Java代码优化案例1：IF语句优化

ゝ一纸荒年。 2023-10-15 09:47 169阅读 0赞

业务中用到了一些判断语句，最开始写在了具体业务方法里面：如下

## 优化前： ##

/**
         * 重点设备及缺陷 数据对象解析
         *
         * @param request
         * @throws IOException
         */
        public static<T> List<T> getImportDataEquipmentDefect(String[] fields, Class<T> clz, HttpServletRequest request)
                throws IOException, InvalidFormatException, SecurityException, NoSuchMethodException, IllegalAccessException, NoSuchFieldException, InvocationTargetException, InstantiationException {
            Workbook wb = getWorkbookFromRequest(request);
            Sheet sheet = wb.getSheetAt(4);
            String departmentName="";
            String maintenanceProject="";
            String dailyPlanDate =null;
            List<T> datas = new ArrayList<>();
            // 获取总行数
            int rows = sheet.getPhysicalNumberOfRows();
            if (rows >= 2) {
                departmentName = sheet.getRow(1).getCell(1).getStringCellValue();
                maintenanceProject = sheet.getRow(3).getCell(0).getStringCellValue();
                dailyPlanDate = getCellValue((HSSFRow)sheet.getRow(1), 10);
            }
                for (int i = 3; i <= sheet.getLastRowNum(); i++) {
                    Row row = sheet.getRow(i);
                    if (row == null) {
                        continue;
                    }
                    if (fields != null) {
                        T obj = clz.getDeclaredConstructor().newInstance();
                        for (int  j= 0;  j< fields.length; j++) {
                            Cell cell = row.getCell(j);
                            String cellValue = getCellValue(cell);
                            String fieldName = fields[j];
                            Field field = null;
                            try {
                                field = obj.getClass().getDeclaredField(fieldName);
                            } catch (NoSuchFieldException e) {
                                field = obj.getClass().getSuperclass().getDeclaredField(fieldName);
                            }
                            field.setAccessible(true);
                            if(fieldName.equals("departmentName")){
                                cellValue = departmentName;
                            }
                            if(fieldName.equals("maintenanceProject")){
                                cellValue = maintenanceProject;
                            }
                            if(fieldName.equals("dailyPlanDate")){
                                cellValue = dailyPlanDate;
                            }
                            setFieldValue(field, obj, cellValue);
                        }
                        datas.add(obj);
                    }
                }
            return datas;
    
        }

## 优化后： ##

直接调用这个setCellValue就行

public void setCellValue(String fieldName) {
        String cellValue = "";
        
        switch(fieldName) {
            case "departmentName":
                cellValue = departmentName;
                break;
            case "maintenanceProject":
                cellValue = maintenanceProject;
                break;
            case "dailyPlanDate":
                cellValue = dailyPlanDate;
                break;
            default:
                break;
        }   
       
    }

优化之前代码的不好之处在于，使用多个`if`语句来判断字段名，这样会使代码显得冗长，并且不易于维护，当需要添加更多字段时，需要不断添加新的`if`语句。而优化之后的代码使用了`switch`语句，可以更简洁地处理这种情况，并且易于扩展，当需要添加新的字段时，只需要在`switch`语句中添加对应的`case`即可。这样可以提高代码的可读性和可维护性。