一个通用的SQL客户程序

能够与任何关系数据库建立连接，并且交互地执行SQL命令，该客户程序能够连接任何jdbc数据源，也可以提交要执行的sqlSELECT命令和非SELECT命令。对于SELECT查询命令，显示执行结果；对于非select命令，显示执行状态。（我的电脑上只有mysql，所以只测了mysql，没有问题）

如下图所示：

代码实现：

  1 import java.awt.*;

  2 import java.awt.event.ActionEvent;

  3 import java.awt.event.ActionListener;

  4 import java.sql.*;

  5 import javax.swing.*;

  6 import javax.swing.border.*;

  7 

  8 

  9 public class SQLClient extends JApplet{

 10     //连接数据库

 11     private Connection connection;

 12     //执行sql命令

 13     private Statement statement;

 14     //输入sql命令 的文本框

 15     private JTextArea jtaSQLCommand=new JTextArea();

 16     //显示sql命令的执行结果的文本框

 17     private JTextArea jtaSQLResult=new JTextArea();

 18     //连接数据库的JDBC相关信息，包括用户名,密码,数据库url，数据库驱动器

 19     JTextField jtfUserName=new JTextField();

 20     JPasswordField jpfPassword=new JPasswordField();

 21     JComboBox jcboURL=new JComboBox(new String[]{

 22             "jdbc:mysql://localhost/world",

 23             "jdbc:odbc:exampleMDBDataSource",

 24             "jdbc:oracle:thin:@liang.armstrong.edu:1521:orcl"

 25     });

 26     JComboBox jcboDriver = new JComboBox(new String[]{

 27             "com.mysql.jdbc.Driver",

 28             "sun.jdbc.odbc.jdbcOdbcDriver",

 29             "oracle.jdbc.driver.OracleDriver"

 30     });

 31     

 32     JButton jbtExecuteSQL =new JButton("Execute SQL Command");

 33     JButton jbtClearSQLCommand=new JButton("Clear");

 34     JButton jbtConnectDB1=new JButton("Connect to DataBase");

 35     JButton jbtClearSQLResult=new JButton("Clear Result");

 36     

 37     //create titled borders

 38     Border titledBorder1=new TitledBorder("Enter an SQL Command");

 39     Border titledBorder2=new TitledBorder("SQL Execute Result");

 40     Border titledBorder3=new TitledBorder("Enter Database Information");

 41     

 42     JLabel jlblConnectionStatus=new JLabel("No connection now");

 43     

 44     public void init(){

 45         JScrollPane jScrollPane1=new JScrollPane(jtaSQLCommand);

 46         jScrollPane1.setBorder(titledBorder1);

 47         JScrollPane jScrollPane2=new JScrollPane(jtaSQLResult);

 48         jScrollPane2.setBorder(titledBorder2);

 49         

 50         JPanel jPanel1=new JPanel(new FlowLayout(FlowLayout.RIGHT));

 51         jPanel1.add(jbtClearSQLCommand);

 52         jPanel1.add(jbtExecuteSQL);

 53         

 54         JPanel jPanel2=new JPanel();

 55         jPanel2.setLayout(new BorderLayout());

 56         jPanel2.add(jScrollPane1,BorderLayout.CENTER);

 57         jPanel2.add(jPanel1,BorderLayout.SOUTH);

 58         jPanel2.setPreferredSize(new Dimension(100,100));

 59         

 60         JPanel jPanel3=new JPanel();

 61         jPanel3.setLayout(new BorderLayout());

 62         jPanel3.add(jlblConnectionStatus,BorderLayout.CENTER);

 63         jPanel3.add(jbtConnectDB1,BorderLayout.EAST);

 64         

 65         JPanel jPanel4=new JPanel();

 66         jPanel4.setLayout(new GridLayout(4,1,10,5));

 67         jPanel4.add(jcboDriver);

 68         jPanel4.add(jcboURL);

 69         jPanel4.add(jtfUserName);

 70         jPanel4.add(jpfPassword);

 71         

 72         JPanel jPanel5=new JPanel();

 73         jPanel5.setLayout(new GridLayout(4,1,10,5));

 74         jPanel5.add(new JLabel("JDBC Driver"));

 75         jPanel5.add(new JLabel("Database URL"));

 76         jPanel5.add(new JLabel("UserName"));

 77         jPanel5.add(new JLabel("Password"));

 78         

 79         JPanel jPanel6 = new JPanel();

 80         jPanel6.setLayout(new BorderLayout());

 81         jPanel6.setBorder(titledBorder3);

 82         jPanel6.add(jPanel4,BorderLayout.CENTER);

 83         jPanel6.add(jPanel5,BorderLayout.WEST);

 84         

 85         JPanel jPanel7 = new JPanel();

 86         jPanel7.setLayout(new BorderLayout());

 87         jPanel7.add(jPanel3,BorderLayout.SOUTH);

 88         jPanel7.add(jPanel6,BorderLayout.CENTER);

 89         

 90         JPanel jPanel8 = new JPanel();

 91         jPanel8.setLayout(new BorderLayout());

 92         jPanel8.add(jPanel2,BorderLayout.CENTER);

 93         jPanel8.add(jPanel7,BorderLayout.WEST);

 94         

 95         JPanel jPanel9=new JPanel(new FlowLayout(FlowLayout.LEFT));

 96         jPanel9.add(jbtClearSQLCommand);

 97         

 98         jcboURL.setEditable(true);

 99         jcboDriver.setEditable(true);

100         

101         add(jPanel8,BorderLayout.NORTH);

102         add(jScrollPane2,BorderLayout.CENTER);

103         add(jPanel9,BorderLayout.SOUTH);

104         //点击execute按钮执行sql语句

105         jbtExecuteSQL.addActionListener(new ActionListener(){

106             public void actionPerformed(ActionEvent arg0) {

107                 executeSQL();

108             }

109         });

110         //连接数据库

111         jbtConnectDB1.addActionListener(new ActionListener(){

112             public void actionPerformed(ActionEvent e) {

113                 // TODO Auto-generated method stub

114                 connectToDB();

115             }

116         });

117         //中兴清除命令的

118         jbtClearSQLCommand.addActionListener(new ActionListener(){

119             public void actionPerformed(ActionEvent e) {

120                 jtaSQLCommand.setText(null);

121             }

122         });

123         

124         jbtClearSQLResult.addActionListener(new ActionListener(){

125             public void actionPerformed(ActionEvent e){

126                 jtaSQLResult.setText(null);

127             }

128         });

129     }

130     

131     private void connectToDB(){

132         String driver=(String)jcboDriver.getSelectedItem();

133         String url=(String)jcboURL.getSelectedItem();

134         String userName=jtfUserName.getText().trim();

135         String password=new String(jpfPassword.getPassword());

136         

137         //连接数据库

138         try{

139             Class.forName(driver);

140             connection=DriverManager.getConnection(url,userName,password);

141             jlblConnectionStatus.setText("Connected to "+url);

142         }catch(java.lang.Exception ex){

143             ex.printStackTrace();

144         }

145     }

146     

147     private void executeSQL(){

148         if(connection==null){

149             jtaSQLResult.setText("Please connect to a database first");

150             return;

151         }else{

152             String sqlCommands=jtaSQLCommand.getText().trim();

153             //trim返回字符串的副本，忽略前导空白和尾部空白。

154             String[] commands=sqlCommands.replace('\n', ' ').split(";");

155             

156             for(String aCommand: commands){

157                 if(aCommand.trim().toUpperCase().startsWith("SELECT")){

158                     //是否以前缀SELECT开始

159                     processSQLSelect(aCommand);

160                 }

161                 else{

162                     processSQLNonSelect(aCommand);

163                 }

164             }

165         }

166     }

167 //执行选择命令

168     private void processSQLSelect(String sqlCommand) {

169         

170         try{

171             statement = connection.createStatement();

172             ResultSet resultSet=statement.executeQuery(sqlCommand);

173             

174             int columnCount=resultSet.getMetaData().getColumnCount();

175             String row=" ";

176             for(int i=1;i<=columnCount;++i)

177                 row+=resultSet.getMetaData().getColumnName(i)+"\t";

178             

179             jtaSQLResult.append(row+"\n");

180             while(resultSet.next()){

181                 row=" ";

182                 for(int i=1;i<=columnCount;++i)

183                     row+=resultSet.getString(i)+"\t";

184                 jtaSQLResult.append(row+'\n');

185             }

186         }catch(SQLException ex){

187             jtaSQLResult.setText(ex.toString());

188         }

189     }

190     //执行非选择命令

191     private void processSQLNonSelect(String sqlCommand) {

192         try{

193             statement=connection.createStatement();

194             statement.executeUpdate(sqlCommand);

195             jtaSQLResult.setText("SQL command excuted");

196         }catch(SQLException ex){

197             jtaSQLResult.setText(ex.toString());

198         }

199     }

200     

201 }