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：

 package com.hongyuan.db;

 import java.math.BigDecimal;
 import java.net.URL;
 import java.sql.Array;
 import java.sql.Blob;
 import java.sql.Clob;
 import java.sql.Connection;
 import java.sql.Date;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.SQLXML;
 import java.sql.Statement;
 import java.sql.Time;
 import java.sql.Timestamp;
 import java.util.ArrayList;
 import java.util.List;

 import javax.sql.DataSource;
 import javax.sql.rowset.CachedRowSet;

 import com.sun.rowset.CachedRowSetImpl;

 public class DBUtil {
     private DataSource ds = null;

     public DataSource getDs() {
         return ds;
     }

     public void setDs(DataSource ds) {
         this.ds = ds;
     }

     public DBUtil() {
     }

     public DBUtil(DataSource ds) {
         this.ds = ds;
     }

     public Connection getConnection() throws SQLException {
         return ds.getConnection();
     }

     public static void close(Connection conn, Statement s, ResultSet rs)
             throws SQLException {
         if (rs != null)
             rs.close();
         if (s != null)
             s.close();
         if (conn != null)
             conn.close();
     }

     public Object query(String sql) throws SQLException {
         return this.query(sql, null);
     }

     public Object query(String sql, List params) throws SQLException {
         Connection conn = null;
         PreparedStatement ps = null;
         ResultSet rs = null;
         try {
             conn = this.getConnection();
             ps = conn.prepareStatement(sql);

             if (null != params) {
                 //初始化查询参数
                 this.initParam(ps, params);
             }
             //处理结果集 http://www.cnblogs.com/roucheng/
             boolean isResultSet = ps.execute();
             List result = new ArrayList();
             do {
                 if (isResultSet) {
                     CachedRowSet crs = new CachedRowSetImpl();
                     crs.populate(ps.getResultSet());
                     result.add(crs);
                 } else {
                     result.add(new Integer(ps.getUpdateCount()));
                 }
             } while ((isResultSet = ps.getMoreResults()) == true
                     || ps.getUpdateCount() != -1);

             if (result.size() == 0) {
                 return null;
             } else if (result.size() == 1) {
                 return result.get(0);
             } else {
                 return result;
             }
         } catch (SQLException e) {
             throw new SQLException("无法执行的sql语句!");
         } finally {
             DBUtil.close(conn, ps, rs);
         }
     }
     //初始化查询参数
     private void initParam(PreparedStatement ps, List params)
             throws SQLException {
         for (int i = 0; i < params.size(); i++) {
             Object param = params.get(i);
             if (param instanceof Byte) {
                 ps.setByte(i + 1, (Byte) param);
             } else if (param instanceof Short) {
                 ps.setShort(i + 1, (Short) param);
             } else if (param instanceof Integer) {
                 ps.setInt(i + 1, (Integer) param);
             } else if (param instanceof Long) {
                 ps.setLong(i + 1, (Long) param);
             } else if (param instanceof Float) {
                 ps.setFloat(i + 1, (Float) param);
             } else if (param instanceof Double) {
                 ps.setDouble(i + 1, (double) param);
             } else if (param instanceof BigDecimal) {
                 ps.setBigDecimal(i + 1, (BigDecimal) param);
             } else if (param instanceof Boolean) {
                 ps.setBoolean(i + 1, (Boolean) param);
             } else if (param instanceof String) {
                 ps.setString(i + 1, (String) param);
             } else if (param instanceof Time) {
                 ps.setTime(i + 1, (Time) param);
             } else if (param instanceof Date) {
                 ps.setDate(i + 1, (Date) param);
             } else if (param instanceof Timestamp) {
                 ps.setTimestamp(i + 1, (Timestamp) param);
             } else if (param instanceof Array) {
                 ps.setArray(i + 1, (Array) param);
             } else if (param instanceof Blob) {
                 ps.setBlob(i + 1, (Blob) param);
             } else if (param instanceof Clob) {
                 ps.setClob(i + 1, (Clob) param);
             } else if (param instanceof SQLXML) {
                 ps.setSQLXML(i + 1, (SQLXML) param);
             } else if (param instanceof URL) {
                 ps.setURL(i, (URL) param);
             } else {
                 ps.setObject(i + 1, param);
             }
         }
     }
 }

上面类的使用 DBUtilTest.java：

 package com.hongyuan.db;

 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;

 import javax.sql.DataSource;

 import org.junit.BeforeClass;
 import org.junit.Test;

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

 public class DBUtilTest {

     private static DataSource ds=null;

     @BeforeClass
     public static void setUpBeforeClass() throws Exception {
         MysqlDataSource mds=new MysqlDataSource();
         mds.setURL("jdbc:mysql://127.0.0.1:3306/test");
         mds.setUser("root");
         mds.setPassword("123456");
         ds=mds;
     }

     @Test
     public void testQuery() throws SQLException {
         DBUtil util=new DBUtil(ds);
         List params=new ArrayList();
         params.add(2);
         Object obj=util.query("select * from emp where id=?",params);
         if(obj instanceof ResultSet){
             ResultSet rs=(ResultSet)obj;
             while(rs.next()){
                 for(int i=0;i<rs.getMetaData().getColumnCount();i++){
                     System.out.print(rs.getObject(i+1)+"\t");
                 }
                 System.out.println();
             }
         }else{
             System.out.println(obj);
         }
     }

 }