jsonobject.java

《AJAX基础》一书的源码

    }


    /**
     * Get an optional value associated with a key.
     * @exception NullPointerException  The key must not be null.
     * @param key   A key string.
     * @return      An object which is the value, or null if there is no value.
     */
    public Object opt(String key) throws NullPointerException {
        if (key == null) {
            throw new NullPointerException("Null key");
        }
        return myHashMap.get(key);
    }


    /**
     * Get an optional boolean associated with a key.
     * It returns false if there is no such key, or if the value is not
     * Boolean.TRUE or the String "true".
     *
     * @param key   A key string.
     * @return      The truth.
     */
    public boolean optBoolean(String key) {
        return optBoolean(key, false);
    }


    /**
     * Get an optional boolean associated with a key.
     * It returns the defaultValue if there is no such key, or if it is not
     * a Boolean or the String "true" or "false" (case insensitive).
     *
     * @param key              A key string.
     * @param defaultValue     The default.
     * @return      The truth.
     */
    public boolean optBoolean(String key, boolean defaultValue) {
        Object o = opt(key);
        if (o != null) {
            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;
            }
        }
        return defaultValue;
    }


    /**
     * Get an optional double associated with a key,
     * or NaN if there is no such key or if its value is not a number.
     * If the value is a string, an attempt will be made to evaluate it as
     * a number.
     *
     * @param key   A string which is the key.
     * @return      An object which is the value.
     */
    public double optDouble(String key)  {
        return optDouble(key, Double.NaN);
    }


    /**
     * Get an optional double associated with a key, or the
     * defaultValue if there is no such key or if its value is not a number.
     * If the value is a string, an attempt will be made to evaluate it as
     * a number.
     *
     * @param key   A key string.
     * @param defaultValue     The default.
     * @return      An object which is the value.
     */
    public double optDouble(String key, double defaultValue)  {
        Object o = opt(key);
        if (o != null) {
            if (o instanceof Number) {
                return ((Number)o).doubleValue();
            }
            try {
                return new Double((String)o).doubleValue();
            }
            catch (Exception e) {
            }
        }
        return defaultValue;
    }


    /**
     * Get an optional int value associated with a key,
     * or zero if there is no such key or if the value is not a number.
     * If the value is a string, an attempt will be made to evaluate it as
     * a number.
     *
     * @param key   A key string.
     * @return      An object which is the value.
     */
    public int optInt(String key) {
        return optInt(key, 0);
    }


    /**
     * Get an optional int value associated with a key,
     * or the default if there is no such key or if the value is not a number.
     * If the value is a string, an attempt will be made to evaluate it as
     * a number.
     *
     * @param key   A key string.
     * @param defaultValue     The default.
     * @return      An object which is the value.
     */
    public int optInt(String key, int defaultValue) {
        Object o = opt(key);
        if (o != null) {
            if (o instanceof Number) {
                return ((Number)o).intValue();
            }
            try {
                return Integer.parseInt((String)o);
            } catch (Exception e) {
            }
        }
        return defaultValue;
    }


    /**
     * Get an optional JSONArray associated with a key.
     * It returns null if there is no such key, or if its value is not a
     * JSONArray.
     *
     * @param key   A key string.
     * @return      A JSONArray which is the value.
     */
    public JSONArray optJSONArray(String key) {
        Object o = opt(key);
        if (o instanceof JSONArray) {
            return (JSONArray) o;
        }
        return null;
    }


    /**
     * Get an optional JSONObject associated with a key.
     * It returns null if there is no such key, or if its value is not a
     * JSONObject.
     *
     * @param key   A key string.
     * @return      A JSONObject which is the value.
     */
    public JSONObject optJSONObject(String key) {
        Object o = opt(key);
        if (o instanceof JSONObject) {
            return (JSONObject)o;
        }
        return null;
    }


    /**
     * Get an optional string associated with a key.
     * It returns an empty string if there is no such key. If the value is not
     * a string and is not null, then it is coverted to a string.
     *
     * @param key   A key string.
     * @return      A string which is the value.
     */
    public String optString(String key) {
        return optString(key, "");
    }


    /**
     * Get an optional string associated with a key.
     * It returns the defaultValue if there is no such key.
     *
     * @param key   A key string.
     * @param defaultValue     The default.
     * @return      A string which is the value.
     */
    public String optString(String key, String defaultValue) {
        Object o = opt(key);
        if (o != null) {
            return o.toString();
        }
        return defaultValue;
    }


    /**
     * Put a key/boolean pair in the JSONObject.
     *
     * @param key   A key string.
     * @param value A boolean which is the value.
     * @return this.
     */
    public JSONObject put(String key, boolean value) {
        put(key, new Boolean(value));
        return this;
    }


    /**
     * Put a key/double pair in the JSONObject.
     *
     * @param key   A key string.
     * @param value A double which is the value.
     * @return this.
     */
    public JSONObject put(String key, double value) {
        put(key, new Double(value));
        return this;
    }


    /**
     * Put a key/int pair in the JSONObject.
     *
     * @param key   A key string.
     * @param value An int which is the value.
     * @return this.
     */
    public JSONObject put(String key, int value) {
        put(key, new Integer(value));
        return this;
    }


    /**
     * Put a key/value pair in the JSONObject. If the value is null,
     * then the key will be removed from the JSONObject if it is present.
     * @exception NullPointerException The key must be non-null.
     * @param key   A key string.
     * @param value An object which is the value. It should be of one of these
     *  types: Boolean, Double, Integer, JSONArray, JSONObject, String, or the
     *  JSONObject.NULL object.
     * @return this.
     */
    public JSONObject put(String key, Object value) throws NullPointerException {
        if (key == null) {
            throw new NullPointerException("Null key.");
        }
        if (value != null) {
            myHashMap.put(key, value);
        } else {
            remove(key);
        }
        return this;
    }


    /**
     * Put a key/value pair in the JSONObject, but only if the
     * value is non-null.
     * @exception NullPointerException The key must be non-null.
     * @param key   A key string.
     * @param value An object which is the value. It should be of one of these
     *  types: Boolean, Double, Integer, JSONArray, JSONObject, String, or the
     *  JSONObject.NULL object.
     * @return this.
     */
    public JSONObject putOpt(String key, Object value) throws NullPointerException {
        if (value != null) {
            put(key, value);
        }
        return this;
    }


    /**
     * Produce a string in double quotes with backslash sequences in all the
     * right places.
     * @param string A String
     * @return  A String correctly formatted for insertion in a JSON message.
     */
    public static String quote(String string) {
        if (string == null || string.length() == 0) {
            return "\"\"";
        }

        char         c;
        int          i;
        int          len = string.length();
        StringBuffer sb = new StringBuffer(len + 4);
        String       t;

        sb.append('"');
        for (i = 0; i < len; i += 1) {
            c = string.charAt(i);
            switch (c) {
            case '\\':
            case '"':
            case '/':
                sb.append('\\');
                sb.append(c);
                break;
            case '\b':
                sb.append("\\b");
                break;
            case '\t':
                sb.append("\\t");
                break;
            case '\n':
                sb.append("\\n");
                break;
            case '\f':
                sb.append("\\f");
                break;
            case '\r':
                sb.append("\\r");
                break;
            default:
                if (c < ' ') {
                    t = "000" + Integer.toHexString(c);
                    sb.append("\\u" + t.substring(t.length() - 4));
                } else {
                    sb.append(c);
                }
            }
        }
        sb.append('"');
        return sb.toString();
    }

    /**
     * Remove a name and its value, if present.
     * @param key The name to be removed.
     * @return The value that was associated with the name,
     * or null if there was no value.
     */
    public Object remove(String key) {
        return myHashMap.remove(key);
    }

    /**
     * Produce a JSONArray containing the values of the members of this
     * JSONObject.
     * @param names A JSONArray containing a list of key strings. This
     * determines the sequence of the values in the result.
     * @return A JSONArray of values.
     */
    public JSONArray toJSONArray(JSONArray names) {
        if (names == null || names.length() == 0) {
            return null;
        }
        JSONArray ja = new JSONArray();
        for (int i = 0; i < names.length(); i += 1) {
            ja.put(this.opt(names.getString(i)));
        }
        return ja;
    }

    /**
     * Make an JSON external form string of this JSONObject. For compactness, no
     * unnecessary whitespace is added.
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     *
     * @return a printable, displayable, portable, transmittable
     *  representation of the object, beginning 
     *  with <code>{</code>&nbsp;<small>(left brace)</small> and ending 
     *  with <code>}</code>&nbsp;<small>(right brace)</small>.
     */
    public String toString() {
        Iterator     keys = keys();
        Object       o = null;
        String       s;
        StringBuffer sb = new StringBuffer();

        sb.append('{');
        while (keys.hasNext()) {
            if (o != null) {
                sb.append(',');
            }
            s = keys.next().toString();
            o = myHashMap.get(s);
            if (o != null) {
                sb.append(quote(s));
                sb.append(':');
                if (o instanceof String) {
                    sb.append(quote((String)o));
                } else if (o instanceof Number) {
                    sb.append(numberToString((Number)o));
                } else {
                    sb.append(o.toString());
                }
            }
        }
        sb.append('}');
        return sb.toString();
    }


    /**
     * Make a prettyprinted JSON external form string of this JSONObject.
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     * @param indentFactor The number of spaces to add to each level of
     *  indentation.
     * @return a printable, displayable, portable, transmittable
     *  representation of the object, beginning
     *  with <code>{</code>&nbsp;<small>(left brace)</small> and ending 
     *  with <code>}</code>&nbsp;<small>(right brace)</small>.
     */
    public String toString(int indentFactor) {
        return toString(indentFactor, 0);
    }


    /**
     * Make a prettyprinted JSON string of this JSONObject.
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     * @param indentFactor The number of spaces to add to each level of
     *  indentation.
     * @param indent The indentation of the top level.
     * @return a printable, displayable, transmittable
     *  representation of the object, beginning 
     *  with <code>{</code>&nbsp;<small>(left brace)</small> and ending 
     *  with <code>}</code>&nbsp;<small>(right brace)</small>.
     */
    String toString(int indentFactor, int indent) {
        int          i;
        Iterator     keys = keys();
        String       pad = "";
        StringBuffer sb = new StringBuffer();
        int newindent = indent + indentFactor;
        for (i = 0; i < newindent; i += 1) {
            pad += ' ';
        }
        sb.append('{');
        while (keys.hasNext()) {
            String s = keys.next().toString();
            Object o = myHashMap.get(s);
            if (o != null) {
                if (sb.length() > 1) {
                    sb.append(",\n");
                } else {
					sb.append('\n');
                }
                sb.append(pad);
                sb.append(quote(s));
                sb.append(": ");
                if (o instanceof String) {
                    sb.append(quote((String)o));
                } else if (o instanceof Number) {
                    sb.append(numberToString((Number) o));
                } else if (o instanceof JSONObject) {
                    sb.append(((JSONObject)o).toString(indentFactor, newindent));
                } else if (o instanceof JSONArray) {
                    sb.append(((JSONArray)o).toString(indentFactor, newindent));
                } else {
                    sb.append(o.toString());
                }
            }
        }
		if (sb.length() > 1) {
			sb.append('\n');
	        for (i = 0; i < indent; i += 1) {
				sb.append(' ');
	        }
		}
        sb.append('}');
        return sb.toString();
    }
}