封裝jdbc、DBUtil

JDBC-util 封裝了jdbc並封裝dbutil方法，查詢直接返回List<map<String,Object>>，將一大堆代碼放在一塊是真的不好看

代碼如下：

package com.cmos.util;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

/**
 * 數據庫連接工具類
 * 
 * @author Wx
 *
 */
public class JDBCUtil {
	private static Properties ps = new Properties();
	static {
		// 讀入配置文件
		InputStream is = JDBCUtil.class.getResourceAsStream("jdbc.properties");
		try {
			ps.load(is);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	/**
	 * 建立連接方法
	 * @return
	 * @throws Exception
	 */
	public static Connection getConnection() throws Exception {
		Connection conn = null;
		if (conn == null) {
			//加載驅動
			Class.forName(ps.getProperty("driver"));
			conn = DriverManager.getConnection(ps.getProperty("url"), ps.getProperty("username"),
					ps.getProperty("password"));
			return conn;
		} else {
			return conn;
		}
	}

	/**
	 * 關閉連接
	 * @param conn
	 * @param pre
	 * @param rs
	 */
	public static void close(Connection conn, PreparedStatement pre, ResultSet rs) {
		if (rs != null)
			try {
				rs.close();
			} catch (SQLException e2) {
				// TODO Auto-generated catch block
				e2.printStackTrace();
			}
		if (pre != null)
			try {
				pre.close();
			} catch (SQLException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
		if (conn != null)
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

	}
	/**
	 * 關閉連接方法
	 * @param conn
	 * @param pre
	 */
	public static void close(Connection conn, PreparedStatement pre) {
		if (pre != null)
			try {
				pre.close();
			} catch (SQLException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
		if (conn != null)
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

	}

}　　

DButil

package com.cmos.util;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class DBUtil {
	private static Connection conn = null;
	private static PreparedStatement pstmt = null;
	private static ResultSet rs = null;
	
	/**
	 * 增刪改操作
	 * @param sql
	 * @param paramsValue
	 * @return
	 */
	public static int execute(String sql, Object[] paramsValue) {
		int result = 0;
		try {
			// 1. 數據庫連接
			conn = JDBCUtil.getConnection();
			// 2. 獲取PreparedStatement
			pstmt = conn.prepareStatement(sql);
			// 3. 得到參數元數據個數
			int count = pstmt.getParameterMetaData().getParameterCount();
			// 4. 利用參數元數據給SQL語句的佔位符需要的參數賦值
			if (paramsValue != null && paramsValue.length > 0) {
				for (int i = 0; i < count; i++) {
					// 循環結束，可以給SQL語句完整賦值
					pstmt.setObject(i + 1, paramsValue[i]);
				}
			}
			// 5. 執行
			result = pstmt.executeUpdate();
		} catch (Exception e) {
			throw new RuntimeException(e);
		} finally {
			JDBCUtil.close(conn, pstmt);
		}
		return result;
	}

	/**
	 * 查詢操作
	 * @param sql
	 * @param params
	 * @return
	 */
	public static List<Map<String, Object>> executeQuery(String sql, Object[] params) {
		List<Map<String, Object>> list = new ArrayList<>();
		try {
			conn = JDBCUtil.getConnection();
			pstmt = conn.prepareStatement(sql);
			// 設置參數
			if (params != null) {
				for (int i = 0; i < params.length; i++) {
					pstmt.setObject(i + 1, params[i]);
				}
			}
			rs = pstmt.executeQuery();
			// 得到ResultSetMetaData對象，這個對象包括列的信息(列的名稱和類型等等)
			ResultSetMetaData metaData = rs.getMetaData();
			// 得到結果集中列的個數
			int columnCount = metaData.getColumnCount();
			while (rs.next()) {
				Map<String, Object> map = new HashMap<String, Object>();
				for (int i = 1; i <= columnCount; i++) {
					// 得到指定的列名的別名
					String name = metaData.getColumnLabel(i);
					Object value = rs.getObject(i);
					map.put(name, value);
				}
				list.add(map);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtil.close(conn, pstmt, rs);
		}
		return list;
	}

}