DBManager类（java jdbc数据库连接及操作）

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();
}
}

}