jdbc 大数据存储 图片读取

package com.itheima.clob.test;

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

import org.junit.Test;

import com.itheima.utils.JdbcUtil;
/**
 * 测试大文本数据读写
 drop database day16;
 create database day16;
 use day16;
 create table testclob(
     id int primary key,
     content longtext
 );
 * @author wangli
 *
 */
public class ClobTest {

    @Test  //写入
    public void testClobAdd(){
        Connection con = null;
        PreparedStatement st =null;

        try {
            con = JdbcUtil.getConnection();
            String sql="insert into testclob values(?,?)";
            st = con.prepareStatement(sql);

            //赋值
            st.setInt(1, 2);
            //st.setString(2, "dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd");

            File file = new File("src/jdbccfg.properties");
            FileReader reader = new FileReader(file);//得到一个文件读取器
            st.setCharacterStream(2, reader, (int)file.length());//int jdk5,  long jdk1.6+
                                                        //MYsql支持的长度有限  ,改成int类型就可以了
                                                        //long类型，可以给oracle用

            st.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            JdbcUtil.release(null, st, con);
        }
    }

    @Test  //读取
    public void testClobReader(){
        Connection con = null;
        PreparedStatement st =null;
        ResultSet rs = null;
        try {
            con = JdbcUtil.getConnection();
            String sql="select * from textclob where id=?";
            st = con.prepareStatement(sql);

            //赋值
            st.setInt(1, 2);

            //3.执行查询
            rs = st.executeQuery();
            if(rs.next()){
                //说明结果集中有记录
                Reader reader = rs.getCharacterStream("content");
                FileWriter fw = new FileWriter("d:/jdbc.properties");
                int len=-1;
                char [] buffer = new char[1024];
                while((len=reader.read(buffer))!=-1){
                    fw.write(buffer, 0, len);
                }

                //关闭流
                fw.close();
                reader.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            JdbcUtil.release(null, st, con);
        }
    }
}