BaseDaoImpl

//------------------------------------------------------import java.util.List;public interface BaseDao {void save(Entity obj) throws Exception ; void update (Entity obj) throws Exception; void delete(int id) throws Exception; List findAll() throws Exception;Entity findById( int id) throws Exception;}//----以上是BaseDao//-----------------------------------------------------package com.base;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.lang.reflect.ParameterizedType;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.util.ArrayList;import java.util.List;import com.util.DBUtils;/** * jdbc连接 ： 1创建连接对象  2拼sql 3 preparedstatemenet * @author _oiYc * @param <Entity> */public class BaseDaoImpl<Entity> implements BaseDao<Entity>{//public protected Class clazz ;public BaseDaoImpl(){//System.out.println(this.getClass());ParameterizedType pt = (ParameterizedType) this.getClass().getGenericSuperclass();//带有真实类型参数的对象clazz = (Class)pt.getActualTypeArguments()[0];System.out.println(clazz);}/*** 保存方法*/public void save(Entity obj) throws Exception {//obj.getSimpleName();Connection conn = DBUtils.createConn();String sql = "insert into " + clazz.getSimpleName() + " values(null ";// 可以获取本类所声明的变量Field[] fs = clazz.getDeclaredFields();//System.out.println(fs.length);for (int i = 1; i < fs.length; i++) {sql += ",? " ;}sql = sql + ")";System.out.println(sql);//进行预编译PreparedStatement ps = DBUtils.getPs(conn, sql);//ps.setString(1, user.getName());for (int i = 1; i < fs.length; i++) {//拼接方法的名称String MethodName = "get" +Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1) ;Method m = clazz.getMethod(MethodName);ps.setObject(i, m.invoke(obj));}ps.executeUpdate();DBUtils.close(ps);DBUtils.close(conn);}/*** 更新方法*/public void update(Entity obj) throws Exception {Connection conn = DBUtils.createConn();// update user set name = ? , age = ? where id = ?String sql = " update " + clazz.getSimpleName() + " set  ";Field[] fs = clazz.getDeclaredFields();for (int i = 1; i < fs.length; i++) {sql += fs[i].getName() + "=?,";}sql = sql.substring(0, sql.length()-1) + " where id = ? ";PreparedStatement ps = DBUtils.getPs(conn, sql);for (int i = 1; i < fs.length; i++) {String methodName = "get" + Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1);Method m  = clazz.getMethod(methodName);ps.setObject(i, m.invoke(obj));// user.getName();}Method m2 = clazz.getMethod("getId");ps.setInt(fs.length,(Integer)m2.invoke(obj));ps.executeUpdate();DBUtils.close(ps);DBUtils.close(conn);}/*** 根据一个id 查找对象*/public Entity findById(int id) throws Exception {Connection conn = DBUtils.createConn();String sql = " select * from  " + clazz.getSimpleName() +  " where id = " + id ;PreparedStatement ps = DBUtils.getPs(conn, sql);ResultSet rs = ps.executeQuery();Entity entity =  (Entity) clazz.newInstance();if(rs.next()){Field[]  fs = clazz.getDeclaredFields();for (int i = 0; i < fs.length; i++) {String methodName = "set" + Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1);Method m = clazz.getDeclaredMethod(methodName, fs[i].getType());m.invoke(entity, rs.getObject(fs[i].getName()));}}DBUtils.close(rs);DBUtils.close(ps);DBUtils.close(conn);return entity;}/*** 查询所有*/public List<Entity> findAll() throws Exception {Connection conn = DBUtils.createConn();String sql =" select * from " + clazz.getSimpleName();PreparedStatement ps = DBUtils.getPs(conn, sql);List<Entity> list = new ArrayList<Entity>();ResultSet rs =  ps.executeQuery();while(rs.next()){Entity entity = (Entity)clazz.newInstance();Field[] fs = clazz.getDeclaredFields();for (int i = 0; i < fs.length; i++) {String methodName = "set"+ Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1);Method m = clazz.getMethod(methodName, fs[i].getType());m.invoke(entity, rs.getObject(fs[i].getName()));}list.add(entity);}DBUtils.close(rs);DBUtils.close(ps);DBUtils.close(conn);return list;}/*** 删除方法*/public void delete(int id) throws Exception {Connection conn = DBUtils.createConn();String sql = " delete from " + clazz.getSimpleName() + " where id =" +id;PreparedStatement ps = DBUtils.getPs(conn, sql);ps.executeUpdate(sql);DBUtils.close(ps);DBUtils.close(conn);}/*** 条件查询的反射封装方法* @param sql* @param params* @return*/public  List<Entity> queryListForParams(String sql,Object[] params ) throws Exception{Connection conn  = DBUtils.createConn();PreparedStatement ps = null;ResultSet rs = null;List list = new ArrayList();try {// 建立statement对象(封装了sql)ps = conn.prepareStatement(sql); // select * from org where id = ? and name = ?  [1 , z3]if(params!=null){for(int i=0;i<params.length;i++){ps.setObject(i+1, params[i]);}}Field[] fs = clazz.getDeclaredFields();rs = ps.executeQuery();while(rs.next()){Object obj = clazz.getConstructor().newInstance();for(int i = 0 ; i <fs.length;i++ ){String methodName = "set" +fs[i].getName().substring(0, 1).toUpperCase()+fs[i].getName().substring(1);Method m = clazz.getMethod(methodName, fs[i].getType());Object value = rs.getObject(fs[i].getName());  m.invoke(obj, value); }list.add(obj);} } catch (Exception e) {e.printStackTrace();}finally{DBUtils.close(rs);DBUtils.close(ps);DBUtils.close(conn);}return list;} }