通用JDBC-demo

1、JDBC 的工具包（utils）：包含获取数据库连接, 关闭数据库资源等方法

JDBCTools_pro.java

package com.app.utils;

import java.beans.PropertyVetoException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

/**
 * JDBC 的工具类
 * 
 * 其中包含: 获取数据库连接, 关闭数据库资源等方法.
 */
public class JDBCTools_pro {
	
	 private static JDBCTools_pro instance;

	 public  ComboPooledDataSource ds;
	 
	 private static String c3p0Properties = "jdbc.properties";

	//处理数据库事务的
	//提交事务
	public static void commit(Connection connection){
		if(connection != null){
			try {
				connection.commit();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	
	//回滚事务
	public static void rollback(Connection connection){
		if(connection != null){
			try {
				connection.rollback();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	
	//开始事务
	public static void beginTx(Connection connection){
		if(connection != null){
			try {
				connection.setAutoCommit(false);
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	
	//private static DataSource dataSource = null;

	//数据库连接池应只被初始化一次. 
	/*static{
		dataSource = new ComboPooledDataSource("helloc3p0");
	}
	
	public static Connection getConnection() throws Exception {
		return dataSource.getConnection();
	}*/
	public JDBCTools_pro() throws Exception {
		
		  Properties p = new Properties();
		  /*
		   * 同一包下
		   * 
		   */
		 // p.load(this.getClass().getClassLoader().getResourceAsStream(c3p0Properties));
		  /*
		   * 根目录下
		   */
		  p.load(this.getClass().getClassLoader().getResourceAsStream(c3p0Properties));
		  
		  ds = new ComboPooledDataSource();
		  
		  ds.setUser(p.getProperty("jdbc.username"));
		  ds.setPassword(p.getProperty("jdbc.password"));
		  ds.setJdbcUrl(p.getProperty("jdbc.url"));
		  ds.setDriverClass(p.getProperty("jdbc.driverClassName"));
		  
		  ds.setMinPoolSize(Integer.parseInt(p.getProperty("C3P0.minPoolSize")));
		  ds.setMaxPoolSize(Integer.parseInt(p.getProperty("C3P0.maxPoolSize")));
		  ds.setMaxIdleTime(Integer.parseInt(p.getProperty("C3P0.maxIdleTime")));
		  ds.setAcquireIncrement(Integer.parseInt(p.getProperty("C3P0.acquireIncrement")));
		  ds.setMaxStatements(Integer.parseInt(p.getProperty("C3P0.maxStatements")));	  
		  ds.setMaxStatementsPerConnection(Integer.parseInt(p.getProperty("C3P0.maxStatementsPerConnection")));
		  ds.setIdleConnectionTestPeriod(Integer.parseInt(p.getProperty("C3P0.idleConnectionTestPeriod")));
		  ds.setAcquireRetryAttempts(Integer.parseInt(p.getProperty("C3P0.acquireRetryAttempts")));

	}
	 public static final JDBCTools_pro getInstance() {
		  if (instance == null) {
		   try {
		    instance = new JDBCTools_pro();
		   } catch (Exception e) {
		    e.printStackTrace();
		   }
		  }
		  return instance;
		 }

		 public synchronized final Connection getConnection() {
		  try {
		   return ds.getConnection();
		  } catch (SQLException e) {
		   e.printStackTrace();
		  }
		  return null;
		 }

	public static void releaseDB(ResultSet resultSet, Statement statement,
			Connection connection) {

		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}

		if (statement != null) {
			try {
				statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}

		if (connection != null) {
			try {
				//数据库连接池的 Connection 对象进行 close 时
				//并不是真的进行关闭, 而是把该数据库连接会归还到数据库连接池中. 
				connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

}

2、JDBC数据库底层实现（dao）

　2.1.1.底层实现

BaseDaoImpl.java

package com.app.dao.impl;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

import com.app.dao.BaseDao;
import com.app.utils.ReflectionUtils;

/**
 * 使用 QueryRunner 提供其具体的实现
 * @param <T>: 子类需传入的泛型类型. 
 */
public class BaseDaoImpl<T> implements BaseDao<T> {

	private QueryRunner queryRunner = null;
	private Class<T> type;
	
	public BaseDaoImpl() {
		queryRunner = new QueryRunner();
		type = ReflectionUtils.getSuperGenericType(getClass());
	}
	
	@Override
	public void batch(Connection connection, String sql, Object[]... args) throws SQLException {
		queryRunner.batch(connection, sql, args);
	}

	@SuppressWarnings("unchecked")
	@Override
	public <E> E getForValue(Connection connection, String sql, Object... args) throws SQLException {
		return (E) queryRunner.query(connection, sql, new ScalarHandler(), args);
	}

	@Override 
	public List<T> getForList(Connection connection, String sql, Object... args) 
			throws SQLException {
		return queryRunner.query(connection, sql, 
				new BeanListHandler<>(type), args);
	}

	@Override
	public T get(Connection connection, String sql, Object... args) throws SQLException { 
		return queryRunner.query(connection, sql, 
				new BeanHandler<>(type), args);
	}

	@Override
	public void update(Connection connection, String sql, Object... args) throws SQLException {
		queryRunner.update(connection, sql, args);
	}
	
}

　　2.1.2.实物类继承　

UserDaoImpl.java

package com.app.dao.impl;

import java.sql.Connection;

import com.app.dao.UserDao;
import com.app.entity.User;
import com.app.utils.JDBCTools_xml;

public class UserDaoImpl extends BaseDaoImpl<User> implements UserDao{
	
	@Override
	public boolean isUserExisted(String id) {
		Connection conn = null;
		boolean flage = false;
		try {
			conn = JDBCTools_xml.getConnection();
			String sql = "SELECT id from users where userId = ?";
			String p = getForValue(conn, sql, id);
			if(null!=p){
				flage = true;
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			JDBCTools_xml.releaseDB(null, null, conn);
		}
		return flage;
	}

	@Override
	public boolean isUserpass(String id, String password) {
		Connection conn = null;
		boolean flage = false;
		try {
			conn = JDBCTools_xml.getConnection();
			String sql = "SELECT id from users where id = ? and password = ?";
			String p = getForValue(conn, sql, id);
			if(null!=p){
				flage = true;
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			JDBCTools_xml.releaseDB(null, null, conn);
		}
		return flage;
	}

	@Override
	public long getNumber() {

		long num = 0;
		Connection conn = null;
		try {
			 conn = JDBCTools_xml.getConnection();
			 String sql = "SELECT count(*) from users";
			 num = getForValue(conn, sql, null);
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JDBCTools_xml.releaseDB(null, null, conn);
		}
		return num;
	}

	@Override
	public User getUserById(String id) {
		Connection conn = null;
		User user = null;
		try {
			conn = JDBCTools_xml.getConnection();
			String sql = "SELECT userId,userName,password "+
							"from users where userId = ?";
			user = get(conn,sql,id);			
		} catch (Exception e) {			
			e.printStackTrace();
		}finally{
			JDBCTools_xml.releaseDB(null, null, conn);
		}
		
		return user;
	}

	@Override
	public void insertUser(String userId, String userName, String password) {
		
		Connection conn = null;
		try {
			conn = JDBCTools_xml.getConnection();
			String sql = "INSERT INTO users VALUES(?,?,?)";
			update(conn, sql, userId,userName,password);			
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JDBCTools_xml.releaseDB(null, null, conn);
		}		
	}

	@Override
	public void deleteUser(String id) {
		
		Connection conn = null;
		try {
			conn = JDBCTools_xml.getConnection();
			String sql = "DELETE from users where userId = ?";
			update(conn, sql, id);
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JDBCTools_xml.releaseDB(null, null, conn);
		}
		
	}

	@Override
	public void updateUser(String userId, String userName, String password) {
		Connection conn = null;
		try {
			conn = JDBCTools_xml.getConnection();
			String sql = "UPDATE users set userName = ?,password = ? where userId = ?";
			update(conn, sql, userName,password,userId);
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JDBCTools_xml.releaseDB(null, null, conn);
		}
		
	}
	
}

　　2.2.1

BaseDao.java

package com.app.dao;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

/**
 * 访问数据的 DAO 接口. 
 * 里边定义好访问数据表的各种方法
 * @param T: DAO 处理的实体类的类型. 
 */
public interface BaseDao<T> {

	void batch(Connection connection, 
			String sql, Object [] ... args) throws SQLException;
	
	<E> E getForValue(Connection connection,
			String sql, Object ... args) throws SQLException;
		
	List<T> getForList(Connection connection,
			String sql, Object ... args) throws SQLException;
	
	T get(Connection connection, String sql, 
			Object ... args) throws SQLException;
	
	void update(Connection connection, String sql, 
			Object ... args) throws SQLException;

}

　　2.2.2

UserDao.java

package com.app.dao;

import com.app.entity.User;

public interface UserDao extends BaseDao<User>{

	boolean isUserExisted(String id);
	
	boolean isUserpass(String id,String password);
	
	long getNumber();
	
	User getUserById(String id);
	
	void updateUser(String Userid, String Username, String password);
	
	void deleteUser(String id);

	void insertUser(String Userid, String Username, String password);
	
}

　　

3、JDBC实物类（entity）

User.java

package com.app.entity;

public class User {

	private String userId;
	private String userName;
	private String password;

	public User() {
		// TODO Auto-generated constructor stub
	}
	
	public User(String userId, String userName, String password) {
		super();
		this.userId = userId;
		this.userName = userName;
		this.password = password;
	}

	public String getUserId() {
		return userId;
	}

	public void setUserId(String userId) {
		this.userId = userId;
	}

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	@Override
	public String toString() {
		return "user [userId=" + userId + ", userName=" + userName + ", password=" + password + "]";
	}

}