The core methods to prevent SQL injection include: 1. Use PreparedStatement to avoid SQL stitching and automatically escape input through parameterized queries; 2. Checksum filtering user input to limit illegal characters and input lengths; 3. Use ORM frameworks such as Hibernate and MyBatis to automatically handle parameter binding; 4. Follow the principle of minimum permissions and limit database account permissions; 5. Desensitize error messages to avoid exposing system structure; 6. Regular update of dependency libraries to fix vulnerabilities; designing from the source to eliminate splicing SQL can effectively defend against the risk of injection.
SQL injection is one of the most common attack methods in web security, especially in Java applications, which can be easily exploited if not handled properly. To prevent SQL injection, the core is to not splice SQL strings, but to use a secure database access method.

Use precompiled statements (PreparedStatement)
This is the most efficient and commonly used method to prevent SQL injection. PreparedStatement
processes user input as parameters instead of splicing directly into SQL statements.
-
PreparedStatement
in Java will automatically escape parameters to avoid malicious input tampering with SQL structure. - Example:
String query = "SELECT * FROM users WHERE username = ? AND password = ?"; PreparedStatement stmt = connection.prepareStatement(query); stmt.setString(1, username); stmt.setString(2, password);
Don't write like this:

String query = "SELECT * FROM users WHERE username = '" username "'";
This way of string splicing is very easy to inject.
Checksum filter input
Although using precompilation can effectively defend against most injections, it is still a good habit to make basic verification of user input.

- Verify the input format, such as fields such as email, mobile phone number, etc. should comply with the specific format.
- For special characters such as
'
,"
,;
etc., you can do whitelist filtering or escape processing. - Using frameworks such as Apache Commons Validator can simplify the verification process.
Common practices include:
- Reject obviously illegal content, such as SQL keywords appearing in usernames.
- Limit input length and reduce input space for unexpected or malicious content.
Using ORM frameworks (such as Hibernate, MyBatis)
In modern Java development, using ORM frameworks can not only improve development efficiency, but also naturally avoid SQL injection problems.
- These frameworks are usually based on
PreparedStatement
and automatically handle parameter binding. - You only need to manipulate the object, and don't need to manually splice SQL.
- Even if native SQL is required, these frameworks provide support for parameterized queries.
For example in Hibernate:
Query<User> query = session.createQuery("FROM User WHERE username = :username", User.class); query.setParameter("username", userInput);
Other supplementary suggestions
- The principle of minimum permissions : Assign minimum permissions to database accounts, which can reduce risks even if attacked.
- Error message desensitization : Do not expose detailed database error information to users to prevent attackers from obtaining system structure.
- Regularly update dependency libraries : Keep version updated when using frameworks such as JDBC drivers and ORM, and fix potential vulnerabilities.
Basically these are the methods. The key to preventing SQL injection is not to "block", but to eliminate the possibility of splicing SQL from the source design. As long as you develop good coding habits, this problem is actually not difficult to solve.
The above is the detailed content of How to prevent SQL injection in Java?. For more information, please follow other related articles on the PHP Chinese website!

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