java_jdbc_oracle简单总结（2016-11-23）

JDBC连接oracle的实例

好久没写过jdbc，基本忘干净了，随意插一个图，简单学习一下。然后干别的。。。。。

使用jdbc操作数据库步骤是固定的

1.将驱动包导入到数据库，每一个数据库的驱动包都不一样，下面我提供一个Oracle数据库的驱动包http://download.csdn.net/detail/hncsy403/4530830将它下载后放入web项目中的 web-inf中的lib中

2.选择项目右键，选择Build Bath，在libraries中add JARs，选择刚才的jar包

学生类bean

package jdbc.bean;

import java.util.Date;

public class Student {

	private int id;
	private String name;
	private String password;
	private String sex;
	private int age;
	private Date birthday;
	private String memo;
	private String photo;
	private Date regTime;

	public int getAge() {
		return age;
	}

	public Date getBirthday() {
		return birthday;
	}

	public int getId() {
		return id;
	}

	public String getMemo() {
		return memo;
	}

	public String getName() {
		return name;
	}

	public String getPassword() {
		return password;
	}

	public String getPhoto() {
		return photo;
	}

	public Date getRegTime() {
		return regTime;
	}

	public String getSex() {
		return sex;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}

	public void setId(int id) {
		this.id = id;
	}

	public void setMemo(String memo) {
		this.memo = memo;
	}

	public void setName(String name) {
		this.name = name;
	}

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

	public void setPhoto(String photo) {
		this.photo = photo;
	}

	public void setRegTime(Date regTime) {
		this.regTime = regTime;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

}

工具类：DBUtil

package jdbc.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBUtil {

	private static final String driverClass = "oracle.jdbc.driver.OracleDriver";
	private static final String jdbcUrl = "jdbc:oracle:thin:@liumo:1521:ORCL";
	private static final String user = "test_lm";
	private static final String password = "test_lm";

	public static Connection getConn() {
		// 1.注册驱动
		try {
			Class.forName(driverClass);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}

		// 2.创建Connection(数据库连接对象)
		Connection conn = null;
		try {
			conn = DriverManager.getConnection(jdbcUrl, user, password);
			conn.setAutoCommit(false);
			return conn;
		} catch (SQLException e) {
			e.printStackTrace();
		}
		/*
		 * Connection是Statement的工厂，一个Connection可以生产多个Statement。
		 * Statement是ResultSet的工厂，一个Statement却只能对应一个ResultSet（它们是一一对应的关系）。
		 * 所以在一段程序里要用多个ResultSet的时候，必须再Connection中获得多个Statement，然后一个Statement对应一个ResultSet。
		 */
		return null;
	}

	/**
	 * 关闭连接(数据库连接对象)
	 * @param conn
	 */
	public static void close(Connection conn) {
		try {
			if (conn != null) {
				conn.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 关闭编译的 SQL 语句的对象
	 * @param stmt
	 */
	public static void close(Statement stmt) {
		try {
			if (stmt != null) {
				stmt.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 关闭结果集
	 * @param rs
	 */
	public static void close(ResultSet rs) {
		try {
			if (rs != null) {
				rs.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 提交事务
	 * @param conn
	 */
	public static void commit(Connection conn) {
		try {
			if (conn != null) {
				conn.commit();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 回滚事务
	 * @param conn
	 */
	public static void rollback(Connection conn) {
		try {
			if (conn != null) {
				conn.rollback();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
}

　　实际的dao：StudentDao

　

package jdbc.dao;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import jdbc.bean.Student;
import jdbc.util.DBUtil;

public class StudentDao {

	/**
	 * 保存
	 * @param student
	 */
	public void save(Student student) {

		Connection conn = DBUtil.getConn();

		PreparedStatement pstmt = null;
		String sql = " insert into t_student(name,password,sex,age,birthday,memo,photo,reg_time) ";
		sql += " values(?,?,?,?,?,?,?,?) ";
		try {
			pstmt = conn.prepareStatement(sql);

			pstmt.setString(1, student.getName());
			pstmt.setString(2, student.getPassword());
			pstmt.setString(3, student.getSex());
			pstmt.setInt(4, student.getAge());
			pstmt.setDate(5, new java.sql.Date(student.getBirthday().getTime())); // 只存年月日这种形式
			pstmt.setString(6, student.getMemo());
			try {
				// 构建一个输入流存blob
				pstmt.setBlob(7, new FileInputStream(student.getPhoto()));
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			}
			pstmt.setTimestamp(8, new java.sql.Timestamp(student.getRegTime().getTime())); // 完整的时间格式
			pstmt.executeUpdate();
			DBUtil.commit(conn);
		} catch (SQLException e) {
			DBUtil.rollback(conn);
			e.printStackTrace();
		} finally {
			DBUtil.close(pstmt);
			DBUtil.close(conn);
		}
	}

	/**
	 * 删除
	 * @param id
	 */
	public void delete(int id) {
		Connection conn = DBUtil.getConn();
		PreparedStatement pstmt = null;
		String sql = " delete from t_student where id=?";
		try {
			pstmt = conn.prepareStatement(sql);

			pstmt.setInt(1, id);
			pstmt.executeUpdate();
			DBUtil.commit(conn);
		} catch (SQLException e) {
			DBUtil.rollback(conn);
			e.printStackTrace();
		} finally {
			DBUtil.close(pstmt);
			DBUtil.close(conn);
		}
	}

	/**
	 * 批量删除
	 * @param ids
	 */
	public void deleteBatch(int[] ids) {

		Connection conn = DBUtil.getConn();
		PreparedStatement pstmt = null;
		String sql = " delete from t_student where id=?";
		try {
			pstmt = conn.prepareStatement(sql);
			for (int id : ids) {
				pstmt.setInt(1, id);
				pstmt.addBatch();
			}
			pstmt.executeBatch();
			DBUtil.commit(conn);
		} catch (SQLException e) {
			DBUtil.rollback(conn);
			e.printStackTrace();
		} finally {
			DBUtil.close(pstmt);
			DBUtil.close(conn);
		}
	}

	/**
	 * 修改
	 * @param student
	 */
	public void update(Student student) {
		Connection conn = DBUtil.getConn();
		PreparedStatement pstmt = null;
		String sql = " update  t_student set name=?,password=?,sex=?,age=?,birthday=?,memo=?,photo=?,reg_time=?  where id=?";
		try {
			pstmt = conn.prepareStatement(sql);

			pstmt.setString(1, student.getName());
			pstmt.setString(2, student.getPassword());
			pstmt.setString(3, student.getSex());
			pstmt.setInt(4, student.getAge());
			pstmt.setDate(5, new java.sql.Date(student.getBirthday().getTime())); // 只存年月日这种形式
			pstmt.setString(6, student.getMemo());
			try {
				// 构建一个输入流存blob
				pstmt.setBlob(7, new FileInputStream(student.getPhoto()));
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			}
			pstmt.setTimestamp(8, new java.sql.Timestamp(student.getRegTime().getTime())); // 完整的时间格式
			pstmt.setInt(9, student.getId());

			pstmt.executeUpdate();
			DBUtil.commit(conn);
		} catch (SQLException e) {
			DBUtil.rollback(conn);
			e.printStackTrace();
		} finally {
			DBUtil.close(pstmt);
			DBUtil.close(conn);
		}
	}

	/**
	 * 查找
	 * @param id
	 * @return
	 */
	public Student find(int id) {
		Connection conn = DBUtil.getConn();
		PreparedStatement pstmt = null;
		ResultSet resultSet = null;
		String sql = " select * from t_student  where id=?";
		Student student = null;
		try {
			pstmt = conn.prepareStatement(sql);

			pstmt.setInt(1, id);
			resultSet = pstmt.executeQuery();

			if (resultSet.next()) {
				student = new Student();
				student.setId(resultSet.getInt("id"));
				student.setName(resultSet.getString("name"));
				student.setAge(resultSet.getInt("age"));
				student.setBirthday(resultSet.getDate("birthday"));
				student.setMemo(resultSet.getString("memo"));
				student.setPassword(resultSet.getString("password"));
				student.setRegTime(resultSet.getTimestamp("reg_time"));
				student.setSex(resultSet.getString("sex"));
				InputStream in = resultSet.getBlob("photo").getBinaryStream();
				String path = "d:\\ltf.jpg";
				try {
					OutputStream out = new FileOutputStream(path);
					copy(in, out);
					out.close();
				} catch (FileNotFoundException e) {
					e.printStackTrace();
				} catch (IOException e) {
					e.printStackTrace();
				}
				student.setPhoto(path);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtil.close(resultSet);
			DBUtil.close(pstmt);
			DBUtil.close(conn);
		}
		return student;
	}

	private void copy(InputStream in, OutputStream out) {
		int i = 0;
		try {
			while ((i = in.read()) != -1) {
				out.write(i);
			}
			out.flush();
		} catch (IOException e) {

			e.printStackTrace();
		}
	}

	/**
	 * 查询多条记录
	 * @return
	 */
	public List<Student> query() {
		Connection conn = DBUtil.getConn();
		PreparedStatement pstmt = null;
		ResultSet resultSet = null;
		String sql = " select * from t_student ";
		List<Student> studentList = new ArrayList<Student>();

		try {
			pstmt = conn.prepareStatement(sql);

			resultSet = pstmt.executeQuery();

			while (resultSet.next()) {
				Student student = new Student();
				student.setId(resultSet.getInt("id"));
				student.setName(resultSet.getString("name"));
				student.setAge(resultSet.getInt("age"));
				student.setBirthday(resultSet.getDate("birthday"));
				student.setMemo(resultSet.getString("memo"));
				student.setPassword(resultSet.getString("password"));
				student.setRegTime(resultSet.getTimestamp("reg_time"));
				student.setSex(resultSet.getString("sex"));
				InputStream in = resultSet.getBlob("photo").getBinaryStream();
				String path = "d:\\ltf.jpg";
				try {
					//将数据库存的图片放到磁盘的某个位置
					OutputStream out = new FileOutputStream(path);
					copy(in, out);
					out.close();
				} catch (FileNotFoundException e) {
					e.printStackTrace();
				} catch (IOException e) {
					e.printStackTrace();
				}
				student.setPhoto(path);
				studentList.add(student);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtil.close(resultSet);
			DBUtil.close(pstmt);
			DBUtil.close(conn);
		}
		return studentList;
	}

}

　　测试类：DaoTest

package jdbc.test;
import static org.junit.Assert.fail;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import jdbc.bean.Student;
import jdbc.dao.StudentDao;

import org.junit.Test;

public class DaoTest {

	@Test
	public void test() {
		fail("Not yet implemented");

	       Student s=new Student();
	        //s.setId(3);
	        s.setName("zss");
	        s.setPassword("zss");
	        s.setSex("女");
	        s.setAge(21);
	        try {
	            s.setBirthday(new SimpleDateFormat("yyyy-MM-dd").parse("1980-01-01"));
	        } catch (ParseException e) {
	            // TODO Auto-generated catch block
	            e.printStackTrace();
	        }
	        s.setMemo("我人还不错");
	        s.setPhoto("c:\\ltf.jpg");
	        s.setRegTime(new Date());

	        StudentDao sd=new StudentDao();
	        //sd.save(s);
	        //sd.update(s);
	        //sd.delete(1);
	        //sd.deleteBatch(new int[]{2,3});
	        System.out.println(sd.query().size());
	}

}

　　

每次SQL操作都需要建立和关闭连接，这势必会消耗大量的资源开销，如何避免

分析：可以采用连接池，对连接进行统一维护，不必每次都建立和关闭。事实上这是很多对JDBC进行封装的工具所采用的。（等看到hibernate，spring连接数据库和事务的时候在研究一下。）

参考：

通过JDBC进行简单的增删改查（以MySQL为例） http://www.cnblogs.com/wuyuegb2312/p/3872607.html

JDBC学习之-如何获取Connection  http://blog.csdn.net/luohuacanyue/article/details/8770450