解决Springboot使用@Autowired注解注入的静态变量在使用时报空指针问题

Myth丶恋晨 2022-11-02 11:43 394阅读 0赞

## 一、背景介绍 ##

我创建了两个Springboot工程，A作为公共工程，打包成Jar包供其他工程使用；B使用A提供的Jar包。A工程中的SceneCaseDebugAPI类的代码如下：

import com.alibaba.fastjson.JSONArray;
    import com.alibaba.fastjson.JSONObject;
    import com.jayway.jsonpath.JsonPath;
    import com.umetrip.qa.model.*;
    import com.umetrip.qa.service.GatewayCaseService;
    import com.umetrip.qa.service.SceneCaseService;
    import com.umetrip.qa.service.ScenePublicParameterService;
    import com.umetrip.qa.service.SceneStepsService;
    import com.umetrip.qa.tester.singlecase.SingleCaseDebugAPI;
    import com.umetrip.qa.utils.JsonStringUtils;
    import com.umetrip.qa.utils.OkhttpUtil;
    import com.umetrip.qa.utils.PrettyTimeTool;
    import com.umetrip.qa.utils.request.ApiRequestCommonUtil;
    import com.umetrip.qa.utils.request.RequestHttp_error;
    import org.jsoup.helper.StringUtil;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Component;
    
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    import java.util.regex.Pattern;
    
    /**
     * @description: 普通java类要使用 @Autowired注解 的话，需要使用@Component注解申明该类是spring组件
     * @time: 2021-02-23 11:12
     */
    @Component
    public class SceneCaseDebugAPI { 
        @Autowired
        static SceneCaseService sceneCaseService;
    
        @Autowired
        static SceneStepsService sceneStepsService;
    
        @Autowired
        static ScenePublicParameterService scenePublicParameterService;
    
        @Autowired
        static GatewayCaseService gatewayCaseService;
    
        @Autowired
        static SingleCaseDebugAPI singleCaseDebugAPI;
    
        public static ApiResult sceneCaseCommonRequest(JSONObject sceneCaseJson){ 
            ApiResult apiResult = new ApiResult();
            //步骤1：从DB中查询出场景用例的详细信息
            System.out.println("sceneCase: " + JSONObject.toJSONString(sceneCaseJson));
            SceneCase sceneCase = JSONObject.parseObject(JSONObject.toJSONString(sceneCaseJson), SceneCase.class);
            String singleSceneCaseRedisKey = "SceneCase" + "_" + sceneCase.getId() + "_" + sceneCase.getSceneName() + "_" + "Result";
            List<SceneSteps> sceneSteps = sceneStepsService.findAllSceneStepsBySceneCaseId(sceneCase.getId());
            // 清空redis中场景用例的用例步骤信息
    //        baseRedisDao.remove(singleSceneCaseRedisKey);
            //设置一个数组存储场景用例步骤的结果
            List<String> stepsResult = new ArrayList<>();
            try{ 
                for(SceneSteps step : sceneSteps){ 
                    System.out.println("当前正在处理的场景用例步骤信息为：" + JSONObject.toJSONString(step));
                    JSONObject stepJson = JSONObject.parseObject(JSONObject.toJSONString(step), JSONObject.class);
                    String sceneStepType = step.getSceneStepType();
                    if(sceneStepType.equals("HTTP用例")){ 
                        ResMsg resMsg = executeHttpCaseStep(sceneCase.getId(), step);
                        stepJson = JSONObject.parseObject(JSONObject.toJSONString(resMsg), JSONObject.class);
                        stepsResult.add(resMsg.getResult());
                    }else if(sceneStepType.equals("等待")){ 
                        Thread.sleep(step.getSceneStepWaitingtime());
                    }else if(sceneStepType.equals("GET请求")){ 
                        ResMsg resMsg = executeGetRequestStep(sceneCase.getId(), step);
                        stepJson = JSONObject.parseObject(JSONObject.toJSONString(resMsg), JSONObject.class);
                        stepsResult.add(resMsg.getResult());
                    }else if(sceneStepType.equals("条件")){ 
                        stepJson.put("debugCaseStartTime", new Date());
                        boolean result = executeConditionStep(sceneCase.getId(), step);
                        if(result){ 
                            stepJson.put("sceneCaseStepResult", "T");
                            stepsResult.add("T");
                        }else { 
                            stepJson.put("sceneCaseStepResult", "F");
                            stepsResult.add("F");
                        }
                    }
                    PrettyTimeTool.createNewInterfaceCaseDebugLog(stepJson.getDate("debugCaseStartTime"), "SingleInterfaceCase", sceneCase.getId(), stepJson);
                }
            }catch (Exception e){ 
                e.printStackTrace();
                apiResult.setCode(400);
                apiResult.setResult("场景用例执行失败");
            }
            // 还需要增加场景用例结果判断逻辑，只要有一个失败步骤失败，场景用例结果即为失败；否则为成功
            if(stepsResult.contains("F")){ 
                apiResult.setCode(400);
                apiResult.setResult("场景用例执行失败");
            }else { 
                apiResult.setCode(200);
                apiResult.setResult("场景用例执行成功");
            }
            return apiResult;
        }
    
        public static ResMsg executeGetRequestStep(Integer sceneCaseId, SceneSteps step){ 
            System.out.println("执行Get请求步骤");
            ResMsg resMsg = new ResMsg();
            ApiRequestCommonUtil apiRequestCommonUtil = new ApiRequestCommonUtil();
            String newUrl = step.getSceneStepGetUrl();
            JSONArray params = JSONArray.parseArray(step.getSceneStepGetParams());
            JSONArray header = JSONArray.parseArray(step.getSceneStepGetHeader());
            System.out.println("请求参数的数据：" + params.size() + " 请求头的数据：" + header.size());
            for(int i = 0; i < params.size(); i++){ 
                JSONObject paramsTableOneRow = params.getJSONObject(i);
                String key = paramsTableOneRow.getString("key");
                String val = paramsTableOneRow.getString("value");
    
                if(val.contains("${")){ 
                    String dbParam = val.substring(2, val.length() - 1);
                    System.out.println("1 dbParam: " + dbParam);
                    // 从场景内公共参数查找变量，当查找不到时，需要去全局公共参数中查找（目前尚未实现）
                    ScenePublicParameter scenePublicParameter = apiRequestCommonUtil.findPublicParamValue(sceneCaseId, dbParam);
                    val = scenePublicParameter.getSceneParameterVal();
                }
                if (i == 0) { 
                    System.out.println("2 newUrl: " + newUrl + " key:" + key + " val:" + val);
                    newUrl = newUrl + "?" + key + "=" + val;
                } else { 
                    System.out.println("3 newUrl: " + newUrl + " key:" + key + " val:" + val);
                    newUrl = newUrl + "&" + key + "=" + val;
                }
            }
            System.out.println("处理后的url：" + newUrl);
            // 处理header
            if(header.size() != 0){ 
                for(int j = 0; j < header.size(); j++){ 
                    JSONObject headerTableOneRow= header.getJSONObject(j);
                    String key = headerTableOneRow.getString("key");
                    String val = headerTableOneRow.getString("value");
                    if(val.contains("${")){ 
                        String dbParam = val.substring(2, val.length() - 1);
                        System.out.println("1 dbParam: " + dbParam);
                        ScenePublicParameter scenePublicParameter = apiRequestCommonUtil.findPublicParamValue(sceneCaseId, dbParam);
                        val = scenePublicParameter.getSceneParameterVal();
                    }
                    headerTableOneRow.put("value", val);
                }
            }
            System.out.println("header str: " + JSONArray.toJSONString(header));
            long startTime = System.currentTimeMillis();
            Date deBugCaseStartTime = new Date();
            // 请求url和header已经准备完毕，真正发送GET请求
            String getResult = OkhttpUtil.dynamicGet(newUrl, header);
            long endTime = System.currentTimeMillis();
            long consumetime = endTime - startTime;
    
            // 判断是否需要将响应体中数据存储至场景内的公共参数表
            if(!StringUtil.isBlank(step.getSceneStepExtractJsonPath())){ 
                String[] jsonPathList = step.getSceneStepExtractJsonPath().split("\r|\n");
                for(int i = 0; i<jsonPathList.length; i++){ 
                    getResponseBodyJsonPathVal(sceneCaseId, getResult, jsonPathList[i]);
                }
            }
            //需要加断言处理
            System.out.println("Get请求的返回结果：" + getResult);
            RequestHttp_error requestHttp = new RequestHttp_error();
            requestHttp.assertResponse(getResult, step.getSceneStepGetExpectResponse(), resMsg);
            resMsg.setConsumetime(consumetime);
            resMsg.setInterfaceType("SceneCase");
            resMsg.setRequestBodyParameters(JSONObject.toJSONString(params));
            resMsg.setResponsebody(getResult);
            resMsg.setUrl(newUrl);
            resMsg.setHttpHeaders(JSONObject.toJSONString(header));
            resMsg.setTestpoint(step.getSceneStepName());
            resMsg.setDebugCaseStartTime(deBugCaseStartTime);
            return resMsg;
        }
    
        public static boolean executeConditionStep(Integer sceneCaseId, SceneSteps step){ 
            System.out.println("执行条件步骤");
            boolean res = false;
            ApiRequestCommonUtil apiRequestCommonUtil = new ApiRequestCommonUtil();
            String firstExpression = step.getSceneFirstExpression();
            String secondExpression = step.getSceneSecondExpression();
            String judgeCondition = step.getSceneExpressionJudgeCondition();
            if(secondExpression.contains("${")){ 
                String dbParam = secondExpression.substring(2, secondExpression.length() - 1);
                System.out.println("1 dbParam: " + dbParam);
                ScenePublicParameter scenePublicParameter = apiRequestCommonUtil.findPublicParamValue(sceneCaseId, dbParam);
                secondExpression = scenePublicParameter.getSceneParameterVal();
            }
    
            switch (judgeCondition){ 
                case "等于":
                    res = firstExpression.equals(secondExpression);
                    break;
                case "不等于":
                    res = !firstExpression.equals(secondExpression);
                    break;
                case "包含":
                    res = firstExpression.contains(secondExpression);
                    break;
                case "不包含":
                    res = !firstExpression.contains(secondExpression);
                    break;
                case "大于":
                    res = Integer.parseInt(firstExpression) > Integer.parseInt(secondExpression);
                    break;
                case "小于":
                    res = Integer.parseInt(firstExpression) < Integer.parseInt(secondExpression);
                    break;
            }
            System.out.println("条件步骤的运行结果：" + res);
            return res;
        }
    
        public static ResMsg executeHttpCaseStep(Integer sceneCaseId, SceneSteps step){ 
            System.out.println("执行Http用例步骤");
            Integer gatewaySingleCaseId = step.getSceneGatewaySingleCaseId();
            GatewayCase gatewayCase = gatewayCaseService.findByPrimaryKey(gatewaySingleCaseId);
            System.out.println("gateway case rparams before：" + gatewayCase.getRparams());
            JSONObject jsonObjectDB = JSONObject.parseObject(JsonStringUtils.StringInDBtoJSONString(gatewayCase.getRparams()));
            ApiRequestCommonUtil.processRequestParameterization(sceneCaseId, jsonObjectDB);
            System.out.println("gateway case rparams after：" + JsonStringUtils.JSONStringtoStringInDB(JSONObject.toJSONString(jsonObjectDB)));
            gatewayCase.setRparams(JsonStringUtils.JSONStringtoStringInDB(JSONObject.toJSONString(jsonObjectDB)));
    
            JSONObject jsonObject = JSONObject.parseObject(JSONObject.toJSONString(gatewayCase), JSONObject.class);
            jsonObject.put("env", "gray");
            jsonObject.put("interfaceType", "GateWay");
    
            Date deBugCaseStartTime = new Date();
            ResMsg resMsg = singleCaseDebugAPI.singleCaseDebug(jsonObject);
            resMsg.setDebugCaseStartTime(deBugCaseStartTime);
            // jsonpath
            if(!StringUtil.isBlank(gatewayCase.getExtractJsonPath())){ 
                String[] jsonPathList = gatewayCase.getExtractJsonPath().split("\r|\n");
                System.out.println("executeHttpCaseStep jsonPathList length:" + jsonPathList.length);
                for(int i = 0; i<jsonPathList.length; i++){ 
                    getResponseBodyJsonPathVal(sceneCaseId, resMsg.getResponsebody(), jsonPathList[i]);
                }
            }
            System.out.println("Http用例执行的结果：" + JSONObject.toJSONString(resMsg));
            return resMsg;
        }
    
        public static void getResponseBodyJsonPathVal(Integer sceneCaseId, String responseBody, String jsonPathKey){ 
            System.out.println("jsonPathKey: " + jsonPathKey);
            try{ 
                Object actualValue = JsonPath.read(responseBody, jsonPathKey);
                System.out.println("actualValue: " + actualValue.toString());
    
                // 存入数据库的字段，以jsonpath分隔出的最后一个为准
                String[] paramList = jsonPathKey.split("\\.");
                System.out.println("paramList length: " + paramList.length);
                String param = paramList[paramList.length - 1];
                System.out.println("param: " + param);
                boolean isNumber = isNumber(actualValue.toString());
                boolean isBoolean = isBoolean(actualValue.toString());
    
                ScenePublicParameter scenePublicParameterDB = scenePublicParameterService.findPublicParamValueBySceneCaseIdAndName(sceneCaseId, param);
                if(scenePublicParameterDB == null){ 
                    System.out.println("新增～～");
                    ScenePublicParameter scenePublicParameter = new ScenePublicParameter();
                    scenePublicParameter.setSceneCaseId(sceneCaseId);
                    scenePublicParameter.setSceneParameterName(param);
    
                    if(isNumber){ 
                        // 这种类型怎么办
                        scenePublicParameter.setSceneParameterType("整数");
                        scenePublicParameter.setSceneParameterVal(String.valueOf(actualValue));
                    } else if(isBoolean){ 
                        scenePublicParameter.setSceneParameterType("布尔");
                        scenePublicParameter.setSceneParameterVal(String.valueOf(actualValue));
                    } else { 
                        scenePublicParameter.setSceneParameterType("字符串");
                        scenePublicParameter.setSceneParameterVal((String)actualValue);
                    }
                    scenePublicParameterService.insert(scenePublicParameter);
                }else { 
                    System.out.println("更新～～");
                    if(isNumber){ 
                        scenePublicParameterDB.setSceneParameterVal(String.valueOf(actualValue));
                    } else if(isBoolean){ 
                        scenePublicParameterDB.setSceneParameterVal(String.valueOf(actualValue));
                    } else { 
                        scenePublicParameterDB.setSceneParameterVal((String)actualValue);
                    }
                    scenePublicParameterService.update(scenePublicParameterDB);
                }
            }catch (Exception e){ 
                e.printStackTrace();
            }
        }
    
        public static boolean isNumber(String str) { 
            //采用正则表达式的方式来判断一个字符串是否为数字，这种方式判断面比较全
            //可以判断正负、整数小数
    
            boolean isInt = Pattern.compile("^-?[1-9]\\d*$").matcher(str).find();
            boolean isDouble = Pattern.compile("^-?([1-9]\\d*\\.\\d*|0\\.\\d*[1-9]\\d*|0?\\.0+|0)$").matcher(str).find();
            return isInt || isDouble;
        }
    
        public static boolean isBoolean(String str){ 
            return str.equals("true") || str.equals("false");
        }
    }

其中的sceneCaseService、sceneStepsService…等五个对象是使用@Autowired从Spring容器中获取的，并都声明成了静态变量。但是在使用上述变量时发现，上述五个变量会报空指针错误

## 二、问题分析 ##

我们都知道静态变量，静态方法都是属于类的；普通变量、普通方法都是属于实例化对象的（即new处理的对象）；Spring依赖注入是在容器中实例化对象；

当我们使用静态变量或静态方法时，不需要new出来一个类的实例化对象，所以使用@Autowired修饰一个静态变量时，该静态变量并没有真正实例化成一个对象，因此该静态变量为null

## 三、解决方法 ##

### 3.1 将@Autowired加到构造方法上 ###

@Component
    public class RuleFunctions { 
    　　@Autowired
    　　private static RuleEntityItemInfoBiz ruleEntityItemInfoBiz;
    　　
    　　@Autowired
    　　public RuleFunctions(RuleEntityItemInfoBiz ruleEntityItemInfoBiz) { 
    RuleFunctions.ruleEntityItemInfoBiz = ruleEntityItemInfoBiz;
    }
    　　public static double calculateCurrentMonthIncomeTax(String fileId, String salaryMonth, String taxPlanId){ 
    　　　　//此处省略方法实现逻辑
    　　}
    }

### 3.2 使用set方法 ###

@Component
    public class RuleFunctions { 
    　　@Autowired
    　　private static RuleEntityItemInfoBiz ruleEntityItemInfoBiz;
    　　
    　　@Autowired
    　　public void setRuleEntityItemInfoBiz(RuleEntityItemInfoBiz ruleEntityItemInfoBiz) { 
    RuleFunctions.ruleEntityItemInfoBiz = ruleEntityItemInfoBiz;
    }
    　　public static double calculateCurrentMonthIncomeTax(String fileId, String salaryMonth, String taxPlanId){ 
    　　　　//此处省略方法实现逻辑
    　　}
    }

### 3.3 使用@PostConstruct注解 ###

#### 3.3.1 @PostConstruct注解 ####

@PostConstruct注解位于javax.annotation包下，可以用来修饰一个非静态的void返回的方法。

被@PostConstruct注解修饰的方法的执行时机是：在服务器加载Servlet的时候运行，并且只会被服务器加载一次；在构造函数之后，init（）方法之前执行

被@PostConstruct注解修饰的方法参数规范：除了拦截器这种特殊情况以外，其他情况都不允许有参数，否则Spring框架会报IllegalStateException；而且返回值要是void，但实际也可以有返回值，至少不会报错，只会忽略

Spring框架中使用到@PostConstruct注解，该注解修饰的方法在整个Bean初始化过程中的执行顺序如下：

Constructor(构造方法) -> @Autowired(依赖注入) -> @PostConstruct(注释的方法)

#### 3.3.2 实际例子 ####

@Component
    public class RuleFunctions { 
    	@Autowired
    	private RuleEntityItemInfoBiz ruleEntityItemInfoBiz;
    
    	private static RuleEntityItemInfoBiz staticRuleEntityItemInfoBiz;　　
    
    	/**
    	*注释用于在完成依赖注入以后执行任何初始化之后需要执行的方法。必须在类投入使用之前调用此方法。
    	*/
    	@PostConstruct
    	public void beforeInit() { 
    		staticRuleEntityItemInfoBiz = ruleEntityItemInfoBiz;
    	}
    	
    　　public static double calculateCurrentMonthIncomeTax(String fileId, String salaryMonth, String taxPlanId){ 
    　　　　//此处省略方法实现逻辑
    　　}
    }

参考博文：[spingboot使用@Resource注入静态变量报空指针的问题解决][spingboot_Resource]

[spingboot_Resource]: http://www.likecs.com/show-112522.html