1、javaclass利用jad反編譯之后，偶爾回碰到一些不正常的代碼，例如：labelO:丄1MISSING_BLOCK_LABEL_30、JVMINSTRret7、JVMINSTRtableswitch13:default269、JVMINSTRmonitorexit、JVMINSTRmonitorenter，這些一般是由特殊的for循環(huán)、trycatchfinally語句塊、synchronized語句反編譯后產(chǎn)生的。下面，就簡單介紹一下，一些反編譯后的特殊代碼的還原規(guī)則。異常下面的代碼前提是類中有如下屬性，Calendarcal=Calendar.getInstance();1、Excep

2、tioin的還原反編譯后的代碼如下：publicbooleanf1()returncal.getTime().after(newDate();Exceptione;e;e.printStackTrace();returnfalse;還原后的Java代碼publicbooleanf1()tryreturncal.getTime().after(newDate();catch(Exceptione)e.printStackTrace();returnfalse;2、finally代碼的還原反編譯后的Java代碼如下：publicbooleanf2()booleanflag=cal.getTime(

3、).after(newDate();System.out.println(finally);returnflag;Exceptione;e;e.printStackTrace();System.out.println(finally);returnfalse;Exceptionexception;exception;System.out.println(finally);throwexception;還原后的代碼如下：publicbooleanf2()tryreturncal.getTime().after(newDate();catch(Exceptione)e.printStackTrac

4、e();returnfalse;finallySystem.out.println(finally);3、MISSING_BLOCK_LABEL_的還原反編譯后的代碼publicObjectf22()Datedate=cal.getTime();System.out.println(finally);returndate;Exceptione;e;e.printStackTrace();System.out.println(finally);breakMISSING_BLOCK_LABEL_45;Exceptionexception;exception;System.out.println(f

5、inally);throwexception;returnnull;還原后的Java代碼publicObjectf22()tryreturncal.getTime();catch(Exceptione)e.printStackTrace();finallySystem.out.println(finally);returnnull;4、異常中:label的還原反編譯后的代碼publicStringf4()throwsExceptionlabelO:tryIntegeri=newInteger(1);if(Value()O)System.out.println(i);breaklabelO;Sy

6、stem.err.println(i);catch(Exceptiondae)System.err.println(dae);thrownewRuntimeException(dae);returnnull;returnHello;注意，這個代碼有點詭異，實際代碼如下：publicStringf4()throwsExceptiontryIntegeri=newInteger(1);if(Value()O)System.out.println(i);elseSystem.err.println(i);returnnull;returnHello;catch(Exceptiondae)System

7、.err.println(dae);thrownewRuntimeException(dae);5、典型數(shù)據(jù)庫操作代碼還原反編譯后代碼publicHashMapf5()Connectionconn=null;HashMaphashmap;HashMapmap=newHashMap();Class.forName();conn=DriverManager.getConnection(jdbc:odbc:);PreparedStatementpstmt=conn.prepareStatement(select*fromtable);pstmt.setString(1,param);Stringco

8、lumnVallue;for(ResultSetrs=pstmt.executeQuery();rs.next();map.put(columnVallue,)columnVallue=rs.getString(column);hashmap=map;if(conn!=null)tryconn.close();catch(SQLExceptionsqlce)sqlce.printStackTrace();returnhashmap;ClassNotFoundExceptioncnfe;cnfe;cnfe.printStackTrace();if(conn!=null)tryconn.close

9、();catch(SQLExceptionsqlce)sqlce.printStackTrace();breakMISSING_BLOCK_LABEL_188;SQLExceptionsqle;sqle;sqle.printStackTrace();if(conn!=null)tryconn.close();catch(SQLExceptionsqlce)sqlce.printStackTrace();breakMISSING_BLOCK_LABEL_188;Exceptionexception;exception;if(conn!=null)tryconn.close();catch(SQL

10、Exceptionsqlce)sqlce.printStackTrace();throwexception;returnnull;實際代碼如下：publicHashMapf5()Connectionconn=null;tryHashMapmap=newHashMap();Class.forName();conn=DriverManager.getConnection(jdbc:odbc:);PreparedStatementpstmt=conn.prepareStatement(select*fromtable);pstmt.setString(1,param);ResultSetrs=pst

11、mt.executeQuery();while(rs.next()StringcolumnVallue=rs.getString(column);map.put(columnVallue,);returnmap;catch(ClassNotFoundExceptioncnfe)cnfe.printStackTrace();catch(SQLExceptionsqle)sqle.printStackTrace();finallyif(conn!=null)tryconn.close();catch(SQLExceptionsqlce)sqlce.printStackTrace();returnn

12、ull;6、兩層異常嵌套代碼還原反編譯后的代碼publicintf6()inti=cal.getTime().compareTo(newDate();System.out.println(finally);returni;Exceptione1;e1;e1.printStackTrace();System.out.println(finally);return-1;Exceptione2;e2;e2.printStackTrace();System.out.println(finally);return-2;Exceptionexception;exception;System.out.pri

13、ntln(finally);throwexception;實際代碼publicintf6()trytryreturncal.getTime().compareTo(newDate();catch(Exceptione1)e1.printStackTrace();return-1;catch(Exceptione2)e2.printStackTrace();return-2;finallySystem.out.println(finally);7、非常詭異的代碼反編譯后的代碼publicintf7()inti=cal.getTime().compareTo(newDate();System.out.println(finally);returni;Exceptione1;e1;e1.printStackTrace();_L2:System.out.println(finally);return-1;Exceptione2;e2;e2.printStackTrace();if(true)goto_L2;elsegoto_L1_L1:Exceptionexception;exception;System.out.println(fi