indexOf(key) < 0) {
+          warnings.push('item ' + i + ' has extra key ' + key + ' not in header');
+        }
+      }
+      rows.push(row);
+    }
+    return { header: header, rows: rows, errors: errors, warnings: warnings };
+  }
+
+  private static stringifyValue(value: Object): string {
+    if (value === null) {
+      return '';
+    }
+    if (typeof value === 'string') {
+      return value as string;
+    }
+    if (typeof value === 'number' || typeof value === 'boolean') {
+      return String(value);
+    }
+    return JSON.stringify(value);
+  }
+}