大文本的存取

package cn.itcast.jdbc.lob;

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.Reader;
import java.io.Writer;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import org.junit.Test;

import cn.itcast.util.JdbcUtil;
//大文本的存取
/*
use day15;
create table t1(
    id int primary key,
    content longtext
);
 */
public class ClobDemo {
    @Test
    public void testAdd(){
        Connection conn = null;
        PreparedStatement stmt = null;
        try{
            conn = JdbcUtil.getConnection();
            stmt = conn.prepareStatement("insert into t1 (id,content) values (?,?)");
            stmt.setInt(1, 1);
            //大数据要使用流的形式
            File file = new File("c:/jpm.txt");
            Reader reader = new FileReader(file);
            stmt.setCharacterStream(2, reader, (int)file.length());//不能使用long的参数，因为mysql根本支持不到那么大的数据，就没有实现
            
            int i = stmt.executeUpdate();
            if(i>0)
                System.out.println("插入成功");
            
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            JdbcUtil.release(null, stmt, conn);
        }
    }
    @Test
    public void testRead(){
        Connection conn = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        try{
            conn = JdbcUtil.getConnection();
            stmt = conn.prepareStatement("select * from t1 where id=?");
            stmt.setInt(1, 1);
            //大数据要使用流的形式
            //保存到E盘上
            rs = stmt.executeQuery();
            if(rs.next()){
                Reader reader = rs.getCharacterStream("content");
                Writer writer = new FileWriter("E:/jpm.txt");
                char c[] = new char[1024];
                int len = -1;
                while((len=reader.read(c))!=-1){
                    writer.write(c, 0, len);
                }
                reader.close();
                writer.close();
            }
            
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            JdbcUtil.release(null, stmt, conn);
        }
    }
}