JDBC

• 【核心语句】

DatabaseMetaData metaData = conn.getMetaData();
ResultSet rs= metaData.getColumns(null, null, tablename+"%", null);

• 重点是第二句的第三参数，如果置空就不分表了，那不是我们想看到的，于是将表名加上通配符%限制一下表的范围，再这样限制表：

while (rs.next()) {
        String tbName = rs.getString("TABLE_NAME"); // 表名

        if(tbName.equalsIgnoreCase(tablename)){
                String columnName = rs.getString("COLUMN_NAME"); // 列名
                ls.add(columnName);
        }
}

• 当取得rs的TABLE_NAME字段后，再限制一次，这下出现的字段就只会是指定表下的了。
• 【代码】

package com.txc.lab;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * 此类用于查出某表下的所有字段名称
 */
public class FieldFinder {
    //-- 以下为连接Oracle数据库的四大参数
    private static final String DRIVER = "oracle.jdbc.driver.OracleDriver";
    private static final String URL = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";
    private static final String USER = "luna";
    private static final String PSWD = "1234";

    public void printFields(String tablename){
        Connection conn = null;

        try{
            Class.forName(DRIVER);
            conn = DriverManager.getConnection(URL, USER, PSWD);

            List<String> ls=getFields(conn,tablename);
            Collections.sort(ls);
            ls.stream().forEach(table -> System.out.println(table));
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    private List<String> getFields(Connection conn,String tablename) throws Exception{
        DatabaseMetaData metaData = conn.getMetaData();
        ResultSet rs = metaData.getColumns(null, null, tablename+"%", null);
        List<String> ls=new ArrayList<>();

        while (rs.next()) {
            String tbName = rs.getString("TABLE_NAME"); // 表名

            if(tbName.equalsIgnoreCase(tablename)){
                String columnName = rs.getString("COLUMN_NAME"); // 列名
                ls.add(columnName);
            }
        }
        return ls;
    }

    public static void main(String[] args){
        FieldFinder finder=new FieldFinder();
        finder.printFields("EMP");
    }
}

• 【参考资料】

https://blog.csdn.net/github_34793283/article/details/114109394