package ikrs.json; import java.io.CharArrayWriter; import java.io.IOException; import java.io.Writer; import java.util.List; import java.util.Map; /** * @author Ikaros Kappler * @date 2013-05-31 * @modified 2013-06-10 Ikaros Kappler (Added the asJSON* methods for explicit type conversion). * @version 1.0.1 **/ public abstract class AbstractJSONValue implements JSONValue { /** * The type of this value. **/ private int type; protected AbstractJSONValue( int type ) throws IllegalArgumentException { super(); if( !this.isValidTypeID(type) ) throw new IllegalArgumentException( "Invalid JSON type ID (" + type + ")." ); this.type = type; } /** * This method indicates if this JSON value is a number. * * @return true if this value represents a number. **/ public boolean isNumber() { return this.type == JSONValue.TYPE_NUMBER; } /** * This method indicates if this JSON value is a boolean. * * @return true if this value represents a boolean value. **/ public boolean isBoolean() { return this.type == JSONValue.TYPE_BOOLEAN; } /** * This method indicates if this JSON value is a string. * * @return true if this value represents a string. **/ public boolean isString() { return this.type == JSONValue.TYPE_STRING; } /** * This method indicates if this JSON value is an array. * * @return true if this value represents an array. **/ public boolean isArray() { return this.type == JSONValue.TYPE_ARRAY; } /** * This method indicates if this JSON value is an object. * * @return true if this value represents an array. **/ public boolean isObject() { return this.type == JSONValue.TYPE_OBJECT; } //--- BEGIN ------------------- Prepare override methods --------------------------- /** * This method indicates if this is JSON NULL. * * @return true if this JSON value is NULL (null). **/ public boolean isNull() { return this.type == JSONValue.TYPE_NULL; } /** * Get the number from this JSON value. * * @return The number from this JSON value. * @throws JSONException If this value does not represent a number. **/ public Number getNumber() throws JSONException { throw new JSONException( "JSON value is not a number." ); } /** * Get the boolean from this JSON value. * * @return The boolean value from this JSON value. * @throws JSONException If this value does not represent a boolean value. **/ public Boolean getBoolean() throws JSONException { throw new JSONException( "JSON value is not a boolean value." ); } /** * Get the string from this JSON value. * * @return The string value from this JSON value. * @throws JSONException If this value does not represent a string. **/ public String getString() throws JSONException { throw new JSONException( "JSON value is not a string." ); } /** * Get the array value as a List from this JSON value. * * @return The array from this JSON value. The array is returned as a Mist. * @throws JSONException If this value does not represent an array. **/ public List getArray() throws JSONException { throw new JSONException( "JSON value is not an array." ); } /** * Get the object value as a Map from this JSON value. * * @return The object from this JSON value. The object is returned as a Map. * @throws JSONException If this value does not represent an object. **/ public Map getObject() throws JSONException { throw new JSONException( "JSON value is not an object." ); } /** * This method tries to convert this JSONValue into a JSONBoolean. * * If that is not possible (because the contained value does not represent * a boolean in any way) the method will throw an JSONException. * * @return This JSON value as a JSON boolean. * @throws JSONException If this value is not convertible to a boolean. **/ public JSONBoolean asJSONBoolean() throws JSONException { throw new JSONException( "Cannot convert this value (" + this.getTypeName() + ") to a JSON boolean (incompatible types)." ); } /** * This method tries to convert this JSONValue into a JSONNumber. * * If that is not possible (because the contained value does not represent * a number in any way) the method will throw an JSONException. * * @return This JSON value as a JSON number. * @throws JSONException If this value is not convertible to a number. **/ public JSONNumber asJSONNumber() throws JSONException { throw new JSONException( "Cannot convert this value (" + this.getTypeName() + ") to a JSON number (incompatible types)." ); } /** * This method tries to convert this JSONValue into a JSONString. * * If that is not possible (because the contained value does not represent * a string in any way) the method will throw an JSONException. * * Note: due to the fact that JSON is usually represented by a string * EACH JSON VALUE SHOULD BE CONVERTIBLE TO A STRING. * * @return This JSON value as a JSON string. * @throws JSONException If this value is not convertible to a boolean. **/ public JSONString asJSONString() throws JSONException { throw new JSONException( "Cannot convert this value (" + this.getTypeName() + ") to a JSON string (incompatible types)." ); } /** * This method tries to convert this JSONValue into a JSONArray. * * If that is not possible (because the contained value does not represent * an array in any way) the method will throw an JSONException. * * @return This JSON value as a JSON array. * @throws JSONException If this value is not convertible to an array. **/ public JSONArray asJSONArray() throws JSONException { throw new JSONException( "Cannot convert this value (" + this.getTypeName() + ") to a JSON array (incompatible types)." ); } /** * This method tries to convert this JSONValue into a JSONObject. * * If that is not possible (because the contained value does not represent * an object in any way) the method will throw an JSONException. * * @return This JSON value as a JSON object. * @throws JSONException If this value is not convertible to an object. **/ public JSONObject asJSONObject() throws JSONException { throw new JSONException( "Cannot convert this value (" + this.getTypeName() + ") to a JSON array (incompatible types)." ); } /** * This method MUST write a valid JSON value to the passed writer. * * @param writer The writer to write to. * @throws IOException If any IO errors occur. **/ public abstract void write( Writer writer ) throws IOException; //--- END --------------------- Prepare override methods --------------------------- /** * Converts this JSON value into a valid JSON string. * * @return This value as a JSON string. **/ public String toJSONString() { try { Writer out = new CharArrayWriter( 4 ); this.write( out ); return out.toString(); // new String( out.toCharArray(), "UTF-8" ); } catch( IOException e ) { // This MUST NOT happen throw new RuntimeException( "Failed to convert object to string by the use of a buffered writer.", e ); } } /** * This method indicates if the passed type ID is supported by this class. * * @param type The type ID. * @return true If the passed type ID is supported by this class **/ public boolean isValidTypeID( int type ) { return (type >= JSONValue.TYPE_NULL && type <= JSONValue.TYPE_OBJECT); } public String getTypeName() { switch( this.type ) { case JSONValue.TYPE_NULL: return "NULL"; case JSONValue.TYPE_BOOLEAN: return "Boolean"; case JSONValue.TYPE_NUMBER: return "Number"; case JSONValue.TYPE_ARRAY: return "Array"; case JSONValue.TYPE_OBJECT: return "Object"; case JSONValue.TYPE_STRING: return "String"; default: return "unknown_type"; } } }