Java中Boolean与字符串或者数字1和0的转换实例

时间:2022-09-04 22:08:12

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

?
1
2
3
4
5
6
7
8
9
10
@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

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
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

?
1
2
3
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

?
1
2
3
4
5
6
7
8
9
10
11
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);
 }
 }

Java中Boolean与字符串或者数字1和0的转换实例

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

以上这篇Java中Boolean与字符串或者数字1和0的转换实例就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持服务器之家。