一、kxml的前身--xmlpull
xmlpull提供了为资源有限的环境（如j2me）和j2ee应用服务器使用的xml解析API，xml pull解析允许使用stream解析的方式。
xmlpull的特点：
* 简单的接口-解析器包含一个接口、一个异常、一个建立解析器的factory；
* 无实现依赖-模仿JAXP的factory类和很容易的切换不同的XmlPull V1 API实现，而无需修改代码；
* 易用性-只有唯一的next()方法用来读取下面5类事件中的一个：
START DOCUMENT-文档起始点，这时解析器还没有准备好读取文档；
START_TAG-解析器读取到了element声明的开始标签，就是xml文件中声明element用的"<"；
TEXT-解析器读取到了element的内容，如element的各种属性和value；
END_TAG-解析器读取到了element声明的结束标签，就是"/>"或者"</...>"；
END_DOCUMENT-解析器读取到文档的结尾，解析工作完毕。
* 多功能性-由于提供了xml解析器的通用接口，所以允许多个实现和在特性和属性上的扩展
* 良好的性能-由于提供了通用的接口，可以说也就为使用快速的xml解析器提供了条件，但是目前最快的解析器，本人还没遇到过。:-)
* 最小化需要-设计上与j2me兼容，从而使其能工作于小型设备和建立使用微量内存的xmlPull兼容的解析器。
二、建立在良好构架上的kxml
xmlpull api提供的通用的xml内容解析功能使用方式：使用一个循环来遍历到下一个事件，并切换到一个针对这个事件的分支语句处理。但是在使用xml解析器时，一些xml element不仅包括text还有其它的element（被称为子元素或者内嵌元素）。对于这样的xml数据，解析处理被简单化到了使用xmlpull api的nextTag和nextText方法。另外，require方法也可以使用一个解析状态的参数来表示希望取得数据的event类型。以上就是kxml使用方法。
如解析下面内容的简单xml文件：
<elements>
<text>text1</text>
<text>text2</text></elements>
解析代码片断如下：
parser.nextTag();parser.require(XmlPullParser.START_TAG, null, "elements");
while(parser.nextTag() == XmlPullParser.START_TAG) { parser.require(XmlPullParser.START_TAG, null, "text");
// handle element content System.out.println("text content: "+ parser.nextText());
parser.require(XmlPullParser.END_TAG, null, "text");}parser.require(XmlPullParser.END_TAG, null, "elements");
从上面的代码看出，的确很简单明了。
三、背向kxml的原因
但是如果真正的使用kxml开发j2me程序时会发现，kxml包和其依赖的xmlpull包不仅无形中增加了程序发布时的大小，而且由于没有最好的解析器带来的负面性能损耗会随着xml文件的大小成非线性增长（还好不是指数级的）。这些成为了kxml的流行障碍。
四、轻量级的xmlReader
幸运的是kobject.org网站上提供了一个轻量级的xmlReader程序，大家可以到http://kobjects.sourceforge.net/utils/ 获取。
作为简单的xml解析器，功能上与kxml类似，但是不支持命名空间和一些传统的事件。整个jar文件大小小于5KB。
以下便是其代码：
XmlReader.java
/* Copyright (c) 2002,2003, Stefan Haustein, Oberhausen, Rhld., Germany *
* 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 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. */package org.kobjects.xml;import java.io.*;
import java.util.*;
/** A minimalistic XML pull parser, similar to kXML, but
not supporting namespaces or legacy events. If you need
support for namespaces, or access to XML comments or
processing instructions, please use kXML(2) instead. */public class XmlReader {
/** Return value of getType before first call to next() */
public final static int START_DOCUMENT = 0;
/** Signal logical end of xml document */
public final static int END_DOCUMENT = 1;
/** Start tag was just read */ public final static int START_TAG = 2;
/** * End tag was just read
*/
public final static int END_TAG = 3;
/** Text was just read */
public final static int TEXT = 4;
final static int CDSECT = 5;
final static int ENTITY_REF = 6;
static final private String UNEXPECTED_EOF =
"Unexpected EOF";
static final private int LEGACY = 999;
// general public boolean relaxed;
private Hashtable entityMap;
private int depth;
private String[] elementStack = new String[4];
// source private Reader reader;
private char[] srcBuf =
new char[Runtime.getRuntime().freeMemory() >= 1048576
? 8192
: 128];
private int srcPos;
private int srcCount;
private boolean eof;
private int line;
private int column;
private int peek0;
private int peek1;
// txtbuffer
private char[] txtBuf = new char[128];
private int txtPos;
// Event-related
private int type;
private String text;
private boolean isWhitespace;
private String name;
private boolean degenerated;
private int attributeCount;
private String[] attributes = new String[16];
private String[] TYPES =
{
"Start Document",
"End Document",
"Start Tag",
"End Tag",
"Text" };
private final int read() throws IOException {
int r = peek0;
peek0 = peek1;
if (peek0 == -1) {
eof = true;
return r;
} else if (r == '\n' || r == '\r') {
line++;
column = 0;
if (r == '\r' && peek0 == '\n')
peek0 = 0; }
column++;
if (srcPos >= srcCount) {
srcCount = reader.read(srcBuf, 0, srcBuf.length);
if (srcCount <= 0) {
peek1 = -1;
return r;
}
srcPos = 0;
}
peek1 = srcBuf[srcPos++];
return r;
}
private final void exception(String desc)
throws IOException {
throw new IOException(
desc + " pos: " + getPositionDescription());
}
private final void push(int c) {
if (c == 0)
return;
if (txtPos == txtBuf.length) {
char[] bigger = new char[txtPos * 4 / 3 + 4];
System.arraycopy(txtBuf, 0, bigger, 0, txtPos);
txtBuf = bigger;
}
txtBuf[txtPos++] = (char) c;
} private final void read(char c) throws IOException {
if (read() != c) {
if (relaxed) {
if (c <= 32) {
skip();
read();
}
}
else {
exception("expected: '" + c + "'");
}
}
}
private final void skip() throws IOException {
while (!eof && peek0 <= ' ')
read();
}
private final String pop(int pos) {
String result = new String(txtBuf, pos, txtPos - pos);
txtPos = pos;
return result;
}
private final String readName() throws IOException {
int pos = txtPos; int c = peek0;
if ((c < 'a' || c > 'z')
&& (c < 'A' || c > 'Z')
&& c != '_'
&& c != ':'
&& !relaxed)
|
