android反编译后有中文乱码,android反编译apk后，java文件中出现的一些类似乱码的问题...

青旅半醒 2022-10-16 03:55 169阅读 0赞

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概述

java class  反编译之后，偶尔回碰到一些不正常的代码

例如：

label0 :\_L1 MISSING\_BLOCK\_LABEL\_30

JVM INSTR ret 7

JVM INSTR tableswitch 1 3: default 269、

JVM INSTR monitorexit

JVM INSTR monitorenter

这些一般是由特殊的for循环、try catch finally语句块、synchronized语句反编译后产生的。

下面，就简单介绍一下，一些反编译后的特殊代码的还原规则。

1、Exceptioin的还原

反编译后的代码如下

public boolean f1() \{

return cal.getTime().after(new Date());

Exception e;

e.printStackTrace();

return false;

还原后的Java代码

public boolean f1() \{

try \{

return cal.getTime().after(new Date());

\} catch (Exception e) \{

e.printStackTrace();

return false;

2、finally代码的还原

反编译后的Java代码如下

public boolean f2() \{

boolean flag = cal.getTime().after(new Date());

System.out.println("finally");

return flag;

Exception e;

e.printStackTrace();

System.out.println("finally");

return false;

Exception exception;

exception;

System.out.println("finally");

throw exception;

\}还原后的代码如下

public boolean f2() \{

try \{

return cal.getTime().after(new Date());

\} catch (Exception e) \{ e.printStackTrace();

return false;

\} finally \{

System.out.println("finally");

3、MISSING\_BLOCK\_LABEL\_的还原

反编译后的代码

public Object f22() \{

Date date = cal.getTime();

System.out.println("finally");

return date;

Exception e;

e.printStackTrace();

System.out.println("finally");

break MISSING\_BLOCK\_LABEL\_45;

Exception exception;

exception;

System.out.println("finally");

throw exception;

return null;

\}还原后的Java代码

public Object f22() \{

try \{

return cal.getTime();

\} catch (Exception e) \{

e.printStackTrace();

\} finally \{

System.out.println("finally");

\} return null;

4、异常中:label的还原

反编译后的代码

public String f4() throws Exception \{

label0: \{

try \{

Integer i = new Integer(1);

if(i.intValue() >0) \{

System.out.println(i);

break label0;

System.err.println(i);

\} catch(Exception dae) \{

System.err.println(dae);

throw new RuntimeException(dae);

return null;

return "Hello";

\}注意，这个代码有点诡异，实际代码如下：

public String f4() throws Exception \{

try \{

Integer i = new Integer(1);

if (i.intValue() >0) \{

System.out.println(i);

\} else \{

System.err.println(i);

return null;

return "Hello";

\} catch (Exception dae) \{

System.err.println(dae);

throw new RuntimeException(dae);

5、典型数据库操作代码还原

反编译后代码

public HashMap f5() \{

Connection conn = null;

HashMap hashmap;

HashMap map = new HashMap();

Class.forName("");

conn = DriverManager.getConnection("jdbc:odbc:");

PreparedStatement pstmt = conn.prepareStatement("select \* from table");

pstmt.setString(1, "param");

String columnVallue;

for(ResultSet rs = pstmt.executeQuery();rs.next();map.put(columnVallue, "")) columnVallue = rs.getString("column");

hashmap = map;

if(conn != null) try \{

conn.close();

\} catch(SQLException sqlce) \{

sqlce.printStackTrace();

return hashmap;

ClassNotFoundException cnfe;

cnfe;

cnfe.printStackTrace();

if(conn != null)

try \{

conn.close();

\} catch(SQLException sqlce) \{

sqlce.printStackTrace();

break MISSING\_BLOCK\_LABEL\_188;

SQLException sqle;

sqle;

sqle.printStackTrace();

if(conn != null) try \{

conn.close();

\} catch(SQLException sqlce) \{

sqlce.printStackTrace();

break MISSING\_BLOCK\_LABEL\_188;

Exception exception;

exception;

if(conn != null) try \{

conn.close();

\} catch(SQLException sqlce) \{

sqlce.printStackTrace();

\} throw exception;

return null;

\}实际代码如下

public HashMap f5() \{

Connection conn = null;

try \{

HashMap map = new HashMap();

Class.forName("");

conn = DriverManager.getConnection("jdbc:odbc:");

PreparedStatement pstmt = conn.prepareStatement("select \* from table");

pstmt.setString(1, "param");

ResultSet rs = pstmt.executeQuery();

while (rs.next()) \{

String columnVallue = rs.getString("column");

map.put(columnVallue, "");

return map;

\} catch (ClassNotFoundException cnfe) \{

cnfe.printStackTrace();

\} catch (SQLException sqle) \{

sqle.printStackTrace();

\} finally \{

if (conn != null) \{

try \{

conn.close();

\} catch (SQLException sqlce) \{

sqlce.printStackTrace();

return null;

6、两层异常嵌套代码还原

反编译后的代码

public int f6() \{

int i = cal.getTime().compareTo(new Date());

System.out.println("finally");

return i;

Exception e1;

e1;

e1.printStackTrace();

System.out.println("finally");

return -1;

Exception e2;

e2;

e2.printStackTrace();

System.out.println("finally");

return -2;

Exception exception;

exception;

System.out.println("finally");

throw exception;

\}实际代码

public int f6() \{

try \{

return cal.getTime().compareTo(new Date());

\} catch (Exception e1) \{

e1.printStackTrace();

return -1;

\} \} catch (Exception e2) \{

e2.printStackTrace();

return -2;

\} finally \{

System.out.println("finally");

7、非常诡异的代码

反编译后的代码

public int f7() \{

int i = cal.getTime().compareTo(new Date());

System.out.println("finally");

return i;

Exception e1;

e1;

e1.printStackTrace();

\_L2: System.out.println("finally");

return -1;

Exception e2;

e2;

e2.printStackTrace();

if(true)

goto \_L2;

else

goto \_L1 \_L1:

Exception exception;

exception;

System.out.println("finally");

throw exception;

\}原始代码

public int f7() \{

try \{

return cal.getTime().compareTo(new Date());

\} catch (Exception e1) \{

e1.printStackTrace();

return -1;

\} \} catch (Exception e2) \{

e2.printStackTrace();

return -1;

\} finally \{

System.out.println("finally");

android反编译后有中文乱码,android反编译apk后，java文件中出现的一些类似乱码的问题...

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