JDBC 复习2 存取mysql 大数据

大数据也称之为LOB(Large Objects)，LOB又分为：clob和blob，clob用于存储大文本，blob用于存储二进制数据

mysql的大数据分为2种 blob 和 text ，没有clob;

对MySQL而言只有blob，而没有clob，mysql存储大文本采用的是Text，Text和blob分别又分为：
　　TINYTEXT、TEXT、MEDIUMTEXT和LONGTEXT
　　TINYBLOB、BLOB、MEDIUMBLOB和LONGBLOB

package dbex.mysql;

import java.io.File;
import java.io.FileReader;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.Reader;
import java.net.URL;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import dbex.DBUtil;

/**
*
* @ClassName: MySqlText
* @Description: 使用jdbc操作MySQL的大文本
* @author penny
* @date 2017年11月27日 下午3:52:32
*
*/
public class MySqlText {

public void doInsert() throws Exception{
//    File txt = new File("../../big.txt");
URL path = MySqlText.class.getResource("../../big.txt");
File txt = new File(path.toExternalForm().substring(5));
//    System.out.println();
Reader br = new FileReader(txt);
OutputStream fw = new PrintStream(System.out);
Connection con = DBUtil.getConnection();
PreparedStatement ppst = con.prepareStatement("insert into ex_txt(context) values(?)");

//    int len =0;
//    byte[] buff= new byte[1024];
//    StringBuffer sb = new StringBuffer();
//    while((len=fr.read(buff))>-1){
//    ((PrintStream)fw).print(sb.append(new String(buff)));//成功打印
//    }

ppst.setCharacterStream(1, br, (int)txt.length());
int row = ppst.executeUpdate();
DBUtil.closeAll(con, ppst, null);
System.out.println(row);

}
void doQuery() throws Exception{
Connection conn = DBUtil.getConnection();
PreparedStatement ppst = conn.prepareStatement("select t.context from ex_txt t where id=2");
ResultSet rs= ppst.executeQuery();
if(rs.next()){
//    rs.getString(1);
Reader reader = rs.getCharacterStream(1);
int len =0;
char[] buff = new char[1024];
while((len=reader.read(buff))>-1){
System.out.println(new String(buff)+len);
}
}
DBUtil.closeAll(conn, ppst, rs);
}
public static void main(String[] args) throws Exception {
//    new MySqlText().doInsert();
new MySqlText().doQuery();
}
}