利用反射机制模拟Hibernate的Session

Java代码  

package com.quan.hibernate.model;

import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;

/**
 * Session的模拟
 */
public class create {

    String url = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=hibernate";
    String user = "sa";
    String password = "123";

    String tableName = "_Student";
    Map<String,String> cfs = new HashMap<String, String>();

    String[] methodNames;

    public create() {
        cfs.put("_id", "id");
        cfs.put("_name","name");
        cfs.put("_age", "age");
        methodNames = new String[cfs.size()];
    }

    public void save(Student s) throws Exception {
        String sql = createSQL();
        Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
        Connection conn = DriverManager.getConnection(url, user, password);
        PreparedStatement ps = conn.prepareStatement(sql);

        for(int i = 0; i<methodNames.length;i++) {
              Method m = s.getClass().getMethod(methodNames[i]);
              Class r= m.getReturnType();
              if(r.getName() == "java.lang.String") {
                  String returnValue = (String)m.invoke(s);
                  ps.setString(i+1, returnValue);
              }
              if(r.getName() == "int") {
                  Integer returnValue = (Integer)m.invoke(s);
                  ps.setInt(i+1, returnValue);
              }
        }

        /*for(int i = 0; i<cfs.size(); i++) {
            ps.setXXX(s.getXXX);
        }*/

        ps.executeUpdate();
        ps.close();
        conn.close();
    }

    private String createSQL() {

        String str1 = "";
        String str2 = "";
        int index = 0;
        for(String s : cfs.keySet()) {
            String v = cfs.get(s);
            v= Character.toUpperCase(v.charAt(0)) + v.substring(1);
            methodNames[index] = "get" + v;
            str1 += s + ",";
        }
        str1 = str1.substring(0, str1.length()-1);

        for(int i = 0; i<cfs.size();i++) {
            str2 += "?,";
        }
        str2 = str2.substring(0, str2.length()-1);

        String sql = "insert into "+tableName+"("+str1+")"+"valses ("+str2+")";

        return sql;
    }
}