java数据库查询类

通用查询数据库辅助类，可实现任意查询语句的查询，还可以进行多结果集查询。

类的代码：

  1 package com.hongyuan.db;

  2 

  3 import java.math.BigDecimal;

  4 import java.net.URL;

  5 import java.sql.Array;

  6 import java.sql.Blob;

  7 import java.sql.Clob;

  8 import java.sql.Connection;

  9 import java.sql.Date;

 10 import java.sql.PreparedStatement;

 11 import java.sql.ResultSet;

 12 import java.sql.SQLException;

 13 import java.sql.SQLXML;

 14 import java.sql.Statement;

 15 import java.sql.Time;

 16 import java.sql.Timestamp;

 17 import java.util.ArrayList;

 18 import java.util.List;

 19 

 20 import javax.sql.DataSource;

 21 import javax.sql.rowset.CachedRowSet;

 22 

 23 import com.sun.rowset.CachedRowSetImpl;

 24 

 25 public class DBUtil {

 26     private DataSource ds = null;

 27 

 28     public DataSource getDs() {

 29         return ds;

 30     }

 31 

 32     public void setDs(DataSource ds) {

 33         this.ds = ds;

 34     }

 35 

 36     public DBUtil() {

 37     }

 38 

 39     public DBUtil(DataSource ds) {

 40         this.ds = ds;

 41     }

 42 

 43     public Connection getConnection() throws SQLException {

 44         return ds.getConnection();

 45     }

 46 

 47     public static void close(Connection conn, Statement s, ResultSet rs)

 48             throws SQLException {

 49         if (rs != null)

 50             rs.close();

 51         if (s != null)

 52             s.close();

 53         if (conn != null)

 54             conn.close();

 55     }

 56 

 57     public Object query(String sql) throws SQLException {

 58         return this.query(sql, null);

 59     }

 60 

 61     public Object query(String sql, List params) throws SQLException {

 62         Connection conn = null;

 63         PreparedStatement ps = null;

 64         ResultSet rs = null;

 65         try {

 66             conn = this.getConnection();

 67             ps = conn.prepareStatement(sql);

 68             

 69             if (null != params) {

 70                 //初始化查询参数

 71                 this.initParam(ps, params);

 72             }

 73             //处理结果集 http://www.cnblogs.com/roucheng/

 74             boolean isResultSet = ps.execute();

 75             List result = new ArrayList();

 76             do {

 77                 if (isResultSet) {

 78                     CachedRowSet crs = new CachedRowSetImpl();

 79                     crs.populate(ps.getResultSet());

 80                     result.add(crs);

 81                 } else {

 82                     result.add(new Integer(ps.getUpdateCount()));

 83                 }

 84             } while ((isResultSet = ps.getMoreResults()) == true

 85                     || ps.getUpdateCount() != -1);

 86 

 87             if (result.size() == 0) {

 88                 return null;

 89             } else if (result.size() == 1) {

 90                 return result.get(0);

 91             } else {

 92                 return result;

 93             }

 94         } catch (SQLException e) {

 95             throw new SQLException("无法执行的sql语句!");

 96         } finally {

 97             DBUtil.close(conn, ps, rs);

 98         }

 99     }

100     //初始化查询参数

101     private void initParam(PreparedStatement ps, List params)

102             throws SQLException {

103         for (int i = 0; i < params.size(); i++) {

104             Object param = params.get(i);

105             if (param instanceof Byte) {

106                 ps.setByte(i + 1, (Byte) param);

107             } else if (param instanceof Short) {

108                 ps.setShort(i + 1, (Short) param);

109             } else if (param instanceof Integer) {

110                 ps.setInt(i + 1, (Integer) param);

111             } else if (param instanceof Long) {

112                 ps.setLong(i + 1, (Long) param);

113             } else if (param instanceof Float) {

114                 ps.setFloat(i + 1, (Float) param);

115             } else if (param instanceof Double) {

116                 ps.setDouble(i + 1, (double) param);

117             } else if (param instanceof BigDecimal) {

118                 ps.setBigDecimal(i + 1, (BigDecimal) param);

119             } else if (param instanceof Boolean) {

120                 ps.setBoolean(i + 1, (Boolean) param);

121             } else if (param instanceof String) {

122                 ps.setString(i + 1, (String) param);

123             } else if (param instanceof Time) {

124                 ps.setTime(i + 1, (Time) param);

125             } else if (param instanceof Date) {

126                 ps.setDate(i + 1, (Date) param);

127             } else if (param instanceof Timestamp) {

128                 ps.setTimestamp(i + 1, (Timestamp) param);

129             } else if (param instanceof Array) {

130                 ps.setArray(i + 1, (Array) param);

131             } else if (param instanceof Blob) {

132                 ps.setBlob(i + 1, (Blob) param);

133             } else if (param instanceof Clob) {

134                 ps.setClob(i + 1, (Clob) param);

135             } else if (param instanceof SQLXML) {

136                 ps.setSQLXML(i + 1, (SQLXML) param);

137             } else if (param instanceof URL) {

138                 ps.setURL(i, (URL) param);

139             } else {

140                 ps.setObject(i + 1, param);

141             }

142         }

143     }

144 }

上面类的使用 DBUtilTest.java：

 1 package com.hongyuan.db;

 2 

 3 import java.sql.ResultSet;

 4 import java.sql.SQLException;

 5 import java.util.ArrayList;

 6 import java.util.List;

 7 

 8 import javax.sql.DataSource;

 9 

10 import org.junit.BeforeClass;

11 import org.junit.Test;

12 

13 import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

14 

15 public class DBUtilTest {

16     

17     private static DataSource ds=null;

18     

19     @BeforeClass

20     public static void setUpBeforeClass() throws Exception {

21         MysqlDataSource mds=new MysqlDataSource();

22         mds.setURL("jdbc:mysql://127.0.0.1:3306/test");

23         mds.setUser("root");

24         mds.setPassword("123456");

25         ds=mds;

26     }

27 

28     @Test

29     public void testQuery() throws SQLException {

30         DBUtil util=new DBUtil(ds);

31         List params=new ArrayList();

32         params.add(2);

33         Object obj=util.query("select * from emp where id=?",params);

34         if(obj instanceof ResultSet){

35             ResultSet rs=(ResultSet)obj;

36             while(rs.next()){

37                 for(int i=0;i<rs.getMetaData().getColumnCount();i++){

38                     System.out.print(rs.getObject(i+1)+"\t");

39                 }

40                 System.out.println();

41             }

42         }else{

43             System.out.println(obj);

44         }

45     }

46 

47 }