Java tutorial
/* * Copyright (C) 2010 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package dk.nodes.webservice.parser; import org.apache.commons.lang3.StringEscapeUtils; import org.json.JSONException; import org.json.JSONObject; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import dk.nodes.utils.NLog; // Note: this class was written without inspecting the non-free org.json sourcecode. /** * A modifiable set of name/value mappings. Names are unique, non-null strings. * Values may be any mix of {@link NJSONObject JSONObjects}, {@link NJSONArray * JSONArrays}, Strings, Booleans, Integers, Longs, Doubles or {@link #NULL}. * Values may not be {@code null}, {@link Double#isNaN() NaNs}, {@link * Double#isInfinite() infinities}, or of any type not listed here. * * <p>This class can coerce values to another type when requested. * <ul> * <li>When the requested type is a boolean, strings will be coerced using a * case-insensitive comparison to "true" and "false". * <li>When the requested type is a double, other {@link Number} types will * be coerced using {@link Number#doubleValue() doubleValue}. Strings * that can be coerced using {@link Double#valueOf(String)} will be. * <li>When the requested type is an int, other {@link Number} types will * be coerced using {@link Number#intValue() intValue}. Strings * that can be coerced using {@link Double#valueOf(String)} will be, * and then cast to int. * <li><a name="lossy">When the requested type is a long, other {@link Number} types will * be coerced using {@link Number#longValue() longValue}. Strings * that can be coerced using {@link Double#valueOf(String)} will be, * and then cast to long. This two-step conversion is lossy for very * large values. For example, the string "9223372036854775806" yields the * long 9223372036854775807.</a> * <li>When the requested type is a String, other non-null values will be * coerced using {@link String#valueOf(Object)}. Although null cannot be * coerced, the sentinel value {@link NJSONObject#NULL} is coerced to the * string "null". * </ul> * * <p>This class can look up both mandatory and optional values: * <ul> * <li>Use <code>get<i>Type</i>()</code> to retrieve a mandatory value. This * fails with a {@code JSONException} if the requested name has no value * or if the value cannot be coerced to the requested type. * <li>Use <code>opt<i>Type</i>()</code> to retrieve an optional value. This * returns a system- or user-supplied default if the requested name has no * value or if the value cannot be coerced to the requested type. * </ul> * * <p><strong>Warning:</strong> this class represents null in two incompatible * ways: the standard Java {@code null} reference, and the sentinel value {@link * NJSONObject#NULL}. In particular, calling {@code put(name, null)} removes the * named entry from the object but {@code put(name, JSONObject.NULL)} stores an * entry whose value is {@code JSONObject.NULL}. * * <p>Instances of this class are not thread safe. Although this class is * nonfinal, it was not designed for inheritance and should not be subclassed. * In particular, self-use by overrideable methods is not specified. See * <i>Effective Java</i> Item 17, "Design and Document or inheritance or else * prohibit it" for further information. */ @Deprecated public class NJSONObject extends JSONObject { private static final Double NEGATIVE_ZERO = -0d; /** * A sentinel value used to explicitly define a name with no value. Unlike * {@code null}, names with this value: * <ul> * <li>show up in the {@link #names} array * <li>show up in the {@link #keys} iterator * <li>return {@code true} for {@link #has(String)} * <li>do not throw on {@link #get(String)} * <li>are included in the encoded JSON string. * </ul> * * <p>This value violates the general contract of {@link Object#equals} by * returning true when compared to {@code null}. Its {@link #toString} * method returns "null". */ public static final Object NULL = new Object() { @Override public boolean equals(Object o) { return o == this || o == null; // API specifies this broken equals implementation } @Override public String toString() { return "null"; } }; private final Map<String, Object> nameValuePairs; private String TAG = NJSONObject.class.getName(); /** * Creates a {@code JSONObject} with no name/value mappings. */ public NJSONObject() { nameValuePairs = new HashMap<String, Object>(); } /** * Creates a new {@code JSONObject} by copying all name/value mappings from * the given map. * * @param copyFrom a map whose keys are of type {@link String} and whose * values are of supported types. * @throws NullPointerException if any of the map's keys are null. */ /* (accept a raw type for API compatibility) */ public NJSONObject(Map copyFrom) { this(); Map<?, ?> contentsTyped = (Map<?, ?>) copyFrom; for (Map.Entry<?, ?> entry : contentsTyped.entrySet()) { /* * Deviate from the original by checking that keys are non-null and * of the proper type. (We still defer validating the values). */ String key = (String) entry.getKey(); if (key == null) { throw new NullPointerException("key == null"); } nameValuePairs.put(key, entry.getValue()); } } /** * Creates a new {@code JSONObject} with name/value mappings from the next * object in the tokener. * * @param readFrom a tokener whose nextValue() method will yield a * {@code JSONObject}. * @throws JSONException if the parse fails or doesn't yield a * {@code JSONObject}. */ public NJSONObject(JSONTokener readFrom) throws JSONException { /* * Getting the parser to populate this could get tricky. Instead, just * parse to temporary JSONObject and then steal the data from that. */ Object object = readFrom.nextValue(); if (object instanceof NJSONObject) { this.nameValuePairs = ((NJSONObject) object).nameValuePairs; } else { throw NJSON.typeMismatch(object, "JSONObject"); } } /** * Creates a new {@code JSONObject} with name/value mappings from the JSON * string. * * @param json a JSON-encoded string containing an object. * @throws JSONException if the parse fails or doesn't yield a {@code * JSONObject}. */ public NJSONObject(String json) throws JSONException { this(new JSONTokener(json)); } /** * Creates a new {@code JSONObject} by copying mappings for the listed names * from the given object. Names that aren't present in {@code copyFrom} will * be skipped. */ public NJSONObject(NJSONObject copyFrom, String[] names) throws JSONException { this(); for (String name : names) { Object value = copyFrom.opt(name); if (value != null) { nameValuePairs.put(name, value); } } } /** * Returns the number of name/value mappings in this object. */ public int length() { return nameValuePairs.size(); } /** * Maps {@code name} to {@code value}, clobbering any existing name/value * mapping with the same name. * * @return this object. */ public NJSONObject put(String name, boolean value) throws JSONException { nameValuePairs.put(checkName(name), value); return this; } /** * Maps {@code name} to {@code value}, clobbering any existing name/value * mapping with the same name. * * @param value a finite value. May not be {@link Double#isNaN() NaNs} or * {@link Double#isInfinite() infinities}. * @return this object. */ public NJSONObject put(String name, double value) throws JSONException { nameValuePairs.put(checkName(name), NJSON.checkDouble(value)); return this; } /** * Maps {@code name} to {@code value}, clobbering any existing name/value * mapping with the same name. * * @return this object. */ public NJSONObject put(String name, int value) throws JSONException { nameValuePairs.put(checkName(name), value); return this; } /** * Maps {@code name} to {@code value}, clobbering any existing name/value * mapping with the same name. * * @return this object. */ public NJSONObject put(String name, long value) throws JSONException { nameValuePairs.put(checkName(name), value); return this; } /** * Maps {@code name} to {@code value}, clobbering any existing name/value * mapping with the same name. If the value is {@code null}, any existing * mapping for {@code name} is removed. * * @param value a {@link NJSONObject}, {@link NJSONArray}, String, Boolean, * Integer, Long, Double, {@link #NULL}, or {@code null}. May not be * {@link Double#isNaN() NaNs} or {@link Double#isInfinite() * infinities}. * @return this object. */ public NJSONObject put(String name, Object value) throws JSONException { if (value == null) { nameValuePairs.remove(name); return this; } if (value instanceof String) { String escapedString = StringEscapeUtils.escapeJson((String) value); nameValuePairs.put(checkName(name), escapedString); return this; } if (value instanceof Number) { // deviate from the original by checking all Numbers, not just floats & doubles NJSON.checkDouble(((Number) value).doubleValue()); } nameValuePairs.put(checkName(name), value); return this; } /** * Equivalent to {@code put(name, value)} when both parameters are non-null; * does nothing otherwise. */ public NJSONObject putOpt(String name, Object value) throws JSONException { if (name == null || value == null) { return this; } return put(name, value); } /** * Appends {@code value} to the array already mapped to {@code name}. If * this object has no mapping for {@code name}, this inserts a new mapping. * If the mapping exists but its value is not an array, the existing * and new values are inserted in order into a new array which is itself * mapped to {@code name}. In aggregate, this allows values to be added to a * mapping one at a time. * * @param value a {@link NJSONObject}, {@link NJSONArray}, String, Boolean, * Integer, Long, Double, {@link #NULL} or null. May not be {@link * Double#isNaN() NaNs} or {@link Double#isInfinite() infinities}. */ public NJSONObject accumulate(String name, Object value) throws JSONException { Object current = nameValuePairs.get(checkName(name)); if (current == null) { return put(name, value); } // check in accumulate, since array.put(Object) doesn't do any checking if (value instanceof Number) { NJSON.checkDouble(((Number) value).doubleValue()); } if (current instanceof NJSONArray) { NJSONArray array = (NJSONArray) current; array.put(value); } else { NJSONArray array = new NJSONArray(); array.put(current); array.put(value); nameValuePairs.put(name, array); } return this; } String checkName(String name) throws JSONException { if (name == null) { throw new JSONException("Names must be non-null"); } return name; } /** * Removes the named mapping if it exists; does nothing otherwise. * * @return the value previously mapped by {@code name}, or null if there was * no such mapping. */ public Object remove(String name) { return nameValuePairs.remove(name); } /** * Returns true if this object has no mapping for {@code name} or if it has * a mapping whose value is {@link #NULL}. */ public boolean isNull(String name) { Object value = nameValuePairs.get(name); return value == null || value == NULL; } /** * Returns true if this object has a mapping for {@code name}. The mapping * may be {@link #NULL}. */ public boolean has(String name) { return nameValuePairs.containsKey(name); } /** * Returns the value mapped by {@code name}. * * @throws JSONException if no such mapping exists. */ public Object get(String name) throws JSONException { Object result = nameValuePairs.get(name); if (result == null) { throw new JSONException("No value for " + name); } return result; } /** * Returns the value mapped by {@code name}, or null if no such mapping * exists. */ public Object opt(String name) { return nameValuePairs.get(name); } /** * Returns the value mapped by {@code name} if it exists and is a boolean or * can be coerced to a boolean. * * @throws JSONException if the mapping doesn't exist or cannot be coerced * to a boolean. */ public boolean getBoolean(String name) throws JSONException { Object object = get(name); Boolean result = NJSON.toBoolean(object); if (result == null) { throw NJSON.typeMismatch(name, object, "boolean"); } return result; } /** * Returns the value mapped by {@code name} if it exists and is a boolean or * can be coerced to a boolean. Returns false otherwise. */ public boolean optBoolean(String name) { return optBoolean(name, false); } /** * Returns the value mapped by {@code name} if it exists and is a boolean or * can be coerced to a boolean. Returns {@code fallback} otherwise. */ public boolean optBoolean(String name, boolean fallback) { Object object = opt(name); Boolean result = NJSON.toBoolean(object); return result != null ? result : fallback; } /** * Returns the value mapped by {@code name} if it exists and is a double or * can be coerced to a double. * * @throws JSONException if the mapping doesn't exist or cannot be coerced * to a double. */ public double getDouble(String name) throws JSONException { Object object = get(name); Double result = NJSON.toDouble(object); if (result == null) { throw NJSON.typeMismatch(name, object, "double"); } return result; } /** * Returns the value mapped by {@code name} if it exists and is a double or * can be coerced to a double. Returns {@code NaN} otherwise. */ public double optDouble(String name) { return optDouble(name, Double.NaN); } /** * Returns the value mapped by {@code name} if it exists and is a double or * can be coerced to a double. Returns {@code fallback} otherwise. */ public double optDouble(String name, double fallback) { Object object = opt(name); Double result = NJSON.toDouble(object); return result != null ? result : fallback; } /** * Returns the value mapped by {@code name} if it exists and is an int or * can be coerced to an int. * * @throws JSONException if the mapping doesn't exist or cannot be coerced * to an int. */ public int getInt(String name) throws JSONException { Object object = get(name); Integer result = NJSON.toInteger(object); if (result == null) { throw NJSON.typeMismatch(name, object, "int"); } return result; } /** * Returns the value mapped by {@code name} if it exists and is an int or * can be coerced to an int. Returns 0 otherwise. */ public int optInt(String name) { return optInt(name, 0); } /** * Returns the value mapped by {@code name} if it exists and is an int or * can be coerced to an int. Returns {@code fallback} otherwise. */ public int optInt(String name, int fallback) { Object object = opt(name); Integer result = NJSON.toInteger(object); return result != null ? result : fallback; } /** * Returns the value mapped by {@code name} if it exists and is a long or * can be coerced to a long. Note that JSON represents numbers as doubles, * so this is <a href="#lossy">lossy</a>; use strings to transfer numbers via JSON. * * @throws JSONException if the mapping doesn't exist or cannot be coerced * to a long. */ public long getLong(String name) throws JSONException { Object object = get(name); Long result = NJSON.toLong(object); if (result == null) { throw NJSON.typeMismatch(name, object, "long"); } return result; } /** * Returns the value mapped by {@code name} if it exists and is a long or * can be coerced to a long. Returns 0 otherwise. Note that JSON represents numbers as doubles, * so this is <a href="#lossy">lossy</a>; use strings to transfer numbers via JSON. */ public long optLong(String name) { return optLong(name, 0L); } /** * Returns the value mapped by {@code name} if it exists and is a long or * can be coerced to a long. Returns {@code fallback} otherwise. Note that JSON represents * numbers as doubles, so this is <a href="#lossy">lossy</a>; use strings to transfer * numbers via JSON. */ public long optLong(String name, long fallback) { Object object = opt(name); Long result = NJSON.toLong(object); return result != null ? result : fallback; } /** * Returns the value mapped by {@code name} if it exists, coercing it if * necessary. * * @throws JSONException if no such mapping exists. */ public String getString(String name) throws JSONException { if (isNull(name)) return null; Object object = get(name); if (object == null) { return null; } String result = NJSON.toString(object); if (result == null) { throw NJSON.typeMismatch(name, object, "String"); } return result; } /** * Returns the value mapped by {@code name} if it exists, coercing it if * necessary. Returns the empty string if no such mapping exists. */ public String optString(String name) { return optString(name, ""); } /** * Returns the value mapped by {@code name} if it exists, coercing it if * necessary. Returns {@code fallback} if no such mapping exists. */ public String optString(String name, String fallback) { if (isNull(name)) return fallback; Object object = opt(name); String result = NJSON.toString(object); return result != null ? result : fallback; } /** * Returns the value mapped by {@code name} if it exists and is a {@code * JSONArray}. * * @throws JSONException if the mapping doesn't exist or is not a {@code * JSONArray}. */ public NJSONArray getJSONArray(String name) throws JSONException { Object object = get(name); if (object instanceof NJSONArray) { return (NJSONArray) object; } else { throw NJSON.typeMismatch(name, object, "JSONArray"); } } public NJSONArray getNJSONArray(String name) throws JSONException { return getJSONArray(name); } /** * Returns the value mapped by {@code name} if it exists and is a {@code * JSONArray}. Returns null otherwise. */ public NJSONArray optJSONArray(String name) { Object object = opt(name); return object instanceof NJSONArray ? (NJSONArray) object : null; } public NJSONArray optNJSONArray(String name) { return optJSONArray(name); } /** * Returns the value mapped by {@code name} if it exists and is a {@code * JSONObject}. * * @throws JSONException if the mapping doesn't exist or is not a {@code * JSONObject}. */ public NJSONObject getJSONObject(String name) throws JSONException { Object object = get(name); if (object instanceof NJSONObject) { return (NJSONObject) object; } else { throw NJSON.typeMismatch(name, object, "JSONObject"); } } public NJSONObject getNJSONObject(String string) throws JSONException { return getJSONObject(string); } /** * Returns the value mapped by {@code name} if it exists and is a {@code * JSONObject}. Returns null otherwise. */ public NJSONObject optJSONObject(String name) { Object object = opt(name); return object instanceof NJSONObject ? (NJSONObject) object : null; } public NJSONObject optNJSONObject(String name) { return optJSONObject(name); } /** * Returns an array with the values corresponding to {@code names}. The * array contains null for names that aren't mapped. This method returns * null if {@code names} is either null or empty. */ public NJSONArray toJSONArray(NJSONArray names) throws JSONException { NJSONArray result = new NJSONArray(); if (names == null) { return null; } int length = names.length(); if (length == 0) { return null; } for (int i = 0; i < length; i++) { String name = NJSON.toString(names.opt(i)); result.put(opt(name)); } return result; } /** * Returns an iterator of the {@code String} names in this object. The * returned iterator supports {@link Iterator#remove() remove}, which will * remove the corresponding mapping from this object. If this object is * modified after the iterator is returned, the iterator's behavior is * undefined. The order of the keys is undefined. */ /* Return a raw type for API compatibility */ public Iterator keys() { return nameValuePairs.keySet().iterator(); } /** * Returns an array containing the string names in this object. This method * returns null if this object contains no mappings. */ public NJSONArray names() { return nameValuePairs.isEmpty() ? null : new NJSONArray(new ArrayList<String>(nameValuePairs.keySet())); } /** * Encodes this object as a compact JSON string, such as: * <pre>{"query":"Pizza","locations":[94043,90210]}</pre> */ @Override public String toString() { try { JSONStringer stringer = new JSONStringer(); writeTo(stringer); return stringer.toString(); } catch (Exception e) { NLog.e(TAG + " toString", e); return null; } } /** * Encodes this object as a human readable JSON string for debugging, such * as: * <pre> * { * "query": "Pizza", * "locations": [ * 94043, * 90210 * ] * }</pre> * * @param indentSpaces the number of spaces to indent for each level of * nesting. */ public String toString(int indentSpaces) throws JSONException { JSONStringer stringer = new JSONStringer(indentSpaces); writeTo(stringer); return stringer.toString(); } void writeTo(JSONStringer stringer) throws JSONException { stringer.object(); for (Map.Entry<String, Object> entry : nameValuePairs.entrySet()) { stringer.key(entry.getKey()).value(entry.getValue()); } stringer.endObject(); } /** * Encodes the number as a JSON string. * * @param number a finite value. May not be {@link Double#isNaN() NaNs} or * {@link Double#isInfinite() infinities}. */ public static String numberToString(Number number) throws JSONException { if (number == null) { throw new JSONException("Number must be non-null"); } double doubleValue = number.doubleValue(); NJSON.checkDouble(doubleValue); // the original returns "-0" instead of "-0.0" for negative zero if (number.equals(NEGATIVE_ZERO)) { return "-0"; } long longValue = number.longValue(); if (doubleValue == (double) longValue) { return Long.toString(longValue); } return number.toString(); } /** * Encodes {@code data} as a JSON string. This applies quotes and any * necessary character escaping. * * @param data the string to encode. Null will be interpreted as an empty * string. */ public static String quote(String data) { if (data == null) { return "\"\""; } try { JSONStringer stringer = new JSONStringer(); stringer.open(JSONStringer.Scope.NULL, ""); stringer.value(data); stringer.close(JSONStringer.Scope.NULL, JSONStringer.Scope.NULL, ""); return stringer.toString(); } catch (JSONException e) { throw new AssertionError(); } } }