在 Java 中判断 Shapefile（.shp）的编码（特别是属性表 .dbf 的编码），由于 Shapefile 本身不直接存储编码信息（除非有.cpg文件），我们可以采取以下策略：
- 优先检查是否存在
.cpg文件，若有则直接读取其内容； - 若无
.cpg文件，则尝试用常见编码（如 UTF-8、GBK）读取 .dbf 文件的字段名或记录内容，通过是否出现乱码或解码异常来判断。
Java 生态中常用读取 Shapefile 的库是GeoTools。下面提供一个完整的 Java 示例代码，使用 GeoTools 实现自动检测编码。具体代码实现如下：
import org.geotools.data.shapefile.ShapefileDataStore; import org.geotools.data.simple.SimpleFeatureCollection; import org.geotools.data.simple.SimpleFeatureIterator; import org.geotools.data.simple.SimpleFeatureSource; import org.opengis.feature.simple.SimpleFeature; import org.opengis.feature.simple.SimpleFeatureType; import java.io.BufferedReader; import java.io.IOException; import java.nio.charset.Charset; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.Arrays; import java.util.List; import java.util.regex.Pattern; public class ShapefileEncodingDetector { private static final List<String> CANDIDATE_ENCODINGS = Arrays.asList("UTF-8", "GBK", "GB2312"); private static final Pattern CHINESE_PATTERN = Pattern.compile("[\u4e00-\u9fff]"); private static final Pattern OBVIOUS_GARBAGE_PATTERN = Pattern.compile(".*[\?]{2,}.*|[\x00-\x08\x0B\x0C\x0E-\x1F].*"); /** * 严谨检测 Shapefile 编码（JDK 8 兼容） */ public static String detectEncoding(String shpFilePath) { Path shpPath = Paths.get(shpFilePath); if (!shpPath.toString().toLowerCase().endsWith(".shp")) { shpPath = Paths.get(shpFilePath + ".shp"); } // Step 1: Check .cpg file (JDK 8 compatible read) Path cpgPath = shpPath.resolveSibling(shpPath.getFileName().toString().replace(".shp", ".cpg")); if (Files.exists(cpgPath)) { String encodingFromCpg = readCpgFile(cpgPath); if (encodingFromCpg != null && Charset.isSupported(encodingFromCpg)) { System.out.println("[INFO] Encoding from .cpg: " + encodingFromCpg); return encodingFromCpg; } } String bestEncoding = null; // Step 2: Try candidate encodings for (String encoding : CANDIDATE_ENCODINGS) { try { ShapefileDataStore store = new ShapefileDataStore(shpPath.toUri().toURL()); store.setCharset(Charset.forName(encoding)); SimpleFeatureSource source = store.getFeatureSource(); SimpleFeatureType schema = source.getSchema(); boolean valid = true; boolean currentHasChinese = false; // Validate field names for (int i = 0; i < schema.getAttributeCount(); i++) { String fieldName = schema.getDescriptor(i).getLocalName(); if (isObviousGarbage(fieldName)) { valid = false; break; } if (containsChinese(fieldName)) { currentHasChinese = true; } } if (!valid) { store.dispose(); continue; } // Validate first few feature attribute values SimpleFeatureCollection features = source.getFeatures(); SimpleFeatureIterator iter = features.features(); try { int count = 0; while (iter.hasNext() && count < 5) { SimpleFeature feature = iter.next(); for (Object attr : feature.getAttributes()) { if (attr == null) continue; String value = attr.toString(); if (isObviousGarbage(value)) { valid = false; break; } if (containsChinese(value)) { currentHasChinese = true; } } if (!valid) break; count++; } } finally { iter.close(); // JDK 8 没有 try-with-resources for AutoCloseable in older GeoTools? } store.dispose(); if (valid) { if (currentHasChinese) { System.out.println("[INFO] Valid encoding with Chinese detected: " + encoding); return encoding; } else { if (bestEncoding == null) { bestEncoding = encoding; } } } } catch (Exception e) { // Skip this encoding continue; } } if (bestEncoding != null) { System.out.println("[INFO] No Chinese found, using safe fallback: " + bestEncoding); return bestEncoding; } System.out.println("[WARN] All encodings failed, defaulting to UTF-8"); return "UTF-8"; } /** * JDK 8 兼容方式读取 .cpg 文件（纯文本，单行编码名） */ private static String readCpgFile(Path cpgPath) { try { // 使用默认字符集（通常是 UTF-8）读取 .cpg，因为 .cpg 本身是 ASCII/UTF-8 StringBuilder content = new StringBuilder(); try (BufferedReader reader = Files.newBufferedReader(cpgPath)) { String line; while ((line = reader.readLine()) != null) { content.append(line.trim()); break; // .cpg 通常只有一行 } } return content.toString().trim(); } catch (IOException e) { System.err.println("[WARN] Failed to read .cpg file: " + e.getMessage()); return null; } } /** * 判断字符串是否包含中文字符 */ private static boolean containsChinese(String s) { return s != null && CHINESE_PATTERN.matcher(s).find(); } /** * 判断是否为明显乱码 */ private static boolean isObviousGarbage(String s) { if (s == null || s.isEmpty()) return false; if (OBVIOUS_GARBAGE_PATTERN.matcher(s).matches()) { return true; } long badCharCount = 0; for (char c : s.toCharArray()) { if (c == '?' || c == '\ufffd') { badCharCount++; } } return badCharCount >= 2 || (s.length() > 0 && (double) badCharCount / s.length() > 0.3); }
