Question

我使用BasicDBObject在mongodb中存储哈希表。现在我想要检索这个哈希表。我怎么能这样做？

HashTable<String, Login> loginHashTable;
HashTable<String, Other> otherHashTable;

DBCollection coll = db.getCollection(users);
BasicDBObject obj = new BasicDBObject();
obj.insert("HashTable1", loginHashTable);
obj.insert("HashTable2", otherHashTable);
coll.insert(obj);

它存储没有错误，但我如何检索特定的hashTable。假设我想要检索loginHashTable。那么，我该怎么做呢？

Somewhat like this:
HashTable <String,Login> retrieveTable = obj.get("HashTable1");

我的登录类是这样的：

public class Login extends ReflectionDBObject implements Serializable
{
    /** Enterprise user name used for authentication. */
    public String username = null;

    /** Enterprise password used for authentication. */
    public String password = null;

    /**Name of manufacturer of mobile phone*/
    public String manufacturer = null;

    /**Name of model of mobile phone*/
    public String model = null;

    /**Language in which Mobile software release is needed*/
    public String language = null;

    /**Current version of the software*/
    public String version = null;

    public static String id;
}

我的另一堂课是这样的：

public class Other extends ReflectionDBObject implements Serializable
{
   public String sessionID = null;
}

Answer 1

它将HashTable作为BasicDBObject（HashMap格式）添加到DB中。因此，为了检索数据，您应首先将HashTable作为HashMap，然后手动将其转换为HashTable。这个示例显示了如何以HashTable格式检索数据。我尝试使用HashTable<String,String>。

为了将Login类插入Mongo，您可以使用对象映射库，例如Morphia。第二种方法，你可以使用ReflectionDBObject。如果扩展ReflectionDBObject，则可以添加Login对象。

登录课程：

public class Login extends ReflectionDBObject {

    /** Enterprise user name used for authentication. */
    private String username;

    /** Enterprise password used for authentication. */
    private String password;

    /**Name of manufacturer of mobile phone*/
    private String manufacturer;

    /**Name of model of mobile phone*/
    private String model;

    /**Language in which Mobile software release is needed*/
    private String language;

    /**Current version of the software*/
    private String version;

    private String id;

    // Getters & Setters
}

其他课程：

public class Other extends ReflectionDBObject{
    public String sessionID;

    // Getter & Setter
}

插入＆amp;查找方法

public void insert() {
    Login login = new Login();
    login.setUsername("test");
    login.setPassword("12345");
    login.setLanguage("english");

    Other other = new Other();
    other.setSessionID("111111");

    Hashtable<String, Login> loginHashTable = new Hashtable<String, Login>();
    loginHashTable.put("login", login);

    Hashtable<String, Other> otherHashTable = new Hashtable<String, Other>();
    otherHashTable.put("other", other);

    DBObject obj = new BasicDBObject();
    obj.put("HashTable1", loginHashTable);
    obj.put("HashTable2", otherHashTable);
    coll.insert(obj);
}

public void find() {
    DBObject query = new BasicDBObject();
    DBCursor cur = coll.find(query);

    for (DBObject obj : cur) {
        HashMap<String, Login> loginHashMap = (HashMap<String, Login>) obj.get("HashTable1");
        Hashtable<String, Login> loginHashTable = new Hashtable<String, Login>();
        loginHashTable.putAll(loginHashMap);

        HashMap<String, Other> otherHashMap = (HashMap<String, Other>) obj.get("HashTable2");
        Hashtable<String, Other> otherHashTable = new Hashtable<String, Other>();
        otherHashTable.putAll(otherHashMap);
    }
}

如何从mongodb中检索Hashtable？

1 个答案: