背景：
上一篇文章
android系统中data下的xml乱码无法查看问题剖析及解决方法
发布后，想要寻找一个可以直接把二进制xml和普通xml进行相互转换的，当时还写了相关的方案，但是当时没有找到现成的开源工具，后来经过相关粉丝提醒找到了和方法2一模一样思路的开源工具那就是abx2xml和xml2abx。
转化命令使用介绍abx2xml和xml2abx
转换前
属于二进制乱码
使用命令转换，命令：
bash
abx2xml ./system/users/0/appwidgets.xml ./system/users/0/appwidgets-read.xml
转化后的./system/users/0/appwidgets-read.xml变成我们常见的普通xml
同样普通xml也可以转成二进制xml，转化命令
bash
xml2abx ./system/users/0/appwidgets-read.xml ./system/users/0/appwidgets-binary.xml然后看看./system/users/0/appwidgets-binary.xml是不是变得二进制不可读了
abx2xml和xml2abx命令解析
abx2xml和xml2abx其实代码都是一样的，本质就是个sh脚本而已，运行的
bash
#!/system/bin/sh
export CLASSPATH=/system/framework/abx.jar
exec app_process /system/bin com.android.commands.abx.Abx "$0" "$@"可以看出本质上都是调用到了Abx这个java类，参数就是一个$0，这个代表命令本身，比如使用使用是：
abx2xml input.xml output.xml
那么这里的 0 就是 a b x 2 x m l ，后面 i n p u t . x m l o u t p u t . x m l 就是 0就是abx2xml，后面input.xml output.xml就是 0就是abx2xml，后面input.xmloutput.xml就是@
源码剖析Abx类
java
public class Abx {
private static final String USAGE = "" +
"usage: abx2xml [-i] input [output]\n" +
"usage: xml2abx [-i] input [output]\n\n" +
"Converts between human-readable XML and Android Binary XML.\n\n" +
"When invoked with the '-i' argument, the output of a successful conversion\n" +
"will overwrite the original input file. Input can be '-' to use stdin, and\n" +
"output can be '-' to use stdout.\n";
private static InputStream openInput(String arg) throws IOException {
if ("-".equals(arg)) {
return System.in;
} else {
return new FileInputStream(arg);
}
}
private static OutputStream openOutput(String arg) throws IOException {
if ("-".equals(arg)) {
return System.out;
} else {
return new FileOutputStream(arg);
}
}
private static void mainInternal(String[] args) {
if (args.length < 2) {
throw new IllegalArgumentException("Missing arguments");
}
final XmlPullParser in;
final XmlSerializer out;
if (args[0].endsWith("abx2xml")) {//这里根据传递近来参数看看是否要二进制xml转普通还是逆过来转
in = Xml.newBinaryPullParser(); //二进制转普通，那么输入就是BinaryPullParser，输出就是普通的
out = Xml.newSerializer();
} else if (args[0].endsWith("xml2abx")) {
in = Xml.newPullParser();//普通转二进制，那么输入就是普通的，输出就是newBinarySerializer
out = Xml.newBinarySerializer();
} else {
throw new IllegalArgumentException("Unsupported conversion");
}
final boolean inPlace = "-i".equals(args[1]);
final String inputArg = inPlace ? args[2] : args[1];
final String outputArg = inPlace ? args[2] + ".tmp" : args[2];
try (InputStream is = openInput(inputArg);
OutputStream os = openOutput(outputArg)) {
in.setInput(is, StandardCharsets.UTF_8.name());//输入设置对应的流InputStream
out.setOutput(os, StandardCharsets.UTF_8.name());//输出设置对应的流OutputStream
out.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true);
Xml.copy(in, out);//再调用 Xml.copy，重点就是在这
out.flush();
} catch (Exception e) {
// Clean up failed output before throwing
if (inPlace) {
new File(outputArg).delete();
}
throw new IllegalStateException(e);
}
// Successful in-place conversion of a file requires a rename
if (inPlace) {
if (!new File(outputArg).renameTo(new File(inputArg))) {
throw new IllegalStateException("Failed rename");
}
}
}
public static void main(String[] args) {
try {
mainInternal(args);
System.exit(0);
} catch (Exception e) {
System.err.println(e.toString());
System.err.println();
System.err.println(USAGE);
System.exit(1);
}
}
}上面代码核心部分有注释，其实整体算比较简单，核心方法就剩下一个Xml.copy方法
XML的相关copy方法如下：
cpp
/**
* Copy the first XML document into the second document.
* <p>
* Implemented by reading all events from the given {@link XmlPullParser}
* and writing them directly to the given {@link XmlSerializer}. This can be
* useful for transparently converting between underlying wire protocols.
*
* @hide
*/
public static void copy(@NonNull XmlPullParser in, @NonNull XmlSerializer out)
throws XmlPullParserException, IOException {
// Some parsers may have already consumed the event that starts the
// document, so we manually emit that event here for consistency
if (in.getEventType() == XmlPullParser.START_DOCUMENT) {
out.startDocument(in.getInputEncoding(), true);
}
while (true) {
final int token = in.nextToken();//不断循环xml的内容节点等，简单说就是in读出什么就往out中写什么
switch (token) {
case XmlPullParser.START_DOCUMENT:
out.startDocument(in.getInputEncoding(), true);
break;
case XmlPullParser.END_DOCUMENT:
out.endDocument();
return;
case XmlPullParser.START_TAG:
out.startTag(normalizeNamespace(in.getNamespace()), in.getName());
for (int i = 0; i < in.getAttributeCount(); i++) {
out.attribute(normalizeNamespace(in.getAttributeNamespace(i)),
in.getAttributeName(i), in.getAttributeValue(i));
}
break;
case XmlPullParser.END_TAG:
out.endTag(normalizeNamespace(in.getNamespace()), in.getName());
break;
case XmlPullParser.TEXT:
out.text(in.getText());
break;
case XmlPullParser.CDSECT:
out.cdsect(in.getText());
break;
case XmlPullParser.ENTITY_REF:
out.entityRef(in.getName());
break;
case XmlPullParser.IGNORABLE_WHITESPACE:
out.ignorableWhitespace(in.getText());
break;
case XmlPullParser.PROCESSING_INSTRUCTION:
out.processingInstruction(in.getText());
break;
case XmlPullParser.COMMENT:
out.comment(in.getText());
break;
case XmlPullParser.DOCDECL:
out.docdecl(in.getText());
break;
default:
throw new IllegalStateException("Unknown token " + token);
}
}
}更多framework详细代码和资料参考如下链接
hal+perfetto+surfaceflinger
https://mp.weixin.qq.com/s/LbVLnu1udqExHVKxd74ILg
其他课程七件套专题：
点击这里
https://mp.weixin.qq.com/s/Qv8zjgQ0CkalKmvi8tMGaw
视频试看：
https://www.bilibili.com/video/BV1wc41117L4/
更多framework假威风耗：androidframework007