dbutils提供的handler转换不能满足实际业务开发的需求。比如枚举转int，时间类型LocalDateTime，实体对象的属性名与字段未能相对应。
mysql表member结构字段： id、member_name、sex、createTime
public class Member {
private long id;
private String memberName;
private Sex sex;
private LocalDateTime createTime;
}
枚举Sex 时间LocalDateTime没有默认提供，需要转换。数据的转换需要实现ColumnHandler接口。此接口提供二个简单方法：1、类型是否匹配public boolean match(Class<?> propType)；
2、转换数据 public Object apply(ResultSet rs, int columnIndex)。
一、定义二个类型转换handler
public class LocalDateTimeHandler implements ColumnHandler {
@Override
public boolean match(Class<?> propType) {
return propType.equals(LocalDateTime.class);
}
@Override
public Object apply(ResultSet rs, int columnIndex) throws SQLException {
if (rs.getTimestamp(columnIndex) != null) {
return rs.getTimestamp(columnIndex).toLocalDateTime();
}
return null;
}
}
public class SexHandler implements ColumnHandler {
@Override
public boolean match(Class<?> propType) {
return propType.equals(Sex.class);
}
@Override
public Object apply(ResultSet rs, int columnIndex) throws SQLException {
for (Sex sex : Sex.values()){
if (sex.getIndex() == rs.getInt(columnIndex)){
return sex;
}
}
return null;
}
}
public enum Sex {
male(1,"男"),
female(0,"女")
;
private int index;
private String description;
Sex(int index, String description){
this.index = index;
this.description = description;
}
public int getIndex() {
return index;
}
public String getDescription() {
return description;
}
}
二、重构BeanProcessor
public class MyBeanProcessor extends BeanProcessor {
private static ServiceLoader<ColumnHandler> columnHandlers = ServiceLoader.load(ColumnHandler.class);
private static List<ColumnHandler> customList = new ArrayList<>();
static {
customList.add(new LocalDateTimeHandler());
customList.add(new SexHandler());
}
public MyBeanProcessor(Map<String, String> columnToPropertyMap){
super(columnToPropertyMap);
}
@Override
protected Object processColumn(ResultSet rs, int index, Class<?> propType)
throws SQLException {
Object retval = rs.getObject(index);
if ( !propType.isPrimitive() && retval == null ) {
return null;
}
for (ColumnHandler handler : columnHandlers) {
if (handler.match(propType)) {
retval = handler.apply(rs, index);
break;
}
}
for (ColumnHandler handler : customList){
if (handler.match(propType)){
retval = handler.apply(rs, index);
break;
}
}
return retval;
}
}
三、传自定义参数转换数据
@Test
public void customQuery() throws SQLException {
QueryRunner queryRunner = new QueryRunner();
String sql = "select * from member";
Map<String, String> map = new HashMap();
map.put("member_name","memberName");
MyBeanProcessor bean = new MyBeanProcessor(map);
RowProcessor convert = new BasicRowProcessor(bean);
BeanListHandler<Member> handler = new BeanListHandler(Member.class,convert);
List<Member> list = queryRunner.query(getConn(),sql, handler);
System.out.println(JSON.toJSONString(list));
}