一个工具类就可以实现啦，直接看代码及注释，很方便理解，从一位博主那里拿到加上自己优化一部分的

注：侵删（忘了原博主信息）

Mysql2EntityGenerator.java

/*** @(#) GenEntityMysql.java 2017-2-8 下午3:06:18* * Copyright (c) 2014-2015 Diyvc, Inc.* 103 Sports Road, Victoria Plaza tower 1104, Tianhe District Guangzhou City, China.* All rights reserved.**/
package com.frend.controller;import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;public class Mysql2EntityGenerator {private String packageOutPath = "com.test.domain";//指定实体生成所在包的路径private String authorName = "frend";//作者名字private String tablename = "";//表名private String[] colnames; // 列名数组private String[] colTypes; //列名类型数组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.*//数据库连接private static final String URL ="jdbc:mysql://127.0.0.1:3306/sqlname";private static final String NAME = "root";private static final String PASSWORD = "root";private static final String DRIVER ="com.mysql.jdbc.Driver";/** 构造函数*/public Mysql2EntityGenerator(Connection con,String tableName){this.tablename = tableName;//创建连接//查要生成实体类的表String sql = "select * from " + tablename;PreparedStatement pStemt = null;try {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);if(colTypes[i].equalsIgnoreCase("datetime")){f_util = true;}if(colTypes[i].equalsIgnoreCase("image") || colTypes[i].equalsIgnoreCase("text")){f_sql = true;}colSizes[i] = rsmd.getColumnDisplaySize(i + 1);}String content = parse(colnames,colTypes,colSizes);try {File directory = new File("");String outputPath = directory.getAbsolutePath()+ "/src/"+this.packageOutPath.replace(".", "/")+"/"+parseName(tablename) + ".java";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();sb.append("package " + this.packageOutPath + ";\r\n");sb.append("\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");}sb.append("import javax.persistence.Column;\r\n");sb.append("import javax.persistence.Entity;\r\n");sb.append("import javax.persistence.GeneratedValue;\r\n");sb.append("import javax.persistence.GenerationType;\r\n");sb.append("import javax.persistence.Id;\r\n");sb.append("import javax.persistence.Table;\r\n");sb.append("import javax.persistence.Temporal;\r\n");sb.append("import javax.persistence.TemporalType;\r\n");sb.append("import org.springframework.format.annotation.DateTimeFormat;\r\n");//注释部分sb.append("   /**\r\n");sb.append("    * "+tablename+" 实体类\r\n");sb.append("    * "+new Date()+" "+this.authorName+"\r\n");sb.append("    */ \r\n");//实体部分sb.append("@Entity\r\n");sb.append("@Table(name = \""+tablename+"\")\r\n");sb.append("public class " + parseName(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++) {String column = parseNameNotFirst(colnames[i]);if(column.equals("fileSize")){System.out.println("here");}sb.append("\r\n");if("id".equals(column)){sb.append("\t@Id\r\n");sb.append("\t@GeneratedValue(strategy = GenerationType.IDENTITY)\r\n");sb.append("\t@Column(name = \""+colnames[i]+"\", unique = true, nullable = false)\r\n");}else{sb.append("\t@Column(name = \""+colnames[i]+"\")\r\n");}if("Date".equals(sqlType2JavaType(colTypes[i]))){sb.append("\t@DateTimeFormat(pattern = \"yyyy-MM-dd HH:mm:ss\")\r\n");sb.append("\t@Temporal(value = TemporalType.TIMESTAMP)\r\n");}sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + column + ";\r\n");}}/*** 功能：生成get、set方法* @param sb*/private void processAllMethod(StringBuffer sb) {for (int i = 0; i < colnames.length; i++) {sb.append("\r\n");sb.append("\tpublic void set" + parseName(colnames[i]) + "(" + sqlType2JavaType(colTypes[i]) + " " + parseNameNotFirst(colnames[i]) + "){\r\n");sb.append("\t\tthis." + parseNameNotFirst(colnames[i]) + "=" + parseNameNotFirst(colnames[i]) + ";\r\n");sb.append("\t}\r\n");sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + parseName(colnames[i]) + "(){\r\n");sb.append("\t\treturn " + parseNameNotFirst(colnames[i]) + ";\r\n");sb.append("\t}\r\n");}}/*** 描述：第一个首字母不大写，后面大写* @param name* @return* String*/public String parseNameNotFirst(String name){StringBuffer sb = new StringBuffer();String[] array = name.split("_");if(array.length > 0){for (int i = 0; i < array.length; i++) {if (i>0) {sb.append(initcap(array[i]));}else{sb.append(array[i]);}}}return sb.toString();}/*** 描述：全部首字母大写* @param name* @return* String*/public String parseName(String name){StringBuffer sb = new StringBuffer();String[] array = name.split("_");if(array.length > 0){for (String string : array) {sb.append(initcap(string));}}return sb.toString();}/*** 功能：将输入字符串的首字母改成大写（修改成驼峰法）* @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("tinyint")){return "Byte";}else if(sqlType.equalsIgnoreCase("smallint")){return "Short";}else if(sqlType.equalsIgnoreCase("int") || sqlType.equalsIgnoreCase("INT UNSIGNED")){return "Integer";}else if(sqlType.equalsIgnoreCase("bigint")){return "Long";}else if(sqlType.equalsIgnoreCase("float")){return "Float";}else if(sqlType.equalsIgnoreCase("decimal") || sqlType.equalsIgnoreCase("numeric") || sqlType.equalsIgnoreCase("real") || sqlType.equalsIgnoreCase("money") || sqlType.equalsIgnoreCase("smallmoney")){return "Double";}else if(sqlType.equalsIgnoreCase("varchar") || sqlType.equalsIgnoreCase("char") || sqlType.equalsIgnoreCase("nvarchar") || sqlType.equalsIgnoreCase("nchar") || sqlType.equalsIgnoreCase("text")){return "String";}else if(sqlType.equalsIgnoreCase("datetime")){return "Date";}else if(sqlType.equalsIgnoreCase("image")){return "Blod";}return null;}/*** 出口* TODO* @param args*/public static void main(String[] args) {List<String> tableList = new ArrayList<String>();Connection con;try {Class.forName(DRIVER);con = DriverManager.getConnection(URL,NAME,PASSWORD);DatabaseMetaData  dm = con.getMetaData();ResultSet rs  = dm.getTables(con.getCatalog(), "root", null, new String[]{"TABLE"});while(rs.next()) {tableList.add(rs.getString("TABLE_NAME"));System.out.println("得到表名："+rs.getString("TABLE_NAME"));}/*if (tableList!=null) {for (String tableName : tableList) {new GenEntityMysql(con,tableName);}}*/new Mysql2EntityGenerator(con,"file_attachment_info");} catch (ClassNotFoundException e1) {e1.printStackTrace();} catch (SQLException e) {e.printStackTrace();}}}

欢迎斧正，另附源码及jar包下载地址（下载支持，谢谢）

http://download.csdn.net/detail/qq_22876421/9755773