自动生成Java实体类

JDBC读取数据库元数据,生成JAVA实体类
package com.nffish.util;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import com.nffish.common.DBSession;
public class GenEntityTool {
    private String tablename = "petDiary";
    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.*
    public GenEntityTool() {
        Connection conn = DBSession.getConnection(); // 得到数据库连接
        String strsql = "select * from " + tablename;
        try {
            PreparedStatement pstmt = conn.prepareStatement(strsql);
            ResultSetMetaData rsmd = pstmt.getMetaData();
            int size = rsmd.getColumnCount(); // 共有多少列
            colnames = new String[size];
            colTypes = new String[size];
            colSizes = new int[size];
            for (int i = 0; i < rsmd.getColumnCount(); i++) {
                colnames[i] = rsmd.getColumnName(i + 1);
                colTypes[i] = rsmd.getColumnTypeName(i + 1);
        &n