dx简述
dx工具是一种用来转换Java class成为DEX格式的工具。多个类被包含在一个dex文件之中。各个类中重复的字符串和其他常数只在DEX中存放一次，以节省空间。Java字节码（bytecode）被转换成Dalvik虚拟机所使用的替代指令集。一个未压缩dex文件通常稍小于一个已经压缩的.jar档（摘自维基百科）。
转化结果
Demo.java
tanzhenxing@tanzhenxing:~/android/Sdk/build-tools/22.0.1$ cat Demo.java
/**
* Created by tanzhenxing on 17-9-15.
*/
public class Demo {
public static void foo() {
int a = 1;
int b = 2;
int c = (a + b) * 5;
}
}
Demo.class
tanzhenxing@tanzhenxing:~/android/Sdk/build-tools/22.0.1$ javap -c Demo.class
Compiled from "Demo.java"
public class Demo {
public Demo();
Code:
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
public static void foo();
Code:
0: iconst_1
1: istore_0
2: iconst_2
3: istore_1
4: iload_0
5: iload_1
6: iadd
7: iconst_5
8: imul
9: istore_2
10: return
}
Demo.dex
tanzhenxing@tanzhenxing:~/android/Sdk/build-tools/22.0.1$ ./dexdump -d Demo.dex
Processing 'Demo.dex'...
Opened 'Demo.dex', DEX version '035'
Class #0 -
Class descriptor : 'LDemo;'
Access flags : 0x0001 (PUBLIC)
Superclass : 'Ljava/lang/Object;'
Interfaces -
Static fields -
Instance fields -
Direct methods -
#0 : (in LDemo;)
name : '<init>'
type : '()V'
access : 0x10001 (PUBLIC CONSTRUCTOR)
code -
registers : 1
ins : 1
outs : 1
insns size : 4 16-bit code units
0000d8: |[0000d8] Demo.<init>:()V
0000e8: 7010 0200 0000 |0000: invoke-direct {v0}, Ljava/lang/Object;.<init>:()V // method@0002
0000ee: 0e00 |0003: return-void
catches : (none)
positions :
0x0000 line=4
locals :
0x0000 - 0x0004 reg=0 this LDemo;
#1 : (in LDemo;)
name : 'foo'
type : '()V'
access : 0x0009 (PUBLIC STATIC)
code -
registers : 0
ins : 0
outs : 0
insns size : 1 16-bit code units
0000f0: |[0000f0] Demo.foo:()V
000100: 0e00 |0000: return-void
catches : (none)
positions :
0x0000 line=9
locals :
Virtual methods -
source_file_idx : 1 (Demo.java)
遇到的问题
问题一：
trouble processing:
bad class file magic (cafebabe) or version (0034.0000)
...while parsing Demo.class
...while processing Demo.class
1 warning
no classfiles specified
问题二
UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dx.cf.iface.ParseException: bad class file magic (cafebabe) or version (0034.0000)
at com.android.dx.cf.direct.DirectClassFile.parse0(DirectClassFile.java:472)
at com.android.dx.cf.direct.DirectClassFile.parse(DirectClassFile.java:406)
at com.android.dx.cf.direct.DirectClassFile.parseToInterfacesIfNecessary(DirectClassFile.java:388)
at com.android.dx.cf.direct.DirectClassFile.getMagic(DirectClassFile.java:251)
at com.android.dx.command.dexer.Main.processClass(Main.java:704)
at com.android.dx.command.dexer.Main.processFileBytes(Main.java:673)
at com.android.dx.command.dexer.Main.access$300(Main.java:83)
at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:602)
at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:170)
at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:144)
at com.android.dx.command.dexer.Main.processOne(Main.java:632)
at com.android.dx.command.dexer.Main.processAllFiles(Main.java:510)
at com.android.dx.command.dexer.Main.runMonoDex(Main.java:280)
at com.android.dx.command.dexer.Main.run(Main.java:246)
at com.android.dx.command.dexer.Main.main(Main.java:215)
at com.android.dx.command.Main.main(Main.java:106)
...while parsing Demo.class
解决办法：
原因：其实问题一和问题二都是因为编译class文件的jdk版本和Android的dx的版本不同导致的。
办法：在低版本的/Sdk/build-tools/x.x.x/目录下执行java javac -source 1.6 -target 1.6 xx.java这样得到的class文件在进行dex转化的时候才不会报错。如果这样处理还报错那么请看看问题三。
问题三：
trouble processing:
class name (com/loadclass/demo/Demo) does not match path (Demo.class)
...while parsing Demo.class
...while processing Demo.class
1 warning
no classfiles specified
解决办法：
去掉java类文件中的包名；
文章到这里就全部讲述完啦，若有其他需要交流的可以留言哦~！~！
