Androidの本当にあった怖い話

Android
2011/1/17
@yusukey

Copyright(c) Yusuke Yamamoto All rights reserved.

http://samuraism.jp/
@yusukey

http://tinyurl.com/android-java

↑
Java Twitter API

• JDK1.4.2
• Google App Engine
• Android

Android Java


Android


new sun.misc.BASE64Encoder().encode(buf);

02-20 18:03:59.843: WARN/dalvikvm(526): VFY: unable to resolve
new-instance 105 (Lsun/misc/BASE64Encoder;) in Ltwitter4j/http/
HttpClient;
02-20 18:03:59.843: WARN/dalvikvm(526): VFY: rejecting opcode
0x22 at 0x0011

:Android sun.misc.* / com.sun.*


• BASE64
(Commons-Codec ok)

• sun.misc.* com.sun.*


XML


XML
• Twitter4J
// XML
private String toString(Element doc){
StringWriter output = new StringWriter();
Transformer t =
TransformerFactory.newInstance()
.newTransformer();
t.transform(new DOMSource(doc),
new StreamResult(output));
return output.toString();
}


07-07 23:55:42.993: ERROR/dalvikvm(11182): Could not find method
javax.xml.transform.TransformerFactory.newInstance,
referenced from method twitter4j.TwitterResponse.toString

:Android XSLT


// XML
private static String toString(Element doc){
StringWriter output = new StringWriter();
try{
Transformer t = TransformerFactory
.newInstance().newTransformer();
t.transform(new DOMSource(doc),
new StreamResult(output));
return output.toString();
}catch(ClassNotFoundException cnfe){
// javax.xml.transform.TransformerFactory
// “”
return “”;
}
}

01-16 23:20:58.637: ERROR/AndroidRuntime(209): Uncaught handler: thread main exiting
due to uncaught exception
01-16 23:20:58.668: ERROR/AndroidRuntime(209): java.lang.VerifyError:
com.example.MyActivity
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1472)
at android.app.Instrumentation.newActivity(Instrumentation.java:1097)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2316)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417)
at android.app.ActivityThread.access$2100(ActivityThread.java:116)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4203)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run
(ZygoteInit.java:791)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
at dalvik.system.NativeStart.main(Native Method)

: VerifyError


-- // XML
-- private static String toString(Element doc){
-- StringWriter output = new StringWriter();
-- try{
-- Transformer t = TransformerFactory
.newInstance().newTransformer();
-- t.transform(new DOMSource(doc),
-- new StreamResult(output));
-- return output.toString();
-- }catch(ClassNotFoundException cnfe){
-- // javax.xml.transform.TransformerFactory
-- // “”
-- return “”;
-- }
--}

Transformer


XML
String xml = "<title>English & </title>";
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance
();
dbf.setCoalescing(true);
dbf.setExpandEntityReferences(true);
ByteArrayInputStream stream = new ByteArrayInputStream(
xml.getBytes());
DocumentBuilder builder = null;
builder = dbf.newDocumentBuilder();
Document doc = builder.parse(stream);

Node titleNode = doc.getFirstChild();
NodeList children = titleNode.getChildNodes();
System.out.println(children.item(0).getTextContent());


String xml = "<title>English & </title>";
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance
();
dbf.setCoalescing(true);
dbf.setExpandEntityReferences(true);
ByteArrayInputStream stream = new &
: “English ByteArrayInputStream(
”
xml.getBytes());
DocumentBuilder builder = “English”
: null;
builder = dbf.newDocumentBuilder();
Document doc = builder.parse(stream);

Node titleNode = doc.getFirstChild();
NodeList children = titleNode.getChildNodes();
System.out.println(children.item(0).getTextContent());

:XML


• Twitter xml, JSON, atom, rss

• JSON
• JavaScript Object Notation
• Web API

Twitter4J JSON


JSON


JSON
(“foo”:null, “longvalue”:”13857270119014401”}

JSONObject json = new JSONObject
("{"foo":null,"longvalue":"13857270119014401"}");
// true
System.out.println(json.isNull("foo"));
// true

System.out.println(null == json.getString("foo"));
// false
System.out.println("null".equals(json.getString("foo")));
// 13857270119014401
System.out.println(json.getLong("longvalue"));


JSONObject json = new JSONObject
("{"foo":null,"longvalue":"13857270119014401"}");
// true true
System.out.println(json.isNull("foo"));
// true true
System.out.println(null == json.getString("foo"));
// false true
System.out.println("null".equals(json.getString("foo")));
// 13857270119014401 13857270119014400
System.out.println(json.getLong("longvalue"));

:json


json.org
twitter4j.internal.org.json.*


• XSLT (Froyo )

• VerifyError

• Eclair(Android 2.1)

• XML

• Froyo(Android 2.2)

• JSON

•
• Sun

• Android
public static final boolean IS_DALVIK;
static{
try {
// dalvik.system.VMRuntime class should be existing on
Android platform.
// @see http://developer.android.com/reference/dalvik/
system/VMRuntime.html
Class.forName("dalvik.system.VMRuntime");
dalvikDetected = true;
} catch (ClassNotFoundException cnfe) {
dalvikDetected = false";
}
IS_DALVIK = dalvikDetected;
}

- Issue 2607 - android -
org.apache.harmony.xml.parsers.DocumentBuilderImpl does not
resolve unicode entity refs
http://code.google.com/p/android/issues/detail?id=2607

- Issue 9244 - android - org.json packages out of date

- Issue 13830 - JSONObject.getString() returns "null" string
literal for null value instead of null object.

- Issue 13831 - JSONObject.getLong() returns rounded and
inaccurate value


Androidの本当にあった怖い話

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