在我们参考别人项目时候特别是SSM项目没有sql文件的时候我们如何由实体类生成数据库表
接下来就和大家一起探讨这个问题
package ltd.newbee.mall;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/***
*
* @Author : 吟雪情枫
* @Description 根据实体类生成建库语句
* @Version : v1.0.0
* @Date : Created in 2020/7/31 10:12
* @Modified By :
**/
public class SqlGenerator {
private static final Logger logger = LoggerFactory.getLogger(SqlGenerator.class);
/**
* 用来存储Java等属性类型与sql中属性类型的对照
* </br>
* 例如：java.lang.Integer 对应 integer
*/
public static Map<String, String> map = new HashMap<>();
public static void main(String[] args) {
map.put("class java.lang.String", "varchar(255)");
map.put("class java.lang.Integer", "int");
map.put("class java.lang.Long", "integer unsigned");
map.put("class java.lang.byte[]", "blob");
map.put("class java.lang.Boolean", "bit");
map.put("class java.math.BigInteger", "bigint unsigned");
map.put("class java.lang.Float", "float");
map.put("class java.lang.Double", "float");
map.put("class java.sql.Date", "datetime");
map.put("class java.sql.Time", "time");
map.put("class java.sql.Timestamp", "datetime");
map.put("class java.util.Date", "datetime");
map.put("class java.lang.Byte", "tinyint");
sqlConstruction();
}
/**
* 生成sql建库语句
*/
private static void sqlConstruction() {
//实体类所在的package在磁盘上的绝对路径
String packageName = "F:/article/newbee-mall/src/main/java/ltd/newbee/mall/entity";
//生成sql的文件夹
String filePath = "F:/article/newbee-mall/newbee";
//项目中实体类的路径
String prefix = "ltd.newbee.mall.entity.";
String className = "";
StringBuffer sqls = new StringBuffer();
//获取包下的所有类名称
List<String> list = getAllClasses(packageName);
for (String str : list) {
className = prefix + str.substring(0, str.lastIndexOf("."));
String sql = generateSql(className, filePath);
sqls.append(sql);
}
System.out.println(sqls.toString());
StringToSql(sqls.toString(), filePath + ".sql");
}
/**
* 根据实体类生成建表语句
*
* @param className 全类名
* @param filePath 磁盘路径
* @return
*/
public static String generateSql(String className, String filePath) {
try {
Class<?> clz = Class.forName(className);
className = clz.getSimpleName();
// 表表名adminUser → tb_admin_user
className = "tb_" + getStandardFields(className);
Field[] fields = clz.getDeclaredFields();
StringBuffer column = new StringBuffer();
String varchar = " CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,";
for (Field f : fields) {
if ("class java.lang.String".equals(f.getType().toString())){
column.append(" \n `" + getStandardFields(f.getName()) + "`" + " " + map.get(f.getType().toString())).append(varchar);
}else {
column.append(" \n `" + getStandardFields(f.getName()) + "`" + " " + map.get(f.getType().toString())).append(",");
}
}
StringBuffer sql = new StringBuffer();
sql.append("\n DROP TABLE IF EXISTS `" + className + "`; ")
.append(" \n CREATE TABLE `" + className + "` (")
.append(" \n `id` int(11) NOT NULL AUTO_INCREMENT,")
.append(" \n " + column)
.append(" \n PRIMARY KEY (`id`) USING BTREE,")
.append("\n INDEX `id`(`id`) USING BTREE")
.append(" \n ) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8 COLLATE = utf8_general_ci;");
return sql.toString();
} catch (ClassNotFoundException e) {
logger.debug("该类未找到！");
return null;
}
}
/**
* 转换为标准等sql字段 例如 adminUser → admin_user
*
* @param str 转换为字符串的字段名
* @return
*/
public static String getStandardFields(String str) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (i != 0 && (c > 'A' && c < 'Z')) {
sb.append("_");
}
sb.append(c);
}
return sb.toString();
}
/**
* 获取包下面等所有实体类名称，类似于获取 XXX.java
*
* @param packageName 全类名
* @return
*/
public static List<String> getAllClasses(String packageName) {
List<String> classList = new ArrayList();
String className = "";
File f = new File(packageName);
if (f.exists() && f.isDirectory()) {
File[] files = f.listFiles();
// 遍历实体类下面等所有.java文件 获取其类名
for (File file : files) {
className = file.getName();
classList.add(className);
}
return classList;
} else {
logger.debug("包路径未找到！");
return null;
}
}
/**
* 将生成等String字符串 写进sql文件
*
* @param str String字符串
* @param path sql文件路径路径
*/
public static void StringToSql(String str, String path) {
byte[] sourceByte = str.getBytes();
FileOutputStream os = null;
if (null != sourceByte) {
try {
//文件路径（路径+文件名）
File file = new File(path);
//文件不存在则创建文件，先创建目录
if (!file.exists()) {
File dir = new File(file.getParent());
dir.mkdirs();
file.createNewFile();
}
//文件输出流用于将数据写入文件
os = new FileOutputStream(file);
os.write(sourceByte);
os.flush();
System.out.println("生成成功!!");
} catch (Exception e) {
e.printStackTrace();
} finally {
// 关闭文件输出流
try {
if (os != null) {
os.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
欢迎大家在下方留言一起谈论一起改善
一起完善该代码块 欢迎一起讨论！！！！
