JDBC处理文本和二进制文件

JDBC支持文本（CLOB）和二进制（BLOB）文件的处理，比如要往数据库里存取文章或者图片。这都是用流的思想来解决的。

来两个Demo看看JDBC是怎么操作文本和二进制文件的。

CLOB：

package com.wxisme.jdbcclob;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;

/**
 * 数据库中对文本对象的操作。
 * @author wxisme
 *
 */

public class CLOBTest {
	/**
	 * 标准时间对象转换成long
	 * @param date
	 * @return long
	 */
	public static long dateTolong(String date) {
		DateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
		long time = 0;
		try {
			time = format.parse(date).getTime();
		} catch (ParseException e) {
			e.printStackTrace();
		}

		return time;
	}
	/**
	 * 向数据库中插入一条带有Clob文本对象字段的记录
	 */
	public void test1() {
		Connection conn = null;
		PreparedStatement ps = null;

		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}

		String c = "jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=utf8";
		try {
			conn = DriverManager.getConnection(c, "root", "1234");
			String sql = "insert into student (name,pswd,time,stime,myImg) values(?,?,?,?,?)";
			ps = conn.prepareStatement(sql);

			java.sql.Date date = new java.sql.Date(dateTolong("2015-5-14 9:25:32"));
			Timestamp stime = new Timestamp(dateTolong("2015-5-14 9:25:32"));
			ps.setString(1, "张三");
			ps.setString(2, "123456");
			ps.setDate(3, date);
			ps.setTimestamp(4, stime);
			ps.setClob(5, new FileReader("e:" +File.separator + "a.txt"));
			ps.executeUpdate();

		} catch (SQLException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}
	public static void main(String[] args) {

		//从数据库中读取Clob文本对象并输出
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		Reader r = null;

		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}

		String c = "jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=utf8";
		try {
			conn = DriverManager.getConnection(c, "root", "1234");
			String sql = "select myImg from student where id=?";
			ps = conn.prepareStatement(sql);
			ps.setInt(1, 1);

			rs = ps.executeQuery();

			while(rs.next()) {
				Clob clob = rs.getClob("myImg");
				r = clob.getCharacterStream();
				int t = 0;
				while((t=r.read()) != -1) {
					System.out.println((char)t);
				}

			}

		} catch (SQLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			try {
				ps.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			try {
				r.close();
			} catch (IOException e) {
				e.printStackTrace();
			}

			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}

	}

}

BLOB：

package com.wxisme.jdbcblob;

import java.io.File;
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.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
 * 数据库操作二进制文件 Blob类的使用
 * @author wxisme
 *
 */
public class BLOBTest {
	/**
	 * 向数据库中插入二进制
	 */
	public void test1() {
		Connection conn = null;
		PreparedStatement ps = null;

		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}

		String c = "jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=utf8";
		try {
			conn = DriverManager.getConnection(c, "root", "1234");
			String sql = "insert into student (img) values(?)";
			ps = conn.prepareStatement(sql);
			ps.setBlob(1, new FileInputStream("e:" + File.separator + "b.jpg"));

			ps.executeUpdate();

		} catch (SQLException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}finally {
			try {
				ps.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	public static void main(String[] args) {

		//从数据库中读取二进制文件并恢复
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		InputStream r = null;
		OutputStream os = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}

		String c = "jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=utf8";
		try {
			conn = DriverManager.getConnection(c, "root", "1234");
			String sql = "select img from student where id=?";
			ps = conn.prepareStatement(sql);
			ps.setInt(1, 3);
			rs = ps.executeQuery();

			os = new FileOutputStream(new File("e:/e.jpg"));
			while(rs.next()) {
				Blob blob = rs.getBlob("img");
				r = blob.getBinaryStream();
				int t = 0;
				while((t=r.read()) != -1) {
					os.write(t);
				}

			}

		} catch (SQLException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			try {
				ps.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
			try {
				r.close();
			} catch (IOException e) {
				e.printStackTrace();
			}

			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}

			try {
				os.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}