java 實(shí)現(xiàn)讀取clob
1.說(shuō)明
jdbc 數(shù)據(jù)類型為Clob,與java的String類型相對(duì)應(yīng)。
2.導(dǎo)入
import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.sql.Statement;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.sql.Clob;
3.代碼實(shí)現(xiàn)
public List<Map<String, Object>> queryForList() { List<Map<String, Object>> rowList = new ArrayList<Map<String, Object>>(); String driver = ''; String url = ''; String username = ''; String password = ''; String sql = ''; log.info('查詢sql條件:' + sql); try { // 加載驅(qū)動(dòng)程序,此處運(yùn)用隱式注冊(cè)驅(qū)動(dòng)程序的方法 Class.forName(driver); log.info('加載驅(qū)動(dòng)成功!'); } catch (ClassNotFoundException e) { log.error('加載驅(qū)動(dòng)程序,此處運(yùn)用隱式注冊(cè)驅(qū)動(dòng)程序的方法出錯(cuò):' + e.getMessage()); e.printStackTrace(); } try { // 創(chuàng)建連接對(duì)象 Connection con = DriverManager.getConnection(url, username, password); // 創(chuàng)建sql執(zhí)行對(duì)象 Statement st = con.createStatement(); // 執(zhí)行sql語(yǔ)句并返回結(jié)果集 ResultSet rs = st.executeQuery(sql); // 獲得結(jié)果集結(jié)構(gòu)信息,元數(shù)據(jù) ResultSetMetaData rsmd = rs.getMetaData(); // 獲得列數(shù) int columnCount = rsmd.getColumnCount(); // 用于接收每行數(shù)據(jù) Map<String, Object> rowData = null; // clob類型 Clob clob = null; // clob轉(zhuǎn)成String String clobString = ''; while (rs.next()) { rowData = new HashMap<String, Object>(); for (int i = 1; i <= columnCount; i++) {// 判斷數(shù)據(jù)類型是否為Clobif (rs.getObject(i) instanceof Clob) {// Clob轉(zhuǎn)String clob = (Clob) rs.getObject(i); clobString = clob.getSubString((long) 1, (int) clob.length()); rowData.put(rsmd.getColumnName(i), clobString);} else { rowData.put(rsmd.getColumnName(i), rs.getObject(i));} } rowList.add(rowData); } // 關(guān)閉相關(guān)的對(duì)象 if (rs != null) { rs.close(); } if (st != null) { st.close(); } if (con != null) { con.close(); } } catch (SQLException e) { e.printStackTrace(); } return rowList;}
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