cayenne-server/src/main/java/org/apache/cayenne/access/types/CharType.java

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 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 ****************************************************************/

package org.apache.cayenne.access.types;

import org.apache.cayenne.CayenneException;

import java.io.IOException;
import java.io.Reader;
import java.io.StringWriter;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

/**
 * Handles <code>java.lang.String</code>, mapping it as either of JDBC types -
 * CLOB or (VAR)CHAR. Can be configured to trim trailing spaces.
 */
public class CharType implements ExtendedType<String> {

	private static final int BUF_SIZE = 8 * 1024;
	private static final int TRIM_VALUES_THRESHOLD = 30;

	protected boolean trimmingChars;
	protected boolean usingClobs;

	public CharType(boolean trimmingChars, boolean usingClobs) {
		this.trimmingChars = trimmingChars;
		this.usingClobs = usingClobs;
	}

	/**
	 * Returns "java.lang.String".
	 */
	@Override
	public String getClassName() {
		return String.class.getName();
	}

	/** Return trimmed string. */
	@Override
	public String materializeObject(ResultSet rs, int index, int type) throws Exception {

		if (type == Types.CLOB || type == Types.NCLOB) {
			return isUsingClobs() ? readClob(rs.getClob(index)) : readCharStream(rs, index);
		}

		return handleString(rs.getString(index), type);
	}

	@Override
	public String materializeObject(CallableStatement cs, int index, int type) throws Exception {

		if (type == Types.CLOB || type == Types.NCLOB) {
			if (!isUsingClobs()) {
				throw new CayenneException("Character streams are not supported in stored procedure parameters.");
			}

			return readClob(cs.getClob(index));
		}

		return handleString(cs.getString(index), type);
	}

	private String handleString(String val, int type) throws SQLException {
		// trim CHAR type
		if (val != null && (type == Types.CHAR || type == Types.NCHAR) && isTrimmingChars()) {
			return rtrim(val);
		}

		return val;
	}

	/** Trim right spaces. */
	protected String rtrim(String value) {
		int end = value.length() - 1;
		int count = end;
		while (end >= 0 && value.charAt(end) <= ' ') {
			end--;
		}
		return end == count ? value : value.substring(0, end + 1);
	}

	@Override
	public void setJdbcObject(PreparedStatement st, String value, int pos, int type, int scale) throws Exception {

		// if this is a CLOB column, set the value as "String"
		// instead. This should work with most drivers
		if (type == Types.CLOB || type == Types.NCLOB) {
			st.setString(pos, value);
		} else if (scale != -1) {
			st.setObject(pos, value, type, scale);
		} else {
			st.setObject(pos, value, type);
		}
	}

	@Override
	public String toString(String value) {
		if (value == null) {
			return "NULL";
		}

		StringBuilder buffer = new StringBuilder();

		buffer.append('\'');

		String literal = value;
		if (literal.length() > TRIM_VALUES_THRESHOLD) {
			literal = literal.substring(0, TRIM_VALUES_THRESHOLD) + "...";
		}

		// escape quotes
		int curPos = 0;
		int endPos = 0;

		while ((endPos = literal.indexOf('\'', curPos)) >= 0) {
			buffer.append(literal.substring(curPos, endPos + 1)).append('\'');
			curPos = endPos + 1;
		}

		if (curPos < literal.length()) {
			buffer.append(literal.substring(curPos));
		}

		buffer.append('\'');

		return buffer.toString();
	}

	protected String readClob(Clob clob) throws IOException, SQLException {
		if (clob == null) {
			return null;
		}

		// sanity check on size
		if (clob.length() > Integer.MAX_VALUE) {
			throw new IllegalArgumentException("CLOB is too big to be read as String in memory: " + clob.length());
		}

		int size = (int) clob.length();
		if (size == 0) {
			return "";
		}

		return clob.getSubString(1, size);
	}

	protected String readCharStream(ResultSet rs, int index) throws IOException, SQLException {
		try (Reader in = rs.getCharacterStream(index);) {
			return in != null ? readValueStream(in, -1, BUF_SIZE) : null;
		}
	}

	protected String readValueStream(Reader in, int streamSize, int bufSize) throws IOException {
		char[] buf = new char[bufSize];
		StringWriter out = streamSize > 0 ? new StringWriter(streamSize) : new StringWriter();

		int read;
		while ((read = in.read(buf, 0, bufSize)) >= 0) {
			out.write(buf, 0, read);
		}
		return out.toString();
	}

	/**
	 * Returns <code>true</code> if 'materializeObject' method should trim
	 * trailing spaces from the CHAR columns. This addresses an issue with some
	 * JDBC drivers (e.g. Oracle), that return Strings for CHAR columns padded
	 * with spaces.
	 */
	public boolean isTrimmingChars() {
		return trimmingChars;
	}

	public void setTrimmingChars(boolean trimingChars) {
		this.trimmingChars = trimingChars;
	}

	public boolean isUsingClobs() {
		return usingClobs;
	}

	public void setUsingClobs(boolean usingClobs) {
		this.usingClobs = usingClobs;
	}
}