JDBC框架

public class JdbcUtils {

	// 表示定义数据库的username
	private final String USERNAME = "root";
	// 定义数据库的password
	private final String PASSWORD = "admin";
	// 定义数据库的驱动信息
	private final String DRIVER = "com.mysql.jdbc.Driver";
	// 定义訪问数据库的地址
	private final String URL = "jdbc:mysql://localhost:3306/testdb";
	// 定义数据库的链接
	private Connection connection;
	// 定义sql语句的运行对象
	private PreparedStatement pstmt;
	// 定义查询返回的结果集合
	private ResultSet resultSet;
	// 实现批处理操作的功能
	private Statement stmt;

	public JdbcUtils() {
		try {
			Class.forName(DRIVER);
			System.out.println("注冊驱动成功!!");
		} catch (Exception e) {
			// TODO: handle exception
		}
	}

	// 定义获得数据库的链接
	public Connection getConnection() {
		try {
			connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
		} catch (Exception e) {
			// TODO: handle exception
		}
		return connection;
	}

	public boolean deleteByBatch(String[] sql) throws SQLException{
		boolean flag = false;
		stmt = connection.createStatement();
		if(sql!=null){
			for(int i=0;i<sql.length;i++){
				stmt.addBatch(sql[i]);
			}
		}
		int[] count = stmt.executeBatch();
		if(count!=null){
			flag = true;
		}
		return flag;
	}
	/**
	 * 完毕对数据库的表的加入删除和改动的操作
	 * 
	 * @param sql
	 * @param params
	 * @return
	 * @throws SQLException
	 */
	public boolean updateByPreparedStatement(String sql, List<Object> params)
			throws SQLException {
		boolean flag = false;
		int result = -1;// 表示当用户运行加入删除和改动的时候所影响数据库的行数
		pstmt = connection.prepareStatement(sql);
		int index = 1;
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		result = pstmt.executeUpdate();
		flag = result > 0 ? true : false;
		return flag;
	}

	/**
	 * 查询返回单条记录
	 * 
	 * @param sql
	 * @param params
	 * @return
	 * @throws SQLException
	 */
	public Map<String, Object> findSimpleResult(String sql, List<Object> params)
			throws SQLException {
		Map<String, Object> map = new HashMap<String, Object>();
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();// 返回查询结果
		ResultSetMetaData metaData = resultSet.getMetaData();
		int col_len = metaData.getColumnCount();// 获得列的名称
		while (resultSet.next()) {
			for (int i = 0; i < col_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				map.put(cols_name, cols_value);
			}
		}
		return map;
	}

	/**
	 * 查询返回多行记录
	 * 
	 * @param sql
	 * @param params
	 * @return
	 * @throws SQLException
	 */
	public List<Map<String, Object>> findMoreResult(String sql,
			List<Object> params) throws SQLException {
		List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();
		ResultSetMetaData metaData = resultSet.getMetaData();
		int cols_len = metaData.getColumnCount();
		while (resultSet.next()) {
			Map<String, Object> map = new HashMap<String, Object>();
			for (int i = 0; i < cols_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				map.put(cols_name, cols_value);
			}
			list.add(map);
		}
		return list;
	}

	// jdbc的封装能够用反射机制来封装：
	public <T> T findSimpleRefResult(String sql, List<Object> params,
			Class<T> cls) throws Exception {
		T resultObject = null;
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();
		ResultSetMetaData metaData = resultSet.getMetaData();
		int cols_len = metaData.getColumnCount();
		while (resultSet.next()) {
			// 通过反射机制创建实例
			resultObject = cls.newInstance();
			for (int i = 0; i < cols_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				Field field = cls.getDeclaredField(cols_name);
				field.setAccessible(true);// 打开javabean的訪问private权限
				field.set(resultObject, cols_value);
			}
		}
		return resultObject;
	}

	/**
	 * 通过反射机制訪问数据库
	 * 
	 * @param <T>
	 * @param sql
	 * @param params
	 * @param cls
	 * @return
	 * @throws Exception
	 */
	public <T> List<T> findMoreRefResult(String sql, List<Object> params,
			Class<T> cls) throws Exception {
		List<T> list = new ArrayList<T>();
		int index = 1;
		pstmt = connection.prepareStatement(sql);
		if (params != null && !params.isEmpty()) {
			for (int i = 0; i < params.size(); i++) {
				pstmt.setObject(index++, params.get(i));
			}
		}
		resultSet = pstmt.executeQuery();
		ResultSetMetaData metaData = resultSet.getMetaData();
		int cols_len = metaData.getColumnCount();
		while (resultSet.next()) {
			T resultObject = cls.newInstance();
			for (int i = 0; i < cols_len; i++) {
				String cols_name = metaData.getColumnName(i + 1);
				Object cols_value = resultSet.getObject(cols_name);
				if (cols_value == null) {
					cols_value = "";
				}
				Field field = cls.getDeclaredField(cols_name);
				field.setAccessible(true);
				field.set(resultObject, cols_value);
			}
			list.add(resultObject);
		}
		return list;
	}

	public void releaseConn() {
		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (stmt != null) {
			try {
				stmt.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (pstmt != null) {
			try {
				pstmt.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}