Java中Boolean与字符串或者数字1和0的转换实例

Java中Boolean与字符串或者数字1和0的转换实例

mysql有个字段是bit，只存储1和0，是二进制存储，那么在java的dao层如何映射成boolean呢

@Column(name="is_standard")

private boolean isStandard;

public void setIsStandard(boolean isStandard){

this.isStandard = isStandard;

}

public boNaSFYzNolean getIsStandard(){

return isStandard;

}

其实就是在底层dao做反射的时候，先判断字段(比如isStandard)的字段类型是否为boolean，如果是，则在查出数据库字段bit is_standard的时候，做转换

private List populateData(ResultSet resultSet, Class clazz) throws Exception {

List dataList = new ArrayList();

List fieldList = MappingAnnotationUtil.getAllFields(clazz);

ResultSetMetaData rsmd = resultSet.getMetaData();

int columnsCount = rsmd.getColumnCount();

List columnNameList = new ArrayList();

for(int i = 0; i < columnsCount; i++){

columnNameList.add(rsmd.getColumnLabel(i+1).toLowerCase());

}

while (resultSet.next()) {

T bean = clazz.newInstance();

for(Field f : fieldList) {

String columnName = MappingAnnotationUtil.getDBCloumnName(clazz, f).toLowerCase();

if(columnNameList.contains(columnName)) {

Object columnValueObj = null;

Class> filedCls = f.getType()http://;

if(filedCls == int.class || filedCls == Integer.class) {

columnValueObj = resultSet.getInt(columnName);

} else if(filedCls == String.class) {

columnValueObj = resultSet.getString(columnName);

} else if(filedCls == boolean.class || filedCls == Boolean.class) {

columnValueObj = resultSet.getBoolean(columnName);

} else if(filedCls == byte.class || filedCls == Byte.class) {

columnValueObj = resultSet.getByte(columnName);

} else if(filedCls == short.class || filedCls == Short.class) {

columnValueObj = resultSet.getShort(columnName);

} else if(filedCls == long.class || filedCls == Long.class) {

columnValueObj = resultSet.getLong(columnName);

} else if(filedCls == float.class || filedCls == Float.class) {

columnValueObj = resultSet.getFloat(columnName);

} else if(filedCls == double.class || filedCls == Double.class) {

columnValueObj = resultSet.getDouble(columnName);

} else if(filedCls == BigDecimal.class) {

columnValueObj = resultSet.getBigDecimal(columnName);

}

else {

columnValueObj = resultSet.getObject(columnName);

}

if (columnValueObj != null) {

Method setterMethod = MappingAnnotationUtil.getSetterMethod(clazz, f);

setterMethod.invoke(bean, new Object[] { columnValueObj });

}

}

}

dataList.add(bean);

}

return dataList;

}

注意这个

else if(filedCls == boolean.class || filedCls == Boolean.class) {

columnValueObj = resultSet.getBoolean(columnName);

}

resultSet.getBoolean(columnName) 就是转换的方法，具体实现为

for (int i = 0; i < trueStrings.length; ++i) {

if (trueStrings[i].equals(stringValue)) {

return type.cast(Boolean.TRUE);

}

}

for (int i = 0; i < falseStrings.length; ++i) {

if (falseStrings[i].equals(stringValue)) {

return type.cast(Boolean.FALSE);

}

}

核心原理就是根据字符串/数字做对比，如果是1,0就返回true/false，其它的直接返回false或抛出异常，字符串如果是[true, yes, y, on, 1]就返回true，如果是[false, no, n, off, 0]就返回false

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