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之前在学校的时候做的都是练习，小儿科，遇到的情况完全都在自己的设想范围内。最近老是遇到字段溢出的情况，但是varchar2好像最长也只有4000个字符。所以不得不另辟蹊径，就找上了clob字段。
package test;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.Writer;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import oracle.sql.CLOB;
public class ClobTest {
private static Connection conn;
static {
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:orcl","wch","wch123");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws SQLException, IOException {
// testInsert();
// testUpdate();
testRead();
}
private static void testInsert() throws SQLException {
String sql = "insert into CLOBTEST values(1, empty_clob(),empty_clob())";
Statement stm = conn.createStatement();
stm.execute(sql);
}
private static void testUpdate() throws SQLException, IOException {
String sql = "select context,c2 from CLOBTEST where id = 1 for update";
Statement stm = conn.createStatement();
ResultSet rs = stm.executeQuery(sql);
while (rs.next()) {
oracle.sql.CLOB c = (CLOB) rs.getClob(1);
Writer w = c.setCharacterStream(1);
w.write("wchwchwch\r\n");
w.write("哈哈哈\r\n哈哈哈ds", 2, 5);
w.flush();
w.close();
c = (CLOB) rs.getClob(2);
w = c.setCharacterStream(1);
w.write("dingsen");
w.flush();
w.close();
}
conn.commit();
}
private static void testRead() throws SQLException, IOException {
String sql = "select context,c2 from CLOBTEST where id = 1";
PreparedStatement pstm = conn.prepareStatement(sql);
ResultSet rs = pstm.executeQuery();
System.out.println("-----------------------------------");
while (rs.next()) {
Clob clob = rs.getClob(1);
BufferedReader r = new BufferedReader(clob.getCharacterStream());
char[] cs = new char[10];
int total = 0;
StringBuilder sb = new StringBuilder();
while ((total = r.read(cs)) != -1) {
sb.append(cs,0,total);
}
System.out.println(sb.toString());
}
}
}