public interface Converter {
/**
* 进行转换操作
* @param val 原对象
* @return 转换后对象
*/
Object convert(Object val);
}
public abstract class AbstractConverter implements Converter{
private boolean useDefaultVal = false;
private Object defaultVal = null;
public boolean isUseDefaultVal() {
return useDefaultVal;
}
public void setUseDefaultVal(boolean useDefaultVal) {
this.useDefaultVal = useDefaultVal;
}
public Object getDefaultVal() {
return defaultVal;
}
public void setDefaultVal(Object defaultVal) {
this.defaultVal = defaultVal;
}
protected abstract Class<?> getTargetClass();
protected abstract Object convert2Type(Object val);
protected abstract String convert2String(Object val);
@Override
public Object convert(Object val) {
if (null == val)
return handleNullVal(val);
if (getTargetClass().equals(val.getClass()))
return getTargetClass().cast(val);
if (getTargetClass().equals(String.class))
return getTargetClass().cast(convert2String(val));
return getTargetClass().cast(convert2Type(val));
}
protected Object handleNullVal(Object val){
if (isUseDefaultVal())
return getDefaultVal();
return val;
}
protected <T> Class<T> primitiveToWrapper(final Class<T> type) {
if (type == null || !type.isPrimitive())
return type;
if (type == Integer.TYPE)
return (Class<T>) Integer.class;
if (type == Double.TYPE)
return (Class<T>) Double.class;
if (type == Long.TYPE)
return (Class<T>) Long.class;
if (type == Boolean.TYPE)
return (Class<T>) Boolean.class;
if (type == Float.TYPE)
return (Class<T>) Float.class;
if (type == Short.TYPE)
return (Class<T>) Short.class;
if (type == Byte.TYPE)
return (Class<T>) Byte.class;
if (type == Character.TYPE)
return (Class<T>) Character.class;
return type;
}
}public abstract class NumberConverter extends AbstractConverter {
@Override
protected Number convert2Type(Object val) {
final Class<?> sourceType = val.getClass();
Number targetVal;
if (val instanceof Number)
targetVal = (Number) val;
else if (val instanceof Boolean)
targetVal = ((Boolean)val).booleanValue() ? 1 : 0;
else if (val instanceof Date)
targetVal = ((Date)val).getTime();
else if (val instanceof Calendar)
targetVal = ((Calendar)val).getTime().getTime();
else
targetVal = toNumber(sourceType, (Class<? extends Number>) getTargetClass(), val.toString().trim());
return toNumber(sourceType, (Class<? extends Number>) getTargetClass(), targetVal);
}
@Override
protected String convert2String(Object val) {
return String.valueOf(val);
}
private Number toNumber(final Class<?> sourceType, final Class<? extends Number> targetType, final Number value){
if (targetType.equals(sourceType))
return targetType.cast(value);
if (targetType.equals(Byte.class)){
final long longValue = value.longValue();
if (longValue > Byte.MAX_VALUE)
throw new IllegalArgumentException("the value is bigger than Byte.MAX_VALUE");
if (longValue < Byte.MIN_VALUE)
throw new IllegalArgumentException("the value is smaller than Byte.MIN_VALUE");
return value.byteValue();
}
if (targetType.equals(Short.class)){
final long longValue = value.longValue();
if (longValue > Short.MAX_VALUE)
throw new IllegalArgumentException("the value is bigger than Short.MAX_VALUE");
if (longValue < Short.MIN_VALUE)
throw new IllegalArgumentException("the value is smaller than Short.MIN_VALUE");
return value.shortValue();
}
if (targetType.equals(Integer.class)){
final long longValue = value.longValue();
if (longValue > Integer.MAX_VALUE)
throw new IllegalArgumentException("the value is bigger than Integer.MAX_VALUE");
if (longValue < Integer.MIN_VALUE)
throw new IllegalArgumentException("the value is smaller than Integer.MIN_VALUE");
return value.intValue();
}
if (targetType.equals(Long.class)) {
return targetType.cast(new Long(value.longValue()));
}
if (targetType.equals(Float.class)){
final double doubleValue = value.doubleValue();
if (doubleValue > Float.MAX_VALUE)
throw new IllegalArgumentException("the value is bigger than Float.MAX_VALUE");
if (doubleValue < Float.MIN_VALUE)
throw new IllegalArgumentException("the value is smaller than Float.MIN_VALUE");
return value.floatValue();
}
if (targetType.equals(Double.class)) {
return targetType.cast(new Double(value.doubleValue()));
}
// BigDecimal
if (targetType.equals(BigDecimal.class)) {
if (value instanceof Float || value instanceof Double) {
return targetType.cast(new BigDecimal(value.toString()));
} else if (value instanceof BigInteger) {
return targetType.cast(new BigDecimal((BigInteger)value));
} else if (value instanceof BigDecimal) {
return targetType.cast(new BigDecimal(value.toString()));
} else {
return targetType.cast(BigDecimal.valueOf(value.longValue()));
}
}
if (targetType.equals(BigInteger.class)) {
if (value instanceof BigDecimal) {
return targetType.cast(((BigDecimal)value).toBigInteger());
} else {
return targetType.cast(BigInteger.valueOf(value.longValue()));
}
}
throw new IllegalArgumentException("can‘t convert from " + sourceType.getName() +" to " + targetType.getName()+" and the value is "+value);
}
private Number toNumber(final Class<?> sourceType, final Class<? extends Number> targetType, final String value){
// Byte
if (targetType.equals(Byte.class)) {
return new Byte(value);
}
// Short
if (targetType.equals(Short.class)) {
return new Short(value);
}
// Integer
if (targetType.equals(Integer.class)) {
return new Integer(value);
}
// Long
if (targetType.equals(Long.class)) {
return new Long(value);
}
// Float
if (targetType.equals(Float.class)) {
return new Float(value);
}
// Double
if (targetType.equals(Double.class)) {
return new Double(value);
}
// BigDecimal
if (targetType.equals(BigDecimal.class)) {
return new BigDecimal(value);
}
// BigInteger
if (targetType.equals(BigInteger.class)) {
return new BigInteger(value);
}
throw new IllegalArgumentException("can‘t convert from " + sourceType.getName() +" to " + targetType.getName()+" and the value is "+value);
}
}
public class IntegerConverter extends NumberConverter {
@Override
protected Class<?> getTargetClass() {
return Integer.class;
}
}public class FloatConverter extends NumberConverter {
@Override
protected Class<?> getTargetClass() {
return Float.class;
}
}原文地址：http://blog.51cto.com/881206524/2104891
