jsonarray.java

《AJAX基础》一书的源码

package org.json;

/*
Copyright (c) 2002 JSON.org

Permission is hereby granted, free of charge, to any person obtaining a copy 
of this software and associated documentation files (the "Software"), to deal 
in the Software without restriction, including without limitation the rights 
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
copies of the Software, and to permit persons to whom the Software is 
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all 
copies or substantial portions of the Software.

The Software shall be used for Good, not Evil.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
SOFTWARE.
*/

import java.text.ParseException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.NoSuchElementException;

/**
 * A JSONArray is an ordered sequence of values. Its external form is a string
 * wrapped in square brackets with commas between the values. The internal form
 * is an object having get() and opt() methods for accessing the values by
 * index, and put() methods for adding or replacing values. The values can be
 * any of these types: Boolean, JSONArray, JSONObject, Number, String, or the
 * JSONObject.NULL object.
 * <p>
 * The constructor can convert a JSON external form string into an
 * internal form Java object. The toString() method creates an external
 * form string.
 * <p>
 * A get() method returns a value if one can be found, and throws an exception
 * if one cannot be found. An opt() method returns a default value instead of
 * throwing an exception, and so is useful for obtaining optional values.
 * <p>
 * The generic get() and opt() methods return an object which you can cast or
 * query for type. There are also typed get() and opt() methods that do typing
 * checking and type coersion for you.
 * <p>
 * The texts produced by the toString() methods are very strict.
 * The constructors are more forgiving in the texts they will accept.
 * <ul>
 * <li>An extra <code>,</code>&nbsp;<small>(comma)</small> may appear just 
 *     before the closing bracket.</li>
 * <li>The null value will be inserted when there 
 *     is <code>,</code>&nbsp;<small>(comma)</small> elision.</li>
 * <li>Strings may be quoted with <code>'</code>&nbsp;<small>(single 
 *     quote)</small>.</li>
 * <li>Strings do not need to be quoted at all if they do not begin with a quote
 *     or single quote, and if they do not contain leading or trailing spaces, 
 *     and if they do not contain any of these characters:
 *     <code>{ } [ ] / \ : , = ; #</code> and if they do not look like numbers
 *     and if they are not the reserved words <code>true</code>, 
 *     <code>false</code>, or <code>null</code>.</li>
 * <li>Values can be followed by <code>;</code> as well as by <code>,</code></li>
 * <li>Numbers may have the <code>0-</code> <small>(octal)</small> or 
 *     <code>0x-</code> <small>(hex)</small> prefix.</li> 
 * <li>Line comments can begin with <code>#</code></li>
 * </ul>

 * @author JSON.org
 * @version 1
 */
public class JSONArray {


    /**
     * The getArrayList where the JSONArray's properties are kept.
     */
    private ArrayList myArrayList;


    /**
     * Construct an empty JSONArray.
     */
    public JSONArray() {
        myArrayList = new ArrayList();
    }


    /**
     * Construct a JSONArray from a JSONTokener.
     * @exception ParseException A JSONArray must start with '['
     * @exception ParseException Expected a ',' or ']'
     * @param x A JSONTokener
     */
    public JSONArray(JSONTokener x) throws ParseException {
        this();
        if (x.nextClean() != '[') {
            throw x.syntaxError("A JSONArray must start with '['");
        }
        if (x.nextClean() == ']') {
            return;
        }
        x.back();
        while (true) {
            if (x.nextClean() == ',') {
                x.back();
                myArrayList.add(null);
            } else {
                x.back();
                myArrayList.add(x.nextValue());
            }
            switch (x.nextClean()) {
			case ';':
            case ',':
                if (x.nextClean() == ']') {
                    return;
                }
                x.back();
                break;
            case ']':
                return;
            default:
                throw x.syntaxError("Expected a ',' or ']'");
            }
        }
    }


    /**
     * Construct a JSONArray from a source string.
     * @exception ParseException The string must conform to JSON syntax.
     * @param string     A string that begins with 
     * <code>[</code>&nbsp;<small>(left bracket)</small>
     *  and ends with <code>]</code>&nbsp;<small>(right bracket)</small>.
     */
    public JSONArray(String string) throws ParseException {
        this(new JSONTokener(string));
    }


    /**
     * Construct a JSONArray from a Collection.
     * @param collection     A Collection.
     */
    public JSONArray(Collection collection) {
        myArrayList = new ArrayList(collection);
    }


    /**
     * Get the object value associated with an index.
     * @exception NoSuchElementException
     * @param index 
     *  The index must be between 0 and length() - 1.
     * @return An object value.
     */
    public Object get(int index) throws NoSuchElementException {
        Object o = opt(index);
        if (o == null) {
            throw new NoSuchElementException("JSONArray[" + index +
                "] not found.");
        }
        return o;
    }


    /**
     * Get the ArrayList which is holding the elements of the JSONArray.
     * @return      The ArrayList.
     */
    ArrayList getArrayList() {
        return myArrayList;
    }


    /**
     * Get the boolean value associated with an index.
     * The string values "true" and "false" are converted to boolean.
     *
     * @exception NoSuchElementException if the index is not found
     * @exception ClassCastException
     * @param index The index must be between 0 and length() - 1.
     * @return      The truth.
     */
    public boolean getBoolean(int index)
            throws ClassCastException, NoSuchElementException {
        Object o = get(index);
        if (o == Boolean.FALSE || 
				(o instanceof String && 
				((String)o).equalsIgnoreCase("false"))) {
            return false;
        } else if (o == Boolean.TRUE || 
				(o instanceof String && 
				((String)o).equalsIgnoreCase("true"))) {
            return true;
        }
        throw new ClassCastException("JSONArray[" + index +
            "] not a Boolean.");
    }


    /**
     * Get the double value associated with an index.
     * @exception NoSuchElementException if the key is not found
     * @exception NumberFormatException
     *  if the value cannot be converted to a number.
     *
     * @param index The index must be between 0 and length() - 1.
     * @return      The value.
     */
    public double getDouble(int index)
            throws NoSuchElementException, NumberFormatException {
        Object o = get(index);
        if (o instanceof Number) {
            return ((Number) o).doubleValue();
        }
        if (o instanceof String) {
            return new Double((String)o).doubleValue();
        }
        throw new NumberFormatException("JSONObject[" +
            index + "] is not a number.");
    }


    /**
     * Get the int value associated with an index.
     * @exception NoSuchElementException if the key is not found
     * @exception NumberFormatException
     *  if the value cannot be converted to a number.
     *
     * @param index The index must be between 0 and length() - 1.
     * @return      The value.
     */
    public int getInt(int index)
            throws NoSuchElementException, NumberFormatException {
        Object o = get(index);
        if (o instanceof Number) {
            return ((Number)o).intValue();
        }
        return (int)getDouble(index);
    }


    /**
     * Get the JSONArray associated with an index.
     * @exception NoSuchElementException if the index is not found or if the
     * value is not a JSONArray
     * @param index The index must be between 0 and length() - 1.
     * @return      A JSONArray value.
     */
    public JSONArray getJSONArray(int index) throws NoSuchElementException {
        Object o = get(index);
        if (o instanceof JSONArray) {
            return (JSONArray)o;
        }
        throw new NoSuchElementException("JSONArray[" + index +
                "] is not a JSONArray.");
    }


    /**
     * Get the JSONObject associated with an index.
     * @exception NoSuchElementException if the index is not found or if the
     * value is not a JSONObject
     * @param index subscript
     * @return      A JSONObject value.
     */
    public JSONObject getJSONObject(int index) throws NoSuchElementException {
        Object o = get(index);
        if (o instanceof JSONObject) {
            return (JSONObject)o;
        }
        throw new NoSuchElementException("JSONArray[" + index +
            "] is not a JSONObject.");
    }


    /**
     * Get the string associated with an index.
     * @exception NoSuchElementException
     * @param index The index must be between 0 and length() - 1.
     * @return      A string value.
     */
    public String getString(int index) throws NoSuchElementException {
        return get(index).toString();
    }


    /**
     * Determine if the value is null.
     * @param index The index must be between 0 and length() - 1.
     * @return true if the value at the index is null, or if there is no value.
     */
    public boolean isNull(int index) {
        Object o = opt(index);
        return o == null || o.equals(null);
    }


    /**
     * Make a string from the contents of this JSONArray. The separator string
     * is inserted between each element.
     * Warning: This method assumes that the data structure is acyclical.
     * @param separator A string that will be inserted between the elements.
     * @return a string.
     */
    public String join(String separator) {
        int i;
        Object o;
        StringBuffer sb = new StringBuffer();
        for (i = 0; i < myArrayList.size(); i += 1) {
            if (i > 0) {
                sb.append(separator);
            }
            o = myArrayList.get(i);
            if (o == null) {
                sb.append("null");
            } else if (o instanceof String) {
                sb.append(JSONObject.quote((String)o));
            } else if (o instanceof Number) {
                sb.append(JSONObject.numberToString((Number)o));
            } else {
                sb.append(o.toString());
            }
        }
        return sb.toString();
    }


    /**
     * Get the length of the JSONArray.
     *
     * @return The length (or size).
     */
    public int length() {
        return myArrayList.size();
    }


    /**
     * Get the optional object value associated with an index.
     * @param index The index must be between 0 and length() - 1.
     * @return      An object value, or null if there is no
     *              object at that index.
     */
    public Object opt(int index) {
        if (index < 0 || index >= length()) {
            return null;
        } else {
            return myArrayList.get(index);
        }
    }


    /**
     * Get the optional boolean value associated with an index.
     * It returns false if there is no value at that index,
     * or if the value is not Boolean.TRUE or the String "true".
     *
     * @param index The index must be between 0 and length() - 1.
     * @return      The truth.
     */
    public boolean optBoolean(int index)  {
        return optBoolean(index, false);
    }


    /**
     * Get the optional boolean value associated with an index.
     * It returns the defaultValue if there is no value at that index or if it is not
     * a Boolean or the String "true" or "false" (case insensitive).
     *
     * @param index The index must be between 0 and length() - 1.
     * @param defaultValue     A boolean default.