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在实际开发过程中，可能需要根据各种不同的条件进行查询，使用这种方式不需要条件写出一种查询方式。
1 package com.xxyh.jdbc; 2 import java.sql.Connection; 3 import java.sql.PreparedStatement; 4 import java.sql.ResultSet; 5 import java.sql.ResultSetMetaData; 6 import java.sql.SQLException; 7 import java.util.Map; 8 public class ResultSetMetaDataTest { 9 10 public static void main(String[] args) throws SQLException { 11 read("select id, name as 姓名 from user"); 12 } 13 14 static Map<String, Object> read(String sql) throws SQLException { 15 Connection conn = null; 16 PreparedStatement ps = null; 17 ResultSet rs = null; 18 19 try { 20 conn = JdbcUtils.getConnection(); 21 ps = conn.prepareStatement(sql); 22 rs = ps.executeQuery(); 23 ResultSetMetaData rsmd = rs.getMetaData(); 24 int count = rsmd.getColumnCount();// 获取返回结果列数 25 for (int i = 1; i <= count; i++) { 26 System.out.print(rsmd.getColumnClassName(i) + "\t"); 27 System.out.print(rsmd.getColumnName(i) + "\t"); 28 System.out.println(rsmd.getColumnLabel(i)); 29 } 30 return null; 31 } finally { 32 JdbcUtils.close(rs, ps, conn); 33 } 34 } 35 }
1 package com.xxyh.jdbc; 2 import java.sql.Connection; 3 import java.sql.PreparedStatement; 4 import java.sql.ResultSet; 5 import java.sql.ResultSetMetaData; 6 import java.sql.SQLException; 7 import java.util.HashMap; 8 import java.util.Map; 9 public class ResultSetMetaDataTest { 10 11 public static void main(String[] args) throws SQLException { 12 Map<String, Object> data = read("select id, name from user where id=1");//1 13 System.out.println(data); 14 } 15 16 static Map<String, Object> read(String sql) throws SQLException { 17 Connection conn = null; 18 PreparedStatement ps = null; 19 ResultSet rs = null; 20 21 try { 22 conn = JdbcUtils.getConnection(); 23 ps = conn.prepareStatement(sql); 24 rs = ps.executeQuery(); 25 ResultSetMetaData rsmd = rs.getMetaData(); 26 int count = rsmd.getColumnCount();// 获取返回结果列数 27 String[] colNames = new String[count]; 28 for (int i = 1; i <= count; i++) { 29 colNames[i-1] = rsmd.getColumnName(i);//2 30 } 31 Map<String, Object> data = null; 32 if (rs.next()) { 33 data = new HashMap<String, Object>(); 34 for (int i = 0; i < colNames.length; i++) { 35 data.put(colNames[i], rs.getObject(colNames[i])); 36 } 37 } 38 return data; 39 } finally { 40 JdbcUtils.close(rs, ps, conn); 41 } 42 } 43 }
1 package com.xxyh.jdbc; 2 import java.sql.Connection; 3 import java.sql.PreparedStatement; 4 import java.sql.ResultSet; 5 import java.sql.ResultSetMetaData; 6 import java.sql.SQLException; 7 import java.util.ArrayList; 8 import java.util.HashMap; 9 import java.util.List; 10 import java.util.Map; 11 public class ResultSetMetaDataTest { 12 13 public static void main(String[] args) throws SQLException { 14 List<Map<String, Object>> datas = read("select id, name from user where id<5"); 15 System.out.println(datas); 16 } 17 18 static List<Map<String, Object>> read(String sql) throws SQLException { 19 Connection conn = null; 20 PreparedStatement ps = null; 21 ResultSet rs = null; 22 23 try { 24 conn = JdbcUtils.getConnection(); 25 ps = conn.prepareStatement(sql); 26 rs = ps.executeQuery(); 27 ResultSetMetaData rsmd = rs.getMetaData(); 28 int count = rsmd.getColumnCount();// 获取返回结果列数 29 String[] colNames = new String[count]; 30 for (int i = 1; i <= count; i++) { 31 colNames[i-1] = rsmd.getColumnName(i); 32 } 33 List<Map<String, Object>> datas = new ArrayList<Map<String, Object>>(); 34 while (rs.next()) { 35 Map<String, Object> data = new HashMap<String, Object>(); 36 for (int i = 0; i < colNames.length; i++) { 37 data.put(colNames[i], rs.getObject(colNames[i])); 38 } 39 datas.add(data); 40 } 41 return datas; 42 } finally { 43 JdbcUtils.close(rs, ps, conn); 44 } 45 } 46 }
JDBC学习笔记(15)：利用结果集元数据将查询结果封装为map
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原文地址：http://www.cnblogs.com/xiaoxiaoyihan/p/4390784.html
