在jdbc封装（基础的CRUD）的时候（查询一条数据，查询多条数据，更新。。。。）经常会用到一个BeanUtil来设置属性值，当对象中存在Date类型的时候，会报错：如下：
2017-11-03 13:47:01 13 ERROR [main] org.apache.commons.beanutils.PropertyUtils - Method invocation failed.
java.lang.IllegalArgumentException: argument type mismatch
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.commons.beanutils.PropertyUtilsBean.invokeMethod(PropertyUtilsBean.java:1773)
at org.apache.commons.beanutils.PropertyUtilsBean.setSimpleProperty(PropertyUtilsBean.java:1759)
at org.apache.commons.beanutils.PropertyUtilsBean.setNestedProperty(PropertyUtilsBean.java:1648)
at org.apache.commons.beanutils.PropertyUtilsBean.setProperty(PropertyUtilsBean.java:1677)
at org.apache.commons.beanutils.BeanUtilsBean.setProperty(BeanUtilsBean.java:1022)
at org.apache.commons.beanutils.BeanUtils.setProperty(BeanUtils.java:313)
at com.voice.Test.Dao2.transforMapListToBeanList(Dao2.java:111)
at com.voice.Test.Dao2.getForList(Unknown Source)
at com.voice.Test.TestAllTest.test(TestAllTest.java:19)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
好吧，先附上代码：
import java.lang.reflect.InvocationTargetException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.commons.beanutils.BeanUtils;
/**
* java类的属性
* 1）在javaEE中，java的类的属性通过getter,setter来定义：get（或者set）方法，去除get（或者set）后，后字母小写即为java类的属性；以前那个那个属性叫做成员变量
* 操作java类的属性有一个工具包：beanutils a.setProperty b.getProperty
*
* dao:data access object
* why:实现功能模块化，有利于代码维护和升级
* what:访问信息的类，包含了CRUD(creat read update delete)；DAO可以被子类继承或者直接使用
* how：适用jdbc编写 DAO 可能会包含的方法
*insert update deleted都可以通过以下
*void update(Strig sql ,Object...args)
*
*查询一条纪录：
*<T> T get(Class<T>clazz,String sql,Object...args)
*
*查询多条数据
*<T> List<T> getForList(Class<t>clazz,String sql,Object...args)
*
*返回某个字段都值或者是统计的值（一共有多少条纪录）
*<E> E getForValue(String sql,Object...args)
*/
public class Dao2 {
public void update(String sql,Object...args) throws Exception{
Connection con = null;
PreparedStatement p = null;
ResultSet r = null;
try {
con = JdbcTools.getConnection();
p = con.prepareStatement(sql);
for(int i=0;i<args.length;i++){
p.setObject(i+1, args[i]);
}
p.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
}finally{
JdbcTools.releaseDB(r, p, con);
}
}
//查询一条纪录：
public <T> T get(Class<T>clazz,String sql,Object...args) throws Exception{
List<T> result = getForList(clazz, sql, args);
if(result.size()>0){
return result.get(0);
}
return null;
}
//查询多条数据
public <T> List<T> getForList(Class<T>clazz,String sql,Object...args) throws Exception{
List<T> list = new ArrayList<>();
Connection con = null;
PreparedStatement p = null;
ResultSet r = null;
try {
//1. 得到结果集
con = JdbcTools.getConnection();
p = con.prepareStatement(sql);
for(int i=0;i<args.length;i++){
p.setObject(i+1, args[i]);
}
r = p.executeQuery();
//1. 处理结果集得到 map对应的list，其中一个map对象就是一条纪录，key是字段名
List<Map<String, Object>> values = handelResultSetToMapList(r);
//1. 把map的list转为clazz对应的list，map的key是clazz的propertyName，而map的value是clazz对应的对象的value
list = transforMapListToBeanList(clazz, values);
} catch (Exception e) {
e.printStackTrace();
}finally{
JdbcTools.releaseDB(r, p, con);
}
return list;
}
private <T> List<T> transforMapListToBeanList(Class<T> clazz, List<Map<String, Object>> values)
throws InstantiationException, IllegalAccessException, InvocationTargetException {
List<T> result = new ArrayList<>();
T bean = null;
if(values.size()>0){
for(Map<String,Object> entry:values){
bean = clazz.newInstance();
for(Map.Entry<String, Object> entry1:entry.entrySet()){
String propertyName = entry1.getKey();
Object propertyValue = entry1.getValue();
if("addTime".equals(propertyName)){
SimpleDateFormat format = new SimpleDateFormat("yyyy-M-dd HH:mm:ss");
try {
propertyValue =format.parse(propertyValue+"");
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
BeanUtils.setProperty(bean, propertyName, propertyValue);
}
//把object对象放入
result.add(bean);
}
}
return result;
}
/**
*处理结果集，得到Map的一个List其中，一个map对象对应一条纪录
*/
private List<Map<String, Object>> handelResultSetToMapList(ResultSet r) throws Exception, SQLException {
List<Map<String,Object>> values = new ArrayList<>();
List<String> lable = getCloumLable(r);
//7.处理resultset ,使用while
while(r.next()){
Map<String,Object> map = new HashMap<String,Object>();
//11.填充的map对象放入5准备的List中
for(String name:lable){
Object obj = r.getObject(name);
map.put(name, obj);
}
values.add(map);
}
return values;
}
//返回某个字段都值或者是统计的值（一共有多少条纪录）
public <E> E getForValue(String sql,Object...args) throws Exception{
//得到结果集，该结果集只有一行且只有一列
Connection con = null;
PreparedStatement p = null;
ResultSet r = null;
try {
con = JdbcTools.getConnection();
p = con.prepareStatement(sql);
for(int i=0;i<args.length;i++){
p.setObject(i+1, args[i]);
}
r = p.executeQuery();
//取得结果集
if(r.next()){
return (E) r.getObject(1);
}
} catch (Exception e) {
e.printStackTrace();
}finally{
JdbcTools.releaseDB(r, p, con);
}
return null;
}
/**
*获取结果集的ColumLable 对应的list（得到数据库字段名）
*/
public List<String> getCloumLable(ResultSet rs) throws Exception{
List<String> list = new ArrayList<>();
ResultSetMetaData a = rs.getMetaData();
for(int i=0;i<a.getColumnCount();i++){
String name = a.getColumnLabel(i+1);
list.add(name);
}
return list;
}
}
很奇怪？难道都不行么？所有的转换都不行，还是只是时间不行？（看到代码标红处，好像不显示颜色，就是 transforMapListToBeanList方法那里！有个日期转换的！）我Debug的时候发现Date类型的属性时，类型是TimeStamp.这个到现在还不是为啥，普通的Date类型，Debug的时候类型是Date，，百度了一下，说就是有Date的时候会出现这个问题。好吧，直接处理掉就可以了，（看到代码标红处）。