Java MySQL数据库操作

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关于MySQL的基础的四种操作

亲手封装的工具类

package com.wkk.util;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

public class DBUtil {

    /**
     * 默认链接
     *
     * @return
     */
    public static Connection getConnection() {
        return getConnection("localhost", "3306", "wkk", "root", "");
    }

    /**
     * @param ip
     * @param port
     * @param dbName
     * @param user
     * @param password
     * @return
     */
    public static Connection getConnection(String ip, String port, String dbName, String user, String password) {
        Connection connection = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(
                    "jdbc:mysql://" + ip + ":" + port + "/" + dbName + "?useUnicode=true&characterEncoding=utf8", user, password);

        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }

    /**
     * 执行sql语句
     *
     * @param sql
     * @return
     */
    public static boolean executeSQL(String sql) {
        Connection connection = getConnection();
        boolean result = false;
        try {
            Statement statement = connection.createStatement();
            statement.executeUpdate(sql);
            statement.close();
            result = true;
        } catch (SQLException e) {
            e.printStackTrace();
            result = false;
        }
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 获取唯一ID
     *
     * @return
     */
    public static String getID() {
        return UUID.randomUUID().toString().replace("-", "");
    }

    /**
     * 根据sql装载对象
     *
     * @param sql
     * @param class_
     */
    public static Object loadObject(String sql, Class class_) {
        Connection connection = getConnection();
        Object object = null;
        try {
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(sql);
            if (resultSet.next()) {
                object = load(resultSet, class_);
            }
            resultSet.close();
            statement.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return object;
    }

    /**
     * 装载集合
     *
     * @param sql
     * @param class_
     * @return
     */
    public static List loadArray(String sql, Class class_) {
        Connection connection = getConnection();
        List<Object> list = new ArrayList<>();
        try {
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(sql);
            while (resultSet.next()) {
                Object object = load(resultSet, class_);
                list.add(object);
            }
            resultSet.close();
            statement.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }

    private static Object load(ResultSet resultSet, Class class_) {
        Object object = null;
        try {
            object = class_.newInstance();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        if (object == null)
            return null;

        ResultSetMetaData resultSetMetaData = null;
        try {
            resultSetMetaData = resultSet.getMetaData();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        int columnCount = 0;
        try {
            columnCount = resultSetMetaData.getColumnCount();
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }

        Field fields[] = class_.getDeclaredFields();
        Map<String, Field> map = new HashMap<>();
        for (Field field : fields) {
            map.put(field.getName().toUpperCase(), field);
        }

        for (int i = 0; i < columnCount; i++) {
            try {
                String name = resultSetMetaData.getColumnName(i + 1);
                Field field = map.get(name.toUpperCase());
                if (field == null) {
                    continue;
                }
                String simpleName = field.getType().getSimpleName();
                Method vMethod = ResultSet.class.getDeclaredMethod("get" + simpleName.substring(0, 1).toUpperCase() + simpleName.substring(1), int.class);
                Object value = vMethod.invoke(resultSet, i + 1);
                Method method = class_.getDeclaredMethod("set" + field.getName().substring(0, 1).toUpperCase() + field.getName().substring(1), field.getType());
                method.invoke(object, value);
            } catch (NoSuchMethodException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return object;
    }

    /**
     * 获取单一值
     */
    public static Object getValue(String sql) {
        Connection connection = getConnection();
        Object object = null;
        try {
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(sql);
            if (resultSet.next()) {
                object = resultSet.getObject(1);
            }
            resultSet.close();
            statement.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return object;
    }

    /**
     * 批量操作
     */
    public static boolean batchUpdate(String sql, int count, BatchSetter batchSetter) {
        Connection connection = DBUtil.getConnection();
        try {
            connection.setAutoCommit(false);
            PreparedStatement preparedStatement = connection.prepareStatement(sql);
            for (int i = 0; i < count; i++) {
                batchSetter.setValues(preparedStatement,i);
                preparedStatement.addBatch();
            }
            preparedStatement.executeBatch();
            connection.commit();
            preparedStatement.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * 批处理设置值的接口
     */
    public interface BatchSetter {
        void setValues(PreparedStatement preparedStatement, int i);
    }


}

1.创建一个测试表

create table user(
userID varchar(32) ,
name varchar(30),
phone varchar(11),
password varchar(30),
createTime datetime,
primary key(userID)
)charset=utf8 ;

2.对应的实体类

package com.wkk.entity;

public class User {

    private String userID;
    private String name;
    private String phone;
    private String password;
    private String createTime;

    public String getUserID() {
        return userID;
    }

    public void setUserID(String userID) {
        this.userID = userID;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getCreateTime() {
        return createTime;
    }

    public void setCreateTime(String createTime) {
        this.createTime = createTime;
    }

    @Override
    public String toString() {
        return "User{" +
                "userID='" + userID + '\'' +
                ", name='" + name + '\'' +
                ", phone='" + phone + '\'' +
                ", password='" + password + '\'' +
                ", createTime='" + createTime + '\'' +
                '}';
    }
}

3.对数据库操作的接口和实现类

package com.wkk.entity.dao;

import com.wkk.entity.User;

import java.util.List;

public interface UserDao {
    /**
     * 创建
     *
     * @param user
     * @return
     */
    boolean createUser(User user);

    /**
     * 删除
     *
     * @param userID
     * @return
     */
    boolean delete(String userID);

    /**
     * 修改名称
     *
     * @param userID
     * @param name
     * @return
     */
    boolean updateUserName(String userID, String name);

    /**
     * 根据用户ID查询
     *
     * @param userID
     * @return
     */
    User getUser(String userID);

    /**
     * 获取user表中总记录数
     *
     * @return
     */
    long getCount();

    /**
     * 随机获取一条数据
     *
     * @return
     */
    User getRandomUser();

    /**
     * 获取全部
     * @return
     */
    List<User> getAll();
}

package com.wkk.entity.dao.impl;

import com.wkk.db.DBUtil;
import com.wkk.entity.User;
import com.wkk.entity.dao.UserDao;

import java.util.List;

public class UserDaoImpl implements UserDao {


    @Override
    public boolean createUser(User user) {
        String sql = "insert into  user (userID,name,phone,password,createTime) value " +
                "('" + DBUtil.getID() + "','" + user.getName() + "','" + user.getPhone() + "','" + user.getPassword() + "',now());";
        return DBUtil.executeSQL(sql);
    }

    @Override
    public boolean delete(String userID) {
        String sql = "delete from user where userID='" + userID + "';";
        return DBUtil.executeSQL(sql);
    }

    @Override
    public boolean updateUserName(String userID, String name) {
        String sql = "update user set name='" + name + "' where userID='" + userID + "';";
        return DBUtil.executeSQL(sql);
    }

    @Override
    public User getUser(String userID) {
        String sql = "select * from user where userID='" + userID + "' ;";
        return (User) DBUtil.loadObject(sql, User.class);
    }

    @Override
    public long getCount() {
        String sql = "select count(*) from user;";
        return (long) DBUtil.getValue(sql);
    }

    @Override
    public User getRandomUser() {
        String sql = "select * from user  order  by rand() limit 1;";
        return (User) DBUtil.loadObject(sql, User.class);
    }

    @Override
    public List<User> getAll() {
        String sql = "select * from user";
        return DBUtil.loadArray(sql, User.class);
    }


}

4.测试

package com.wkk.db;

import com.wkk.entity.User;
import com.wkk.entity.dao.UserDao;
import com.wkk.entity.dao.impl.UserDaoImpl;

import java.util.List;
import java.util.Random;

public class Test {

    public static void main(String agr[]) {
        UserDao userDao = new UserDaoImpl();
        //1.初始化10条数据
        for (int i = 0; i < 10; i++) {
            User user = new User();
            user.setPassword("888888");
            user.setPhone(getPhone());
            user.setName(getName());
            userDao.createUser(user);
        }
        //2.查询总记录条数
        System.out.println(userDao.getCount());
        //3.随机查询一条数据
        User user = userDao.getRandomUser();
        System.out.println(user);
        //4.删除
        userDao.delete(user.getUserID());
        System.out.println(userDao.getCount());
        //5.修改
        user = userDao.getRandomUser();
        System.out.println(user);
        userDao.updateUserName(user.getUserID(), "李四");
        //6.查询
        user = userDao.getUser(user.getUserID());
        System.out.println(user);
        System.out.println();
        //7.查询全部
        List<User> list = userDao.getAll();
        for (User user1 : list) {
            System.out.println(user1);
        }
    }

    public static String getName() {
        String name = "";
        for (int i = 0; i < 2; i++) {
            name += new String(new char[]{(char) (new Random().nextInt(20902) + 19968)});
        }
        return name;
    }

    public static String getPhone() {
        String phone = "";
        for (int i = 0; i < 11; i++) {
            phone += String.valueOf((int) (Math.random() * 10));
        }
        return phone;
    }
}

运行结果:

10
User{userID='055226a0de1548e9abb6bb130ad56373', name='姀莵', phone='72417557386', password='888888', createTime='2018-01-10 12:18:32.0'}
9
User{userID='510831be2c3c4a40a157ae378834d474', name='燔蠭', phone='94456920210', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='510831be2c3c4a40a157ae378834d474', name='李四', phone='94456920210', password='888888', createTime='2018-01-10 12:18:32.0'}

User{userID='0284a7411c63489d85ac73145b18aad5', name='雠鉘', phone='71624562102', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='0e95276060fb402a9de985df4623d648', name='辜腭', phone='58807577008', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='181b27acfb474933a92a279e4c6eda78', name='聿飜', phone='08291959176', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='1a3d161ebcc842e99d51eaffa05a3173', name='鞛釚', phone='39505832540', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='2aae35c5ff094aecbde56f7ab76e3402', name='燍薈', phone='58669312637', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='2d29f73665b44d6a98f377345437c1a7', name='妀秛', phone='69024250227', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='510831be2c3c4a40a157ae378834d474', name='李四', phone='94456920210', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='976960c0a7ea418ca976d472af67a3e1', name='笣叡', phone='50958385645', password='888888', createTime='2018-01-10 12:18:32.0'}
User{userID='af860f1e12e84014bd2f2d4f8c7bd26e', name='漕鑛', phone='49590492862', password='888888', createTime='2018-01-10 12:18:32.0'}

Process finished with exit code 0

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