JSONWriter.java.svn-base
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上传日期:2022-07-12
资源大小:5257k
文件大小:10k
源码类别:
Jsp/Servlet
开发平台:
Java
- package org.json;
- import java.io.IOException;
- import java.io.Writer;
- /*
- Copyright (c) 2006 JSON.org
- Permission is hereby granted, free of charge, to any person obtaining a copy
- of this software and associated documentation files (the "Software"), to deal
- in the Software without restriction, including without limitation the rights
- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- copies of the Software, and to permit persons to whom the Software is
- furnished to do so, subject to the following conditions:
- The above copyright notice and this permission notice shall be included in all
- copies or substantial portions of the Software.
- The Software shall be used for Good, not Evil.
- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- SOFTWARE.
- */
- /**
- * JSONWriter provides a quick and convenient way of producing JSON text.
- * The texts produced strictly conform to JSON syntax rules. No whitespace is
- * added, so the results are ready for transmission or storage. Each instance of
- * JSONWriter can produce one JSON text.
- * <p>
- * A JSONWriter instance provides a <code>value</code> method for appending
- * values to the
- * text, and a <code>key</code>
- * method for adding keys before values in objects. There are <code>array</code>
- * and <code>endArray</code> methods that make and bound array values, and
- * <code>object</code> and <code>endObject</code> methods which make and bound
- * object values. All of these methods return the JSONWriter instance,
- * permitting a cascade style. For example, <pre>
- * new JSONWriter(myWriter)
- * .object()
- * .key("JSON")
- * .value("Hello, World!")
- * .endObject();</pre> which writes <pre>
- * {"JSON":"Hello, World!"}</pre>
- * <p>
- * The first method called must be <code>array</code> or <code>object</code>.
- * There are no methods for adding commas or colons. JSONWriter adds them for
- * you. Objects and arrays can be nested up to 20 levels deep.
- * <p>
- * This can sometimes be easier than using a JSONObject to build a string.
- * @author JSON.org
- * @version 2008-09-22
- */
- public class JSONWriter {
- private static final int maxdepth = 20;
- /**
- * The comma flag determines if a comma should be output before the next
- * value.
- */
- private boolean comma;
- /**
- * The current mode. Values:
- * 'a' (array),
- * 'd' (done),
- * 'i' (initial),
- * 'k' (key),
- * 'o' (object).
- */
- protected char mode;
- /**
- * The object/array stack.
- */
- private JSONObject stack[];
- /**
- * The stack top index. A value of 0 indicates that the stack is empty.
- */
- private int top;
- /**
- * The writer that will receive the output.
- */
- protected Writer writer;
- /**
- * Make a fresh JSONWriter. It can be used to build one JSON text.
- */
- public JSONWriter(Writer w) {
- this.comma = false;
- this.mode = 'i';
- this.stack = new JSONObject[maxdepth];
- this.top = 0;
- this.writer = w;
- }
- /**
- * Append a value.
- * @param s A string value.
- * @return this
- * @throws JSONException If the value is out of sequence.
- */
- private JSONWriter append(String s) throws JSONException {
- if (s == null) {
- throw new JSONException("Null pointer");
- }
- if (this.mode == 'o' || this.mode == 'a') {
- try {
- if (this.comma && this.mode == 'a') {
- this.writer.write(',');
- }
- this.writer.write(s);
- } catch (IOException e) {
- throw new JSONException(e);
- }
- if (this.mode == 'o') {
- this.mode = 'k';
- }
- this.comma = true;
- return this;
- }
- throw new JSONException("Value out of sequence.");
- }
- /**
- * Begin appending a new array. All values until the balancing
- * <code>endArray</code> will be appended to this array. The
- * <code>endArray</code> method must be called to mark the array's end.
- * @return this
- * @throws JSONException If the nesting is too deep, or if the object is
- * started in the wrong place (for example as a key or after the end of the
- * outermost array or object).
- */
- public JSONWriter array() throws JSONException {
- if (this.mode == 'i' || this.mode == 'o' || this.mode == 'a') {
- this.push(null);
- this.append("[");
- this.comma = false;
- return this;
- }
- throw new JSONException("Misplaced array.");
- }
- /**
- * End something.
- * @param m Mode
- * @param c Closing character
- * @return this
- * @throws JSONException If unbalanced.
- */
- private JSONWriter end(char m, char c) throws JSONException {
- if (this.mode != m) {
- throw new JSONException(m == 'o' ? "Misplaced endObject." :
- "Misplaced endArray.");
- }
- this.pop(m);
- try {
- this.writer.write(c);
- } catch (IOException e) {
- throw new JSONException(e);
- }
- this.comma = true;
- return this;
- }
- /**
- * End an array. This method most be called to balance calls to
- * <code>array</code>.
- * @return this
- * @throws JSONException If incorrectly nested.
- */
- public JSONWriter endArray() throws JSONException {
- return this.end('a', ']');
- }
- /**
- * End an object. This method most be called to balance calls to
- * <code>object</code>.
- * @return this
- * @throws JSONException If incorrectly nested.
- */
- public JSONWriter endObject() throws JSONException {
- return this.end('k', '}');
- }
- /**
- * Append a key. The key will be associated with the next value. In an
- * object, every value must be preceded by a key.
- * @param s A key string.
- * @return this
- * @throws JSONException If the key is out of place. For example, keys
- * do not belong in arrays or if the key is null.
- */
- public JSONWriter key(String s) throws JSONException {
- if (s == null) {
- throw new JSONException("Null key.");
- }
- if (this.mode == 'k') {
- try {
- stack[top - 1].putOnce(s, Boolean.TRUE);
- if (this.comma) {
- this.writer.write(',');
- }
- this.writer.write(JSONObject.quote(s));
- this.writer.write(':');
- this.comma = false;
- this.mode = 'o';
- return this;
- } catch (IOException e) {
- throw new JSONException(e);
- }
- }
- throw new JSONException("Misplaced key.");
- }
- /**
- * Begin appending a new object. All keys and values until the balancing
- * <code>endObject</code> will be appended to this object. The
- * <code>endObject</code> method must be called to mark the object's end.
- * @return this
- * @throws JSONException If the nesting is too deep, or if the object is
- * started in the wrong place (for example as a key or after the end of the
- * outermost array or object).
- */
- public JSONWriter object() throws JSONException {
- if (this.mode == 'i') {
- this.mode = 'o';
- }
- if (this.mode == 'o' || this.mode == 'a') {
- this.append("{");
- this.push(new JSONObject());
- this.comma = false;
- return this;
- }
- throw new JSONException("Misplaced object.");
- }
- /**
- * Pop an array or object scope.
- * @param c The scope to close.
- * @throws JSONException If nesting is wrong.
- */
- private void pop(char c) throws JSONException {
- if (this.top <= 0) {
- throw new JSONException("Nesting error.");
- }
- char m = this.stack[this.top - 1] == null ? 'a' : 'k';
- if (m != c) {
- throw new JSONException("Nesting error.");
- }
- this.top -= 1;
- this.mode = this.top == 0 ? 'd' : this.stack[this.top - 1] == null ? 'a' : 'k';
- }
- /**
- * Push an array or object scope.
- * @param c The scope to open.
- * @throws JSONException If nesting is too deep.
- */
- private void push(JSONObject jo) throws JSONException {
- if (this.top >= maxdepth) {
- throw new JSONException("Nesting too deep.");
- }
- this.stack[this.top] = jo;
- this.mode = jo == null ? 'a' : 'k';
- this.top += 1;
- }
- /**
- * Append either the value <code>true</code> or the value
- * <code>false</code>.
- * @param b A boolean.
- * @return this
- * @throws JSONException
- */
- public JSONWriter value(boolean b) throws JSONException {
- return this.append(b ? "true" : "false");
- }
- /**
- * Append a double value.
- * @param d A double.
- * @return this
- * @throws JSONException If the number is not finite.
- */
- public JSONWriter value(double d) throws JSONException {
- return this.value(new Double(d));
- }
- /**
- * Append a long value.
- * @param l A long.
- * @return this
- * @throws JSONException
- */
- public JSONWriter value(long l) throws JSONException {
- return this.append(Long.toString(l));
- }
- /**
- * Append an object value.
- * @param o The object to append. It can be null, or a Boolean, Number,
- * String, JSONObject, or JSONArray, or an object with a toJSONString()
- * method.
- * @return this
- * @throws JSONException If the value is out of sequence.
- */
- public JSONWriter value(Object o) throws JSONException {
- return this.append(JSONObject.valueToString(o));
- }
- }