ADD file via upload

EmployeeHistory.java

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+/**
+ * 员工历史记录类
+ * 负责记录员工的历史变更信息，如职位变更、薪资调整等
+ * 遵循单一职责原则，只负责历史记录的管理
+ */
+package com.employeetraining.history;
+
+import com.employeetraining.model.Employee;
+
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+
+public class EmployeeHistory {
+    private String employeeId;
+    private List<HistoryRecord> historyRecords;
+    private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+    
+    public EmployeeHistory(String employeeId) {
+        this.employeeId = employeeId;
+        this.historyRecords = new ArrayList<>();
+    }
+    
+    /**
+     * 记录职位变更
+     */
+    public void recordPositionChange(String oldPosition, String newPosition) {
+        String description = String.format("职位变更: 从 '%s' 变更为 '%s'", oldPosition, newPosition);
+        addRecord(HistoryType.POSITION_CHANGE, description);
+    }
+    
+    /**
+     * 记录薪资调整
+     */
+    public void recordSalaryChange(double oldSalary, double newSalary) {
+        String description = String.format("薪资调整: 从 %.2f 调整为 %.2f", oldSalary, newSalary);
+        addRecord(HistoryType.SALARY_CHANGE, description);
+    }
+    
+    /**
+     * 记录部门变更
+     */
+    public void recordDepartmentChange(String oldDepartment, String newDepartment) {
+        String description = String.format("部门变更: 从 '%s' 变更为 '%s'", oldDepartment, newDepartment);
+        addRecord(HistoryType.DEPARTMENT_CHANGE, description);
+    }
+    
+    /**
+     * 添加自定义记录
+     */
+    public void addCustomRecord(String description) {
+        addRecord(HistoryType.CUSTOM, description);
+    }
+    
+    /**
+     * 内部方法：添加记录
+     */
+    private void addRecord(HistoryType type, String description) {
+        HistoryRecord record = new HistoryRecord(LocalDateTime.now(), type, description);
+        historyRecords.add(record);
+    }
+    
+    /**
+     * 获取所有历史记录
+     */
+    public List<HistoryRecord> getAllRecords() {
+        return new ArrayList<>(historyRecords); // 返回副本，防止外部修改
+    }
+    
+    /**
+     * 根据类型获取历史记录
+     */
+    public List<HistoryRecord> getRecordsByType(HistoryType type) {
+        return historyRecords.stream()
+                .filter(record -> record.getType() == type)
+                .toList();
+    }
+    
+    /**
+     * 获取最新的历史记录
+     */
+    public Optional<HistoryRecord> getLatestRecord() {
+        if (historyRecords.isEmpty()) {
+            return Optional.empty();
+        }
+        return Optional.of(historyRecords.get(historyRecords.size() - 1));
+    }
+    
+    /**
+     * 获取记录总数
+     */
+    public int getRecordCount() {
+        return historyRecords.size();
+    }
+    
+    /**
+     * 历史记录类型枚举
+     */
+    public enum HistoryType {
+        POSITION_CHANGE,
+        SALARY_CHANGE,
+        DEPARTMENT_CHANGE,
+        CUSTOM
+    }
+    
+    /**
+     * 历史记录内部类
+     */
+    public class HistoryRecord {
+        private final LocalDateTime timestamp;
+        private final HistoryType type;
+        private final String description;
+        
+        public HistoryRecord(LocalDateTime timestamp, HistoryType type, String description) {
+            this.timestamp = timestamp;
+            this.type = type;
+            this.description = description;
+        }
+        
+        public LocalDateTime getTimestamp() {
+            return timestamp;
+        }
+        
+        public String getFormattedTimestamp() {
+            return timestamp.format(formatter);
+        }
+        
+        public HistoryType getType() {
+            return type;
+        }
+        
+        public String getDescription() {
+            return description;
+        }
+        
+        @Override
+        public String toString() {
+            return "[" + getFormattedTimestamp() + "] " + type + ": " + description;
+        }
+    }
+}