jdbc配置及使用测试

源码：https://github.com/xiaostudy/jdbc_test1

这是没有使用连接池的

目录

创建的sql语句create.sql

 DROP TABLE IF EXISTS t_user;

 CREATE TABLE t_user(
 id INT(11) PRIMARY KEY AUTO_INCREMENT,
 user_name VARCHAR(20) NOT NULL DEFAULT "",
 password VARCHAR(20) NOT NULL DEFAULT ""
 )ENGINE = INNODB DEFAULT CHARSET = utf8 COMMENT = '用户表';

maven配置pom.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

     <groupId>com.xiaostudy</groupId>
     <artifactId>jdbc_test1</artifactId>
     <version>1.0.0</version>

     <properties>
         <jdbc.version>5.1.46</jdbc.version>
     </properties>

     <dependencies>
         <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
         <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
             <version>${jdbc.version}</version>
         </dependency>
     </dependencies>
 </project>

Base实体类User.java

 package com.xiaostudy.Base;

 /**
  * Created with IntelliJ IDEA.
  * User: Administrator
  * Date: 2019/5/4
  * Time: 12:10
  * Description: No Description
  */
 public class User {

     private Integer id;
     private String userName;
     private String password;

     public Integer getId() {
         return id;
     }

     public void setId(Integer id) {
         this.id = id;
     }

     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;
     }

     @Override
     public String toString() {
         return "User{" +
                 "id=" + id +
                 ", userName='" + userName + '\'' +
                 ", password='" + password + '\'' +
                 '}';
     }
 }

mysql连接配置db.properties

 driver = com.mysql.jdbc.Driver
 url = jdbc:mysql://localhost:3306/lw_test?useUnicode=true&characterEncoding=UTF-8
 userName = root
 password = root

重点，jdbc配置JdbcUtil.java

 package com.xiaostudy.util;

 import java.io.FileInputStream;
 import java.io.IOException;
 import java.sql.*;
 import java.util.Properties;

 /**
  * Created with IntelliJ IDEA.
  * User: xiaostudy
  * Date: 2019/5/4
  * Time: 11:58
  * Description: No Description
  */
 public class JdbcUtil {

     private static Connection connection;

     public static Connection getConnection() {
         if(null != connection) {
             return connection;
         }

         Properties pt = new Properties();
         try {
             FileInputStream fis = new FileInputStream("src\\main\\resources\\db.properties");
             pt.load(fis);
         } catch (IOException e) {
             e.printStackTrace();
         }
         String driver = pt.getProperty("driver");
         String url = pt.getProperty("url");
         String userName = pt.getProperty("userName");
         String password = pt.getProperty("password");

         if(null == driver || null == url || null == userName || null == password) {
             return null;
         }

         Connection conn = null;
         try {
             Class.forName(driver); //classLoader,加载对应驱动
             conn = DriverManager.getConnection(url, userName, password);
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         } catch (SQLException e) {
             e.printStackTrace();
         }
         return conn;
     }

     public static void close(PreparedStatement pstmt, Connection conn,ResultSet rs) {
         try {
             if(null != rs) {
                 rs.close();
                 rs = null;
             }
             if(null != pstmt) {
                 pstmt.close();
                 pstmt = null;
             }
             if(null != conn) {
                 conn.close();
                 conn = null;
             }
         } catch (SQLException e) {
             e.printStackTrace();
         }
     }
 }

操作数据库UserDao.java

 package com.xiaostudy.dao;

 import com.xiaostudy.Base.User;
 import com.xiaostudy.util.JdbcUtil;
 import com.xiaostudy.util.MyDataSource;

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

 /**
  * Created with IntelliJ IDEA.
  * User: xiaostudy
  * Date: 2019/5/4
  * Time: 16:47
  * Description: No Description
  */
 public class UserDao {

     public int insert(User user) {
         if(null == user) {
             return 0;
         }

         Connection conn = JdbcUtil.getConnection();
         if(null == conn) {
             return 0;
         }

         int i = 0;
         String sql = "insert into t_user (user_name,password) values(?,?)";
         PreparedStatement pstmt = null;
         try {
             pstmt = (PreparedStatement) conn.prepareStatement(sql);
             pstmt.setString(1, user.getUserName());
             pstmt.setString(2, user.getPassword());
             i = pstmt.executeUpdate();
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             JdbcUtil.close(pstmt, conn, null);
         }
         return i;
     }

     public int update(User user) {
         if(null == user || null == user.getId() || user.getId() <= 0) {
             return 0;
         }

         Connection conn = JdbcUtil.getConnection();
         if(null == conn) {
             return 0;
         }

         int i = 0;
         String sql = "update t_user set user_name='" + user.getUserName() + "', password='" + user.getPassword() + "' where id='" + user.getId() + "' ";
         PreparedStatement pstmt = null;
         try {
             pstmt = (PreparedStatement) conn.prepareStatement(sql);
             i = pstmt.executeUpdate();
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             JdbcUtil.close(pstmt, conn, null);
         }
         return i;
     }

     public List<User> getAll() {
         List<User> list = new ArrayList<User>();
         Connection conn = JdbcUtil.getConnection();
         if(null == conn) {
             return list;
         }

         String sql = "select id, user_name, password from t_user";
         PreparedStatement pstmt = null;
         ResultSet rs = null;
         try {
             pstmt = (PreparedStatement)conn.prepareStatement(sql);
             rs = pstmt.executeQuery();
             while (rs.next()) {
                 User user = new User();
                 user.setId(rs.getInt(1));
                 user.setUserName(rs.getString("user_name"));
                 user.setPassword(rs.getString("password"));
                 list.add(user);
             }
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             JdbcUtil.close(pstmt, conn, rs);
         }
         return list;
     }

     public User getUserByUserName(String userName) {
         if(null == userName || userName.trim().length() <= 0) {
             return null;
         }

         Connection conn = JdbcUtil.getConnection();
         if(null == conn) {
             return null;
         }

         User user = new User();
         String sql = "select id, user_name, password from t_user where user_name='" + userName + "'";
         PreparedStatement pstmt = null;
         ResultSet rs = null;
         try {
             pstmt = (PreparedStatement)conn.prepareStatement(sql);
             rs = pstmt.executeQuery();
             while (rs.next()) {
                 user.setId(rs.getInt(1));
                 user.setUserName(rs.getString("user_name"));
                 user.setPassword(rs.getString("password"));
             }
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             JdbcUtil.close(pstmt, conn, rs);
         }
         return user;
     }

     public int delete(String userName) {
         if(null == userName || userName.trim().length() <= 0) {
             return 0;
         }

         Connection conn = JdbcUtil.getConnection();
         if(null == conn) {
             return 0;
         }

         int i = 0;
         String sql = "delete from t_user where user_name='" + userName + "'";
         PreparedStatement pstmt = null;
         try {
             pstmt = (PreparedStatement) conn.prepareStatement(sql);
             i = pstmt.executeUpdate();
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             JdbcUtil.close(pstmt, conn, null);
         }
         return i;
     }
 }

测试Test_jdbc.java

 package com.xiaostudy.test;

 import com.xiaostudy.Base.User;
 import com.xiaostudy.dao.UserDao;
 import com.xiaostudy.util.JdbcUtil;

 import java.util.List;

 /**
  * Created with IntelliJ IDEA.
  * User: Administrator
  * Date: 2019/5/4
  * Time: 15:05
  * Description: No Description
  */
 public class Test_jdbc {

     public static void main(String[] agrs) {
         UserDao userDao = new UserDao();

         //查询全部用户
         List<User> list = userDao.getAll();
         System.out.println(list);
         //查询某个用户名下的用户
 //        User user = userDao.getUserByUserName("张三");
 //        System.out.println(user);

         // 新建用户
 //        User user = new User();
 //        user.setUserName("张三");
 //        user.setPassword("123");
 //        int insert = userDao.insert(user);
 //        System.out.println(insert);

         //新建用户
 //        User user = new User();
 //        user.setUserName("李四");
 //        user.setPassword("123444");
 //        int insert = userDao.insert(user);
 //        System.out.println(insert);

         //删除用户
 //        int i = userDao.delete("李四");
 //        System.out.println(i);

         //修改用户
 //        User user = userDao.getUserByUserName("李四");
 //        user.setPassword("1995");
 //        int i = userDao.update(user);
 //        System.out.println(i);

 //        list = userDao.getAll();
 //        System.out.println(list);
     }
 }

---

以下是使用自定义的连接池

目录

自定义的连接池MyDataSource.java

 package com.xiaostudy.util;

 import java.io.PrintWriter;
 import java.sql.*;
 import java.util.LinkedList;
 import java.util.logging.Logger;

 import javax.sql.DataSource;

 public class MyDataSource implements DataSource {
     private static LinkedList<Connection> pool=new LinkedList<Connection>();
     static{
         for (int i = 0; i < 5; i++) {
             Connection conn=JdbcUtil.getConnection();
             pool.add(conn);
         }
     }

     @Override
     public Connection getConnection() throws SQLException {
         Connection conn=null;
         if (0 == pool.size()) {
             for (int i = 0; i < 5; i++) {
                 conn=JdbcUtil.getConnection();
                 pool.add(conn);
             }
         }
         conn=pool.remove(0);
         return conn;
     }

     public static void close(Connection conn){
         pool.add(conn);
     }

     public static void close(PreparedStatement pstmt, Connection conn, ResultSet rs) {
         if(null != conn) {
             pool.add(conn);
         }
         JdbcUtil.close(pstmt, null, rs);
     }

     @Override
     public PrintWriter getLogWriter() throws SQLException {
         return null;
     }

     @Override
     public int getLoginTimeout() throws SQLException {
         // TODO Auto-generated method stub
         return 0;
     }

     @Override
     public Logger getParentLogger() throws SQLFeatureNotSupportedException {
         // TODO Auto-generated method stub
         return null;
     }

     @Override
     public void setLogWriter(PrintWriter arg0) throws SQLException {
         // TODO Auto-generated method stub

     }

     @Override
     public void setLoginTimeout(int arg0) throws SQLException {
         // TODO Auto-generated method stub

     }

     @Override
     public boolean isWrapperFor(Class<?> arg0) throws SQLException {
         // TODO Auto-generated method stub
         return false;
     }

     @Override
     public <T> T unwrap(Class<T> arg0) throws SQLException {
         // TODO Auto-generated method stub
         return null;
     }

     @Override
     public Connection getConnection(String arg0, String arg1)
             throws SQLException {

         return null;
     }

 }

使用连接池的dao，UserDao_MyDataSource.java

 package com.xiaostudy.dao;

 import com.xiaostudy.Base.User;
 import com.xiaostudy.util.MyDataSource;

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

 /**
  * Created with IntelliJ IDEA.
  * User: xiaostudy
  * Date: 2019/5/4
  * Time: 16:47
  * Description: No Description
  */
 public class UserDao_MyDataSource {

     private static MyDataSource myDataSource;

     static {
         myDataSource = new MyDataSource();
     }

     public int insert(User user) {
         if(null == user) {
             return 0;
         }

         Connection conn = null;
         try {
             conn = myDataSource.getConnection();
         } catch (SQLException e) {
             e.printStackTrace();
         }
         if(null == conn) {
             return 0;
         }

         int i = 0;
         String sql = "insert into t_user (user_name,password) values(?,?)";
         PreparedStatement pstmt = null;
         try {
             pstmt = (PreparedStatement) conn.prepareStatement(sql);
             pstmt.setString(1, user.getUserName());
             pstmt.setString(2, user.getPassword());
             i = pstmt.executeUpdate();
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             MyDataSource.close(pstmt, conn, null);
         }
         return i;
     }

     public int update(User user) {
         if(null == user || null == user.getId() || user.getId() <= 0) {
             return 0;
         }

         Connection conn = null;
         try {
             conn = myDataSource.getConnection();
         } catch (SQLException e) {
             e.printStackTrace();
         }
         if(null == conn) {
             return 0;
         }

         int i = 0;
         String sql = "update t_user set user_name='" + user.getUserName() + "', password='" + user.getPassword() + "' where id='" + user.getId() + "' ";
         PreparedStatement pstmt = null;
         try {
             pstmt = (PreparedStatement) conn.prepareStatement(sql);
             i = pstmt.executeUpdate();
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             MyDataSource.close(pstmt, conn, null);
         }
         return i;
     }

     public List<User> getAll() {
         List<User> list = new ArrayList<User>();
         Connection conn = null;
         try {
             conn = myDataSource.getConnection();
         } catch (SQLException e) {
             e.printStackTrace();
         }
         if(null == conn) {
             return list;
         }

         String sql = "select id, user_name, password from t_user";
         PreparedStatement pstmt = null;
         ResultSet rs = null;
         try {
             pstmt = (PreparedStatement)conn.prepareStatement(sql);
             rs = pstmt.executeQuery();
             while (rs.next()) {
                 User user = new User();
                 user.setId(rs.getInt(1));
                 user.setUserName(rs.getString("user_name"));
                 user.setPassword(rs.getString("password"));
                 list.add(user);
             }
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             MyDataSource.close(pstmt, conn, rs);
         }
         return list;
     }

     public User getUserByUserName(String userName) {
         if(null == userName || userName.trim().length() <= 0) {
             return null;
         }

         Connection conn = null;
         try {
             conn = myDataSource.getConnection();
         } catch (SQLException e) {
             e.printStackTrace();
         }
         if(null == conn) {
             return null;
         }

         User user = new User();
         String sql = "select id, user_name, password from t_user where user_name='" + userName + "'";
         PreparedStatement pstmt = null;
         ResultSet rs = null;
         try {
             pstmt = (PreparedStatement)conn.prepareStatement(sql);
             rs = pstmt.executeQuery();
             while (rs.next()) {
                 user.setId(rs.getInt(1));
                 user.setUserName(rs.getString("user_name"));
                 user.setPassword(rs.getString("password"));
             }
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             MyDataSource.close(pstmt, conn, rs);
         }
         return user;
     }

     public int delete(String userName) {
         if(null == userName || userName.trim().length() <= 0) {
             return 0;
         }

         Connection conn = null;
         try {
             conn = myDataSource.getConnection();
         } catch (SQLException e) {
             e.printStackTrace();
         }
         if(null == conn) {
             return 0;
         }

         int i = 0;
         String sql = "delete from t_user where user_name='" + userName + "'";
         PreparedStatement pstmt = null;
         try {
             pstmt = (PreparedStatement) conn.prepareStatement(sql);
             i = pstmt.executeUpdate();
         } catch (SQLException e) {
             e.printStackTrace();
         } finally {
             MyDataSource.close(pstmt, conn, null);
         }
         return i;
     }
 }

测试，就是把之前的

UserDao userDao = new UserDao();
换成
UserDao_MyDataSource userDao = new UserDao_MyDataSource();

 package com.xiaostudy.test;

 import com.xiaostudy.Base.User;
 import com.xiaostudy.dao.UserDao_MyDataSource;

 import java.util.List;

 /**
  * Created with IntelliJ IDEA.
  * User: Administrator
  * Date: 2019/5/4
  * Time: 15:05
  * Description: No Description
  */
 public class Test_jdbc2 {

     public static void main(String[] agrs) {
         UserDao_MyDataSource userDao = new UserDao_MyDataSource();

         //查询全部用户
         List<User> list = userDao.getAll();
         System.out.println(list);
         //查询某个用户名下的用户
 //        User user = userDao.getUserByUserName("张三");
 //        System.out.println(user);

         // 新建用户
 //        User user = new User();
 //        user.setUserName("张三");
 //        user.setPassword("123");
 //        int insert = userDao.insert(user);
 //        System.out.println(insert);

         //新建用户
 //        User user = new User();
 //        user.setUserName("李四");
 //        user.setPassword("123444");
 //        int insert = userDao.insert(user);
 //        System.out.println(insert);

         //删除用户
 //        int i = userDao.delete("李四");
 //        System.out.println(i);

         //修改用户
 //        User user = userDao.getUserByUserName("李四");
 //        user.setPassword("1995");
 //        int i = userDao.update(user);
 //        System.out.println(i);

 //        list = userDao.getAll();
 //        System.out.println(list);
     }
 }