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 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);
  }
  }

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。