java_jdbc_反射技术将查询结果封装为对象

package cn.itcast.Reflect;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import cn.itcast.JdbcUtils;

//反射获取数据库内容
public class ORMTest {

        public static void main(String[] args) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException, SQLException, InstantiationException {

                User2 user = (User2)getObject("select id as Id,username as Username,password as Password from t_user where ,User2.class);
                System.out.println(user.getUsername());
        }
        
        public static Object getObject(String sql,Class clazz) throws SQLException,
                        IllegalAccessException, IllegalArgumentException,
                        InvocationTargetException, InstantiationException {
                Connection conn = null;
                PreparedStatement ps = null;
                ResultSet rs = null;
                try {
                        conn = JdbcUtils.getConnection();
                        ps = conn.prepareStatement(sql);
                        rs = ps.executeQuery();

                        java.sql.ResultSetMetaData rsmd = rs.getMetaData();

                        int count = rsmd.getColumnCount();
                        String[] colNames = new String[count];

                        for (int i = 1; i <= count; i++) {
                                colNames[i - 1] = rsmd.getColumnLabel(i);

                        }

                        Object obj = null;
                        Method[] ms = clazz.getMethods();
                        if (rs.next()) {
                                obj = clazz.newInstance();
                                for (int i = 0; i < colNames.length; i++) {
                                        String colName = colNames[i];
                                        String methodName = "set" + colName;
                                        
                                        for (Method m : ms) {
                                                if (methodName.equals(m.getName())) {
                                                        m.invoke(obj, rs.getObject(colName));
                                                }
                                        }

                                }
                        }
                        return obj;
                } finally {
                        JdbcUtils.free(rs, ps, conn);
                }
        }
}