sqlstatement.java

来自「本人课程设计时做的一个用struts框架实现的基于cmmi2的项目管理系统的原型」· Java 代码 · 共 196 行

package com.cmmi2pms.common.comdb;

import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * The Statement Class which is execute a sql
 * 
 * @author xunzy
 * @version 0.01
 *
 */
public class SqlStatement
{
	//Internal JDBC objects
	private Connection conn = null;
	private PreparedStatement pstmt = null;
	//Holds the SQL statement for execution
	private String sql;
	
	/**
	 * Default constructor 
	 */
	public SqlStatement(){}
	
	//Initialize the Statement object
	private void initStatement() throws SQLException
	{
		//Only initialize PrepareStatement if member sql is not null.
		if(sql==null)
		{
			throw new SqlStatementException("SQL string is null");
		}
		pstmt = conn.prepareStatement(sql);
	}
	
	/**
	 * Close PreparedStatement object
	 * 
	 * @throws SQLException
	 */
	public void close() throws SQLException
	{
		if(pstmt!=null)
		{
			System.out.println("Closing SqlStatement!");
			pstmt.close();
			pstmt=null;
		}
	}
	
	/**
	 * Used to set SQL statement and reinitialize PreparedStatement object
	 * 
	 * @param sql
	 * @throws SQLException
	 */
	public void setSql(String sql) throws SQLException
	{
		this.sql=sql;
		pstmt=null;
		initStatement();
	}
	
	/**
	 * Returns the current SQL statement
	 * 
	 * @return String
	 */
	public String getSql()
	{
		return sql;
	}
	
	/**
	 * Executes static SQL statement supplied as a parameter
	 * 
	 * @param sql
	 * @return ResultSet
	 * @throws SQLException
	 */
	public ResultSet executeQuery(String sql) throws SQLException
	{
		setSql(sql);
		return executeQuery();
	}
	
	/**
	 * Executes an SELECT statement
	 * 
	 * @return ResultSet
	 * @throws SQLException
	 */
	public ResultSet executeQuery() throws SQLException
	{
		//Check to see if pstmt statement is null.
		if(pstmt ==null)
		{
			throw new SqlStatementException("PreparedStatement not initialized");
		}
		return pstmt.executeQuery();
	}
	
	/**
	 * <p>Executes static UPDATE, INSERT, or DELETE statement
	 * supplied as a parameter
	 * 
	 * @param sql
	 * @return int The counts which the sql updates , deletes or inserts
	 * @throws SQLException
	 */
	public int execute(String sql) throws SQLException
	{
		setSql(sql);
		return execute();
	}
	
	/**
	 * Executes a SQL UPDATE, INSERT, or DELETE statement
	 * 
	 * @return int The counts which the sql updates , deletes or inserts
	 * @throws SQLException
	 */
	public int execute() throws SQLException
	{
		if(pstmt ==null)
		{
			throw new SqlStatementException("PreparedStatement not initialized");
		}
		int count = pstmt.executeUpdate();
		return count;
	}
	
	/**
	 * Sets the Connection object to valid database connection
	 * 
	 * @param conn
	 */
	public void setConnection(Connection conn)
	{
		this.conn = conn;
	}
	
	//The following set methods set the appropriate value in a PreparedStatement.
	/**
	 * The set methods set the string value in a PreparedStatement.
	 * 
	 * @param index
	 * @param value
	 * @throws SQLException
	 */
	public void setString(int index, String value) throws SQLException
	{
		pstmt.setString(index,value);
	}
	
	/**
	 * The set methods set the int value in a PreparedStatement.
	 * 
	 * @param index
	 * @param value
	 * @throws SQLException
	 */
	public void setInt(int index, int value) throws SQLException
	{
		pstmt.setInt(index,value);
	}
	
	/**
	 * The set methods set the double value in a PreparedStatement.
	 * 
	 * @param index
	 * @param value
	 * @throws SQLException
	 */
	public void setDouble(int index, double value) throws SQLException
	{
		pstmt.setDouble(index,value);
	}
	
	/**
	 * The set methods set the date value in a PreparedStatement.
	 * 
	 * @param index
	 * @param value
	 * @throws SQLException
	 */
	public void setDate(int index, Date value) throws SQLException
	{
		pstmt.setDate(index,value);
	}
	//End set methods
}