Java Servlet中的强制转换问题
我有一个servlet程序。这是我的代码:Java Servlet中的强制转换问题,java,servlets,Java,Servlets,我有一个servlet程序。这是我的代码: public class CompanionProxy extends HttpServlet { DeviceDAOHibernateImpl daoImpl = null; Logger log = Logger.getLogger("CompanionProxy"); public void init(){ daoImpl = new DeviceDAOHibernateImpl(); Pr
public class CompanionProxy extends HttpServlet {
DeviceDAOHibernateImpl daoImpl = null;
Logger log = Logger.getLogger("CompanionProxy");
public void init(){
daoImpl = new DeviceDAOHibernateImpl();
ProxyParser parser = ProxyParserFactory.getParser(ProxyParser.Type.XML);
log.info("Config file Path "+parser.getClass().getName());
ArrayList<Device> aDeviceList = parser.parse("c:\\proxy_setup_load.xml");//CommonConstants.CONFIG_FILE_PATH);
for (Iterator iterator = aDeviceList.iterator(); iterator.hasNext();) {
Device device = (Device) iterator.next();
try {
daoImpl.create(device);
} catch (ProxyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
List<Device> listDevices = daoImpl.list();
for (Iterator iterator = listDevices.iterator(); iterator.hasNext();) {
Device device = (Device) iterator.next();
log.info(device.toString());
}
} catch (ProxyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
@SuppressWarnings("unchecked")
Map<String, String> map = request.getParameterMap();
log.info(map.toString());
HashMap<String, String> requestMap = new HashMap<String, String>();
requestMap.putAll(map);
requestMap.put(CommonConstants.DEVICE_IP, request.getRemoteAddr());
String reqType = requestMap.get(CommonConstants.REQ_PARAM);
if (reqType.equals(CommonConstants.REGISTER_DEVICE)) {
Device device = ProxyRequestParser.parseRegisterRequest(requestMap);
try {
daoImpl.create(device);
} catch (ProxyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else if (reqType.equals(CommonConstants.UNREGISTER_DEVICE)) {
Device device;
try {
device = daoImpl.findByIPAddr(requestMap.get(CommonConstants.DEVICE_IP));
daoImpl.delete(device);
} catch (ProxyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
// some code...
}
此错误的原因是什么?如何修复它?检查API
getParameterMap()
返回Map
,而不是Map
当您从强制转换映射中检索对象时,您隐式地将其强制转换为字符串,而它应该是字符串数组
Java将“类型数组”表示为“[Ltype”
如果您确定您的请求参数是单一的(或者愿意做出这样的假设),只需通过获取数组的第一个条目来将它们展平
HashMap<String, String> requestMap = flatten(map);
...
public static Map<String, String> flatten(Map<String, String[]> arrayMap){
Map<String, String> r = new HashMap<String, String>();
for (Map.Entry<String, String[]> entry: arrayMap.entrySet()){
String[] value = entry.getValue();
if (value !=null && value .length>0) r.put(entry.getKey(), value[0]);
}
return r;
}
HashMap requestMap=plant(map);
...
公共静态地图展平(地图阵列地图){
Map r=新的HashMap();
对于(Map.Entry:arrayMap.entrySet()){
String[]value=entry.getValue();
如果(value!=null&&value.length>0)r.put(entry.getKey(),value[0]);
}
返回r;
}
检查API。getParameterMap()
返回Map
,而不是Map
当您从强制转换映射中检索对象时,您隐式地将其强制转换为字符串,而它应该是字符串数组
Java将“类型数组”表示为“[Ltype”
如果您确定您的请求参数是单一的(或者愿意做出这样的假设),只需通过获取数组的第一个条目来将它们展平
HashMap<String, String> requestMap = flatten(map);
...
public static Map<String, String> flatten(Map<String, String[]> arrayMap){
Map<String, String> r = new HashMap<String, String>();
for (Map.Entry<String, String[]> entry: arrayMap.entrySet()){
String[] value = entry.getValue();
if (value !=null && value .length>0) r.put(entry.getKey(), value[0]);
}
return r;
}
HashMap requestMap=plant(map);
...
公共静态地图展平(地图阵列地图){
Map r=新的HashMap();
对于(Map.Entry:arrayMap.entrySet()){
String[]value=entry.getValue();
如果(value!=null&&value.length>0)r.put(entry.getKey(),value[0]);
}
返回r;
}
Map-Map=request.getParameterMap();它在logMap-Map=request.getParameterMap()中显示INFO:Map=>{req=[Ljava.lang.string;@1b9f88b};它显示INFO:Map=>{req=[Ljava.lang.string;@1b9f88b}如果你真的需要一张地图,你能帮我怎么做吗?把它展平。我添加了一个例子。你能帮我怎么做吗?如果你真的需要一张地图,把它展平。我添加了一个例子。