Spring-JdbcTemplate operation database

1. Concept and preparation

1. What is JdbcTemplate?
   Spring framework encapsulates JDBC, and using JdbcTemplate can easily implement database operations.
2. Preparation
   (1) Introduce related jar packages and dependencies
   
   (2) Configure the database connection pool in the spring configuration file

    <!--数据库连接池配置-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close">
        <property name="url" value="jdbc:mysql:///user_db"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    </bean>

(3) Configure the jdbcTemplate object and inject the DataSource

    <!--创建jdbcTemplate对象-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <!--注入dataSource-->
        <property name="dataSource" ref="dataSource"/>
    </bean>

(4) Create the service class, create the dao class, and inject the jdbcTemplate object in the dao class

• Configuration file

<!--组件扫描-->
    <context:component-scan base-package="org.example"></context:component-scan>

• service class

@Service
public class BookService {
    //注入dao
    @Autowired
    private BookDao userDao;
}

• dao class

public interface BookDao {
    
    
}

@Repository
public class BookDaoImpl implements BookDao{
    
    

    //注入JdbcTemplate
    @Autowired
    private JdbcTemplate jdbcTemplate;
}

2. Jdbc Template operation database (add)

1. Create entity class corresponding to database table

public class Book {
    
    
    private String bookId;
    private String bookName;
    private String bookStatus;

    public String getBookId() {
    
    
        return bookId;
    }

    public void setBookId(String bookId) {
    
    
        this.bookId = bookId;
    }

    public String getBookName() {
    
    
        return bookName;
    }

    public void setBookName(String bookName) {
    
    
        this.bookName = bookName;
    }

    public String getBookStatus() {
    
    
        return bookStatus;
    }

    public void setBookStatus(String bookStatus) {
    
    
        this.bookStatus = bookStatus;
    }
}

2. Write service and dao
   (1) Add database operation in dao

public interface BookDao {
    
    
    void add(Book book);
}

@Service
public class BookService {
    
    
    //注入dao
    @Autowired
    private BookDao bookDao;

    public void addBook(Book book) {
    
    
        bookDao.add(book);
    }
}

(2) Call the update method in the jdbcTemplate object to implement the operation.

There are two parameters: the first parameter is a sql statement, and the second parameter is a variable parameter, which sets the value of the sql statement.

@Repository
public class BookDaoImpl implements BookDao{
    
    

    //注入JdbcTemplate
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public void add(Book book) {
    
    
        //1. 创建sql语句
        String sql = "insert into t_book values(?,?,?)";
        //2. 调用方法实现
        int update = jdbcTemplate.update(sql, book.getBookId(), book.getBookName(), book.getBookStatus());
        System.out.println(update);
    }
}

Three, JdbcTemplate operation database (modify and delete)

    @Override
    public void updateBook(Book book) {
    
    
        String sql = "update t_book set book_name=?,book_status=? where book_id=?";
        Object[] args = {
    
    book.getBookName(), book.getBookStatus(), book.getBookId()};
        int update = jdbcTemplate.update(sql, args);
        System.out.println(update);
    }

    @Override
    public void delete(String id) {
    
    
        String sql = "delete from t_book where book_id=?";
        int update = jdbcTemplate.update(sql, id);
        System.out.println(update);
    }

Four, JdbcTemplate operating database (the query returns a certain value)

1. How many records are in the query table, the return is a certain value.
2. Use Jdbctemplate to realize that the query returns a certain value.
   

    @Override
    public int selectCount() {
    
    
        String sql = "select count(*) from t_book";
        Integer count = jdbcTemplate.queryForObject(sql, Integer.class);
        return count;
    }

5. JdbcTemplate operation database (the query returns an object)
1. Scenario: Please check the book for details.
2. JdbcTemplate query returns the object.

There are three parameters
. The first is: sql statement and the
second is: RowMapper, which is an interface, which returns different types of data. Use the implementation class in this interface to complete data encapsulation. The
third parameter: sql statement value

    @Override
    public Book findOne(String id) {
    
    
        String sql = "select * from t_book where book_id=?";
        Book book = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<Book>(Book.class), id);
        return book;
    }

6. JdbcTemplate operation database (query return collection)
1. Scenario: Query book list pagination...
2. Call JdbcTemplate method to implement query return method

    @Override
    public List<Book> findAllBook() {
    
    
        String sql = "select * from t_book";
        List<Book> bookList = jdbcTemplate.query(sql, new BeanPropertyRowMapper<Book>(Book.class));
        return bookList;
    }

Seven, JdbcTemplate operation database (batch operation)
1. Batch operation: multiple records in the operation table
2. JdbcTemplate realizes batch addition operation

There are two parameters: the first parameter: sql statement. The second parameter: List collection, add multiple records of data

    @Override
    public void batchAddBook(List<Object[]> batchArgs) {
    
    
        String sql = "insert into t_book values(?,?,?)";
        int[] ints = jdbcTemplate.batchUpdate(sql, batchArgs);
        System.out.println(Arrays.toString(ints));
    }

3. JdbcTemplate realizes batch modification operation

    @Override
    public void batchUpdateBook(List<Object[]> objects) {
    
    
        String sql = "update t_book set book_name=?, book_status=? where book_id=?";
        jdbcTemplate.batchUpdate(sql, objects);
    }

Note: Each item in the Ojbect[] array should correspond to the placeholder "?" in the sql statement one by one, don't make a mistake in the order.
4. JdbcTemplate realizes batch delete operation

   @Override
    public void batchDeleteBook(List<Object[]> objects) {
    
    
        String sql = "delete from t_book where book_id=? and book_name=? and book_status=?";
        jdbcTemplate.batchUpdate(sql, objects);
    }