Java Path Normalize normalize(String path)

Description

Resolves relative path segments '.'

License

Apache License

Declaration

public static String normalize(String path) 

Method Source Code

//package com.java2s;
/*/*from  ww  w. ja  va 2 s  . co m*/
 * 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.
 */

public class Main {
    /**
     * Resolves relative path segments '.' and '..' in the absolute path.
     * Returns null if not possible (.. points above root) or if path is not
     * absolute.
     */
    public static String normalize(String path) {

        // don't care for empty paths
        if (path.length() == 0) {
            return path;
        }

        // prepare the path buffer with trailing slash (simplifies impl)
        int absOffset = (path.charAt(0) == '/') ? 0 : 1;
        char[] buf = new char[path.length() + 1 + absOffset];
        if (absOffset == 1) {
            buf[0] = '/';
        }
        path.getChars(0, path.length(), buf, absOffset);
        buf[buf.length - 1] = '/';

        int lastSlash = 0; // last slash in path
        int numDots = 0; // number of consecutive dots after last slash

        int bufPos = 0;
        for (int bufIdx = lastSlash; bufIdx < buf.length; bufIdx++) {
            char c = buf[bufIdx];
            if (c == '/') {
                if (numDots == 2) {
                    if (bufPos == 0) {
                        return null;
                    }

                    do {
                        bufPos--;
                    } while (bufPos > 0 && buf[bufPos] != '/');
                }

                lastSlash = bufIdx;
                numDots = 0;
            } else if (c == '.' && numDots < 2) {
                numDots++;
            } else {
                // find the next slash
                int nextSlash = bufIdx + 1;
                while (nextSlash < buf.length && buf[nextSlash] != '/') {
                    nextSlash++;
                }

                // append up to the next slash (or end of path)
                if (bufPos < lastSlash) {
                    int segLen = nextSlash - bufIdx + 1;
                    System.arraycopy(buf, lastSlash, buf, bufPos, segLen);
                    bufPos += segLen;
                } else {
                    bufPos = nextSlash;
                }

                numDots = 0;
                lastSlash = nextSlash;
                bufIdx = nextSlash;
            }
        }

        String resolved;
        if (bufPos == 0 && numDots == 0) {
            resolved = (absOffset == 0) ? "/" : "";
        } else if ((bufPos - absOffset) == path.length()) {
            resolved = path;
        } else {
            resolved = new String(buf, absOffset, bufPos - absOffset);
        }

        return resolved;
    }
}

Related

1. normalize(final String path)
2. normalize(final String path)
3. normalize(final String pathname)
4. normalize(String path)
5. normalize(String path)
6. normalize(String path)
7. normalize(String path)
8. normalize(String path)
9. normalize(String path)