Java 工具类自动生成实体类文件

在一些程序中，实体类是数据不可缺少的一部分，简单点说就是属性类，通常定义在model层里面。一般的实体类对应一个数据表，其中的属性对应数据表中的字段。属性可以对字段定义和状态进行判断和过滤，把相关信息用一个实体类封装后，在程序中可以把实体类作为参数传递，更加方便。然而，当数据表中字段过多时，就不好写了，需要一个一个地封装，显得有点麻烦，而且浪费时间，所以，弄了一个工具类，根据表名去查询该表的字段生成实体类，代码如下：

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;

public class TableToPo {
	private String tablename = "SYS_MaterType";// 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.*
	private boolean f_math = false;// 是否需要导入包java.math.*
	public TableToPo() {
		Connection con = Dbutil.getConnection();
		PreparedStatement ps = null;
		ResultSetMetaData rs = null;
		String strsql = "select * from " + tablename;
		try {
			ps = con.prepareStatement(strsql);
			rs = ps.getMetaData();
			int size = rs.getColumnCount();
			colnames = new String[size];
			colTypes = new String[size];
			colSizes = new int[size];
			for (int i = 0; i < rs.getColumnCount(); i++) {
				colnames[i] = rs.getColumnName(i + 1);
				colTypes[i] = rs.getColumnTypeName(i + 1);
				if (colTypes[i].equalsIgnoreCase("datetime")
						|| colTypes[i].equalsIgnoreCase("date")
						|| colTypes[i].equalsIgnoreCase("smalldatetime")
						|| colTypes[i].equalsIgnoreCase("time")) {
					f_sql = true;
				}
				if (colTypes[i].equalsIgnoreCase("money")
						|| colTypes[i].equalsIgnoreCase("decimal")
						|| colTypes[i].equalsIgnoreCase("smallmoney")
						|| colTypes[i].equalsIgnoreCase("numeric")) {
					f_math = true;
				}
				colSizes[i] = rs.getColumnDisplaySize(i + 1);
			}
			String content = parse(colnames, colTypes, colSizes);
			FileWriter fileWriter = new FileWriter(initcap(tablename) + ".java");
			PrintWriter pw = new PrintWriter(fileWriter);
			pw.println(content);
			pw.flush();
			pw.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			try {
				ps.close();
				con.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		}
	}
	/**
	 * 解析处理(生成实体类主体代码)
	 */
	private String parse(String[] colNames, String[] colTypes, int[] colSizes) {
		StringBuffer sb = new StringBuffer();
		if (f_util) {
			sb.append("import java.util.Date;\r\n");
		}
		if (f_sql) {
			sb.append("import java.sql.*;\r\n");
		}
		if (f_math) {
			sb.append("import java.math.BigDecimal;\r\n\r\n\r\n");
		}
		sb.append("public class " + initcap(tablename) + " {\r\n");
		processAllAttrs(sb);
		processAllMethod(sb);
		sb.append("}\r\n");
		System.out.println(sb.toString());
		return sb.toString();
	}
	/**
	 * 生成所有的方法
	 * 
	 * @param sb
	 */
	private void processAllMethod(StringBuffer sb) {
		for (int i = 0; i < colnames.length; i++) {
			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");
			sb.append("\tpublic void set" + initcap(colnames[i]) + "("
					+ sqlType2JavaType(colTypes[i]) + " " + colnames[i]
					+ "){\r\n");
			sb.append("\t\tthis." + colnames[i] + "=" + colnames[i] + ";\r\n");
			sb.append("\t}\r\n");

		}
	}
	/**
	 * 解析输出属性
	 * 
	 * @return
	 */
	private void processAllAttrs(StringBuffer sb) {
		for (int i = 0; i < colnames.length; i++) {
			sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " "
					+ colnames[i] + ";\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);
	}

	private String sqlType2JavaType(String sqlType) {
		if (sqlType.equalsIgnoreCase("bit")) {
			return "Boolean";
		} else if (sqlType.equalsIgnoreCase("timestamp")
				|| sqlType.equalsIgnoreCase("binary")
				|| sqlType.equalsIgnoreCase("image")
				|| sqlType.equalsIgnoreCase("varbinary")) {
			return "byte[]";
		} else if (sqlType.equalsIgnoreCase("smallint")
				|| sqlType.equalsIgnoreCase("tinyint")) {
			return "short";
		} else if (sqlType.equalsIgnoreCase("int")) {
			return "Integer";
		} else if (sqlType.equalsIgnoreCase("bigint")) {
			return "long";
		} else if (sqlType.equalsIgnoreCase("real")) {
			return "float";
		} else if (sqlType.equalsIgnoreCase("real")
				|| sqlType.equalsIgnoreCase("float")) {
			return "double";
		} else if (sqlType.equalsIgnoreCase("money")
				|| sqlType.equalsIgnoreCase("decimal")
				|| sqlType.equalsIgnoreCase("smallmoney")
				|| sqlType.equalsIgnoreCase("numeric")) {
			return "BigDecimal";
		} else if (sqlType.equalsIgnoreCase("varchar")
				|| sqlType.equalsIgnoreCase("char")
				|| sqlType.equalsIgnoreCase("nvarchar")
				|| sqlType.equalsIgnoreCase("nchar")
				|| sqlType.equalsIgnoreCase("text")
				|| sqlType.equalsIgnoreCase("ntext")
				|| sqlType.equalsIgnoreCase("uniqueidentifier")) {
			return "String";
		} else if (sqlType.equalsIgnoreCase("date")) {
			return "Date";//Date
		} else if (sqlType.equalsIgnoreCase("smalldatetime")
				|| sqlType.equalsIgnoreCase("datetime")) {
			return "Timestamp";
		} else if (sqlType.equalsIgnoreCase("time")) {
			return "Time";
		}
		return null;
	}
	public static void main(String[] args) {
		new TableToPo();
	}
}

工具类执行效果：