package cn.java.jdbc;
import java.io.InputStream;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class Configuration {
  private String url;
  private String driver;
  private String username;
  private String password;
  public Configuration() {
  }
  public Configuration(String url, String driver, String username,
      String password) {
    super();
    this.url = url;
    this.driver = driver;
    this.username = username;
    this.password = password;
  }
  public static Configuration getConfigure()
  {
    try {
      InputStream in = Configuration.class.getResourceAsStream("/db.xml");
      if (null!=in) {
        return load(in);
      }
      return null;
    } catch (DocumentException e) {
      e.printStackTrace();
      return null;
    }
  }
  private static Configuration load(InputStream in) throws DocumentException {
    SAXReader reader = new SAXReader();
    Document doc = reader.read(in);
    Element jdbc = doc.getRootElement();
    String url = jdbc.element("url").getText();
    String driver = jdbc.element("driver").getText();
    String username = jdbc.element("username").getText();
    String password = jdbc.element("password").getText();
    Configuration cfg = new Configuration(url, driver, username, password);
    return cfg;
  }
  public String getUrl() {
    return url;
  }
  public void setUrl(String url) {
    this.url = url;
  }
  public String getDriver() {
    return driver;
  }
  public void setDriver(String driver) {
    this.driver = driver;
  }
  public String getUsername() {
    return username;
  }
  public void setUsername(String username) {
    this.username = username;
  }
  public String getPassword() {
    return password;
  }
  public void setPassword(String password) {
    this.password = password;
  }
}

<?xml version="1.0" encoding="UTF-8"?>
<jdbc>
<url>jdbc:mysql://localhost:3306/test</url>
<driver>com.mysql.jdbc.Driver</driver>
<username>root</username>
<password></password>
</jdbc>

package cn.java.jdbc;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class ConnectionFactory {
  private static ConnectionFactory connectionFactory=null;
  private static Configuration config=Configuration.getConfigure();
  private ConnectionFactory()
  {
    try {
    Class.forName(config.getDriver());
  } catch (ClassNotFoundException e) {
  }
  }
  public Connection getConnection() throws SQLException
  {
    Connection con=null;
    try {
      con=DriverManager.getConnection(config.getUrl(), config.getUsername(), config.getPassword());
      return con;
    }finally{
//     if (null != con) {
//       con.close();
//     }
    }
  }
  public static ConnectionFactory getInstance()
  {
    if (null==connectionFactory) {
      connectionFactory=new ConnectionFactory();
    }
    return connectionFactory;
  }
}

package cn.java.jdbc;
import java.sql.Connection;
import java.sql.SQLException;
import javax.sql.DataSource;
import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;
public class ConnectionFactory2 {
  private DataSource ds ;
  private static ConnectionFactory2 connectionFactory2 = null;
  private ConnectionFactory2() {
    MysqlDataSource myDS = new MysqlDataSource() ;
    myDS.setServerName("localhost");
    myDS.setDatabaseName("test");
    myDS.setPort(3306) ;
    myDS.setUser("root");
    myDS.setCharacterEncoding("utf-8");
    myDS.setPassword("");
    this.ds = myDS ;
  }
  public Connection getConnection() throws SQLException {
    Connection conn = null;
    try {
      conn = ds.getConnection() ;
      conn.setAutoCommit(false);
      return conn;
    } catch (SQLException e) {
      if (null != conn) {
        conn.close();
      }
      throw e;
    }
  }
  public static ConnectionFactory2 getInstance() {
    if (null == connectionFactory2) {
      connectionFactory2 = new ConnectionFactory2();
    }
    return connectionFactory2;
  }
}

package cn.java.jdbc;
public class User {
  private int id;
  private String name;
  public User() {
  }
  public User(int id, String name) {
    this.id = id;
    this.name = name;
  }
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
}

package cn.java.jdbc;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class UserDao {
  private PreparedStatement st = null;
  private ResultSet rs = null;
  public UserDao() {
  }
  public void insert( Connection con,String name) throws SQLException,IOException {
    String sql="insert into user(name) values(?) ";
    try{
      st=con.prepareStatement(sql);
      st.setString(1, name);
      st.executeUpdate();
    }finally{
      if (null!=st) {
        st.close();
      }
    }
  }
  public void delete(Connection con,int id) throws SQLException,IOException {
    String sql="delete from user where id=?";
    try{
      st=con.prepareStatement(sql);
      st.setInt(1, id);
      st.executeUpdate();
    }finally{
      if (null!=st) {
        st.close();
      }
    }
  }
  public void update( Connection con,int id,String name) throws SQLException,IOException {
    String sql="update user set name=? where id=?";
    try{
      st=con.prepareStatement(sql);
      st.setString(1, name);
      st.setInt(2, id);
      st.executeUpdate();
    }finally{
      if (null!=st) {
        st.close();
      }
    }
  }
  public User query(Connection con,int index) throws SQLException,IOException{
    User user=new User();
    String sql="select * from user where id=?";
    try{
      st=con.prepareStatement(sql);
      st.setInt(1, index);
      rs=st.executeQuery();
      while (rs.next()) {
        user.setId(rs.getInt(1));
        user.setName(rs.getString(2));
        break;
      }
    }finally{
      if (null!=rs) {
        rs.close();
      }
      if (null!=st) {
        st.close();
      }
    }
    return user;
  }
  public List<User> queryAll(Connection con) throws SQLException,IOException {
    List<User> list=new ArrayList<>();
    String sql="select * from user";
    try {
      st=con.prepareStatement(sql);
      rs=st.executeQuery();
      while (rs.next()) {
        User user=new User();
        user.setId(rs.getInt(1));
        user.setName(rs.getString(2));
        list.add(user);
      }
    }finally{
      if (null!=rs) {
        rs.close();
      }
      if (null!=st) {
        st.close();
      }
    }
    return list;
  }
}

package cn.java.jdbc;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
public class TestJdbc {
  public static void main(String[] args) {
    Connection con=null;
    try {
      con=(Connection) ConnectionFactory.getInstance().getConnection();
      UserDao userDao=new UserDao();
      //con=(Connection) ConnectionFactory2.getInstance().getConnection();
      if (null!=con) {
        System.out.println("Link JDBC SUCESS");
        //userDao.insert(con, "zhangsir");
        //userDao.delete(con, 4);
        //userDao.update(con, 1, "david");
        List<User> list=userDao.queryAll(con);
        for (User user : list) {
          System.out.println("id="+user.getId()+" name="+user.getName());
        }
      }
    } catch (SQLException e) {
      e.printStackTrace();
    } catch (IOException e) {
    e.printStackTrace();
    }finally{
      if (null!=con) {
        try {
          con.close();
        } catch (SQLException e) {
        }
      }
    }
  }
}