Hibernate查询方式:HQL和Criteria

 

    HQL查询方法一般使用的比较多,一般是通过query方式来查询的.例子如下:

 

/**
	 * 根据名字来查询
	 * 
	 * @param name
	 */
	static void query(String name) {
		Session s = null;
		try{
			s = HibernateUtil.getSession();
//			String hql = "from User as user where user.name=?";
			String hql = "from User as user where user.name=:name";//采用这种方式的时候,就用setString(String,String)
			Query query = s.createQuery(hql);
			query.setString("name", name);
			List list = query.list();
			//查询从某一条开始到某一条的分页
			query.setFirstResult(10);
			query.setMaxResults(20);
			for(int i = 0;i<list.size();i++){
				System.out.println(list.get(i));
			}
		}finally{
			if(s!=null){
				s.close();
			}
		}
	}

 

 而Criteria是一种比HQL更面向对象的查询方式:

   创建方式如下:Criteria crit = session.createCriteria(Object.class);

                       crit.add(Restrictions.eqProperty(a,b));

 

eg:

static void query(String name) {
		Session s = null;
		try{
			s = HibernateUtil.getSession();
            Criteria c = s.createCriteria(User.class);
            c.add(Restrictions.eq("name", name));
            c.add(Restrictions.gt("birthday", new Date()));
            List list = c.list();
			for(int i = 0;i<list.size();i++){
				System.out.println(list.get(i));
			}
		}finally{
			if(s!=null){
				s.close();
			}
		}
	}

 

关于Restrictions的API如下

public class Restrictions {

	Restrictions() {
		//cannot be instantiated
	}

	/**
	 * Apply an "equal" constraint to the identifier property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static Criterion idEq(Object value) {
		return new IdentifierEqExpression(value);
	}
	/**
	 * Apply an "equal" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression eq(String propertyName, Object value) {
		return new SimpleExpression(propertyName, value, "=");
	}
	/**
	 * Apply a "not equal" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression ne(String propertyName, Object value) {
		return new SimpleExpression(propertyName, value, "<>");
	}
	/**
	 * Apply a "like" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression like(String propertyName, Object value) {
		return new SimpleExpression(propertyName, value, " like ");
	}
	/**
	 * Apply a "like" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression like(String propertyName, String value, MatchMode matchMode) {
		return new SimpleExpression(propertyName, matchMode.toMatchString(value), " like " );
	}
	/**
	 * A case-insensitive "like", similar to Postgres <tt>ilike</tt>
	 * operator
	 *
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static Criterion ilike(String propertyName, String value, MatchMode matchMode) {
		return new IlikeExpression(propertyName, value, matchMode);
	}
	/**
	 * A case-insensitive "like", similar to Postgres <tt>ilike</tt>
	 * operator
	 *
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static Criterion ilike(String propertyName, Object value) {
		return new IlikeExpression(propertyName, value);
	}
	/**
	 * Apply a "greater than" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression gt(String propertyName, Object value) {
		return new SimpleExpression(propertyName, value, ">");
	}
	/**
	 * Apply a "less than" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression lt(String propertyName, Object value) {
		return new SimpleExpression(propertyName, value, "<");
	}
	/**
	 * Apply a "less than or equal" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression le(String propertyName, Object value) {
		return new SimpleExpression(propertyName, value, "<=");
	}
	/**
	 * Apply a "greater than or equal" constraint to the named property
	 * @param propertyName
	 * @param value
	 * @return Criterion
	 */
	public static SimpleExpression ge(String propertyName, Object value) {
		return new SimpleExpression(propertyName, value, ">=");
	}
	/**
	 * Apply a "between" constraint to the named property
	 * @param propertyName
	 * @param lo value
	 * @param hi value
	 * @return Criterion
	 */
	public static Criterion between(String propertyName, Object lo, Object hi) {
		return new BetweenExpression(propertyName, lo, hi);
	}
	/**
	 * Apply an "in" constraint to the named property
	 * @param propertyName
	 * @param values
	 * @return Criterion
	 */
	public static Criterion in(String propertyName, Object[] values) {
		return new InExpression(propertyName, values);
	}
	/**
	 * Apply an "in" constraint to the named property
	 * @param propertyName
	 * @param values
	 * @return Criterion
	 */
	public static Criterion in(String propertyName, Collection values) {
		return new InExpression( propertyName, values.toArray() );
	}
	/**
	 * Apply an "is null" constraint to the named property
	 * @return Criterion
	 */
	public static Criterion isNull(String propertyName) {
		return new NullExpression(propertyName);
	}
	/**
	 * Apply an "equal" constraint to two properties
	 */
	public static PropertyExpression eqProperty(String propertyName, String otherPropertyName) {
		return new PropertyExpression(propertyName, otherPropertyName, "=");
	}
	/**
	 * Apply a "not equal" constraint to two properties
	 */
	public static PropertyExpression neProperty(String propertyName, String otherPropertyName) {
		return new PropertyExpression(propertyName, otherPropertyName, "<>");
	}
	/**
	 * Apply a "less than" constraint to two properties
	 */
	public static PropertyExpression ltProperty(String propertyName, String otherPropertyName) {
		return new PropertyExpression(propertyName, otherPropertyName, "<");
	}
	/**
	 * Apply a "less than or equal" constraint to two properties
	 */
	public static PropertyExpression leProperty(String propertyName, String otherPropertyName) {
		return new PropertyExpression(propertyName, otherPropertyName, "<=");
	}
	/**
	 * Apply a "greater than" constraint to two properties
	 */
	public static PropertyExpression gtProperty(String propertyName, String otherPropertyName) {
		return new PropertyExpression(propertyName, otherPropertyName, ">");
	}
	/**
	 * Apply a "greater than or equal" constraint to two properties
	 */
	public static PropertyExpression geProperty(String propertyName, String otherPropertyName) {
		return new PropertyExpression(propertyName, otherPropertyName, ">=");
	}
	/**
	 * Apply an "is not null" constraint to the named property
	 * @return Criterion
	 */
	public static Criterion isNotNull(String propertyName) {
		return new NotNullExpression(propertyName);
	}
	/**
	 * Return the conjuction of two expressions
	 *
	 * @param lhs
	 * @param rhs
	 * @return Criterion
	 */
	public static LogicalExpression and(Criterion lhs, Criterion rhs) {
		return new LogicalExpression(lhs, rhs, "and");
	}
	/**
	 * Return the disjuction of two expressions
	 *
	 * @param lhs
	 * @param rhs
	 * @return Criterion
	 */
	public static LogicalExpression or(Criterion lhs, Criterion rhs) {
		return new LogicalExpression(lhs, rhs, "or");
	}
	/**
	 * Return the negation of an expression
	 *
	 * @param expression
	 * @return Criterion
	 */
	public static Criterion not(Criterion expression) {
		return new NotExpression(expression);
	}
	/**
	 * Apply a constraint expressed in SQL, with the given JDBC
	 * parameters. Any occurrences of <tt>{alias}</tt> will be
	 * replaced by the table alias.
	 *
	 * @param sql
	 * @param values
	 * @param types
	 * @return Criterion
	 */
	public static Criterion sqlRestriction(String sql, Object[] values, Type[] types) {
		return new SQLCriterion(sql, values, types);
	}
	/**
	 * Apply a constraint expressed in SQL, with the given JDBC
	 * parameter. Any occurrences of <tt>{alias}</tt> will be replaced
	 * by the table alias.
	 *
	 * @param sql
	 * @param value
	 * @param type
	 * @return Criterion
	 */
	public static Criterion sqlRestriction(String sql, Object value, Type type) {
		return new SQLCriterion(sql, new Object[] { value }, new Type[] { type } );
	}
	/**
	 * Apply a constraint expressed in SQL. Any occurrences of <tt>{alias}</tt>
	 * will be replaced by the table alias.
	 *
	 * @param sql
	 * @return Criterion
	 */
	public static Criterion sqlRestriction(String sql) {
		return new SQLCriterion(sql, ArrayHelper.EMPTY_OBJECT_ARRAY, ArrayHelper.EMPTY_TYPE_ARRAY);
	}

	/**
	 * Group expressions together in a single conjunction (A and B and C...)
	 *
	 * @return Conjunction
	 */
	public static Conjunction conjunction() {
		return new Conjunction();
	}

	/**
	 * Group expressions together in a single disjunction (A or B or C...)
	 *
	 * @return Conjunction
	 */
	public static Disjunction disjunction() {
		return new Disjunction();
	}

	/**
	 * Apply an "equals" constraint to each property in the
	 * key set of a <tt>Map</tt>
	 *
	 * @param propertyNameValues a map from property names to values
	 * @return Criterion
	 */
	public static Criterion allEq(Map propertyNameValues) {
		Conjunction conj = conjunction();
		Iterator iter = propertyNameValues.entrySet().iterator();
		while ( iter.hasNext() ) {
			Map.Entry me = (Map.Entry) iter.next();
			conj.add( eq( (String) me.getKey(), me.getValue() ) );
		}
		return conj;
	}
	
	/**
	 * Constrain a collection valued property to be empty
	 */
	public static Criterion isEmpty(String propertyName) {
		return new EmptyExpression(propertyName);
	}

	/**
	 * Constrain a collection valued property to be non-empty
	 */
	public static Criterion isNotEmpty(String propertyName) {
		return new NotEmptyExpression(propertyName);
	}
	
	/**
	 * Constrain a collection valued property by size
	 */
	public static Criterion sizeEq(String propertyName, int size) {
		return new SizeExpression(propertyName, size, "=");
	}
	
	/**
	 * Constrain a collection valued property by size
	 */
	public static Criterion sizeNe(String propertyName, int size) {
		return new SizeExpression(propertyName, size, "<>");
	}
	
	/**
	 * Constrain a collection valued property by size
	 */
	public static Criterion sizeGt(String propertyName, int size) {
		return new SizeExpression(propertyName, size, "<");
	}
	
	/**
	 * Constrain a collection valued property by size
	 */
	public static Criterion sizeLt(String propertyName, int size) {
		return new SizeExpression(propertyName, size, ">");
	}
	
	/**
	 * Constrain a collection valued property by size
	 */
	public static Criterion sizeGe(String propertyName, int size) {
		return new SizeExpression(propertyName, size, "<=");
	}
	
	/**
	 * Constrain a collection valued property by size
	 */
	public static Criterion sizeLe(String propertyName, int size) {
		return new SizeExpression(propertyName, size, ">=");
	}
	
	public static NaturalIdentifier naturalId() {
		return new NaturalIdentifier();
	}
		
}

 

除了构造函数,全都是静态的.