限制Android方法数量的原因是:
Android应用以DEX文件的形式存储字节码文件,在Dalvik字节码规范里,方法引用索引method
referenceindex只有16位,即65536个。
Op & Format |
Mnemonic / Syntax |
Arguments |
6e..72 35c |
invoke-kind {vC, vD, vE, vF, vG}, [email protected] |
B: method reference index (16 bits) |
注意是method reference,这里限制的是自己代码、Android框架、第三方库三者方法数量的总和。
dex里方法只能索引65536个,但是报错不在这里。Android打包dex的过程如下:
//Main.java
-> main() -> run() ->不分包执行runMonoDex()(或者分包执行runMultiDex())->
writeDex()
// DexFile
->toDex() -> toDex0()
//
MethodIdsSection extends MemberIdsSection extends UniformItemSection extends Section
->Section 的prepare() -> UniformItemSection的prepare0() ->MemberIdsSection的orderItems() -> getTooManyMembersMessage()
//Main.java
->getTooManyIdsErrorMessage()
MemberIdsSection里执行了这么一段代码
protected void orderItems() {
int idx = 0;
if (items().size() >DexFormat.MAX_MEMBER_IDX + 1) {
throw newDexIndexOverflowException(getTooManyMembersMessage());
}
for (Object i : items()) {
((MemberIdItem) i).setIndex(idx);
idx++;
}
}
getTooManyMembersMessage核心代码如下:构建了错误信息字符串。
private String getTooManyMembersMessage() {
try {
String memberType = this instanceofMethodIdsSection ? "method" : "field";
formatter.format("Too many %s references:%d; max is %d.%n" +
Main.getTooManyIdsErrorMessage() + "%n" +
"References bypackage:",
memberType, items().size(),DexFormat.MAX_MEMBER_IDX + 1);
return formatter.toString();
}
}
}
可见代码里检测了方法数量的上限,超过就会报错。这里的限制DexFormat.MAX_MEMBER_IDX
出自
public final classDexFormat {
/**
* Maximum addressable field or methodindex.
* The largest addressable member is0xffff, in the "instruction formats" spec as [email protected] or
* [email protected]
*/
public static final int MAX_MEMBER_IDX =0xFFFF;
}
因此方法不能超过65536。这里的根源还是在dex字节码规范里方法引用索引的限制,但是强制报错是在这里限制的。
另外,域的数量也有此限制。
错误信息:
Error:Errorconverting bytecode to dex:
Cause:com.android.dex.DexIndexOverflowException:field ID not in [0, 0xffff]: 65536(笔者开发时遇到的是域数量问题,方法数量问题错误信息于此类似)
:XXXXXX:transformClassesWithDexForDebug FAILED
Error:Executionfailed for task ‘:XXXXXX:transformClassesWithDexForDebug‘.
>com.android.build.api.transform.TransformException:com.android.ide.common.process.ProcessException:java.util.concurrent.ExecutionException:com.android.ide.common.process.ProcessException:org.gradle.process.internal.ExecException:
Process ‘command ‘C:\ProgramFiles\Java\jdk1.8.0_73\bin\java.exe‘‘ finished withnon-zero exit value 2
解决方法:
1,配置building.gradle,开启MultiDex
android {
defaultConfig {
multiDexEnabled true
}
}
dependencies{
compile‘com.android.support:multidex:1.0.0‘
}
2,配置应用
方法1:在AndroidManifest.xml的application中声明android.support.multidex.MultiDexApplication;
<?xmlversion="1.0" encoding="utf-8"?>
<manifestxmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.multidex.myapplication">
<application
...
android:name="android.support.multidex.MultiDexApplication">
...
</application>
</manifest>
方法2:让你自己的Application类继承MultiDexApplication
方法3:让你自己的Application类重写attachBaseContext
方法,
@Override
protected voidattachBaseContext(Context base) {
super.attachBaseContext(base);
MultiDex.install(this);
}
其他错误情况:
Error:java.lang.OutOfMemoryError: Java heap space.
Please assign morememory to Gradle in the project‘s gradle.properties file.
For example, thefollowing line, in the gradle.properties file, sets the maximum Java heap sizeto 1,024 MB:
<em>org.gradle.jvmargs=-Xmx1024m</em>
:XXXXXX:transformClassesWithDexForDebugFAILED
Error:Executionfailed for task ‘:XXXXXX:transformClassesWithDexForDebug‘.
>com.android.build.api.transform.TransformException: java.lang.RuntimeException:com.android.ide.common.process.ProcessException:java.util.concurrent.ExecutionException:com.android.ide.common.process.ProcessException:
org.gradle.process.internal.ExecException:Process ‘command ‘C:\Program Files\Java\jdk1.8.0_73\bin\java.exe‘‘finished with non-zero exit value 3
解决方法:
Building.gradle里
dexOptions {
javaMaxHeapSize "4g"
}
javaMaxHeapSize对应正则表达式是"\\d+[kKmMgGtT]?"4g指4G字节。
DexOptions类包含了获取JavaMaxHeapSize的方法,对应Building.gradle里dexOptions设置的javaMaxHeapSize。
参考:
http://source.android.com/devices/tech/dalvik/dalvik-bytecode.html
http://developer.android.com/intl/es/tools/building/multidex.html