java JDBC 万能DAO的实现的补充 实现了增删查改

package com.lp.DAO;

import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.lp.bean.city;
import com.lp.bean.goods;
import com.sun.org.apache.bcel.internal.generic.GETSTATIC;

/**
 * 2015.7.20 利用java反射机制实现万能DAO 即使bean层的实体类字段改变 也能实现增删查改
 * 
 * @author  liupeng
 */
public class DaoPro {

	// 由数据库名称得到数据库中的所有列
	public List<String> getColumns(String tableName) {
		Connection connection = DbHelper.getCon();
		Statement statement = DbHelper.getStatement();
		ResultSet resultSet = null;
		List<String> list = new ArrayList<String>();
		try {
			String sql = "select * from " + tableName + " where 1=2";
			resultSet = DbHelper.getStatement().executeQuery(sql);
			ResultSetMetaData data = resultSet.getMetaData();
			int columnsCount = data.getColumnCount();
			for (int i = 1; i <= columnsCount; i++) {
				String s = data.getColumnName(i);
				list.add(s);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DbHelper.cloRes(connection, statement, resultSet);
		}
		return list;
	}

	// 得到数据库中的所有数据
	public List getList(Class cl) {

		int i = 0;
		List objs = new ArrayList();
		Connection connection = DbHelper.getCon();
		Statement statement = DbHelper.getStatement();
		ResultSet resultSet = null;
		Field[] fields = cl.getDeclaredFields();
		List<String> columnsName = getColumns(cl.getSimpleName());
		String sql = "select * from " + cl.getSimpleName();
		try {
			System.out.println(sql);
			resultSet = statement.executeQuery(sql);
			System.out.println(i++);

			while (resultSet.next()) {
				System.out.println(i++);
				Object obj = cl.newInstance();
				for (String str : columnsName) {

					for (Field ff : fields) {

						if (str.equals(ff.getName())) {

							ff.setAccessible(true);
							ff.set(obj, resultSet.getObject(ff.getName()));

							break;
						}
					}

				}
				objs.add(obj);
			}

		} catch (SQLException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (InstantiationException e) {
			e.printStackTrace();
		}
		return objs;
	}

	// 添加数据返回主键的方法
	public int addData(Object object) {
		int id = 0;
		Connection connection = DbHelper.getCon();
		ResultSet resultSet = null;
		PreparedStatement preparedStatement = null;
		String tableName = object.getClass().getSimpleName();
		Field[] fields = object.getClass().getDeclaredFields();
		List<String> allColumns = getColumns(tableName);
		StringBuffer buffer = new StringBuffer();
		StringBuffer buffer1 = new StringBuffer();
		buffer.append("insert into ");
		buffer.append(tableName);
		buffer.append(" (");
		for (int i = 1; i < allColumns.size(); i++) {
			buffer.append(allColumns.get(i));
			buffer1.append("?");
			if (i != allColumns.size() - 1) {
				buffer.append(",");
				buffer1.append(",");
			}

		}
		buffer.append(") values (");
		buffer.append(buffer1);
		buffer.append(")");
		// System.out.println(buffer.toString());
		try {
			preparedStatement = connection.prepareStatement(buffer.toString());
			for (int i = 1; i < allColumns.size(); i++) {

				for (int j = 0; j < fields.length; j++) {

					if ((fields[j].getName()).equals(allColumns.get(i))) {

						fields[j].setAccessible(true);
						if (fields[j].get(object) == null) {
							preparedStatement.setObject(i, "此字段无填充");
						} else {
							preparedStatement.setObject(i,
									fields[j].get(object));
						}

						break;
					}

				}

			}
			int a = preparedStatement.executeUpdate();

			if (a > 0) {
				resultSet = preparedStatement.getGeneratedKeys();
				if (resultSet.next()) {
					id = resultSet.getInt(1);
				}

			}
		} catch (SQLException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} finally {

			DbHelper.cloRes(connection, preparedStatement, resultSet);
		}
		return id;

	}

	// 根据实体类实现一个或者多个条件查询
	public List getByBean(Object object) {
		List some = new ArrayList();
		Connection connection = DbHelper.getCon();
		PreparedStatement preparedStatement = null;
		ResultSet resultSet = null;
		try {
			// 得到实体类不为空的属性和属性值
			List<String> listVal = new ArrayList<String>();
			List<String> listField = new ArrayList<String>();
			Field[] fields = object.getClass().getDeclaredFields();
			for (int i = 0; i < fields.length; i++) {
				fields[i].setAccessible(true);
				// 把id字段除去，知道id就不用查了
				if (fields[i].get(object) != null
						&& !(fields[i].get(object) instanceof Integer)) {
					listVal.add((String) fields[i].get(object));
					listField.add(fields[i].getName());
				}
			}
			// 拼接sql语句
			StringBuffer buffer = new StringBuffer();
			buffer.append("select ");
			buffer.append("*");
			buffer.append(" from ");
			buffer.append(object.getClass().getSimpleName());
			buffer.append(" where ");
			for (int i = 0; i < listField.size(); i++) {
				buffer.append(listField.get(i));
				buffer.append("=");
				buffer.append("‘" + listVal.get(i) + "‘");
				if (i != listField.size() - 1) {
					buffer.append(" and ");
				}

			}
			System.out.println(buffer.toString());
			// 执行查询
			preparedStatement = connection.prepareStatement(buffer.toString());
			resultSet = preparedStatement.executeQuery();

			int count = resultSet.getMetaData().getColumnCount();

			while (resultSet.next()) {
				Object ob = object.getClass().newInstance();
				//获取不含id的列
				List<String> list = getColumns(object.getClass()
						.getSimpleName());
				list.add("id");
				Field[] fields2 = object.getClass().getDeclaredFields();
				for (int j = 0; j < fields2.length; j++) {
					fields2[j].setAccessible(true);
					for (int i = 1; i <= list.size()-1; i++) {
						if (list.get(i).equals(fields2[j].getName())) {
							fields2[j].set(ob, resultSet.getObject(list.get(i)));
						}
					}
					

				}
				some.add(ob);

			}

		} catch (SQLException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (InstantiationException e) {
			e.printStackTrace();
		} finally {

			DbHelper.cloRes(connection, preparedStatement, resultSet);
		}
		return some;
	}

	// 更新数据，由实体类封装的id，得到主键，实现更新
	public boolean updateBean(Object object) {
		int id = 0;
		int a = 0;
		Connection connection = DbHelper.getCon();
		Statement statement = null;
		ResultSet resultSet = null;
		Field[] fields = object.getClass().getDeclaredFields();
		// 得到id的值，确定要更新那一条数据
		try {
			for (int i = 0; i < fields.length; i++) {
				fields[i].setAccessible(true);
				if (fields[i].getName().equals("id")) {
					if ((Integer) fields[i].get(object) != 0) {
						id = (Integer) fields[i].get(object);
					} else {
						return false;
					}

				}
			}
			// 拼接 sql 语句
			StringBuffer buffer = new StringBuffer();
			buffer.append("update ");
			buffer.append(object.getClass().getSimpleName());
			buffer.append(" set ");
			List<String> list = getColumns(object.getClass().getSimpleName());
			list.remove("id");
			for (int i = 0; i < list.size(); i++) {
				for (int j = 0; j < fields.length; j++) {
					if (fields[j].getName().equals(list.get(i))) {
						if (fields[j].get(object) != null) {
							buffer.append(list.get(i));
							buffer.append("=");
							buffer.append("‘" + fields[j].get(object) + "‘,");

						}

					}
				}

			}
			buffer.delete(buffer.length() - 1, buffer.length());

			buffer.append(" where id=");
			buffer.append(id);
			System.out.println(buffer.toString());
			statement = connection.createStatement();
			a = statement.executeUpdate(buffer.toString());
			System.out.println(a);

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			DbHelper.cloRes(connection, statement, resultSet);
		}

		if (a > 0) {
			return true;
		}
		return false;

	}

	public static void main(String[] args) {
		goods c = new goods();
		c.setGoodDetail("我的更改");
		goods good = (goods) new DaoPro().getByBean(c).get(0);
		System.out.println(good.getId());
	}

}