struts2 enum值相关

最新推荐文章于 2025-03-23 00:36:35 发布

iteye_11997

最新推荐文章于 2025-03-23 00:36:35 发布

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分类专栏： struts 文章标签： JDBC Hibernate

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本文介绍了一种使用自定义枚举类型与整数值相结合的方法来实现数据库映射，并提供了具体的实现代码示例。

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public enum Dimension implements Serializable, IntegerValuedEnum {
    LARGE(234, 60, 0), SMALL(125, 125, 1);

    private final int width;
    private final int height;
    private final int code;

    private Dimension(int width, int height, int code) {
        this.width = width;
        this.height = height;
        this.code = code;
    }

    public int getWidth() {
        return width;
    }

    public int getHeight() {
        return height;
    }

    @Override
    public int getCode() {
        return code;
    }

    public String getDisplay() {
        return "" + this.width + "*" + this.height;
    }
}

public class IntegerValuedEnumType<T extends Enum & IntegerValuedEnum> implements
        EnhancedUserType, ParameterizedType {

    /**
     * Enum class for this particular user type.
     */
    private Class<T> enumClass;

    /**
     * Value to use if null.
     */
    private Integer defaultValue;

    public IntegerValuedEnumType() { }

    public void setParameterValues(Properties parameters) {
        String enumClassName = parameters.getProperty("enum");
        try {
            enumClass = (Class<T>) Class.forName(enumClassName).asSubclass(Enum.class)
                    .asSubclass(IntegerValuedEnum.class); 
        } catch (ClassNotFoundException e) {
            throw new HibernateException("Enum class not found", e);
        }
        
        String defaultValueStr = parameters.getProperty("defaultValue");
        if (defaultValueStr != null && !defaultValueStr.isEmpty()) {
            try {
                setDefaultValue(Integer.parseInt(defaultValueStr));
            } catch (NumberFormatException e) {
                throw new HibernateException("Invalid default value", e);
            }
        }
    }

    public Integer getDefaultValue() {
        return defaultValue;
    }

    public void setDefaultValue(Integer defaultValue) {
        this.defaultValue = defaultValue;
    }

    /**
     * The class returned by <tt>nullSafeGet()</tt>.
     * 
     * @return Class
     */
    public Class returnedClass() {
        return enumClass;
    }

    public int[] sqlTypes() {
        return new int[] { Types.TINYINT };
    }

    public boolean isMutable() {
        return false;
    }

    /**
     * Retrieve an instance of the mapped class from a JDBC resultset.
     * Implementors should handle possibility of null values.
     * 
     * @param rs         a JDBC result set
     * @param names     the column names
     * @param owner     the containing entity
     * @return Object
     * @throws HibernateException
     * @throws SQLException
     */
    public Object nullSafeGet(ResultSet rs, String[] names, Object owner)
        throws SQLException {
        
        Integer value = rs.getInt(names[0]);
        if (value == null) {
            value = getDefaultValue();
            if (value == null) { // no default value
                return null;
            }
        }
        String name = IntegerValuedEnumReflect.getNameFromValue(enumClass, value);
        if (rs.wasNull() || name == null || name.isEmpty()) {
        	return null;
        } else {
        	return Enum.valueOf(enumClass, name);
        }
    }

    /**
     * Write an instance of the mapped class to a prepared statement.
     * Implementors should handle possibility of null values. A multi-column
     * type should be written to parameters starting from <tt>index</tt>.
     * 
     * @param st        a JDBC prepared statement
     * @param value        the object to write
     * @param index        statement parameter index
     * @throws HibernateException
     * @throws SQLException
     */
    public void nullSafeSet(PreparedStatement st, Object value, int index)
        throws SQLException {
        
        if (value == null) {
            st.setNull(index, Types.TINYINT);
        } else {
            st.setInt(index, ((T) value).getCode());
        }
    }

    public Object assemble(Serializable cached, Object owner) {
        return cached;
    }

    public Serializable disassemble(Object value) {
        return (Enum) value;
    }

    public Object deepCopy(Object value) {
        return value;
    }

    public boolean equals(Object x, Object y) {
        return x == y;
    }

    public int hashCode(Object x) {
        return x.hashCode();
    }

    public Object replace(Object original, Object target, Object owner) {
        return original;
    }

    public String objectToSQLString(Object value) {
        return '\'' + String.valueOf(((T) value).getCode()) + '\'';
    }

    public String toXMLString(Object value) {
        return String.valueOf(((T) value).getCode());
    }

    public Object fromXMLString(String xmlValue) {
        Integer value = Integer.parseInt(xmlValue);
        String name = IntegerValuedEnumReflect.getNameFromValue(enumClass, value);
        if (name == null || name.isEmpty()) {
        	return null;
        } else {
        	return Enum.valueOf(enumClass, name);
        }
    }
}

public final class IntegerValuedEnumReflect {

    /**
     * Don't let anyone instantiate this class.
     * 
     * @throws UnsupportedOperationException
     *             Always.
     */
    private IntegerValuedEnumReflect() {
        throw new UnsupportedOperationException("This class must not be instanciated.");
    }

    /**
     * All Enum constants (instances) declared in the specified class.
     * 
     * @param enumClass        Class to reflect
     * @return Array of all declared EnumConstants (instances).
     */
    private static <T extends Enum> T[] getValues(Class<T> enumClass) {
        return enumClass.getEnumConstants();
    }

    /**
     * All possible string values of the string valued enum.
     * 
     * @param enumClass        Class to reflect.
     * @return Available integer values.
     */
    public static <T extends Enum & IntegerValuedEnum> int[] getStringValues(
            Class<T> enumClass) {
        T[] values = getValues(enumClass);
        int[] result = new int[values.length];
        for (int i = 0; i < values.length; i++) {
            result[i] = values[i].getCode();
        }
        return result;
    }

    /**
     * Name of the enum instance which hold the respecified string value. If
     * value has duplicate enum instances than returns the first occurrence.
     * 
     * @param enumClass        Class to inspect.
     * @param value            The int value.
     * @return name of the enum instance.
     */
    public static <T extends Enum & IntegerValuedEnum> String getNameFromValue(
            Class<T> enumClass, int value) {
        T[] values = getValues(enumClass);
        for (int i = 0; i < values.length; i++) {
            if (values[i].getCode() == value) {
                return values[i].name();
            }
        }
        return null;
    }
}

public class IntegerValuedEnumSetType<T extends Enum<T> & IntegerValuedEnum> implements
        EnhancedUserType, ParameterizedType {

    /**
     * Enum class for this particular user type.
     */
    private Class<T> enumClass;

    public IntegerValuedEnumSetType() { }

    public void setParameterValues(Properties parameters) {
        String enumClassName = parameters.getProperty("enum");
        try {
            enumClass = (Class<T>) Class.forName(enumClassName).asSubclass(Enum.class)
                    .asSubclass(IntegerValuedEnum.class); 
        } catch (ClassNotFoundException e) {
            throw new HibernateException("Enum class not found", e);
        }
    }

    /**
     * The class returned by <tt>nullSafeGet()</tt>.
     * 
     * @return Class
     */
    public Class returnedClass() {
        return enumClass;
    }

    public int[] sqlTypes() {
        return new int[] { Types.TINYINT };
    }

    public boolean isMutable() {
        return false;
    }

    /**
     * Retrieve an instance of the mapped class from a JDBC resultset.
     * Implementors should handle possibility of null values.
     * 
     * @param rs         a JDBC result set
     * @param names     the column names
     * @param owner     the containing entity
     * @return Object
     * @throws HibernateException
     * @throws SQLException
     */
    public Object nullSafeGet(ResultSet rs, String[] names, Object owner)
        throws SQLException {
        
        Integer value = rs.getInt(names[0]);
        if (value == null) {
            return null;
        }

        return decode(value);
    }

    /**
     * Write an instance of the mapped class to a prepared statement.
     * Implementors should handle possibility of null values. A multi-column
     * type should be written to parameters starting from <tt>index</tt>.
     * 
     * @param st        a JDBC prepared statement
     * @param value        the object to write
     * @param index        statement parameter index
     * @throws HibernateException
     * @throws SQLException
     */
    public void nullSafeSet(PreparedStatement st, Object value, int index)
        throws SQLException {
        
        if (value == null) {
            st.setNull(index, Types.TINYINT);
        } else {
            st.setInt(index, encode((EnumSet<T>)value));
        }
    }

    public Object assemble(Serializable cached, Object owner) {
        return cached;
    }

    public Serializable disassemble(Object value) {
        return (Enum) value;
    }

    public Object deepCopy(Object value) {
        return value;
    }

    public boolean equals(Object x, Object y) {
        return x == y;
    }

    public int hashCode(Object x) {
        return x.hashCode();
    }

    public Object replace(Object original, Object target, Object owner) {
        return original;
    }

    public String objectToSQLString(Object value) {
        return '\'' + String.valueOf(encode((EnumSet<T>)value)) + '\'';
    }

    public String toXMLString(Object value) {
        return String.valueOf(encode((EnumSet<T>)value));
    }

    public Object fromXMLString(String xmlValue) {
    	try {
    		Integer value = Integer.parseInt(xmlValue);
    		return decode(value);
    	} catch (NumberFormatException e) {
    		return EnumSet.noneOf(enumClass);
    	}
        
    }
    
    /*
     * Encode the EnumSet into an integer based on bit on/off
     */
    private int encode(EnumSet<T> set) {
        int ret = 0;
        for (T val : set) {
            ret |= 1 << val.getCode();
        }
        return ret;
    }

    /*
     * Decode the integer back to a EnumSet based on bit on/off
     */
    private EnumSet<T> decode(int code) {
		Map<Integer, T> codeMap = new HashMap<Integer, T>();
		for (T val : EnumSet.allOf(enumClass)) {
			codeMap.put(val.getCode(), val);
		}
    	  
        EnumSet<T> result = EnumSet.noneOf(enumClass);
        while (code != 0) {
            int ordinal = Integer.numberOfTrailingZeros(code);
            code ^= Integer.lowestOneBit(code);
            result.add(codeMap.get(ordinal));
        }
        return result;
    }
}

public interface IntegerValuedEnum {

    /**
     * Current int value stored in the enum.
     * @return int value.
     */
    int getCode();

}

maping.xml

<property name="dimension" column="DIMENSION">
            <type name="com.xxx.bbb.hibernate.IntegerValuedEnumType">
                <param name="enum">com.xxx.bbb.beans.Dimension</param>
            </type>
        </property>

存到数据库只是 0 1 2

转换器

public class DimensionConverter extends StrutsTypeConverter {

    @Override
    public Object convertFromString(Map arg0, String[] values, Class clazz) {
        if (values != null && values.length > 0 && values[0] != null
                && !values[0].isEmpty()) {
            String value = values[0];
            if (value.equals("0")) {
                return Dimension.LARGE;
            } else if (value.equals("1")) {
                return Dimension.SMALL;
            } 
        }
        return null;
    }

    @Override
    public String convertToString(Map arg0, Object o) {
        System.out.println(o.toString());
        Dimension dimension = (Dimension) o;
        return String.valueOf(dimension.getCode());
    }
}

$("#dimensionSelect").val(${request.dimension.code});

<s:select id="dimensionSelect" name="dimension" list="#{@beans.Dimension@LARGE.code:@beans.Dimension@LARGE.display, @beans.Dimension@SMALL.code:@beans.Dimension@SMALL.display}" tabindex="4"/>