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();
}
}
}
}