Hibernate方法模拟

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package cn.itcast.hibernate;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class PoolUtils {

private static DataSource source = new ComboPooledDataSource();

//返回连接池

   public static DataSource getSource(){
       return source;
   }

}

package cn.itcast.hibernate;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;

public class Hibernate {

public static <T> void save(T t) throws Exception{

//获取class对象

Class clazz = t.getClass();

//获取类的不含包的名称

String className = clazz.getSimpleName();

//生成sql语句

StringBuffer sb = new StringBuffer("insert into "+className+" values(");

//获取类上的字段

Field[] fs = clazz.getDeclaredFields();

//获取字段的个数

int len = fs.length;

//根据字段的个数来确定问号的个数

          for(int i=0;i<len;i++){
              if(i!=len-1)
                  sb.append(" ?,");
              else
                  sb.append(" ?)");
          }

//把StringBuffer类型变为String类型

String sql = sb.toString();

//获取参数个数来生成相同长度的数组

Object[] params = new Object[len];

//把参数加入到数组中

for(int i=0;i<len;i++){

//使用暴力访问

fs[i].setAccessible(true);

//获取参数的值根据字段其中返回的值为Object类型

              params[i]=fs[i].get(t);
          }

         /* Method[] ms = clazz.getDeclaredMethods();
          int i=0;
          for(Method m:ms){
              if(m.getReturnType()==void.class)
                  continue;
              params[i++]=m.invoke(t, null);
              System.out.println(params[i-1]);
          }*/

        //获取QueryRunner
       QueryRunner runner = new QueryRunner(PoolUtils.getSource());

//执行语句

runner.update(sql, params);
}

//此方法是动态的生成数据库中的表结构（此类只有int和string类型)

public static void createTable(Class clazz) throws Exception{

//拼接sql语句

       StringBuffer sb = new StringBuffer("create table "+clazz.getSimpleName() +"( ");
       Field[] fs = clazz.getDeclaredFields();

       for(int i=0;i<fs.length;i++){
           String fn = fs[i].getName();
           String type =fs[i].getType().getSimpleName();
           if(type.equals("int")||("Integer").equals(type)){
               if(i==0)
               sb.append(fn +" int primary key , ");
               else if(i==fs.length-1)
               sb.append(fn +" int );");
               else
               sb.append(fn + " int , ");
           }
           if(type.equals("String"))
               if(i==fs.length-1)
               sb.append(fn +" varchar(225) );");
               else
               sb.append(fn +" varchar(225) , ");
       }
       System.out.println(sb);

       QueryRunner runner = new QueryRunner(PoolUtils.getSource());

       runner.update(sb.toString());
   }
}

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