Java根据实体生成SQL数据库表的示例代码

林译川

2026-10-13 • 👁 0人浏览过

本文主要给大家分享了两个版本的Java代码，都能实现一键生成实体类建表SQL，大家可以根据自己的需求选择

1.0版本的完整代码

这是一个自动生成 SQL 语句的类，只需要修改变量 CLS 的参数为对应类（如User.class），然后执行main方法，就可以得到该类的建表SQL语句，以及对应的插入模拟SQL。

package com.zyq.util;import java.lang.reflect.Field;import java.util.Date;import java.util.LinkedHashMap;import java.util.Map;import java.util.Objects;import com.zyq.entity.Command;import io.swagger.annotations.ApiModel;import io.swagger.annotations.ApiModelProperty;/*** 这是一个自动生成 SQL 语句的类，只需要修改变量 CLS 的参数为对应类（如User.class） * 然后执行main方法，就可以得到该类的建表SQL语句，以及对应的插入模拟SQL。


** @author ZhangYuanqiang* @since 2021年4月13日*/ public class CreateTableSqlUtil {private static final Class CLS = Command.class;private static final String LINE = "\r\n";private static Map map = new LinkedHashMap();public static void main(String[] args) throws Exception {// 获取建表 SQL createSQL();// 获取（参数条）测试数据 SQL createInsertData(2);}/*** 获取建表SQL（执行后控制台会自动输出建表语句SQL）
** @throws Exception*/ private static void createSQL() throws Exception {StringBuilder sb = new StringBuilder();sb.append("CREATE TABLE `").append(getSqlAttrName(CLS.getSimpleName())).append("` (").append(LINE);sb.append("  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID',").append(LINE);sb.append("  `create_time` datetime DEFAULT NULL COMMENT '创建时间',").append(LINE);sb.append("  `update_time` datetime DEFAULT NULL COMMENT '创建时间',").append(LINE);sb.append("  `deleted` smallint DEFAULT 0 COMMENT '是否已删除：0-未删除，1-已删除',").append(LINE);sb.append("  `version` smallint DEFAULT 0 COMMENT '版本号',").append(LINE);// 获取其他参数Field[] fields = CLS.getDeclaredFields();for (Field field : fields) {String type = field.getType().getSimpleName();String key = getSqlAttrName(field.getName());String comment = getComment(field, false);switch (type) {case "String":sb.append("  `").append(key).append("` varchar(255) DEFAULT NULL COMMENT ").append(comment).append(",").append(LINE);break;case "int":case "Integer":comment = getComment(field, true);if (isStatusAndType(field.getName())) {sb.append("  `").append(key).append("` smallint(2) DEFAULT 0 COMMENT ").append(comment).append(",").append(LINE);} else {sb.append("  `").append(key).append("` int(11) DEFAULT 0 COMMENT ").append(comment).append(",").append(LINE);}break;case "long":case "Long":comment = getComment(field, true);sb.append("  `").append(key).append("` bigint(20) DEFAULT 0 COMMENT ").append(comment).append(",").append(LINE);break;case "Date":sb.append("  `").append(key).append("` datetime DEFAULT NULL COMMENT ").append(comment).append(",").append(LINE);break;default:throw new Exception("未知属性类型：" + type);}}sb.append("  PRIMARY KEY (`id`)").append(LINE);sb.append(") ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 COMMENT'").append(getApiModelName()).append("表';").append(LINE);System.out.println("-- 创建表SQL");System.out.println(sb.toString());}/*** 创建测试数据 SQL（控制台会自动打印SQL）

** @param size_需要生成多少条测试数据*/ private static void createInsertData(int size) {if (size <= 0) {return;}System.out.println("-- 测试数据 " + size + " 条");long id = 1;String date = "'" + DateUtil.formatDateTime(new Date()) + "'";for (int i = 0; i < size; i++) {String attrs = "";String params = "";for (String attr : map.keySet()) {attrs += ", " + attr;params += ", " + map.get(attr);}String sql = String.format("INSERT INTO " + getSqlAttrName(CLS.getSimpleName())+ " (id, create_time, update_time %s) VALUES (%s, %s, %s %s);",attrs, id, date, date, params);id++;System.out.println(sql);}}private static String getSqlAttrName(String attr) {char[] array = attr.toCharArray();StringBuilder sb = new StringBuilder();int idx = 0;for (char c : array) {if (c >= 'a' && c <= 'z') {sb.append(c);} else {if (idx > 0) {sb.append("_");}sb.append(String.valueOf(c).toLowerCase());}idx++;}return sb.toString();}private static String getApiModelName() {ApiModel model = CLS.getAnnotation(ApiModel.class);if (Objects.isNull(model)) {return "";}return BaseUtil.getString(model.value());}private static String getComment(Field field, boolean isNumber) {String sqlFiledName = getSqlAttrName(field.getName());ApiModelProperty property = field.getAnnotation(ApiModelProperty.class);if (Objects.isNull(property)) {if (isNumber) {map.put(sqlFiledName, "0");} else {map.put(sqlFiledName, "NULL");}return "''";}// 是否有默认值String expmale = BaseUtil.getString(property.example());if (isNumber) {map.put(sqlFiledName, expmale);} else {map.put(sqlFiledName, "'" + expmale + "'");}return "'" + BaseUtil.getString(property.value()) + "'";}private static boolean isStatusAndType(String s) {s = s.toLowerCase();return s.endsWith("status") || s.endsWith("type");}}

2.0版实体生成建表SQL的完整代码

package com.zyq.ok;import java.io.*;import java.lang.invoke.SerializedLambda;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import java.math.BigDecimal;import java.time.LocalDate;import java.util.*;import java.util.function.Function;/*** @author Yuanqiang.Zhang* @since 2023/7/5*/ public class ClassUtils {public static void main(String[] args) throws Exception {Table table = getTable(User.class);System.out.println(table.sql());}/*** Java类转化为数据库表对象** @param c java实体类* @param 泛型* @return 数据库表对象*/ private static Table getTable(Class c) {List codes = getClassSourceCodes(c);Map columnMap = getFieldColumnMap(c, codes);Class superclass = c.getSuperclass();if (Objects.nonNull(superclass)) {if (superclass != Object.class) {List sourceCodes = getClassSourceCodes(c);Map superColumnMap = getFieldColumnMap(superclass, sourceCodes);columnMap.putAll(superColumnMap);}}if (columnMap.isEmpty()) {return null;}// 获取主键（如果包含名为 id 的属性，则以 id 为主键，否则，则取类中第一个属性为主键）


Column key;if (columnMap.containsKey("id")) {key = columnMap.get("id");} else {key = columnMap.entrySet().stream().findFirst().get().getValue();}// 剩下的则是其他属性LinkedList columns = new LinkedList<>(columnMap.values());if (!columns.get(0).getName().equals(key.getName())) {Column copyKey = key.copy();columns.remove(key);columns.addFirst(copyKey);}Table table = new Table();table.setName(getSqlName(c.getSimpleName()));table.setComment(getTableComment(codes));table.setColumns(columns);return table;}private static  Map getFieldColumnMap(Class c, List codes) {Map fieldCommentMap = getClassFieldComment(codes, c.getSimpleName());Field[] fields = c.getDeclaredFields();Map columnMap = new LinkedHashMap<>();for (Field field : fields) {if (!Modifier.isStatic(field.getModifiers())) {String fieldName = field.getName();String columnName = getSqlName(fieldName);Column column = new Column();column.setName(columnName);column.setType(getSqlType(field));column.setComment(fieldCommentMap.get(fieldName));columnMap.put(fieldName, column);}}return columnMap;}/*** 获取 mysql 数据类型** @param field java 属性* @return mysql的*/ private static String getSqlType(Field field) {Class type = field.getType();String name = getSqlName(field.getName());if (type == String.class) {return "varchar(255)";} else if (type == int.class || type == Integer.class) {if (Constant.TINYINT_WORDS.contains(name)) {return "tinyint(4)";}if (name.startsWith("is_") || name.endsWith("_type") || name.endsWith("_status")) {return "tinyint(4)";}return "int(11)";} else if (type == long.class || type == Long.class) {return "bigint(20)";} else if (type == double.class || type == Double.class) {// 最大为 (53, 15) return "double(20,2)";} else if (type == boolean.class || type == Boolean.class) {return "boolean";} else if (type == Date.class || type == LocalDate.class) {return "datetime";} else if (type == BigDecimal.class) {// 最大为 decimal(65, 30) return "decimal(20,2)";} else {// 其他类型则不处理return null;}}/*** 获取类文件源码内容** @param clazz 类对象* @return 类源码内容*/ private static List getClassSourceCodes(Class clazz) {String classPath = clazz.getName().replace(Constant.POINT, Constant.LEFT_LINE) + Constant.POINT_JAVA;String filePath;if (new File(Constant.POM_XML).exists()) {filePath = Constant.SRC_MAIN_JAVA + classPath;} else {filePath = Constant.SRC + classPath;}File file = new File(filePath);List lines = new ArrayList<>();try (BufferedReader reader = new BufferedReader(new FileReader(file))) {String line;while ((line = reader.readLine()) != null) {lines.add(line);}} catch (IOException e) {e.printStackTrace();}return lines;}/*** 获取表备注（默认取类文档注释第一行文字）
** @param codes 类源码内容* @return 表备注*/ private static String getTableComment(List codes) {if (codes.isEmpty()) {return null;}// 按规范来说，第一个格式为 [ * xxx] 的行，即为表的文档注释String comment = null;for (String line : codes) {String trimLine = line.trim();if (trimLine.startsWith(Constant.STAR) && line.length() > 1) {comment = trimLine.substring(1).trim();break;}}if (Objects.isNull(comment)) {return null;}// 按SQL表备注习惯来说，一般称为[xxx表]，因此如果备注不以"表"字结尾，我们这里补加上if (comment.endsWith(Constant.TABLE)) {return comment;}return comment + Constant.TABLE;}/*** 获取类属性注释（文档注释、多行注释、单行注释、行尾注释）
** @param codes 类源码内容* @return 表备注*/ private static Map getClassFieldComment(List codes, String className) {boolean fieldLineStart = false;Map filedCommentMap = new LinkedHashMap<>();String comment = null;boolean commentStart = false;for (int i = 0; i < codes.size(); i++) {String code = codes.get(i).trim();if (!fieldLineStart) {if (code.contains(String.format("class %s", className))) {fieldLineStart = true;}continue;}if (commentStart) {String str = trim(code, Constant.CHAR_STAR).trim();if (!str.isEmpty()) {comment = str;commentStart = false;continue;}} else {if (code.startsWith("/*")) {commentStart = true;if (code.endsWith("*/")) {comment = getSingleLineDocComment(code);commentStart = false;continue;}}if (code.startsWith("//")) {comment = code.substring(2).trim();commentStart = false;continue;}}// 如果进入方法区域，则停止解析if (code.contains("(") && code.contains(")") && code.endsWith("{")) {return filedCommentMap;}// 属性判定if (code.contains(";") && !code.startsWith("//")) {String fileLine = code;if (code.contains("//")) {String[] arr = code.split("//");if (arr.length > 1 && Objects.isNull(comment)) {comment = arr[1].trim();}fileLine = arr[0];}String fieldName = getFieldName(fileLine);filedCommentMap.put(fieldName, comment);comment = null;commentStart = false;}}return filedCommentMap;}private static String getFieldName(String s) {String[] arr = s.split(" ");for (int i = arr.length - 1; i >= 0; i--) {String str = arr[i];if (!str.isEmpty() && !str.equals(";")) {return str.replace(";", "");}}return "";}/*** 获取单行文档注释** @param code 单行注释* @return 注释内容*/ private static String getSingleLineDocComment(String code) {// code 应该长这样（/*xxx*/），我们可以先取中间的xxx String xxx = code.substring(2, code.length() - 2);// xxx 首尾可能还包含 *，需要进一步将 xxx 首尾多余的 * 去掉，剩下的就是注释return trim(xxx, Constant.CHAR_STAR).trim();}/*** 去掉首尾指定的符号（该方法参考的是String类中的trim()方法）

** @param s 字符串* @param c 去掉的指定符号* @return 不包含首尾指定字符*/ public static String trim(String s, char c) {int var1 = s.length();int var2 = 0;char[] var3;for (var3 = s.toCharArray(); var2 < var1 && var3[var2] <= c; ++var2) {}while (var2 < var1 && var3[var1 - 1] <= c) {--var1;}return var2 <= 0 && var1 >= s.length() ? s : s.substring(var2, var1);}/*** 根据驼峰命名获取下划线命名** @param javaName java的驼峰命名* @return sql中的下划线命名*/ private static String getSqlName(String javaName) {StringBuilder sqlName = new StringBuilder();for (int i = 0; i < javaName.length(); i++) {char c = javaName.charAt(i);if (Character.isUpperCase(c)) {if (i > 0) {sqlName.append(Constant.UNDERLINE);}sqlName.append(Character.toLowerCase(c));} else {sqlName.append(c);}}return sqlName.toString();}/*** 常量类*/ static class Constant {private static final String POM_XML = "pom.xml";private static final String POINT = ".";private static final String LEFT_LINE = "/";private static final String POINT_JAVA = ".java";private static final String SRC = "src/";private static final String SRC_MAIN_JAVA = "src/main/java/";private static final String STAR = "*";private static final String TABLE = "表";private static final String UNDERLINE = "_";private static final char CHAR_STAR = '*';private static final List TINYINT_WORDS = Arrays.asList("deleted", "sex", "age", "status", "type", "state");}/*** SQL表*/ static class Table {private String tablePrefix;private String columnPrefix;private String name;private String comment;private LinkedList columns;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getComment() {return comment;}public void setComment(String comment) {this.comment = comment;}public List getColumns() {return columns;}public void setColumns(LinkedList columns) {this.columns = columns;}public String getTablePrefix() {return tablePrefix;}public void setTablePrefix(String tablePrefix) {this.tablePrefix = tablePrefix;}public String getColumnPrefix() {return columnPrefix;}public void setColumnPrefix(String columnPrefix) {this.columnPrefix = columnPrefix;}public String sql() {if (Objects.isNull(columns)) {columns = new LinkedList<>();}List lines = new ArrayList<>();String tableName;if (Objects.nonNull(tablePrefix)) {tableName = tablePrefix + name;} else {tableName = name;}lines.add(String.format("CREATE TABLE `%s` (", tableName));Column key = columns.get(0);String type = key.getType();if (type.startsWith("tinyint") || type.startsWith("int") || type.startsWith("bigint")) {key.setIncreased(true);String comment = key.getComment();if (Objects.isNull(comment) || comment.isEmpty()) {key.setComment("主键");}}for (int i = 0; i < columns.size(); i++) {if (columns.get(i).isEffective()) {lines.add(columns.get(i).sql(columnPrefix));}}if (key.isEffective()) {lines.add(String.format(" PRIMARY KEY (`%s`)", key.getName()));}StringBuffer sb = new StringBuffer();sb.append(") ENGINE=InnoDB");if (key.isEffective() && key.isIncreased()) {sb.append(" AUTO_INCREMENT=1");}sb.append(" DEFAULT CHARSET=utf8");if (Objects.isNull(comment)) {sb.append(" COMMENT='';");} else {sb.append(" COMMENT='").append(comment).append("';");}lines.add(sb.toString());return String.join("\n", lines);}public Table key(SerializableFunction fn) {String newKeyName = getSqlName(getFieldName(fn));Column find = null;for (Column column : columns) {if (column.getName().equals(newKeyName)) {find = column;}}if (Objects.nonNull(find)) {Column copy = find.copy();columns.remove(find);columns.addFirst(copy);}return this;}public Table column(SerializableFunction fn, String type, String comment, String defaultValue) {String fieldName = getFieldName(fn);String columnName = getSqlName(fieldName);for (Column column : columns) {if (column.getName().equals(columnName)) {if (Objects.nonNull(type)) {column.setType(type);}if (Objects.nonNull(comment)) {column.setComment(comment);}if (Objects.nonNull(defaultValue)) {column.setDefaultValue(defaultValue);}break;}}return this;}public Table invalid(SerializableFunction... fns) {if (Objects.nonNull(fns)) {for (SerializableFunction fn : fns) {String fieldName = getFieldName(fn);String columnName = getSqlName(fieldName);for (Column column : columns) {if (column.getName().equals(columnName)) {column.setEffective(false);break;}}}}return this;}private static String getFieldName(SerializableFunction func) {// 通过获取对象方法，判断是否存在该方法String getter = null;try {Method method = func.getClass().getDeclaredMethod("writeReplace");method.setAccessible(Boolean.TRUE);// 利用jdk的SerializedLambda 解析方法引用SerializedLambda serializedLambda = (SerializedLambda) method.invoke(func);getter = serializedLambda.getImplMethodName();} catch (Exception e) {e.printStackTrace();}if (Objects.isNull(getter)) {return null;}String fieldName;if (getter.startsWith("get")) {fieldName = getter.substring(3);} else if (getter.startsWith("is")) {fieldName = getter.substring(2);} else {fieldName = getter;}return Character.toLowerCase(fieldName.charAt(0)) + fieldName.substring(1);}}/*** SQL表字段*/ static class Column {private String name;private String type;private String comment;private String defaultValue;private boolean effective = true;private boolean increased;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getType() {return type;}public void setType(String type) {this.type = type;}public String getComment() {return comment;}public void setComment(String comment) {this.comment = comment;}public String getDefaultValue() {return defaultValue;}public void setDefaultValue(String defaultValue) {this.defaultValue = defaultValue;}public boolean isEffective() {return effective;}public void setEffective(boolean effective) {this.effective = effective;}public boolean isIncreased() {return increased;}public void setIncreased(boolean increased) {this.increased = increased;}public Column copy() {Column copy = new Column();copy.setName(this.name);copy.setType(this.getType());copy.setComment(this.comment);copy.setDefaultValue(this.defaultValue);copy.setEffective(this.effective);copy.setIncreased(this.increased);return copy;}public String sql(String columnPrefix) {StringBuffer sb = new StringBuffer();// 字段名称sb.append("`");if (Objects.nonNull(columnPrefix)) {sb.append(columnPrefix);}sb.append(name).append("`");// 字段类型sb.append(" ").append(type);// 是否自增if (increased) {sb.append(" NOT NULL AUTO_INCREMENT");} else {// 默认值if (Objects.isNull(defaultValue)) {if (type.startsWith("tinyint") || type.startsWith("int") || type.startsWith("bigint")) {sb.append(" DEFAULT 0");} else if (type.startsWith("varchar")) {sb.append(" DEFAULT ''");} else {sb.append(" DEFAULT NULL");}} else {sb.append(" DEFAULT '").append(defaultValue).append("'");}}// 备注if (Objects.isNull(comment)) {sb.append(" COMMENT ''");} else {sb.append(" COMMENT '").append(comment).append("'");}return " " + sb + ",";}}@FunctionalInterface public interface SerializableFunction extends Function, Serializable {}}到此这篇关于Java根据实体生成SQL数据库表的示例代码的文章就介绍到这了,更多相关Java实体生成数据库表内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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