queryrunner.java

实现了从Google

     * 
     * @param sql The SQL statement to execute.
     * @param param The replacement parameter.
     * @param rsh The handler used to create the result object from 
     * the <code>ResultSet</code>.
     * 
     * @return An object generated by the handler.
     * @throws SQLException
     */
    public Object query(String sql, Object param, ResultSetHandler rsh)
        throws SQLException {

        return this.query(sql, new Object[] { param }, rsh);
    }

    /**
     * Executes the given SELECT SQL query and returns a result object.
     * The <code>Connection</code> is retrieved from the 
     * <code>DataSource</code> set in the constructor.
     * 
     * @param sql The SQL statement to execute.
     * @param params Initialize the PreparedStatement's IN parameters with 
     * this array.
     * 
     * @param rsh The handler used to create the result object from 
     * the <code>ResultSet</code>.
     * 
     * @return An object generated by the handler.
     * @throws SQLException
     */
    public Object query(String sql, Object[] params, ResultSetHandler rsh)
        throws SQLException {

        Connection conn = this.ds.getConnection();

        try {
            return this.query(conn, sql, params, rsh);

        } finally {
            DbUtils.close(conn);
        }
    }

    /**
     * Executes the given SELECT SQL without any replacement parameters.
     * The <code>Connection</code> is retrieved from the
     * <code>DataSource</code> set in the constructor.
     * 
     * @param sql The SQL statement to execute.
     * @param rsh The handler used to create the result object from 
     * the <code>ResultSet</code>.
     * 
     * @return An object generated by the handler.
     * @throws SQLException
     */
    public Object query(String sql, ResultSetHandler rsh) throws SQLException {
        return this.query(sql, (Object[]) null, rsh);
    }

    /**
     * Throws a new exception with a more informative error message.
     * 
     * @param cause The original exception that will be chained to the new 
     * exception when it's rethrown. 
     * 
     * @param sql The query that was executing when the exception happened.
     * 
     * @param params The query replacement paramaters; <code>null</code> is a 
     * valid value to pass in.
     * 
     * @throws SQLException
     */
    protected void rethrow(SQLException cause, String sql, Object[] params)
        throws SQLException {

        StringBuffer msg = new StringBuffer(cause.getMessage());

        msg.append(" Query: ");
        msg.append(sql);
        msg.append(" Parameters: ");

        if (params == null) {
            msg.append("[]");
        } else {
            msg.append(Arrays.asList(params));
        }

        SQLException e = new SQLException(msg.toString());
        e.setNextException(cause);

        throw e;
    }

    /**
     * Sets the <code>DataSource</code> this runner will use to get
     * database connections from.  This should be called after creating a
     * runner with the default constructor if you intend to use the
     * execute methods without passing in a <code>Connection</code>.
     * 
     * @param dataSource The DataSource to use.
     */
    public void setDataSource(DataSource dataSource) {
        this.ds = dataSource;
    }

    /**
     * Execute an SQL INSERT, UPDATE, or DELETE query without replacement
     * parameters.
     * 
     * @param conn The connection to use to run the query.
     * @param sql The SQL to execute.
     * @return The number of rows updated.
     * @throws SQLException
     */
    public int update(Connection conn, String sql) throws SQLException {
        return this.update(conn, sql, (Object[]) null);
    }

    /**
     * Execute an SQL INSERT, UPDATE, or DELETE query with a single replacement
     * parameter.
     * 
     * @param conn The connection to use to run the query.
     * @param sql The SQL to execute.
     * @param param The replacement parameter.
     * @return The number of rows updated.
     * @throws SQLException
     */
    public int update(Connection conn, String sql, Object param)
        throws SQLException {

        return this.update(conn, sql, new Object[] { param });
    }

    /**
     * Execute an SQL INSERT, UPDATE, or DELETE query.
     * 
     * @param conn The connection to use to run the query.
     * @param sql The SQL to execute.
     * @param params The query replacement parameters.
     * @return The number of rows updated.
     * @throws SQLException
     */
    public int update(Connection conn, String sql, Object[] params)
        throws SQLException {

        PreparedStatement stmt = null;
        int rows = 0;

        try {
            stmt = this.prepareStatement(conn, sql);
            this.fillStatement(stmt, params);

            rows = stmt.executeUpdate();

        } catch (SQLException e) {
            this.rethrow(e, sql, params);

        } finally {
            DbUtils.close(stmt);
        }

        return rows;
    }

    /**
     * Executes the given INSERT, UPDATE, or DELETE SQL statement without
     * any replacement parameters. The <code>Connection</code> is retrieved 
     * from the <code>DataSource</code> set in the constructor.
     * 
     * @param sql The SQL statement to execute.
     * @throws SQLException
     * @return The number of rows updated.
     */
    public int update(String sql) throws SQLException {
        return this.update(sql, (Object[]) null);
    }

    /**
     * Executes the given INSERT, UPDATE, or DELETE SQL statement with
     * a single replacement parameter.  The <code>Connection</code> is 
     * retrieved from the <code>DataSource</code> set in the constructor.
     * 
     * @param sql The SQL statement to execute.
     * @param param The replacement parameter.
     * @throws SQLException
     * @return The number of rows updated.
     */
    public int update(String sql, Object param) throws SQLException {
        return this.update(sql, new Object[] { param });
    }

    /**
     * Executes the given INSERT, UPDATE, or DELETE SQL statement.  The 
     * <code>Connection</code> is retrieved from the <code>DataSource</code> 
     * set in the constructor.
     * 
     * @param sql The SQL statement to execute.
     * @param params Initializes the PreparedStatement's IN (i.e. '?') 
     * parameters.
     * @throws SQLException
     * @return The number of rows updated.
     */
    public int update(String sql, Object[] params) throws SQLException {

        Connection conn = this.ds.getConnection();

        try {
            return this.update(conn, sql, params);

        } finally {
            DbUtils.close(conn);
        }
    }

    /**
     * Wrap the <code>ResultSet</code> in a decorator before processing it.
     * This implementation returns the <code>ResultSet</code> it is given
     * without any decoration.
     *
     * <p>
     * Often, the implementation of this method can be done in an anonymous 
     * inner class like this:
     * </p>
     * <pre> 
     * QueryRunner run = new QueryRunner() {
     *     protected ResultSet wrap(ResultSet rs) {
     *         return StringTrimmedResultSet.wrap(rs);
     *     }
     * };
     * </pre>
     * 
     * @param rs The <code>ResultSet</code> to decorate; never 
     * <code>null</code>.
     * @return The <code>ResultSet</code> wrapped in some decorator. 
     */
    protected ResultSet wrap(ResultSet rs) {
        return rs;
    }

}