private static Serializer serializer;
private static Map<Long, User> users = new HashMap<>();
// private static Map<Long, Admin> admins = new HashMap<>();
private static Map<Long, Movie> movies = new HashMap<>();
private static Map<Long, Rating> ratings = new HashMap<>();
private static Map<String, Movie> movietitle = new HashMap<>();
private static Map<String, Movie> moviedate = new HashMap<>();
private static Map<String, User> Login = new HashMap<>();
private static Map<String, Admin> AdminLogin = new HashMap<>();
// more lines of codes
@SuppressWarnings("unchecked")
public void load() throws Exception {
serializer.read();
users = (Map<Long, User>) serializer.pop();
movies = (Map<Long, Movie>) serializer.pop();
ratings = (Map<Long, Rating>) serializer.pop();
AdminLogin = (Map<String, Admin>) serializer.pop();
User.counter = (Long) serializer.pop();
Movie.counter = (Long) serializer.pop();
}
// more lines of codes
错误
******Security framework of XStream not initialized, XStream is probably
vulnerable.
****Exception in thread "main" java.lang.ClassCastException: java.lang.Long cannot be cast to java.util.Map
at Recommendation.RecommendationAPI.load(RecommendationAPI.java:211)
at Recommendation.Client.main(Client.java:34)**
正如你们所见，每当我尝试加载已在文件夹中创建的 XML 文件时，我都会收到错误。我可以创建没有错误的 XML 文件，但在加载文件时，正如您在上面看到的，我遇到了错误。我不知道为什么它说
LongMapAdminLogin = (Map<String, Admin>) serializer.pop();
main中的错误基本上是我使用load()方法
//XMLSerializer
package utils;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Stack;
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;
public class XMLSerializer implements Serializer
{
private Stack<Object> stack = new Stack<>();
private File file;
public XMLSerializer(File file)
{
this.file = file;
}
@Override
public void push(Object o)
{
stack.push(o);
}
@Override
public Object pop()
{
return stack.pop();
}
@SuppressWarnings("unchecked")
@Override
public void read() throws Exception
{
ObjectInputStream inputStream = null;
try
{
XStream xstream = new XStream(new DomDriver());
inputStream = xstream.createObjectInputStream(new FileReader(file));
stack = (Stack<Object>) inputStream.readObject();
}
finally
{
if (inputStream != null)
{
inputStream.close();
}
}
}
@Override
public void write() throws Exception
{
ObjectOutputStream outputStream = null;
try
{
XStream xstream = new XStream(new DomDriver());
outputStream = xstream.createObjectOutputStream(new FileWriter(file));
outputStream.writeObject(stack);
}
finally
{
if (outputStream != null)
{
outputStream.close();
}
}
}
//Serializer
package utils;
public interface Serializer {
void push(Object o);
Object pop();
void write() throws Exception;
void read() throws Exception;
}
//CSVLoader
package utils;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import values.Admin;
import values.Movie;
import values.Rating;
import values.User;
import edu.princeton.cs.introcs.In;
public class CSVLoader {
public List<User> loadUsers(String filename) throws Exception {
File usersFile = new File(filename);
In inUsers = new In(usersFile);
String delims = "[|]";
List<User> users = new ArrayList<User>();
while (!inUsers.isEmpty()) {
String userDetails = inUsers.readLine();
String[] userTokens = userDetails.split(delims);
if (userTokens.length == 7) {
String firstName = userTokens[1];
String lastName = userTokens[2];
int age = Integer.valueOf(userTokens[3]);
String gender = userTokens[4];
String occupation = userTokens[5];
String zip = userTokens[6];
String username = "";
String password = "";
users.add(new User(firstName, lastName, age, gender, occupation,zip,username,password));
} else {
throw new Exception("Invalid User length: " + userTokens.length);
}
}
return users;
}
public List<Admin> loadAdmins(String filename) throws Exception {
File AdminFile = new File(filename);
In inAdmins = new In(AdminFile);
String delims = "[|]";
List<Admin> admins = new ArrayList<Admin>();
while (!inAdmins.isEmpty()) {
String adminDetails = inAdmins.readLine();
String[] adminTokens = adminDetails.split(delims);
if (adminTokens.length == 7) {
String firstName = adminTokens[1];
String lastName = adminTokens[2];
int age = Integer.valueOf(adminTokens[3]);
String gender = adminTokens[4];
String username = adminTokens[5];
String password = adminTokens[6];
admins.add(new Admin(firstName, lastName, age, gender, username,password));
} else {
throw new Exception("Invalid User length: " + adminTokens.length);
}
}
return admins;
}
public List<Movie> loadMovies(String filename) throws Exception {
File movieFile = new File(filename);
In inMovies= new In(movieFile);
String delims = "[|]";
List<Movie> movies = new ArrayList<Movie>();
while (!inMovies.isEmpty()) {
String movieDetails = inMovies.readLine();
String[] movieTokens = movieDetails.split(delims);
if (movieTokens.length == 23) {
String title = movieTokens[1];
String date = movieTokens[2];
String url = movieTokens[3];
movies.add(new Movie(title, date, url));
}
else
{
throw new Exception("Invalid Movie length: " + movieTokens.length);
}
}
return movies;
}
public List<Rating> loadRatings(String filename) throws Exception {
File ratingFile = new File(filename);
In inRating = new In(ratingFile);
String delims = "[|]";
List<Rating> ratings = new ArrayList<Rating>();
while (!inRating.isEmpty()) {
String ratingDetails = inRating.readLine();
String[] ratingTokens = ratingDetails.split(delims);
if (ratingTokens.length == 4) {
Long userid = Long.valueOf(ratingTokens[0]);
Long itemid = Long.valueOf(ratingTokens[1]);
int rating = Integer.valueOf(ratingTokens[2]);
int timestamp = Integer.valueOf(ratingTokens[3]);
ratings.add(new Rating(userid, itemid, rating,timestamp));
}
else
{
throw new Exception("Invalid Ratings length: " + ratingTokens.length);
}
}
return ratings;
}
}
//XML File
<object-stream>
<java.util.Stack serialization="custom">
<unserializable-parents/>
<vector>
<default>
<capacityIncrement>0</capacityIncrement>
<elementCount>6</elementCount>
<elementData>
<map>
<entry>
<string>keden12</string>
<values.Admin>
<fname>Kamil</fname>
<lname>Bigos</lname>
<age>24</age>
<gender>M</gender>
<id>0</id>
<username>keden12</username>
<password>admin</password>
</values.Admin>
</entry>
</map>
<long>943</long>
<long>1682</long>
<map>
<entry>
<long>0</long>
<values.User>
<fname>Leonard</fname>
<lname>Hernandez</lname>
<age>24</age>
<gender>M</gender>
<occupation>technician</occupation>
<zip>85711</zip>
<id>0</id>
<username></username>
<password></password>
<ratingsUser/>
</values.User>
</entry>
<entry>
<long>1</long>
<values.User>
<fname>Melody</fname>
<lname>Roberson</lname>
<age>53</age>
<gender>F</gender>
<occupation>other</occupation>
<zip>94043</zip>
<id>1</id>
<username></username>
<password></password>
<ratingsUser/>
</values.User>
</entry>
<entry>
<long>2</long>
<values.User>
<fname>Gregory</fname>
<lname>Newton</lname>
<age>23</age>
<gender>M</gender>
<occupation>writer</occupation>
<zip>32067</zip>
<id>2</id>
<username></username>
<password></password>
<ratingsUser/>
</values.User>
</entry>
<entry>
<long>3</long>
<values.User>
<fname>Oliver</fname>
<lname>George</lname>
<age>24</age>
<gender>M</gender>
<occupation>technician</occupation>
<zip>43537</zip>
<id>3</id>
<username></username>
<password></password>
<ratingsUser/>
</values.User>
</entry>
</map>
<map>
<entry>
<long>0</long>
<values.Movie>
<movieid>0</movieid>
<title>Toy Story (1995)</title>
<releasedate>01-Jan-1995</releasedate>
<url>http://us.imdb.com/M/title-exact?Toy%20Story%20(1995)</url>
</values.Movie>
</entry>
<entry>
<long>1</long>
<values.Movie>
<movieid>1</movieid>
<title>GoldenEye (1995)</title>
<releasedate>01-Jan-1995</releasedate>
<url>http://us.imdb.com/M/title-exact?GoldenEye%20(1995)</url>
</values.Movie>
</entry>
<entry>
<long>2</long>
<values.Movie>
<movieid>2</movieid>
<title>Four Rooms (1995)</title>
<releasedate>01-Jan-1995</releasedate>
<url>http://us.imdb.com/M/title-exact?Four%20Rooms%20(1995) </url>
</values.Movie>
</entry>
</map>
<map>
<entry>
<long>1</long>
<values.Rating>
<userid>1</userid>
<itemid>94</itemid>
<rating>-3</rating>
<timestamp>875072956</timestamp>
<usersRatings/>
</values.Rating>
</entry>
<entry>
<long>2</long>
<values.Rating>
<userid>2</userid>
<itemid>296</itemid>
<rating>1</rating>
<timestamp>888550871</timestamp>
<usersRatings/>
</values.Rating>
</entry>
<entry>
<long>3</long>
<values.Rating>
<userid>3</userid>
<itemid>346</itemid>
<rating>5</rating>
<timestamp>889237455</timestamp>
<usersRatings/>
</values.Rating>
</entry>
<entry>
<long>4</long>
<values.Rating>
<userid>4</userid>
<itemid>301</itemid>
<rating>5</rating>
<timestamp>892002353</timestamp>
<usersRatings/>
</values.Rating>
</entry>
</map>
<null/>
<null/>
<null/>
<null/>
</elementData>
</default>
</vector>
</java.util.Stack>
</object-stream>
堆栈保留顺序。 XML 示例的元素顺序为“map、map、map、long、long、map”（从下往上）。因此，对于第四个 .pop()，您将得到一个“long”（1682），但尝试将其转换为地图。
（我希望 TO 在发布后的六年内解决这个问题。）