JDBC 关于大文本数据

大文本数据Clob，在不同的数据库中类型名不一致，有的是text格式，有的是clob，还有其他一些格式

 

package test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Date;

public class ClobTest {

    public static void main(String[] args) throws SQLException, IOException, ClassNotFoundException {
        read();
    }

    static void create() throws SQLException, IOException {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        Reader reader = null;
        try {
            conn = JdbcUtils.getConnection();
            //3，Statement用于“运送”sql语句和sql语句执行结果
            String sql = "insert into clob_test(big_text) values (?)";

            ps = conn.prepareStatement(sql);
            //ps.setAsciiStream(int parameterIndex, InputStream x, int length)
            File file = new File("src/test/ClobTest.java");
            reader = new BufferedReader(new FileReader(file));
            ps.setCharacterStream(1, reader,file.length());
            //4,执行sql
            int count = ps.executeUpdate();

            System.out.println(count);

        } finally {
            JdbcUtils.free(rs, ps, conn);
            if(reader!=null) {
                reader.close();//为了方便这样写了
            }
        }
    }
   

    private static void read() throws ClassNotFoundException, SQLException, IOException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        Date bithday = null;
        try {
            conn = JdbcUtils.getConnection();

            st = conn.createStatement();
           
            rs = st.executeQuery("select big_text from clob_test");
           
            while(rs.next()) {

                Clob clob = rs.getClob(1);
                BufferedReader reader = new BufferedReader(clob.getCharacterStream());
               
                //Reader rd = rs.getCharacterStream(1);//这样也可以的
                //String s = rs.getString(1);//String也可以 关键是你的内存有没有那么大
                File file = new File("src/ClobTest_bak.java");
                BufferedWriter writer = new BufferedWriter(new FileWriter(file));
                String line = null;
                while((line=reader.readLine())!=null) {
                    writer.write(line);
                    writer.newLine();
                    writer.flush();
                }
                writer.close();
                reader.close();
            }
        } finally {
            JdbcUtils.free(rs, st, conn);
        }

    }
}