本代码是利用java反射,读取数据库表自动根据表名生成实体类,数据库采用老牌SQLSERVER 2000,驱动为JTDS,其他数据库可根据情况自定修改。
代码中包含了大部分数据库类型与JAVA类型的转换,少数未包含进去的会在生成代码时打印出来,方面后期查找修改。
本文章参考大牛文章,根据自己情况改写,非常感谢大牛提供思路,原文章地址为:https://blog.csdn.net/goodleiwei/article/details/8439023。
import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.PrintWriter; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.text.SimpleDateFormat; import java.util.Date; /** * 从数据库表反射出实体类,自动生成实体类 * * @author Zero * */ public class SqlHelper { //基本数据配置 private String packageOutPath = "com.xxx.entity.system";// 指定实体生成所在包的路径 private String authorName = "Zero";// 作者名字 private String tablename = "xxx";// 表名 private String[] colnames; // 列名数组 private String[] colTypes; // 列名类型数组 private String version = "V0.01"; // 版本 private int[] colSizes; // 列名大小数组 private boolean f_util = false; // 是否需要导入包java.util.* private boolean f_sql = false; // 是否需要导入包java.sql.* private boolean f_lang = false; // 是否需要导入包java.sql.* private String defaultPath = "/src/main/java/"; // 数据库连接 private static final String URL = "jdbc:jtds:sqlserver://192.168.29.128:1433/xxx"; private static final String NAME = "sa"; private static final String PASS = "xxx"; private static final String DRIVER = "net.sourceforge.jtds.jdbc.Driver"; /* * 构造函数 */ public SqlHelper() { // 创建连接 Connection con; // 查要生成实体类的表 String sql = "select * from " + tablename; PreparedStatement pStemt = null; try { try { Class.forName(DRIVER); } catch (ClassNotFoundException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } con = DriverManager.getConnection(URL, NAME, PASS); pStemt = con.prepareStatement(sql); ResultSetMetaData rsmd = pStemt.getMetaData(); int size = rsmd.getColumnCount(); // 统计列 colnames = new String[size]; colTypes = new String[size]; colSizes = new int[size]; for (int i = 0; i < size; i++) { colnames[i] = rsmd.getColumnName(i + 1); colTypes[i] = rsmd.getColumnTypeName(i + 1); //自动生成包配置 // if (colTypes[i].equalsIgnoreCase("datetime")) { // f_util = true; // } if (colTypes[i].equalsIgnoreCase("image") || colTypes[i].equalsIgnoreCase("text") || colTypes[i].equalsIgnoreCase("datetime") || colTypes[i].equalsIgnoreCase("time") || colTypes[i].equalsIgnoreCase("date") || colTypes[i].equalsIgnoreCase("datetime2")) { f_sql = true; } // if (colTypes[i].equalsIgnoreCase("int")) { // f_lang = true; // } colSizes[i] = rsmd.getColumnDisplaySize(i + 1); } String content = parse(colnames, colTypes, colSizes); try { File directory = new File(""); String path = this.getClass().getResource("").getPath(); System.out.println(path); String outputPath = directory.getAbsolutePath() + this.defaultPath + this.packageOutPath.replace(".", "/") + "/" + initcap(tablename) + ".java"; System.out.println("执行完毕,生成路径为:"+outputPath); FileWriter fw = new FileWriter(outputPath); PrintWriter pw = new PrintWriter(fw); pw.println(content); pw.flush(); pw.close(); } catch (IOException e) { e.printStackTrace(); } } catch (SQLException e) { e.printStackTrace(); } finally { } } /** * 功能:生成实体类主体代码 * * @param colnames * @param colTypes * @param colSizes * @return */ private String parse(String[] colnames, String[] colTypes, int[] colSizes) { StringBuffer sb = new StringBuffer(); // 生成package包路径 sb.append("package " + this.packageOutPath + ";\r\n"); // 判断是否导入工具包 if (f_util) { sb.append("import java.util.Date;\r\n"); } if (f_sql) { sb.append("import java.sql.*;\r\n"); } if (f_lang) { sb.append("import java.lang.*;\r\n"); } sb.append("\r\n"); // 注释部分 sb.append(" /**\r\n"); sb.append(" * @文件名称:" + this.tablename + ".java\r\n"); sb.append(" * @创建时间:" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()) + "\r\n"); sb.append(" * @创 建 人:" + this.authorName + " \r\n"); sb.append(" * @文件描述:" + tablename + " 实体类\r\n"); sb.append(" * @文件版本:" + this.version + " \r\n"); sb.append(" */ \r\n"); // 实体部分 sb.append("\r\n\r\npublic class " + initcap(tablename) + "{\r\n"); processAllAttrs(sb);// 属性 processAllMethod(sb);// get set方法 sb.append("}\r\n"); // System.out.println(sb.toString()); return sb.toString(); } /** * 功能:生成所有属性 * * @param sb */ private void processAllAttrs(StringBuffer sb) { for (int i = 0; i < colnames.length; i++) { sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + colnames[i] + ";\r\n"); } } /** * 功能:生成所有方法 * * @param sb */ private void processAllMethod(StringBuffer sb) { for (int i = 0; i < colnames.length; i++) { sb.append("\tpublic void set" + initcap(colnames[i]) + "(" + sqlType2JavaType(colTypes[i]) + " " + colnames[i] + "){\r\n"); sb.append("\tthis." + colnames[i] + "=" + colnames[i] + ";\r\n"); sb.append("\t}\r\n"); sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnames[i]) + "(){\r\n"); sb.append("\t\treturn " + colnames[i] + ";\r\n"); sb.append("\t}\r\n"); } } /** * 功能:将输入字符串的首字母改成大写 * * @param str * @return */ private String initcap(String str) { char[] ch = str.toCharArray(); if (ch[0] >= 'a' && ch[0] <= 'z') { ch[0] = (char) (ch[0] - 32); } return new String(ch); } /** * 功能:获得列的数据类型 * * @param sqlType * @return */ private String sqlType2JavaType(String sqlType) { if (sqlType.equalsIgnoreCase("bit")) { return "Boolean"; } else if (sqlType.equalsIgnoreCase("decimal") || sqlType.equalsIgnoreCase("money") || sqlType.equalsIgnoreCase("smallmoney") || sqlType.equalsIgnoreCase("numeric") || sqlType.equalsIgnoreCase("bigint")) { return "Long"; } else if (sqlType.equalsIgnoreCase("float")) { return "Double"; } else if (sqlType.equalsIgnoreCase("int") || sqlType.equalsIgnoreCase("int identity")) { return "Integer"; } else if (sqlType.equalsIgnoreCase("image") || sqlType.equalsIgnoreCase("varbinary(max)") || sqlType.equalsIgnoreCase("varbinary") || sqlType.equalsIgnoreCase("udt") || sqlType.equalsIgnoreCase("timestamp") || sqlType.equalsIgnoreCase("binary")) { return "Byte[]"; } else if (sqlType.equalsIgnoreCase("nchar") || sqlType.equalsIgnoreCase("nvarchar(max)") || sqlType.equalsIgnoreCase("nvarchar") || sqlType.equalsIgnoreCase("nvarchar(ntext)") || sqlType.equalsIgnoreCase("uniqueidentifier") || sqlType.equalsIgnoreCase("xml") || sqlType.equalsIgnoreCase("char") || sqlType.equalsIgnoreCase("varchar(max)") || sqlType.equalsIgnoreCase("text") || sqlType.equalsIgnoreCase("varchar")) { return "String"; } else if (sqlType.equalsIgnoreCase("real")) { return "Float"; } else if (sqlType.equalsIgnoreCase("smallint") || sqlType.equalsIgnoreCase("tinyint")) { return "Short"; } else if (sqlType.equalsIgnoreCase("date") || sqlType.equalsIgnoreCase("datetime") || sqlType.equalsIgnoreCase("time") || sqlType.equalsIgnoreCase("datetime2")) { return "Date"; } else { System.out.println("数据类型异常,类型为:" + sqlType); } return null; } /** * 出口 TODO * * @param args */ public static void main(String[] args) { new SqlHelper(); } }