NoSuchMethodError of BeanUtils.copyProperty(due to wrong access level)
为了节省开发时间，今天打算做一个数据集合类，可以直接将java中的ResultSet，或者其他Collection派生类的内容copy到该集合中，然后加入自定义的一些方法，比如支持直接导出Excel、CSV、KDF、Image、HTML等。这里借助Apache Commons BeanUtils的和反射(Reflection)，将数据库中的一行记录保存为一个对象，然后插入数据集中，结果老是报错如下：
USING CONVERTER org.apache.commons.beanutils.converters.IntegerConverter@1befab0
java.lang.reflect.InvocationTargetException: Cannot set id
at org.apache.commons.beanutils.BeanUtilsBean.copyProperty(BeanUtilsBean.java:449)
at org.apache.commons.beanutils.BeanUtils.copyProperty(BeanUtils.java:129)… …
Caused by: java.lang.NoSuchMethodException: Property ‘id’ has no setter method
at org.apache.commons.beanutils.PropertyUtilsBean.setSimpleProperty(PropertyUtilsBean.java:1746)
at org.apache.commons.beanutils.BeanUtilsBean.copyProperty(BeanUtilsBean.java:447)
代码段如下：
private void dumpResultSet(ResultSet rs, Class clazz) throws Exception {
ResultSetMetaData metaData = (ResultSetMetaData) rs.getMetaData();
int colCnt = metaData.getColumnCount();
Field[] fields = clazz.getDeclaredFields();
while (rs.next()) {
Object newInstance = clazz.newInstance();
for (int i = 1; i <= colCnt; i++) {
try {
Object value = rs.getObject(i);
for (int j = 0; j < fields.length; j++) {
Field f = fields[j];
if (f.getName().equalsIgnoreCase(
metaData.getColumnName(i).replaceAll("_", ""))) {
log.info("f.getName:" + f.getName());
BeanUtils.copyProperty(newInstance, f.getName(),
value);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
list.add(newInstance);
}
}
The root cause: public is required for class UserInfo, or else you’ll get the ‘NoSuchMethodError‘ exception, DO NOT ignore the access level
public class UserInfo {
private int id;
private String user;
private String password;
public UserInfo() {
}
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
Eclipse一直提示：NoSuchMethodError，可是UserInfo里面明明有对应的setter方法，最后，才鬼使神差的发现，只要将UserInfo整个类声明为public就可以了。我一直都把注意力放到是否把setter和getter设置为public，却忽略了Bean的访问级别，希望碰到类似问题的朋友可以注意一下。
[ad]