我在mysql （版本5.5）中有一个名为refund_rule的表。这是它的定义：
CREATE TABLE `refund_rule` (
`ID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`PERCENTAGE` char(0) DEFAULT NULL COMMENT 'BOOLEAN shortcut.NULL<=>false,EMPTY<=>true',
`DEDUCTION_AMOUNT` int(10) unsigned DEFAULT NULL,
PRIMARY KEY (`ID`)
);
Hibernate （版本3.2）中的相应类名为RefundRule。 HBM文件如下所示：
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="hibernatesample.dao.RefundRule" table="refund_rule" catalog="back_end_proc">
<id name="id" type="java.lang.Integer">
<column name="ID" />
<generator class="identity" />
</id>
<property name="percentage" type="string">
<column name="PERCENTAGE" length="0">
<comment>BOOLEAN shortcut.NULL<=>false,EMPTY<=>true</comment>
</column>
</property>
<property name="deductionAmount" type="java.lang.Integer">
<column name="DEDUCTION_AMOUNT" />
</property>
</class>
</hibernate-mapping>
NetBeans （版本7.0）中向导生成的类是：
public class RefundRule implements java.io.Serializable {
private Integer id;
private String percentage;
private Integer deductionAmount;
public CancellationRule() {
}
public CancellationRule(String percentage, Integer deductionAmount) {
this.percentage = percentage;
this.deductionAmount = deductionAmount;
}
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
public String getPercentage() {
return this.percentage;
}
public void setPercentage(String percentage) {
this.percentage = percentage;
}
public Integer getDeductionAmount() {
return this.deductionAmount;
}
public void setDeductionAmount(Integer deductionAmount) {
this.deductionAmount = deductionAmount;
}
}
我在其中添加了另外两种方法setPercentage(boolean)＆amp; isPercentage()，并更改了方法setPercentage(String)，以便我可以在我的Java （版本1.6）程序中将String对象用作boolean。
public class RefundRule implements java.io.Serializable {
.
.
.
public String getPercentage() {
return this.percentage;
}
public void setPercentage(String percentage) {
this.percentage = percentage==null?null:"";
}
.
.
.
public void setPercentage(boolean percentage){
setPercentage(percentage?"":null);
}
public boolean isPercentage(){
return percentage!=null;
}
}
我的问题是：
有什么方法可以只保留两种方法：setPercentage(boolean)和isPercentage()，并将boolean percentage变量映射到mysql中的PERCENTAGE CHAR(0)变量。
=============================================== ====================
在 2013-11-23 上添加编辑
根据@GreyBeardedGeek的回答，我在代码中进行了以下更改：
（简要说明）
type - 属性（与上述变更相关的代码）
CharToBoolUserType类：
import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import org.hibernate.HibernateException;
import org.hibernate.usertype.UserType;
public class CharToBoolUserType implements UserType {
private static final int[] SQL_TYPES = {Types.CHAR};
@Override
public Object assemble(Serializable serializable, Object object) throws HibernateException {
return serializable;
}
@Override
public Object deepCopy(Object object) throws HibernateException {
return object;
}
@Override
public Serializable disassemble(Object value) throws HibernateException {
return (Serializable) value;
}
@Override
public boolean equals(Object x, Object y) throws HibernateException {
if (x == y) {
return true;
} else if (x == null || y == null) {
return false;
} else {
return x.equals(y);
}
}
@Override
public boolean isMutable() {
return false;
}
@Override
public Object nullSafeGet(ResultSet resultSet, String[] names, Object owner) throws HibernateException, SQLException {
return resultSet.getObject(names[0]) != null;
}
@Override
public void nullSafeSet(PreparedStatement preparedStatement, Object value, int index) throws HibernateException, SQLException {
preparedStatement.setObject(index, ((Boolean) value).booleanValue() ? "" : null);
}
@Override
public Object replace(Object original, Object target, Object owner) throws HibernateException {
return original;
}
@Override
public Class returnedClass() {
return boolean.class;
}
@Override
public int[] sqlTypes() {
return SQL_TYPES;
}
@Override
public int hashCode(Object object) throws HibernateException {
if (object == null) {
return 0;
}
// is `object` a String ? Or boolean?
return 1;
}
}
文件RefundRule.hbm.xml：
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="hibernatesample.dao.RefundRule" table="refund_rule" catalog="back_end_proc">
<id name="id" type="java.lang.Integer">
<column name="ID" />
<generator class="identity" />
</id>
<property name="percentage" type="hibernatesample.dao.CharToBoolUserType">
<column name="PERCENTAGE" length="0">
<comment>BOOLEAN shortcut.NULL<=>false,EMPTY<=>true</comment>
</column>
</property>
<property name="deductionAmount" type="java.lang.Integer">
<column name="DEDUCTION_AMOUNT" />
</property>
</class>
</hibernate-mapping>
由于我希望class CharToBoolUserType的代码在所有意义上都是完整的，我有以下问题：
1. object，hashCode(Object object)或Boolean中String的课程是什么？谁叫这种方法？
2. public Object replace(Object original, Object target, Object owner)方法应该做什么？将original替换为target并将其设置/放入owner。在这种情况下：original类型为String，target类型为Boolean，owner类型为RefundRule？
欢迎任何改进此代码的建议。
=============================================== ==
仅供参考，RefundRule类现在就像这样：
public class RefundRule implements java.io.Serializable {
private Integer id;
private boolean percentage;
private Integer deductionAmount;
public RefundRule() {
}
public RefundRule(boolean percentage, Integer deductionAmount) {
this.percentage = percentage;
this.deductionAmount = deductionAmount;
}
public Integer getId() {
return this.id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getDeductionAmount() {
return this.deductionAmount;
}
public void setDeductionAmount(Integer deductionAmount) {
this.deductionAmount = deductionAmount;
}
public void setPercentage(boolean percentage){
this.percentage=percentage;
}
public boolean isPercentage(){
return percentage;
}
}
答案 0 :(得分：1)
我相信您正在寻找Hibernate的UserType，它允许您提供自定义类型映射。
例如，请参阅http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/types.html#types-custom