在 MyBatis 中,可以通過自定義攔截器來記錄更新前后的值。以下是一個簡單的示例:
首先,創建一個實現 org.apache.ibatis.plugin.Interceptor
接口的攔截器類,重寫 intercept
方法:
public class UpdateInterceptor implements Interceptor {
@Override
public Object intercept(Invocation invocation) throws Throwable {
// 獲取方法參數
Object[] args = invocation.getArgs();
MappedStatement ms = (MappedStatement) args[0];
Object parameter = args[1];
BoundSql boundSql = ms.getBoundSql(parameter);
Configuration configuration = ms.getConfiguration();
Object parameterObject = boundSql.getParameterObject();
List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
String sql = boundSql.getSql();
// 獲取更新前的值
Executor executor = (Executor) invocation.getTarget();
Connection connection = executor.getTransaction().getConnection();
PreparedStatement preparedStatement = connection.prepareStatement(sql);
ResultSet rs = preparedStatement.executeQuery();
ResultSetMetaData metaData = rs.getMetaData();
int columnCount = metaData.getColumnCount();
while (rs.next()) {
for (int i = 1; i <= columnCount; i++) {
String columnName = metaData.getColumnName(i);
Object value = rs.getObject(i);
System.out.println("Column: " + columnName + ", Value: " + value);
}
}
rs.close();
preparedStatement.close();
// 執行更新操作
Object result = invocation.proceed();
// 獲取更新后的值
// ...
return result;
}
@Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
@Override
public void setProperties(Properties properties) {
// 可以在這里設置一些屬性
}
}
然后,在 MyBatis 配置文件中配置該攔截器:
<plugins>
<plugin interceptor="com.example.UpdateInterceptor">
<!-- 可以在這里設置一些屬性 -->
</plugin>
</plugins>
這樣,當執行更新操作時,攔截器會記錄更新前后的值。請注意,在實際生產環境中,需要根據具體情況完善和優化該攔截器的邏輯。