修改以上代码,在构造函数中给定一个类的class,将查询结果储存到该类的对象中
时间: 2024-02-27 12:54:52 浏览: 90
好的,以下是修改后的代码:
```java
public class CamelCaseResultTransformer<T> implements ResultTransformer {
private static final long serialVersionUID = 1L;
private Class<T> resultClass;
public CamelCaseResultTransformer(Class<T> resultClass) {
this.resultClass = resultClass;
}
@SuppressWarnings("unchecked")
@Override
public Object transformTuple(Object[] tuple, String[] aliases) {
T result;
try {
result = resultClass.newInstance();
} catch (InstantiationException | IllegalAccessException e) {
throw new RuntimeException("Error creating result object", e);
}
for (int i = 0; i < tuple.length; i++) {
if (tuple[i] != null) {
String camelCaseName = toCamelCase(aliases[i]);
try {
Field field = resultClass.getDeclaredField(camelCaseName);
field.setAccessible(true);
field.set(result, tuple[i]);
} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {
throw new RuntimeException("Error setting field value: " + camelCaseName, e);
}
}
}
return result;
}
@SuppressWarnings("rawtypes")
@Override
public List transformList(List collection) {
return collection;
}
private String toCamelCase(String name) {
String[] parts = name.split("_");
StringBuilder camelCaseName = new StringBuilder();
for (String part : parts) {
if (camelCaseName.length() == 0) {
camelCaseName.append(part.toLowerCase());
} else {
camelCaseName.append(part.substring(0, 1).toUpperCase());
camelCaseName.append(part.substring(1).toLowerCase());
}
}
return camelCaseName.toString();
}
}
```
在上述代码中,我们修改了`CamelCaseResultTransformer`类的构造方法,添加了一个`Class<T>`类型的参数`resultClass`,表示我们要将查询结果转换为该类的对象。在`transformTuple()`方法中,我们通过`resultClass.newInstance()`方法创建一个新的`result`对象,并将查询结果转换为驼峰命名的变量名,然后通过反射设置该对象的属性值。最后,我们返回该`result`对象。
使用该自定义`ResultTransformer`的方式如下:
```java
Session session = sessionFactory.openSession();
Query query = session.createSQLQuery("SELECT id, first_name, last_name FROM person")
.setResultTransformer(new CamelCaseResultTransformer<>(Person.class));
List<Person> resultList = query.getResultList();
session.close();
```
在上述代码中,我们创建了一个SQL查询,查询`person`表中的`id`、`first_name`和`last_name`字段。我们通过`setResultTransformer()`方法将查询结果转换为驼峰命名的`Person`对象,并将结果存储在`resultList`中。注意,我们在查询结束后需要关闭`Session`对象。
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