Java中Boolean与字符串或者数字1和0的转换实例

2019-11-26 11:53:09

字体：大中小

来源：转载

供稿：网友

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 boolean 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<T> populateData(ResultSet resultSet, Class<T> clazz) throws Exception { List<T> dataList = new ArrayList<T>(); List<Field> fieldList = MappingAnnotationUtil.getAllFields(clazz); ResultSetMetaData rsmd = resultSet.getMetaData(); int columnsCount = rsmd.getColumnCount(); List<String> columnNameList = new ArrayList<String>(); 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();      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);  }  }