根据SQL语句生成Java Bean

未优化版本！
 

    private String tablename = "";
    private String[] colnames;
    private String[] colTypes;
    private int[] colSizes; // 列名大小
    private int[] colScale; // 列名小数精度
    private boolean importUtil = false;
    private boolean importSql = false;
    private boolean importMath = false;


    public void tableToEntity(String tName) throws Exception {
        tablename = tName;
        //数据连Connection获取,自己想办法就行.
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/oa", "root", "root");
        String strsql = "SELECT * FROM " + tablename + " limit 1";//读一行记录
        try {
            PreparedStatement pstmt = conn.prepareStatement(strsql);
            pstmt.executeQuery();
            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];
            colScale = new int[size];
            for (int i = 0; i < rsmd.getColumnCount(); i++) {
                rsmd.getCatalogName(i + 1);
                colnames[i] = rsmd.getColumnName(i + 1).toLowerCase();
                colTypes[i] = rsmd.getColumnTypeName(i + 1).toLowerCase();
                colScale[i] = rsmd.getScale(i + 1);
                if ("datetime".equals(colTypes[i])) {
                    importUtil = true;
                }
                if ("image".equals(colTypes[i]) || "text".equals(colTypes[i])) {
                    importSql = true;
                }
                if (colScale[i] > 0) {
                    importMath = true;
                }
                colSizes[i] = rsmd.getPrecision(i + 1);
            }

            String[] s = tablename.split("_");
            String str = "";
            if (s.length <= 1) {
                str = initcap(s[0]);
            } else {
                str = initcap(s[0]);
                for (int v = 1; v < s.length; v++) {
                    str += initcap(s[v]);
                }
            }
            tablename = str;

            String content = parse();
            try {
                FileWriter fw = new FileWriter(initcap(tablename) + ".java");
                PrintWriter pw = new PrintWriter(fw);
                pw.println(content);
                pw.flush();
                pw.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 解析处理(生成实体类主体代码)
     */
    private String parse() {
        StringBuffer sb = new StringBuffer();
        sb.append("package com.husa.pojos;");
        sb.append("\r\nimport java.io.Serializable;\r\n");
        sb.append("\r\nimport lombok.Data;\r\n");
        sb.append("\r\nimport lombok.experimental.Accessors;\r\n");
        sb.append("\r\nimport javax.persistence.GeneratedValue;\r\n");
        sb.append("\r\nimport javax.persistence.Id;\r\n");
        if (importUtil) {
            sb.append("import java.time.LocalDateTime;\r\n");
        }
        if (importSql) {
            sb.append("import java.sql.*;\r\n\r\n");
        }
        if (importMath) {
            sb.append("import java.math.*;\r\n\r\n");
        }
        sb.append("@Data\r\n");
        sb.append("@Accessors(chain = true)\r\n");
        sb.append("public class " + tablename + " implements Serializable {\r\n");
        processAllAttrs(sb);
        sb.append("}\r\n");
        return sb.toString();
    }

    /**
     * 解析输出属性
     *
     * @return
     */
    private void processAllAttrs(StringBuffer sb) {
        sb.append("\tprivate static final long serialVersionUID = 1L;\r\n");
        sb.append("\t @Id\r\n");
        sb.append("\t@GeneratedValue(generator = \"JDBC\")\r\n");

        for (int i = 0; i < colnames.length; i++) {
            String[] s = colnames[i].split("_");
            String str = "";
            if (s.length <= 1) {
                str = s[0];
            } else {
                str = s[0];
                for (int v = 1; v < s.length; v++) {
                    str += initcap(s[v]);
                }
            }
            sb.append("\tprivate " + oracleSqlType2JavaType(colTypes[i], colScale[i], colSizes[i]) + " "
                    + str + ";\r\n");
        }
        sb.append("\r\n");
    }

    /**
     * 把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);
    }

    /**
     * 设别类型
     *
     * @param sqlType
     * @param scale
     * @return
     */
    private String oracleSqlType2JavaType(String sqlType, int scale, int size) {
        if (sqlType.equals("integer")) {
            return "Integer";
        } else if (sqlType.equals("long")) {
            return "Long";
        } else if (sqlType.equals("float")
                || sqlType.equals("float precision")
                || sqlType.equals("double")
                || sqlType.equals("double precision")
        ) {
            return "BigDecimal";
        } else if (sqlType.equals("number")
                || sqlType.equals("decimal")
                || sqlType.equals("numeric")
                || sqlType.equals("real")) {
            return scale == 0 ? (size < 10 ? "Integer" : "Long") : "BigDecimal";
        } else if (sqlType.equals("varchar")
                || sqlType.equals("varchar2")
                || sqlType.equals("char")
                || sqlType.equals("nvarchar")
                || sqlType.equals("nchar")) {
            return "String";
        } else if (sqlType.equals("datetime")
                || sqlType.equals("date")
                || sqlType.equals("timestamp")) {
            return "LocalDateTime";
        } else if (sqlType.equalsIgnoreCase("TINYINT")) {
            return "Boolean";
        } else if (sqlType.equalsIgnoreCase("INT")) {
            return "Integer";
        }
        return null;
    }

    public static void main(String[] args) throws Exception {
        Demo t = new Demo();
        // 获取 javaBean
        t.tableToEntity("table_name");
    }