自己写的一个数据库模板类,可以直接操作封装好的数据对象类

package com.drug.db;

import java.lang.reflect.Field;
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.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;

/**
 * 自己写的一个数据库工具类,希望可以封装所有的数据库操作
 * 直接对封装好的数据库对象javaBean进行操作
 * 
 * 数据库中表中的字段名必须首字母大写
 * 封装好的数据对象类javaBean中的变量必须和数据库表中的字段相对应,(首字母不用大写)
 * 
 * 这样以后修改数据库,只需要对应的修改一下数据对象类javaBean就行了,呵呵
 * 
 * 本人java还在自学中,望大家多多指正
 */
public class DBUtil {

    /**
     * 方 法 名: getTableRowCount
     * 功能描述: 获取表的行数
     * 输入参数:  tableName:表名
     * 返 回 值: int
     * 编 码 人:  zmj
     * 编码时间:  2010-2-8 上午11:10:26
     */
    public int getTableRowCount(String tableName) {
        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        int rowCount = -1;
        try {
            String sql = "select * from " + tableName;
            con = getCon();
            pst = con.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);
            rs = pst.executeQuery();
            rs.last();
            rowCount = rs.getRow();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            close(con, pst, rs);
        }
        return rowCount;
    }

    /**
     * 方 法 名:hasElem
     * 功能描述:判断表中是否含有该元素
     * 输入参数: tableName:表名,keyName:查询的键值,key用来查询的键
     * 返 回 值: boolean
     * 编 码 人:  zmj
     * 编码时间:  2010-2-20 上午10:26:33
     */
    public boolean hasElem(String tableName, String keyName, Object key) {
        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        String sql = "select * from " + tableName + " where "
                + firstUpper(keyName) + "=?";
        try {
            con = getCon();
            pst = con.prepareStatement(sql);
            setObject(pst, 1, key);
            rs = pst.executeQuery();
            if (rs.next()) {
                return true;
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            close(con, pst, rs);
        }

        return false;
    }

    /**
     * 方 法 名:getTableElem
     * 功能描述: 获取数据库中一个表中的全部数据
     * 输入参数:tableName:表名,beanName:用来封闭的javaBean
     * 返 回 值: ArrayList<Object>
     * 编 码 人:  zmj
     * 编码时间:  2010-2-20 上午08:16:52
     */
    public ArrayList<Object> getTableElem(String tableName, String beanName) {
        return getElemList(tableName, beanName, 1, -1);
    }

    /***
     * 方 法 名:getTable 
     * 功能描述:获取数据库中一个表中的数据 
     * 输入参数:tableName:表名,beanName:用来封装的javaBean,offset:偏移量,count:取出的记录条数,为-1时表示全部
     * 返 回值:ArrayList<Object> 
     * 编 码 人: zmj 
     * 编码时间: 2010-2-8
     * **/
    public ArrayList<Object> getElemList(String tableName, String beanName,
            int offset, int count) {
        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        ArrayList<Object> rs_list = new ArrayList<Object>();
        try {
            String sql = "select * from " + tableName;
            con = getCon();
            pst = con.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);
            rs = pst.executeQuery();
            String[] paramName = tableColName(rs);
            Class<?> beanClass = Class.forName(beanName);
            if (offset > 1)
                rs.absolute(offset - 1);
            else if (offset < 0 && offset != -1)
                return rs_list;
            while (rs.next() && (count == -1 || count-- > 0)) {
                Object bean = beanClass.newInstance();
                saveBean(bean, rs, paramName);
                rs_list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } finally {
            close(con, pst, rs);
        }
        return rs_list;
    }

    /**
     * 方 法 名:fuzzySearch
     * 功能描述: 进行模糊查询
     * 输入参数: tableName:表名,beanName:用来封装的javaBean,
            keyName:查询的键值,key用来查询的键,offset:偏移量,count:返回的最大个数,-1表示全部
     * 返 回 值: ArrayList<Object>
     * 编 码 人:  zmj
     * 编码时间:  2010-2-8 下午01:44:23
     */
    public ArrayList<Object> fuzzySearch(String tableName, String beanName,
            String fuzzyKeyName, String fuzzyKey, Object[][] key, int offset,
            int count) {
        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        ArrayList<Object> rs_list = new ArrayList<Object>();
        try {
            String sql = "select * from " + tableName + " where "
                    + firstUpper(fuzzyKeyName) + " like ?";
            for (int i = 0; i < key.length; i++) {
                if (key[i].length == 2) {
                    sql += " and " + firstUpper((String) key[i][0]) + "=?";
                }
            }
            con = getCon();
            pst = con.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);
            pst.setObject(1, "%" + fuzzyKey + "%");
            for (int i = 0; i < key.length; i++) {
                if (key[i].length == 2) {
                    this.setObject(pst, i + 2, key[i][1]);
                }
            }
            rs = pst.executeQuery();
            String[] paramName = tableColName(rs);
            Class<?> beanClass = Class.forName(beanName);
            if (offset > 1)
                rs.absolute(offset - 1);
            else if (offset < 0 && offset != -1)
                return rs_list;
            while (rs.next() && (count == -1 || count-- > 0)) {
                Object bean = beanClass.newInstance();
                saveBean(bean, rs, paramName);
                rs_list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } finally {
            close(con, pst, rs);
        }
        return rs_list;
    }

    /***
     * 方 法 名:getElem 
     * 功能描述:获取数据库中一个表中的一条记录 
     * 输入参数:tableName:表名,beanName:javaBean的名字 
     * 返 回 值:Object 
     * 编 码 人: zmj 
     * 编码时间: 2010-2-8
     * @throws SQLException 
     * **/
    public Object getElem(String tableName, String keyName, Object key,
            String beanName) {
        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        String sql = "select * from " + tableName + " where "
                + firstUpper(keyName) + "=?";
        String[] paramName = null;
        try {
            con = getCon();
            pst = con.prepareStatement(sql);
            setObject(pst, 1, key);
            rs = pst.executeQuery();
            paramName = tableColName(rs);
            Class<?> beanClass;
            beanClass = Class.forName(beanName);
            Object bean = null;
            bean = beanClass.newInstance();
            if (rs.next()) {
                saveBean(bean, rs, paramName);
            }
            return bean;
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } finally {
            close(con, pst, rs);
        }

        return null;
    }

    /***
     * 方 法 名:insert 
     * 功能描述:将JavaBean添加到数据库表table中 
     * 输入参数: tableName:表名,bean:javaBean
     * 返 回 值:int
     * 编 码 人: zmj 
     * 编码时间: 2010-2-8
     * **/
    public int insert(String tableName, Object bean) {
        Connection con = null;
        PreparedStatement pst = null;
        StringBuilder sql = new StringBuilder("insert into " + tableName + "(");
        try {
            Object[][] beanObj = bean2Array(bean);
            int n = beanObj.length;
            if (n < 1) {
                return 0;
            }
            for (int i = 0; i < n; i++) {
                if (i != 0)
                    sql.append(",");
                sql.append(beanObj[i][0]);
            }
            sql.append(") values(");
            for (int i = 0; i < n; i++) {
                if (i != 0)
                    sql.append(",");
                sql.append("?");
            }
            sql.append(")");
            con = getCon();
            pst = con.prepareStatement(sql.toString());
            for (int i = 0; i < n; i++) {
                setObject(pst, i + 1, beanObj[i][1]);
            }
            return pst.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } finally {
            close(con, pst);
        }
        return 0;
    }

    /**
     * 方 法 名:updateElem
     * 功能描述: 更新表中的一个元素
     * 输入参数: tableName,keyName,key,bean
     * 返 回 值: int
     * 编 码 人:  zmj
     * 编码时间:  2010-2-8 上午11:30:18
     */
    public int updateElem(String tableName, String keyName, Object key,
            Object bean) {
        Connection con = null;
        PreparedStatement pst = null;
        StringBuilder sql = new StringBuilder("update " + tableName + " set ");
        try {
            Object[][] beanObj = bean2Array(bean);
            int n = beanObj.length;
            if (n < 1) {
                return 0;
            }
            for (int i = 0; i < n; i++) {
                if (i != 0)
                    sql.append(",");
                sql.append(beanObj[i][0] + "=?");
            }
            sql.append(" where " + firstUpper(keyName) + "=?");
            con = getCon();
            pst = con.prepareStatement(sql.toString());
            int i = 0;
            for (; i < n; i++) {
                setObject(pst, i + 1, beanObj[i][1]);
            }
            setObject(pst, i + 1, key);
            return pst.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } finally {
            close(con, pst);
        }
        return 0;
    }

    /**
     * 方 法 名: deleteElem
     * 功能描述: 删除表中的一条记录
     * 输入参数:  tableName:表名, keyName:键名 key:键值
     * 返 回 值: int
     * 编 码 人:  zmj
     * 编码时间:  2010-2-8 下午01:47:08
     */
    public int deleteElem(String tableName, String keyName, Object key) {
        Connection con = null;
        PreparedStatement pst = null;
        StringBuilder sql = new StringBuilder("delete from " + tableName);
        try {
            sql.append(" where " + firstUpper(keyName) + "=?");
            con = getCon();
            pst = con.prepareStatement(sql.toString());
            setObject(pst, 1, key);
            int count = pst.executeUpdate();
            return count;
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } finally {
            close(con, pst);
        }
        return 0;
    }

    /**
     * 方 法 名:setObject
     * 功能描述:私有方法,设置preparedStatement的setXXX项
     * 输入参数: pst:PreparedStatement对象,i:列的位置,obj:要插入的对象
     * 返 回 值: void
     * 编 码 人:  zmj
     * 编码时间:  2010-2-8 上午11:13:02
     */
    private void setObject(PreparedStatement pst, int i, Object obj)
            throws SQLException {
        if (obj == null) {
            pst.setString(i, null);
        } else if (obj.getClass() == java.util.Date.class) {
            long l = ((java.util.Date) obj).getTime();
            java.sql.Timestamp t = new java.sql.Timestamp(l);
            pst.setTimestamp(i, t);
        } else {
            pst.setObject(i, obj);
        }
    }

    // 私有方法,把javabean存放到Object二维数组中
    private Object[][] bean2Array(Object bean) {
        Class<? extends Object> beanClass = bean.getClass();
        Field[] field = beanClass.getDeclaredFields();
        Method[] method = beanClass.getDeclaredMethods();
        ArrayList<Object> list = new ArrayList<Object>();
        for (int i = 0; i < field.length; i++) {
            for (int j = 0; j < method.length; j++) {
                String methodName = method[j].getName();
                if (isGetMethod(methodName)
                        && methodName.contains(firstUpper(field[i].getName()))) {
                    Object o = null;
                    try {
                        o = method[j].invoke(bean);
                    } catch (IllegalArgumentException e) {
                        e.printStackTrace();
                    } catch (IllegalAccessException e) {
                        e.printStackTrace();
                    } catch (InvocationTargetException e) {
                        e.printStackTrace();
                    }
                    if (o != null) {
                        list.add(field[i].getName());
                        list.add(o);
                    }
                }
            }
        }
        int m = list.size();
        if (m < 1 || m % 2 != 0) {
            return new Object[0][0];
        }
        Object[][] bean_obj = new Object[m / 2][2];
        Iterator<Object> iter = list.iterator();
        int i = 0;
        while (iter.hasNext()) {
            bean_obj[i][0] = iter.next();
            bean_obj[i][1] = iter.next();
            i++;
        }
        return bean_obj;
    }

    // 私有方法,返回表中列名
    private String[] tableColName(ResultSet rs) throws SQLException {
        ResultSetMetaData rsmd = rs.getMetaData();
        int n = rsmd.getColumnCount();
        String[] name = new String[n];
        for (int i = 0; i < n; i++) {
            name[i] = rsmd.getColumnName(i + 1);
        }
        return name;
    }

    // 私有方法,保存ResultSet一行记录到一个javaBean中
    private void saveBean(Object bean, ResultSet rs, String[] paramName)
            throws SQLException {
        Method[] method = bean.getClass().getDeclaredMethods();
        for (int i = 0; i < paramName.length; i++) {
            for (int j = 0; j < method.length; j++) {
                String methodName = method[j].getName();
                if (methodName.endsWith(paramName[i])
                        && isSetMethod(methodName)) {
                    Object param = rs.getObject(paramName[i]);
                    if (param != null) {
                        // 如果为Timestamp类,则转换为Date类
                        if (param.getClass() == java.sql.Timestamp.class) {
                            long l = ((java.sql.Timestamp) param).getTime();
                            param = new java.util.Date(l);
                        }
                        try {
                            method[j].invoke(bean, param);
                        } catch (IllegalArgumentException e) {
                            e.printStackTrace();
                        } catch (IllegalAccessException e) {
                            e.printStackTrace();
                        } catch (InvocationTargetException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
    }

    // 私有方法,判断是否为getter方法
    private boolean isGetMethod(String methodName) {
        if (methodName == null)
            return false;
        return methodName.startsWith("is") || methodName.startsWith("get");
    }

    // 私有方法,判断是否为setter方法
    private boolean isSetMethod(String methodName) {
        if (methodName == null)
            return false;
        return methodName.startsWith("set");
    }

    // 私有方法,将首字母大写
    private String firstUpper(String s) {
        return s.substring(0, 1).toUpperCase() + s.substring(1);
    }

    // 私有方法,获取数据库连接
    private Connection getCon() throws ClassNotFoundException, SQLException {
        DB.getInstance();
        return DB.getConnection();
    }

    // 私有方法,关闭数据库操作1,用于查询数据库操作
    private void close(Connection con, PreparedStatement pst, ResultSet rs) {
        try {
            if (rs != null)
                rs.close();
            if (pst != null)
                pst.close();
            if (con != null)
                DB.release(con);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 私有方法,关闭数据库操作2,用于更新数据库操作
    //我用的数据库为access,不知道为什么,数据库Connection不关闭,数据库不更新,求解!!
    private void close(Connection con, PreparedStatement pst) {
        try {
            if (pst != null)
                pst.close();
            if (con != null) {
                con.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

 /*
 * 自己写的一个很简单的数据库连接池
 */

package com.drug.db;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Stack;

public class DB {
    private static DB DB_INSTANCE = null;
    private static int MAX = 40;
    private static Stack<Connection> CON_POOL = new Stack<Connection>();
    // 数据库配置
    private static String className = "sun.jdbc.odbc.JdbcOdbcDriver";
    private static String url = "jdbc:odbc:test";
    // 同步对象
    private final static byte[] lock = new byte[0];

    private DB() throws ClassNotFoundException {
        Class.forName(className);

    }

    // 返回单一实例
    public static DB getInstance() throws ClassNotFoundException {
        if (DB_INSTANCE == null) {
            DB_INSTANCE = new DB();
        }
        return DB_INSTANCE;
    }

    // 获取连接
    public static Connection getConnection() throws SQLException {
        synchronized (lock) {
            if (CON_POOL.isEmpty()) {
                return DriverManager.getConnection(url);
            }
            return CON_POOL.pop();
        }
    }

    // 释放连接
    public static void release(Connection con) throws SQLException {
        synchronized (lock) {
            if (con == null || con.isClosed()) {
                return;
            } else if (CON_POOL.size() < MAX + 1) {
                CON_POOL.push(con);
            } else {
                con.close();
            }
        }
    }
}

 

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