java--生成实体类方法

    由于工作中使用eclipse开发，没有安装hibernate插件，所以无法使用自动生成实体类的功能，为了方便在网上找了段别人写的自动生成实体类方法，稍加修改，直接运行就可以生成对应表的实体类。

    注意使用时方法中的数据库地址、用户名、密码要改下，还有要记得录入想要生成实体类的表明，private String tablename = "ad_campaign";

 

方法如下：

package com.test;

import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

public class CreateBean {
	private String tablename = "ad_campaign";

	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 String url = "jdbc:mysql://localhost:3306/haierdb";
	private String user = "permitdbuser";
	private String pwd = "permitdbpwd";

	public Connection getConnection() {
		Connection conn = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection(url, user, pwd);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}

	public void createBeanMethod() {
		Connection conn = getConnection(); // 得到数据库连接
	    //myDB为数据库名
		String strsql = "select * from " + tablename;
		PreparedStatement pstmt = null;
		ResultSetMetaData rsmd = null;
		try {
			pstmt = conn.prepareStatement(strsql);
			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);
				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 {
				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 {
				pstmt.close();
				conn.close();
			} catch (SQLException e) {
				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\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 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");

			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");
		}
	}

	/**
	 * 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 "bool";
		} else if (sqlType.equalsIgnoreCase("tinyint")) {
			return "byte";
		} else if (sqlType.equalsIgnoreCase("smallint")) {
			return "short";
		} else if (sqlType.equalsIgnoreCase("int")) {
			return "int";
		} 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")) {
			return "double";
		} else if (sqlType.equalsIgnoreCase("money")
				|| sqlType.equalsIgnoreCase("smallmoney")) {
			return "double";
		} else if (sqlType.equalsIgnoreCase("varchar")
				|| sqlType.equalsIgnoreCase("char")
				|| sqlType.equalsIgnoreCase("nvarchar")
				|| sqlType.equalsIgnoreCase("nchar")) {
			return "String";
		} else if (sqlType.equalsIgnoreCase("datetime")) {
			return "Date";
		}

		else if (sqlType.equalsIgnoreCase("image")) {
			return "Blob";
		} else if (sqlType.equalsIgnoreCase("text")) {
			return "Clob";
		}
		return null;
	}

	public static void main(String[] args) {
		CreateBean createBean = new CreateBean();
		createBean.createBeanMethod();
	}
}