Preface

Many steps of database operation are repeated , It is not worth spending a lot of time and manpower to edit , So we can write a tool class by ourselves , When encapsulating several same methods of database operation , It's much more convenient to call directly . In short , To simplify the JDBC operation , Can write less code .

One 、 What are the main steps of encapsulating database operations ？

1. The import related jar package .
2. Create a profile , Go to the configuration file to edit the specific value of the database connection .
3. Write the loading and implementation configuration file in the tool class .
4. To realize the connection of database , close .
5. To implement transaction related operations , Open transaction , Commit transaction , Roll back the transaction .

Two 、 Use steps

1. Import and stock in

The code is as follows （ Example ）：

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

2. Load configuration files and transaction information

The code is as follows （ Example ）：

public class DbUtils {
    
    private static DruidDataSource ds;
    private static final ThreadLocal<Connection> THREAD_LOCAL = new ThreadLocal<>();

    static {
    
        Properties properties = new Properties();
        InputStream is = DbUtils.class.getResourceAsStream("/database.properties");
        try {
    
            properties.load(is);
            ds = (DruidDataSource) DruidDataSourceFactory.createDataSource(properties);
        } catch (IOException e) {
    
            e.printStackTrace();
        } catch (Exception e) {
    
            e.printStackTrace();
        }
    }

3. The connection and closing methods of the database are encapsulated

  // Database connection 
  public static Connection getConnection() {
    
        Connection connection = THREAD_LOCAL.get();
        try {
    
            if (connection == null) {
    
                connection = ds.getConnection();
                THREAD_LOCAL.set(connection);
            }
        } catch (SQLException e) {
    
            e.printStackTrace();
        }
        return connection;
    }

// Database shutdown 
    public static void closeAll(Connection connection, Statement statement, ResultSet resultSet) {
    
        try {
    
            if (resultSet != null) {
    
                resultSet.close();
            }
            if (statement != null) {
    
                statement.close();
            }
            if (connection != null) {
    
                connection.close();
                THREAD_LOCAL.remove();
            }
        } catch (SQLException e) {
    
            e.printStackTrace();
        }
    }

4. Operations related to database transactions

// The beginning of the business 
 public static void begin() {
    
        Connection connection = null;
        try {
    
            connection = getConnection();
            connection.setAutoCommit(false);
        } catch (SQLException e) {
    
            e.printStackTrace();
        }
    }
    
// Commit of transaction 
    public static void commit() {
    
        Connection connection = null;
        try {
    
            connection = getConnection();
            connection.commit();
        } catch (SQLException e) {
    
            e.printStackTrace();
        } finally {
    
            closeAll(connection, null, null);
        }
    }
    
// Rollback of transaction 
    public static void rollback() {
    
        Connection connection = null;
        try {
    
            connection = getConnection();
            connection.rollback();
        } catch (SQLException e) {
    
            e.printStackTrace();
        } finally {
    
            closeAll(connection, null, null);
        }
    }

5. Database connection configuration information

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/ems?useUnicode=true&characterEncoding=UTF-8
username=root
password=123456
# Initialize connection 
initialSize=10
# Maximum number of connections 
maxActive=30
# Minimum free connection 
maxIdle=5
# Timeout waiting time 
maxWait=3000

summary

If there are any mistakes , I hope you will point out that , Thank you for your care .