1 /*
2 * Copyright 2002-2009 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package net.sf.json.util;
17
18 import java.io.StringWriter;
19
20 /**
21 * JSONStringer provides a quick and convenient way of producing JSON text. The
22 * texts produced strictly conform to JSON syntax rules. No whitespace is added,
23 * so the results are ready for transmission or storage. Each instance of
24 * JSONStringer can produce one JSON text.
25 * <p>
26 * A JSONStringer instance provides a <code>value</code> method for appending
27 * values to the text, and a <code>key</code> method for adding keys before
28 * values in objects. There are <code>array</code> and <code>endArray</code>
29 * methods that make and bound array values, and <code>object</code> and
30 * <code>endObject</code> methods which make and bound object values. All of
31 * these methods return the JSONWriter instance, permitting cascade style. For
32 * example,
33 *
34 * <pre>
35 * myString = new JSONStringer()
36 * .object()
37 * .key("JSON")
38 * .value("Hello, World!")
39 * .endObject()
40 * .toString();</pre>
41 *
42 * which produces the string
43 *
44 * <pre>
45 * {"JSON":"Hello, World!"}</pre>
46 *
47 * <p>
48 * The first method called must be <code>array</code> or <code>object</code>.
49 * There are no methods for adding commas or colons. JSONStringer adds them for
50 * you. Objects and arrays can be nested up to 20 levels deep.
51 * <p>
52 * This can sometimes be easier than using a JSONObject to build a string.
53 *
54 * @author JSON.org
55 * @version 2
56 */
57 public class JSONStringer extends JSONBuilder {
58 /**
59 * Make a fresh JSONStringer. It can be used to build one JSON text.
60 */
61 public JSONStringer() {
62 super( new StringWriter() );
63 }
64
65 /**
66 * Return the JSON text. This method is used to obtain the product of the
67 * JSONStringer instance. It will return <code>null</code> if there was a
68 * problem in the construction of the JSON text (such as the calls to
69 * <code>array</code> were not properly balanced with calls to
70 * <code>endArray</code>).
71 *
72 * @return The JSON text.
73 */
74 public String toString() {
75 return this.mode == 'd' ? this.writer.toString() : null;
76 }
77 }