如何在使用列表进行迭代时正确刷新列表

Question

我有以下问题。我正在从SonicWall中删除一些防火墙规则。我这样做的方法是从sonic wall中获取所有规则，找到匹配的规则，将它们存储在一个列表中，并使用这个列表来发出删除它们的命令。删除规则的方法是使用SSH和带有ID的命令。我遇到的问题是，每次删除ID时，所有ID都会更改，导致第二个命令尝试删除不存在的访问规则(或者更糟糕的是错误的访问规则)。为了克服这一点，在每次删除过程之后，我刷新列表i，以获得更新后的元素以及它们的新ID。我面临的问题是列表的更新是不正确的(它发生在for each循环中)，因为列表被用作迭代器(导致发出错误的命令)。

用新元素更新这个列表的最好和最安全的方法是什么？

下面是有问题的代码部分：

multiResult = expect.expect(anyOf(regexp("(.*)" + promptPattern)));     
        accessRules = getAccessRules(multiResult, accessRule);
        if(accessRules == null){
            Trc.trc("No access rules found to delete");
            return false;
        }

        numberOfRulesToDelete = accessRules.size();
        int size = numberOfRulesToDelete;
        IntList deleteRulesId = new IntList();

        while(numberOfRulesToDelete != 0){
            for(AccessRule arToDelete : accessRules){
            expect.sendLine("configure");
            multiResult = expect.expect(anyOf(regexp("(.*)" + confmodePromptPattern)));
            Result showCmdResult = multiResult.getResults().get(0);
            GenericCmdDto outPut = null;
            ObjectMapper objectMapper = new ObjectMapper();
            GenericFailedCmdDto failedOutPut = null;
            String swResponse = null;

            swResponse = handleSWConfModeResponse(showCmdResult);
            outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
            if(outPut.getSuccess()){//if change to configure command was successfull
                Result confCmdResult = null;
                Trc.trc("Configure command: " + outPut.getSuccess());
                expect.sendLine("no access-rule id "  + arToDelete.getIndex());
                MultiResult confResult = expect.expect(anyOf(regexp("(.*)" + confmodePromptPattern)));
                confCmdResult = confResult.getResults().get(0);

                swResponse = handleSWConfModeResponse(confCmdResult);
                outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
                if(outPut.getSuccess()){//if the delete command was successfull
                Trc.trc("Delete command issued successfully");
                expect.sendLine("commit");
                confCmdResult = expect.expect(anyOf(regexp("(.*)" + confmodePromptPattern)));

                swResponse = handleSWConfModeResponse(confCmdResult);
                outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
                if(outPut.getSuccess()){//if the commit command was successfull
                    Trc.trc("Commit command issued succesfully!");
                    Trc.trc("Deleted successfully access rule: " + arToDelete.getIndex());
                    deleteRulesId.addElement(arToDelete.getIndex());

                    expect.sendLine("exit");//change to no conf mode
                    confCmdResult = expect.expect(anyOf(regexp("(.*)" + promptPattern)));

                    swResponse = handleSWPromptModeResponse(confCmdResult);
                    outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
                    if(outPut.getSuccess()){//if the exit command was successfull
                    Trc.trc("Exit command issued successfully!");
                    operationSuccess = outPut.getSuccess();
                    }else{//if exit unsucessfull                
                    failedOutPut = objectMapper.readValue(createFailedJSONResponse(swResponse.getBytes()), GenericFailedCmdDto.class);
                    operationSuccess = outPut.getSuccess();
                    Trc.trc("Commit command has failed! Message: " + failedOutPut.getMessage() + ", Code: " + failedOutPut.getCode());
                    Trc.trc("Changing to show mode....");
                    expect.sendLine("exit");
                    multiResult = expect.expect(anyOf(regexp("(.*)" + promptPattern)));
                    showCmdResult = multiResult.getResults().get(0);

                    swResponse = handleSWPromptModeResponse(confCmdResult);

                    outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
                    if(outPut.getSuccess()){
                        Trc.trc("Exiting from conf mode..");
                        Trc.trc("Exit command: " + outPut.getSuccess());
                    }
                    return operationSuccess;
                    }
                }else{//if commit unsucessfull
                    failedOutPut = objectMapper.readValue(createFailedJSONResponse(swResponse.getBytes()), GenericFailedCmdDto.class);
                    operationSuccess = outPut.getSuccess();
                    Trc.trc("Commit command has failed! Message: " + failedOutPut.getMessage() + ", Code: " + failedOutPut.getCode());
                    Trc.trc("Changing to show mode....");
                    expect.sendLine("exit");
                    multiResult = expect.expect(anyOf(regexp("(.*)" + promptPattern)));
                    showCmdResult = multiResult.getResults().get(0);

                    swResponse = handleSWPromptModeResponse(showCmdResult);
                    outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
                    if(outPut.getSuccess()){
                    Trc.trc("Exiting from conf mode..");
                    Trc.trc("Exit command: " + outPut.getSuccess());
                    }
                    return operationSuccess;
                }
                }else{//if delete unsucessfull
                failedOutPut = objectMapper.readValue(createFailedJSONResponse(swResponse.getBytes()), GenericFailedCmdDto.class);
                operationSuccess = outPut.getSuccess();
                Trc.trc("Commit command has failed! Message: " + failedOutPut.getMessage() + ", Code: " + failedOutPut.getCode());
                Trc.trc("Changing to show mode....");
                expect.sendLine("exit");
                multiResult = expect.expect(anyOf(regexp("(.*)" + promptPattern)));
                showCmdResult = multiResult.getResults().get(0);

                swResponse = handleSWPromptModeResponse(showCmdResult);
                outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
                if(outPut.getSuccess()){
                    Trc.trc("Exiting from conf mode..");
                    Trc.trc("Exit command: " + outPut.getSuccess());
                }
                return operationSuccess;
                }

            }
            else{//if configure unsuccessfull
                failedOutPut = objectMapper.readValue(createFailedJSONResponse(swResponse.getBytes()), GenericFailedCmdDto.class);
                operationSuccess = outPut.getSuccess();
                Trc.trc("Commit command has failed! Message: " + failedOutPut.getMessage() + ", Code: " + failedOutPut.getCode());
                Trc.trc("Changing to show mode....");
                expect.sendLine("exit");
                multiResult = expect.expect(anyOf(regexp("(.*)" + promptPattern)));
                showCmdResult = multiResult.getResults().get(0);

                swResponse = handleSWPromptModeResponse(showCmdResult);
                outPut = objectMapper.readValue(createSuccessfullJSONResponse(swResponse.getBytes()), GenericCmdDto.class);
                if(outPut.getSuccess()){
                Trc.trc("Exiting from conf mode..");
                Trc.trc("Exit command: " + outPut.getSuccess());
                }
                return operationSuccess;
            }     
            expect.sendLine("show access-rules from " + accessRule.getFromZone() + " to " + accessRule.getToZone());
            multiResult = expect.expect(anyOf(regexp("(.*)" + promptPattern)));
            accessRules = getAccessRules(multiResult, accessRule);
            if(accessRules != null){
                numberOfRulesToDelete = accessRules.size();
            }else{
                Trc.trc("Deleting process complete!");
                numberOfRulesToDelete = 0;
                for(int i = 0; i < deleteRulesId.size(); i++){
                Trc.trc("Deleted " + size + " successfully rules: " + deleteRulesId.getElementAt(i));
                }
            }
            }  
        }
        return operationSuccess;

Answer 1

你不应该在遍历列表的时候更新它。

请使用副本。

Answer 2

使用列表的迭代器会对您有所帮助吗？您可以使用迭代器delete方法并立即从列表中移除该项。