读取TEXT

读取TEXT
PreparedStatement ps = conn.prepareStatement("select file from clob");
ResultSet rs = ps.executeQuery();
if (rs.next()) {
Reader reader = rs.getCharacterStream(int?columnIndex);
// 这个Reader就是从数据库中读取数据的流, 操作这个流来读取数据
}


也可以使用rs.getString(), 在字符串太大的情况下, 同样有可能超出虚拟机内存
import java.io.*;
import java.sql.*;


public class TestTextField {


public TestTextField() throws IOException {
Connection con = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
try {
con = DriverManager.getConnection("jdbc:mysql://localhost/loginDb",
"root", "admin");


String sql = "insert into text(introduce) values(?);";


pstmt = con.prepareStatement(sql);


File f = new File("res/introduce.txt");
// File f = new File("src/T1.java");


FileReader fr = new FileReader(f);


pstmt.setCharacterStream(1, fr, (int) f.length());


pstmt.executeUpdate();


sql = "select * from text";
rs = pstmt.executeQuery(sql);


File newFile = new File("res/new.txt");


if (rs.next()) {
Reader r = rs.getCharacterStream(2);
BufferedReader br = new BufferedReader(r);


BufferedWriter bw = new BufferedWriter(new FileWriter(
"res/new.txt"));


String s = "";
while ((s = br.readLine()) != null) {
bw.write(s + "\n");
}


bw.flush();
br.close();
r.close();
bw.close();
}


} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
rs.close();
pstmt.close();
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}


public static void main(String[] args) {
try {
new TestTextField();
} catch (IOException e) {
e.printStackTrace();
}
}


}