DBManager类（java jdbc数据库连接及操作）

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DbManager.java
package com.helloweenvsfei.util;import java.sql.Connection;import java.sql.Date;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.sql.Timestamp;import java.sql.Types;import com.mysql.jdbc.Driver;public class DbManager {    /**     * 获取默认数据库连接     *      * @return     * @throws SQLException     */    public static Connection getConnection() throws SQLException {        return getConnection("databaseWeb", "root", "admin");    }    /**     * 获取数据库连接     *      * @param dbName     * @param userName     * @param password     * @return     * @throws SQLException     */    public static Connection getConnection(String dbName, String userName,            String password) throws SQLException {        String url = "jdbc:mysql://localhost:3306/" + dbName                + "?characterEncoding=utf-8";        DriverManager.registerDriver(new Driver());        return DriverManager.getConnection(url, userName, password);    }    /**     * 设置 PreparedStatement 参数     *      * @param preStmt     * @param params     * @throws SQLException     */    public static void setParams(PreparedStatement preStmt, Object... params)            throws SQLException {        if (params == null || params.length == 0)            return;        for (int i = 1; i <= params.length; i++) {            Object param = params[i - 1];            if (param == null) {                preStmt.setNull(i, Types.NULL);            } else if (param instanceof Integer) {                preStmt.setInt(i, (Integer) param);            } else if (param instanceof String) {                preStmt.setString(i, (String) param);            } else if (param instanceof Double) {                preStmt.setDouble(i, (Double) param);            } else if (param instanceof Long) {                preStmt.setDouble(i, (Long) param);            } else if (param instanceof Timestamp) {                preStmt.setTimestamp(i, (Timestamp) param);            } else if (param instanceof Boolean) {                preStmt.setBoolean(i, (Boolean) param);            } else if (param instanceof Date) {                preStmt.setDate(i, (Date) param);            }        }    }    /**     * 执行 SQL，返回影响的行数     *      * @param sql     * @return     * @throws SQLException     */    public static int executeUpdate(String sql) throws SQLException {        return executeUpdate(sql, new Object[] {});    }    /**     * 带参数执行SQL，返回影响的行数     *      * @param sql     * @param params     * @return     * @throws SQLException     */    public static int executeUpdate(String sql, Object... params)            throws SQLException {        Connection conn = null;        PreparedStatement preStmt = null;        try {            conn = getConnection();            preStmt = conn.prepareStatement(sql);            setParams(preStmt, params);            return preStmt.executeUpdate();        } finally {            if (preStmt != null)                preStmt.close();            if (conn != null)                conn.close();        }    }    /**     * 获取总数。     *      * @param sql     *            格式必须为 SELECT count(*) FROM ...     * @return     * @throws SQLException     */    public static int getCount(String sql) throws SQLException {        Connection conn = null;        Statement stmt = null;        ResultSet rs = null;        try {            conn = getConnection();            stmt = conn.createStatement();            rs = stmt.executeQuery(sql);            rs.next();            return rs.getInt(1);        } finally {            if (rs != null)                rs.close();            if (stmt != null)                stmt.close();            if (conn != null)                conn.close();        }    }}
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