Unsupported major.minor version

 当你在编译Java时,遇到Unsupported major.minor version类似如下问题提示:

Unsupported major.minor version 50.0
Unsupported major.minor version 49.0
Unsupported major.minor version 48.0

均属于Java版本问题(注意一下自己的系统环境变量的设置问题,可能高版本的被低版本的覆盖了),即JDK版本过低,只要选择相对应的JDK版本编译即可。
48,49,50是Java编译器内部的版本号

Unsupported major.minor version 50.0 对应要使用 JDK1.6(JRE1.6)
Unsupported major.minor version 49.0 对应要使用 JDK1.5(JRE1.5)
Unsupported major.minor version 48.0 对应要使用 JDK1.4(JRE1.4)

问题解决方法就是重新用老的JDK编译,并在老的JDK环境下(包括修改JAVA_HOME,PATH,CLASSPATH)运行(可能造成Web应用程序失败),JDK版本的不兼容给所有的Java开发人员带来了很多麻烦
这是DronCAN的初始化函数,哪个是设置节点的函数void AP_DroneCAN::init(uint8_t driver_index, bool enable_filters) { if (driver_index != _driver_index) { debug_dronecan(AP_CANManager::LOG_ERROR, "DroneCAN: init called with wrong driver_index"); return; } if (_initialized) { debug_dronecan(AP_CANManager::LOG_ERROR, "DroneCAN: init called more than once\n\r"); return; } uint8_t node = _dronecan_node; if (node < 1 || node > 125) { // reset to default if invalid _dronecan_node.set(AP_DRONECAN_DEFAULT_NODE); node = AP_DRONECAN_DEFAULT_NODE; } node_info_rsp.name.len = hal.util->snprintf((char*)node_info_rsp.name.data, sizeof(node_info_rsp.name.data), "org.ardupilot:%u", driver_index); node_info_rsp.software_version.major = AP_DRONECAN_SW_VERS_MAJOR; node_info_rsp.software_version.minor = AP_DRONECAN_SW_VERS_MINOR; node_info_rsp.hardware_version.major = AP_DRONECAN_HW_VERS_MAJOR; node_info_rsp.hardware_version.minor = AP_DRONECAN_HW_VERS_MINOR; #if HAL_CANFD_SUPPORTED if (option_is_set(Options::CANFD_ENABLED)) { canard_iface.set_canfd(true); } #endif uint8_t uid_len = sizeof(uavcan_protocol_HardwareVersion::unique_id); uint8_t unique_id[sizeof(uavcan_protocol_HardwareVersion::unique_id)]; mem_pool = NEW_NOTHROW uint32_t[_pool_size/sizeof(uint32_t)]; if (mem_pool == nullptr) { debug_dronecan(AP_CANManager::LOG_ERROR, "DroneCAN: Failed to allocate memory pool\n\r"); return; } canard_iface.init(mem_pool, (_pool_size/sizeof(uint32_t))*sizeof(uint32_t), node); if (!hal.util->get_system_id_unformatted(unique_id, uid_len)) { return; } unique_id[uid_len - 1] += node; memcpy(node_info_rsp.hardware_version.unique_id, unique_id, uid_len); //Start Servers if (!_dna_server.init(unique_id, uid_len, node)) { debug_dronecan(AP_CANManager::LOG_ERROR, "DroneCAN: Failed to start DNA Server\n\r"); return; }
03-14
这是飞控中DronCAN的初始化函数,哪个是给其他设备设置节点语句void AP_DroneCAN::init(uint8_t driver_index, bool enable_filters) { if (driver_index != _driver_index) { debug_dronecan(AP_CANManager::LOG_ERROR, “DroneCAN: init called with wrong driver_index”); return; } if (_initialized) { debug_dronecan(AP_CANManager::LOG_ERROR, “DroneCAN: init called more than once\n\r”); return; } uint8_t node = _dronecan_node; if (node < 1 || node > 125) { // reset to default if invalid _dronecan_node.set(AP_DRONECAN_DEFAULT_NODE); node = AP_DRONECAN_DEFAULT_NODE; } node_info_rsp.name.len = hal.util->snprintf((char*)node_info_rsp.name.data, sizeof(node_info_rsp.name.data), "org.ardupilot:%u", driver_index); node_info_rsp.software_version.major = AP_DRONECAN_SW_VERS_MAJOR; node_info_rsp.software_version.minor = AP_DRONECAN_SW_VERS_MINOR; node_info_rsp.hardware_version.major = AP_DRONECAN_HW_VERS_MAJOR; node_info_rsp.hardware_version.minor = AP_DRONECAN_HW_VERS_MINOR; #if HAL_CANFD_SUPPORTED if (option_is_set(Options::CANFD_ENABLED)) { canard_iface.set_canfd(true); } #endif uint8_t uid_len = sizeof(uavcan_protocol_HardwareVersion::unique_id); uint8_t unique_id[sizeof(uavcan_protocol_HardwareVersion::unique_id)]; mem_pool = NEW_NOTHROW uint32_t[_pool_size/sizeof(uint32_t)]; if (mem_pool == nullptr) { debug_dronecan(AP_CANManager::LOG_ERROR, "DroneCAN: Failed to allocate memory pool\n\r"); return; } canard_iface.init(mem_pool, (_pool_size/sizeof(uint32_t))*sizeof(uint32_t), node); if (!hal.util->get_system_id_unformatted(unique_id, uid_len)) { return; } unique_id[uid_len - 1] += node; memcpy(node_info_rsp.hardware_version.unique_id, unique_id, uid_len); //Start Servers if (!_dna_server.init(unique_id, uid_len, node)) { debug_dronecan(AP_CANManager::LOG_ERROR, "DroneCAN: Failed to start DNA Server\n\r"); return; }
03-14
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