生成代码路径、基本信息及数据库配置

    private String packageOutPath = "main.java.com.demo.code.entity";//指定实体生成所在包的路径
    private String packagePath = "com.demo.code.entity";//实体类包头
    private String authorName = "Zhang Wei";//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://localhost:3306/demo?useUnicode=true&characterEncoding=utf-8&useSSL=false";
    private static final String NAME = "root";  
    private static final String PASS = "password";
    private static final String DRIVER ="com.mysql.jdbc.Driver";  

自动生成实体类完整代码

package com.demo.code;

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.List;

/** 
 * 从数据库表反射出实体类，自动生成实体类 
 * @author Zhang Wei
 * 
 */
public class GenEntityMysql {
      
    private String packageOutPath = "main.java.com.demo.code.entity";//指定实体生成所在包的路径
    private String packagePath = "com.demo.code.entity";//实体类包头
    private String authorName = "Zhang Wei";//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://localhost:3306/demo?useUnicode=true&characterEncoding=utf-8&useSSL=false";
    private static final String NAME = "root";  
    private static final String PASS = "password";
    private static final String DRIVER ="com.mysql.jdbc.Driver";  
  
    /* 
     * 构造函数 
     */  
    public GenEntityMysql(){  
        //获取所有的表名
        List<String> list=getTableName();  
        
        for(int p=0;p<list.size();p++){  
            tablename = list.get(p);  
            //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) {  
                    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);  
                      
                    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(".", "/")+"/"+initcap(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{   
            }  
        }  
        System.out.println("生成完毕！");  
    }  
    /** 
      * Java方法 得到当前数据库下所有的表名
      */  
    private List<String> getTableName() {  
         List<String> list=new ArrayList<String>();  
         try {    
             DatabaseMetaData meta = DriverManager.getConnection(URL,NAME,PASS).getMetaData();    
             ResultSet rs = meta.getTables(null, null, null,new String[]{"TABLE"});  
             while (rs.next()) {  
                 list.add(rs.getString(3));    
             }    
           }catch(Exception e){    
               e.printStackTrace();    
           }  
        return list;  
     }  
    /** 
     * 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();  
        //包路径
        sb.append("package " + this.packagePath + ";\r\n");  
        sb.append("\r\n");  


        sb.append("import java.io.Serializable;\r\n");
        //如果存在时间类型的字段，加入Date引用
        if(f_util){
            sb.append("import java.util.Date;\r\n\r\n");
        }
        
        //引用
        sb.append("import javax.persistence.*;\r\n");
        sb.append("import lombok.AllArgsConstructor;\r\n");
        sb.append("import lombok.Builder;\r\n");
        sb.append("import lombok.Data;\r\n");
        sb.append("import lombok.NoArgsConstructor;\r\n");
        sb.append("import lombok.ToString;\r\n");
        
        //注解
        sb.append("@Data\r\n");  
        sb.append("@Builder\r\n");  
        sb.append("@NoArgsConstructor\r\n");  
        sb.append("@AllArgsConstructor\r\n");  
        sb.append("@ToString\r\n");  
        sb.append("@Entity\r\n");  
        sb.append("@Table(name = \"" + tablename + "\" )\r\n");
        
        //实体部分  
        sb.append("public class " + initcap(tablename) + " implements Serializable {\r\n\r\n");
        //序列化
        sb.append("\tprivate static final long serialVersionUID = 1L;\r\n\r\n");
        processAllAttrs(sb);//属性  
        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++) {  
            //字段下划线分割处理
            String rStr = "";
            String[] strs = colnames[i].split("_");
            if(strs.length > 1){
                for (int j = 0; j < strs.length; j++) {
                    
                    char[] chc = strs[j].toCharArray();  
                    if(j > 0){
                        if(chc[0] >= 'a' && chc[0] <= 'z'){  
                            chc[0] = (char)(chc[0] - 32);  
                        }
                    }
                    rStr += new String(chc);
                }
            }else{
                rStr = colnames[i];
            }
            //id列单独增加注解标识
            if(rStr.equals("id")){
                sb.append("\t@Id\r\n\t@GeneratedValue(strategy = GenerationType.IDENTITY)\r\n");
            }
            //组装属性
            sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + rStr + ";\r\n\r\n");  
        }  
        sb.append("\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);  
        }  
        //特殊需要对_进行分割组装
        String rStr = "";
        String[] strs = str.split("_");
        for (int i = 0; i < strs.length; i++) {
            char[] chc = strs[i].toCharArray();  
            if(chc[0] >= 'a' && chc[0] <= 'z'){  
                chc[0] = (char)(chc[0] - 32);  
            }
            strs[i] = new String(chc);
            rStr += strs[i];
        }
        
        return new String(rStr);  
    }  
  
    /** 
     * 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")){  
            //INT UNSIGNED无符号整形  
            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;  
    }  
    
    public static void main(String[] args) {
        new GenEntityMysql();
    }
    
}

pom.xml依赖包

<!-- MySql -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!-- lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.18</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.0</version>
        </dependency>