DB的封装

package com.bjsxt.bbs;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DB {
public static Connection getConn() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bbs", "root" , "root");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}

public static Statement createStmt(Connection conn) {
Statement stmt = null;
try {
stmt = conn.createStatement();
} catch (SQLException e) {
e.printStackTrace();
}
return stmt;
}

public static ResultSet executeQuery(Statement stmt, String sql) {
ResultSet rs = null;
try {
rs = stmt.executeQuery(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return rs;
}

/*public static ResultSet executeQuery(Connection conn, String sql) {
Statement stmt = null;
ResultSet rs = null;
try {
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
} catch (SQLException e) {
e.printStackTrace();
}

//      finally {
//          close(stmt);
//      }

return rs;
}*/

public static int executeUpdate(Connection conn, String sql) {
int ret = 0;
Statement stmt = null;
try {
stmt = conn.createStatement();
ret = stmt.executeUpdate(sql);
} catch (SQLException e) {
e.printStackTrace();
} finally {
close(stmt);
}
return ret;
}

public static PreparedStatement prepareStmt(Connection conn, String sql) {
PreparedStatement pstmt = null;
try {
pstmt = conn.prepareStatement(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return pstmt;
}

public static PreparedStatement prepareStmt(Connection conn, String sql, int autoGeneratedKeys) {
PreparedStatement pstmt = null;
try {
pstmt = conn.prepareStatement(sql, autoGeneratedKeys);
} catch (SQLException e) {
e.printStackTrace();
}
return pstmt;
}

public static void close(Connection conn) {
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}

public static void close(Statement stmt) {
if(stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
stmt = null;
}
}

public static void close(ResultSet rs) {
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
rs = null;
}
}
}