jsonarray.java

json的JAVA实现,用于根据JAVA对象生成json string

     * Get the optional int value associated with an index.
     * The defaultValue is returned if there is no value for the index,
     * or if the value is not a number and cannot be converted to a number.
     * @param index The index must be between 0 and length() - 1.
     * @param defaultValue     The default value.
     * @return      The value.
     */
    public int optInt(int index, int defaultValue) {
        try {
            return getInt(index);
        } catch (Exception e) {
            return defaultValue;
        }
    }


    /**
     * Get the optional JSONArray associated with an index.
     * @param index subscript
     * @return      A JSONArray value, or null if the index has no value,
     * or if the value is not a JSONArray.
     */
    public JSONArray optJSONArray(int index) {
        Object o = opt(index);
        return o instanceof JSONArray ? (JSONArray)o : null;
    }


    /**
     * Get the optional JSONObject associated with an index.
     * Null is returned if the key is not found, or null if the index has
     * no value, or if the value is not a JSONObject.
     *
     * @param index The index must be between 0 and length() - 1.
     * @return      A JSONObject value.
     */
    public JSONObject optJSONObject(int index) {
        Object o = opt(index);
        return o instanceof JSONObject ? (JSONObject)o : null;
    }


    /**
     * Get the optional long value associated with an index.
     * Zero is returned if there is no value for the index,
     * or if the value is not a number and cannot be converted to a number.
     *
     * @param index The index must be between 0 and length() - 1.
     * @return      The value.
     */
    public long optLong(int index) {
        return optLong(index, 0);
    }


    /**
     * Get the optional long value associated with an index.
     * The defaultValue is returned if there is no value for the index,
     * or if the value is not a number and cannot be converted to a number.
     * @param index The index must be between 0 and length() - 1.
     * @param defaultValue     The default value.
     * @return      The value.
     */
    public long optLong(int index, long defaultValue) {
        try {
            return getLong(index);
        } catch (Exception e) {
            return defaultValue;
        }
    }


    /**
     * Get the optional string value associated with an index. It returns an
     * empty string if there is no value at that index. If the value
     * is not a string and is not null, then it is coverted to a string.
     *
     * @param index The index must be between 0 and length() - 1.
     * @return      A String value.
     */
    public String optString(int index) {
        return optString(index, "");
    }


    /**
     * Get the optional string associated with an index.
     * The defaultValue is returned if the key is not found.
     *
     * @param index The index must be between 0 and length() - 1.
     * @param defaultValue     The default value.
     * @return      A String value.
     */
    public String optString(int index, String defaultValue) {
        Object o = opt(index);
        return o != null ? o.toString() : defaultValue;
    }


    /**
     * Append a boolean value. This increases the array's length by one.
     *
     * @param value A boolean value.
     * @return this.
     */
    public JSONArray put(boolean value) {
        put(value ? Boolean.TRUE : Boolean.FALSE);
        return this;
    }


    /**
     * Put a value in the JSONArray, where the value will be a
     * JSONArray which is produced from a Collection.
     * @param value A Collection value.
     * @return      this.
     */
    public JSONArray put(Collection value) {
        put(new JSONArray(value));
        return this;
    }


    /**
     * Append a double value. This increases the array's length by one.
     *
     * @param value A double value.
     * @throws JSONException if the value is not finite.
     * @return this.
     */
    public JSONArray put(double value) throws JSONException {
        Double d = new Double(value);
        JSONObject.testValidity(d);
        put(d);
        return this;
    }


    /**
     * Append an int value. This increases the array's length by one.
     *
     * @param value An int value.
     * @return this.
     */
    public JSONArray put(int value) {
        put(new Integer(value));
        return this;
    }


    /**
     * Append an long value. This increases the array's length by one.
     *
     * @param value A long value.
     * @return this.
     */
    public JSONArray put(long value) {
        put(new Long(value));
        return this;
    }


    /**
     * Put a value in the JSONArray, where the value will be a
     * JSONObject which is produced from a Map.
     * @param value A Map value.
     * @return      this.
     */
    public JSONArray put(Map value) {
        put(new JSONObject(value));
        return this;
    }


    /**
     * Append an object value. This increases the array's length by one.
     * @param value An object value.  The value should be a
     *  Boolean, Double, Integer, JSONArray, JSONObject, Long, or String, or the
     *  JSONObject.NULL object.
     * @return this.
     */
    public JSONArray put(Object value) {
        this.myArrayList.add(value);
        return this;
    }


    /**
     * Put or replace a boolean value in the JSONArray. If the index is greater
     * than the length of the JSONArray, then null elements will be added as
     * necessary to pad it out.
     * @param index The subscript.
     * @param value A boolean value.
     * @return this.
     * @throws JSONException If the index is negative.
     */
    public JSONArray put(int index, boolean value) throws JSONException {
        put(index, value ? Boolean.TRUE : Boolean.FALSE);
        return this;
    }


    /**
     * Put a value in the JSONArray, where the value will be a
     * JSONArray which is produced from a Collection.
     * @param index The subscript.
     * @param value A Collection value.
     * @return      this.
     * @throws JSONException If the index is negative or if the value is
     * not finite.
     */
    public JSONArray put(int index, Collection value) throws JSONException {
        put(index, new JSONArray(value));
        return this;
    }


    /**
     * Put or replace a double value. If the index is greater than the length of
     *  the JSONArray, then null elements will be added as necessary to pad
     *  it out.
     * @param index The subscript.
     * @param value A double value.
     * @return this.
     * @throws JSONException If the index is negative or if the value is
     * not finite.
     */
    public JSONArray put(int index, double value) throws JSONException {
        put(index, new Double(value));
        return this;
    }


    /**
     * Put or replace an int value. If the index is greater than the length of
     *  the JSONArray, then null elements will be added as necessary to pad
     *  it out.
     * @param index The subscript.
     * @param value An int value.
     * @return this.
     * @throws JSONException If the index is negative.
     */
    public JSONArray put(int index, int value) throws JSONException {
        put(index, new Integer(value));
        return this;
    }


    /**
     * Put or replace a long value. If the index is greater than the length of
     *  the JSONArray, then null elements will be added as necessary to pad
     *  it out.
     * @param index The subscript.
     * @param value A long value.
     * @return this.
     * @throws JSONException If the index is negative.
     */
    public JSONArray put(int index, long value) throws JSONException {
        put(index, new Long(value));
        return this;
    }


    /**
     * Put a value in the JSONArray, where the value will be a
     * JSONObject which is produced from a Map.
     * @param index The subscript.
     * @param value The Map value.
     * @return      this.
     * @throws JSONException If the index is negative or if the the value is
     *  an invalid number.
     */
    public JSONArray put(int index, Map value) throws JSONException {
        put(index, new JSONObject(value));
        return this;
    }


    /**
     * Put or replace an object value in the JSONArray. If the index is greater
     *  than the length of the JSONArray, then null elements will be added as
     *  necessary to pad it out.
     * @param index The subscript.
     * @param value The value to put into the array. The value should be a
     *  Boolean, Double, Integer, JSONArray, JSONObject, Long, or String, or the
     *  JSONObject.NULL object.
     * @return this.
     * @throws JSONException If the index is negative or if the the value is
     *  an invalid number.
     */
    public JSONArray put(int index, Object value) throws JSONException {
        JSONObject.testValidity(value);
        if (index < 0) {
            throw new JSONException("JSONArray[" + index + "] not found.");
        }
        if (index < length()) {
            this.myArrayList.set(index, value);
        } else {
            while (index != length()) {
                put(JSONObject.NULL);
            }
            put(value);
        }
        return this;
    }


    /**
     * Produce a JSONObject by combining a JSONArray of names with the values
     * of this JSONArray.
     * @param names A JSONArray containing a list of key strings. These will be
     * paired with the values.
     * @return A JSONObject, or null if there are no names or if this JSONArray
     * has no values.
     * @throws JSONException If any of the names are null.
     */
    public JSONObject toJSONObject(JSONArray names) throws JSONException {
        if (names == null || names.length() == 0 || length() == 0) {
            return null;
        }
        JSONObject jo = new JSONObject();
        for (int i = 0; i < names.length(); i += 1) {
            jo.put(names.getString(i), this.opt(i));
        }
        return jo;
    }


    /**
     * Make a JSON text of this JSONArray. For compactness, no
     * unnecessary whitespace is added. If it is not possible to produce a
     * syntactically correct JSON text then null will be returned instead. This
     * could occur if the array contains an invalid number.
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     *
     * @return a printable, displayable, transmittable
     *  representation of the array.
     */
    public String toString() {
        try {
            return '[' + join(",") + ']';
        } catch (Exception e) {
            return null;
        }
    }


    /**
     * Make a prettyprinted JSON text of this JSONArray.
     * 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, transmittable
     *  representation of the object, beginning
     *  with <code>[</code>&nbsp;<small>(left bracket)</small> and ending
     *  with <code>]</code>&nbsp;<small>(right bracket)</small>.
     * @throws JSONException
     */
    public String toString(int indentFactor) throws JSONException {
        return toString(indentFactor, 0);
    }


    /**
     * Make a prettyprinted JSON text of this JSONArray.
     * 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 indention of the top level.
     * @return a printable, displayable, transmittable
     *  representation of the array.
     * @throws JSONException
     */
    String toString(int indentFactor, int indent) throws JSONException {
        int len = length();
        if (len == 0) {
            return "[]";
        }
        int i;
        StringBuffer sb = new StringBuffer("[");
        if (len == 1) {
            sb.append(JSONObject.valueToString(this.myArrayList.get(0),
                    indentFactor, indent));
        } else {
            int newindent = indent + indentFactor;
            sb.append('\n');
            for (i = 0; i < len; i += 1) {
                if (i > 0) {
                    sb.append(",\n");
                }
                for (int j = 0; j < newindent; j += 1) {
                    sb.append(' ');
                }
                sb.append(JSONObject.valueToString(this.myArrayList.get(i),
                        indentFactor, newindent));
            }
            sb.append('\n');
            for (i = 0; i < indent; i += 1) {
                sb.append(' ');
            }
        }
        sb.append(']');
        return sb.toString();
    }


    /**
     * Write the contents of the JSONArray as JSON text to a writer.
     * For compactness, no whitespace is added.
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     *
     * @return The writer.
     * @throws JSONException
     */
    public Writer write(Writer writer) throws JSONException {
        try {
            boolean b = false;
            int     len = length();

            writer.write('[');

            for (int i = 0; i < len; i += 1) {
                if (b) {
                    writer.write(',');
                }
                Object v = this.myArrayList.get(i);
                if (v instanceof JSONObject) {
                    ((JSONObject)v).write(writer);
                } else if (v instanceof JSONArray) {
                    ((JSONArray)v).write(writer);
                } else {
                    writer.write(JSONObject.valueToString(v));
                }
                b = true;
            }
            writer.write(']');
            return writer;
        } catch (IOException e) {
           throw new JSONException(e);
        }
    }
}