Connecting to Databases Using Java JDBC
Jul 08, 2025 am 02:41 AM
The key to connecting to a database with Java JDBC is the driver, URL format and connection method. First, we need to introduce the JDBC driver of the corresponding database, such as MySQL uses mysql-connector-java, PostgreSQL uses postgresql.jar, Oracle uses ojdbc8.jar, and ensure that the version matches the database; second, we need to correctly configure the connection information, such as the URL format of MySQL is jdbc:mysql://hostname: port/database name? Parameter 1=value 1¶meter 2=value 2. Common problems include the time zone not set, SSL is not closed, host name or port error; finally, pay attention to exception handling and resource release, use try-with-resources to automatically close the Connection, Statement, and ResultSet, capture and print SQLException information. It is recommended to use a connection pool such as HikariCP to manage connection multiplexing to avoid resource leakage. When encountering problems, you should first check the basic configurations such as driver, URL, network and permissions, and then adjust the code.
Answer the question directly: It is not difficult to use Java JDBC to connect to the database, but some details are easy to get stuck. The key is to understand the core points of driver, URL format and connection method.
Get the right JDBC driver ready
JDBC itself is just an interface specification, and the specific way to connect depends on the driver provided by the database manufacturer. For example, MySQL needs to use mysql-connector-java , PostgreSQL is postgresql.jar , and Oracle is ojdbc8.jar .
You have to confirm first:
- Whether the project has introduced the corresponding jar package (see pom.xml for Maven)
- If it is not a Maven project, manually add the driver to the classpath
- Do not mix different versions of drivers, especially old projects may rely on old versions
For example, the URL writing method of MySQL 8.x is much different from that of 5.x. If the driver version is not correct, ClassNotFound will be reported or the database will not be connected.
Properly configure database connection information
The format of JDBC connection strings is usually like this:
jdbc: Database type://hostname:port/database name? Parameter 1=value 1¶meter 2=value 2
Take MySQL as an example:
String url = "jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC"; String user = "root"; String password = "yourpassword"; Connection conn = DriverManager.getConnection(url, user, password);
Common pitfalls:
- No time zone is specified (MySQL will warn)
- Forgot to turn off SSL (some environments must be turned off)
- Network problems such as wrong host name, non-port, and non-existent database
Suggested practices:
- Take out these parameters and put them in the configuration file, and do not hardcode them in the code.
- Before testing the connection, you can ping or telnet to see if the port is open
Handle connection exceptions and resource releases
The connection failure is not necessarily because of the wrong password, it may be because the driver is not loaded, the URL format is wrong, or the firewall is blocked.
Typical practices in Java are:
- Use try-with-resources to automatically close Connection, Statement, and ResultSet
- Capture SQLException and print details
Sample code:
try (Connection conn = DriverManager.getConnection(url, user, password);
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM users")) {
while (rs.next()) {
System.out.println(rs.getString("username"));
}
} catch (SQLException e) {
e.printStackTrace();
}Note:
- Don't forget to close the resources, otherwise it will easily cause connection leakage
- Using connection pools (such as HikariCP) can better manage connection reuse and avoid frequent creation and destruction
Basically that's it. JDBC even says that the database is simple, but problems such as network, permissions, and driver versions may occur during actual deployment. When encountering problems, don’t rush to modify the code, check the basic configuration first.
The above is the detailed content of Connecting to Databases Using Java JDBC. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How to use PHP database connection to implement paging query
Sep 08, 2023 pm 02:28 PM
How to use PHP database connection to implement paging query. When developing web applications, it often involves the need to query the database and perform paging display. As a commonly used server-side scripting language, PHP has powerful database connection functions and can easily implement paging queries. This article will introduce in detail how to use PHP database connection to implement paging query, and attach corresponding code examples. Prepare the database Before we start, we need to prepare a database containing the data to be queried. Here we take the MySQL database as an example,
Advanced PHP database connections: transactions, locks, and concurrency control
Jun 01, 2024 am 11:43 AM
Advanced PHP database connections involve transactions, locks, and concurrency control to ensure data integrity and avoid errors. A transaction is an atomic unit of a set of operations, managed through the beginTransaction(), commit(), and rollback() methods. Locks prevent simultaneous access to data via PDO::LOCK_SHARED and PDO::LOCK_EXCLUSIVE. Concurrency control coordinates access to multiple transactions through MySQL isolation levels (read uncommitted, read committed, repeatable read, serialized). In practical applications, transactions, locks and concurrency control are used for product inventory management on shopping websites to ensure data integrity and avoid inventory problems.
Common database connection and data reading and writing problems in C#
Oct 10, 2023 pm 07:24 PM
Common database connection and data reading and writing problems in C# require specific code examples. In C# development, database connection and data reading and writing are frequently encountered problems. Correct handling of these problems is the key to ensuring code quality and performance. This article will introduce some common database connection and data reading and writing problems, and provide specific code examples to help readers better understand and solve these problems. Database connection issues 1.1 Connection string errors When connecting to the database, a common error is that the connection string is incorrect. The connection string contains the connection to the database
Why does my PHP database connection fail?
Jun 05, 2024 pm 07:55 PM
Reasons for a PHP database connection failure include: the database server is not running, incorrect hostname or port, incorrect database credentials, or lack of appropriate permissions. Solutions include: starting the server, checking the hostname and port, verifying credentials, modifying permissions, and adjusting firewall settings.
How to connect to and operate databases and handle SQL queries
Aug 02, 2023 am 09:06 AM
How to connect and operate the database and process SQL queries. In the process of developing applications, database connection and operation are a very important part. Database is an important tool for storing and managing data, and SQL (StructuredQueryLanguage) is a standard language for querying and operating databases. In this article, we will learn how to connect to and operate a database and show some code examples for handling SQL queries. Connect to the database: First, we need to connect to the database to proceed
WordPress database connection error solution revealed
Mar 05, 2024 pm 01:42 PM
WordPress is currently one of the most popular website building platforms in the world, but during use, you sometimes encounter database connection errors. This kind of error will cause the website to be unable to be accessed normally, causing trouble to the website administrator. This article will reveal how to solve WordPress database connection errors and provide specific code examples to help readers solve this problem more quickly. Problem Analysis WordPress database connection errors are usually caused by the following reasons: Incorrect database username or password data
How to configure database connection in mybatis
Jan 15, 2024 pm 02:12 PM
How to configure database connection in mybatis: 1. Specify the data source; 2. Configure the transaction manager; 3. Configure the type processor and mapper; 4. Use environment elements; 5. Configure aliases. Detailed introduction: 1. Specify the data source. In the "mybatis-config.xml" file, you need to configure the data source. The data source is an interface, which provides a database connection; 2. Configure the transaction manager to ensure the normality of database transactions. For processing, you also need to configure the transaction manager; 3. Configure the type processor and mapper, etc.
The first step in learning Go language: how to implement database connection and operation
Jan 23, 2024 am 08:10 AM
Learn Go language from scratch: How to implement database connection and operation, specific code examples are required 1. Introduction Go language is an open source programming language, developed by Google, and widely used to build high-performance, reliable server-side software . In Go language, using a database is a very common requirement. This article will introduce how to implement database connection and operation in Go language, and give specific code examples. 2. Choose the appropriate database driver. In the Go language, there are many third-party database drivers to choose from, such as My
