jsonobject.java

json的JAVA实现,用于根据JAVA对象生成json string

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


    /**
     * Put a key/long pair in the JSONObject.
     *
     * @param key   A key string.
     * @param value A long which is the value.
     * @return this.
     * @throws JSONException If the key is null.
     */
    public JSONObject put(String key, long value) throws JSONException {
        put(key, new Long(value));
        return this;
    }


    /**
     * Put a key/value pair in the JSONObject, where the value will be a
     * JSONObject which is produced from a Map.
     * @param key   A key string.
     * @param value A Map value.
     * @return      this.
     * @throws JSONException
     */
    public JSONObject put(String key, Map value) throws JSONException {
        put(key, new JSONObject(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.
     * @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, Long, String,
     *  or the JSONObject.NULL object.
     * @return this.
     * @throws JSONException If the value is non-finite number
     *  or if the key is null.
     */
    public JSONObject put(String key, Object value) throws JSONException {
        if (key == null) {
            throw new JSONException("Null key.");
        }
        if (value != null) {
            testValidity(value);
            this.myHashMap.put(key, value);
        } else {
            remove(key);
        }
        return this;
    }


    /**
     * Put a key/value pair in the JSONObject, but only if the
     * key and the value are both 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, Long, String,
     *  or the JSONObject.NULL object.
     * @return this.
     * @throws JSONException If the value is a non-finite number.
     */
    public JSONObject putOpt(String key, Object value) throws JSONException {
        if (key != null && value != null) {
            put(key, value);
        }
        return this;
    }


    /**
     * Produce a string in double quotes with backslash sequences in all the
     * right places. A backslash will be inserted within </, allowing JSON
     * text to be delivered in HTML. In JSON text, a string cannot contain a
     * control character or an unescaped quote or backslash.
     * @param string A String
     * @return  A String correctly formatted for insertion in a JSON text.
     */
    public static String quote(String string) {
        if (string == null || string.length() == 0) {
            return "\"\"";
        }

        char         b;
        char         c = 0;
        int          i;
        int          len = string.length();
        StringBuffer sb = new StringBuffer(len + 4);
        String       t;

        sb.append('"');
        for (i = 0; i < len; i += 1) {
            b = c;
            c = string.charAt(i);
            switch (c) {
            case '\\':
            case '"':
                sb.append('\\');
                sb.append(c);
                break;
            case '/':
                if (b == '<') {
                    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 < ' ' || (c >= '\u0080' && c < '\u00a0') ||
                               (c >= '\u2000' && c < '\u2100')) {
                    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 this.myHashMap.remove(key);
    }


    /**
     * Throw an exception if the object is an NaN or infinite number.
     * @param o The object to test.
     * @throws JSONException If o is a non-finite number.
     */
    static void testValidity(Object o) throws JSONException {
        if (o != null) {
            if (o instanceof Double) {
                if (((Double)o).isInfinite() || ((Double)o).isNaN()) {
                    throw new JSONException(
                        "JSON does not allow non-finite numbers.");
                }
            } else if (o instanceof Float) {
                if (((Float)o).isInfinite() || ((Float)o).isNaN()) {
                    throw new JSONException(
                        "JSON does not allow non-finite numbers.");
                }
            }
        }
    }


    /**
     * 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.
     * @throws JSONException If any of the values are non-finite numbers.
     */
    public JSONArray toJSONArray(JSONArray names) throws JSONException {
        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 a JSON text of this JSONObject. For compactness, no whitespace
     * is added. If this would not result in a syntactically correct JSON text,
     * then null will be returned instead.
     * <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() {
        try {
            Iterator     keys = keys();
            StringBuffer sb = new StringBuffer("{");

            while (keys.hasNext()) {
                if (sb.length() > 1) {
                    sb.append(',');
                }
                Object o = keys.next();
                sb.append(quote(o.toString()));
                sb.append(':');
                sb.append(valueToString(this.myHashMap.get(o)));
            }
            sb.append('}');
            return sb.toString();
        } catch (Exception e) {
            return null;
        }
    }


    /**
     * Make a prettyprinted JSON text 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>.
     * @throws JSONException If the object contains an invalid number.
     */
    public String toString(int indentFactor) throws JSONException {
        return toString(indentFactor, 0);
    }


    /**
     * Make a prettyprinted JSON text 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>.
     * @throws JSONException If the object contains an invalid number.
     */
    String toString(int indentFactor, int indent) throws JSONException {
        int          i;
        int          n = length();
        if (n == 0) {
            return "{}";
        }
        Iterator     keys = keys();
        StringBuffer sb = new StringBuffer("{");
        int          newindent = indent + indentFactor;
        Object       o;
        if (n == 1) {
            o = keys.next();
            sb.append(quote(o.toString()));
            sb.append(": ");
            sb.append(valueToString(this.myHashMap.get(o), indentFactor,
                    indent));
        } else {
            while (keys.hasNext()) {
                o = keys.next();
                if (sb.length() > 1) {
                    sb.append(",\n");
                } else {
                    sb.append('\n');
                }
                for (i = 0; i < newindent; i += 1) {
                    sb.append(' ');
                }
                sb.append(quote(o.toString()));
                sb.append(": ");
                sb.append(valueToString(this.myHashMap.get(o), indentFactor,
                        newindent));
            }
            if (sb.length() > 1) {
                sb.append('\n');
                for (i = 0; i < indent; i += 1) {
                    sb.append(' ');
                }
            }
        }
        sb.append('}');
        return sb.toString();
    }


    /**
     * Make a JSON text of an Object value. If the object has an
     * value.toJSONString() method, then that method will be used to produce
     * the JSON text. The method is required to produce a strictly
     * conforming text. If the object does not contain a toJSONString
     * method (which is the most common case), then a text will be
     * produced by other means. If the value is an array or Collection,
     * then a JSONArray will be made from it and its toJSONString method
     * will be called. If the value is a MAP, then a JSONObject will be made
     * from it and its toJSONString method will be called. Otherwise, the
     * value's toString method will be called, and the result will be quoted.
     *
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     * @param value The value to be serialized.
     * @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>.
     * @throws JSONException If the value is or contains an invalid number.
     */
    static String valueToString(Object value) throws JSONException {
        if (value == null || value.equals(null)) {
            return "null";
        }
        if (value instanceof JSONString) {
            Object o;
            try {
                o = ((JSONString)value).toJSONString();
            } catch (Exception e) {
                throw new JSONException(e);
            }
            if (o instanceof String) {
                return (String)o;
            }
            throw new JSONException("Bad value from toJSONString: " + o);
        }
        if (value instanceof Number) {
            return numberToString((Number) value);
        }
        if (value instanceof Boolean || value instanceof JSONObject ||
                value instanceof JSONArray) {
            return value.toString();
        }
        if (value instanceof Map) {
            return new JSONObject((Map)value).toString();
        }
        if (value instanceof Collection) {
            return new JSONArray((Collection)value).toString();
        }
        if (value.getClass().isArray()) {
            return new JSONArray(value).toString();
        }
        return quote(value.toString());
    }


    /**
     * Make a prettyprinted JSON text of an object value.
     * <p>
     * Warning: This method assumes that the data structure is acyclical.
     * @param value The value to be serialized.
     * @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>.
     * @throws JSONException If the object contains an invalid number.
     */
     static String valueToString(Object value, int indentFactor, int indent)
            throws JSONException {
        if (value == null || value.equals(null)) {
            return "null";
        }
        try {
            if (value instanceof JSONString) {
                Object o = ((JSONString)value).toJSONString();
                if (o instanceof String) {
                    return (String)o;
                }
            }
        } catch (Exception e) {
            /* forget about it */
        }
        if (value instanceof Number) {
            return numberToString((Number) value);
        }
        if (value instanceof Boolean) {
            return value.toString();
        }
        if (value instanceof JSONObject) {
            return ((JSONObject)value).toString(indentFactor, indent);
        }
        if (value instanceof JSONArray) {
            return ((JSONArray)value).toString(indentFactor, indent);
        }
        if (value instanceof Map) {
            return new JSONObject((Map)value).toString(indentFactor, indent);
        }
        if (value instanceof Collection) {
            return new JSONArray((Collection)value).toString(indentFactor, indent);
        }
        if (value.getClass().isArray()) {
            return new JSONArray(value).toString(indentFactor, indent);
        }
        return quote(value.toString());
    }


     /**
      * Write the contents of the JSONObject 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;
            Iterator keys = keys();
            writer.write('{');

            while (keys.hasNext()) {
                if (b) {
                    writer.write(',');
                }
                Object k = keys.next();
                writer.write(quote(k.toString()));
                writer.write(':');
                Object v = this.myHashMap.get(k);
                if (v instanceof JSONObject) {
                    ((JSONObject)v).write(writer);
                } else if (v instanceof JSONArray) {
                    ((JSONArray)v).write(writer);
                } else {
                    writer.write(valueToString(v));
                }
                b = true;
            }
            writer.write('}');
            return writer;
        } catch (IOException e) {
            throw new JSONException(e);
        }
     }
}