Template pattern JdbcTemplate in the Spring framework
JdbcTemplate is a template pattern implementation class in the Spring framework used to simplify JDBC operations. It encapsulates basic JDBC operations, allowing developers to perform database operations in a more concise manner, avoiding tedious exception handling and resource release. JdbcTemplate provides a series of methods, including querying, updating, batch processing, and other operations.
The following is the complete source code of JdbcTemplate:
public class JdbcTemplate {
private DataSource dataSource;
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
public void execute(String sql) {
Connection conn = null;
Statement stmt = null;
try {
conn = dataSource.getConnection();
stmt = conn.createStatement();
stmt.execute(sql);
} catch (SQLException e) {
//Exception handling
} finally {
//Resource release
try {
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
//Exception handling
}
}
}
public <T> List<T> query(String sql, RowMapper<T> rowMapper) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = dataSource.getConnection();
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
List<T> results = new ArrayList<>();
int rowNum = 0;
while (rs.next()) {
results.add(rowMapper.mapRow(rs, rowNum++));
}
return results;
} catch (SQLException e) {
//Exception handling
return null;
} finally {
//Resource release
try {
if (rs != null) {
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
//Exception handling
}
}
}
public int update(String sql) {
Connection conn = null;
Statement stmt = null;
try {
conn = dataSource.getConnection();
stmt = conn.createStatement();
return stmt.executeUpdate(sql);
} catch (SQLException e) {
//Exception handling
return -1;
} finally {
//Resource release
try {
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
//Exception handling
}
}
}
}
The execute method in JdbcTemplate is used to execute SQL statements, the query method is used to perform query operations and return the result set, and the update method is used to perform update operations and return the number of affected rows.
JdbcTemplate uses the template pattern, encapsulating public JDBC operations in Template method pattern, and leaving specific operations to subclasses. Developers only need to inherit JdbcTemplate and implement the RowMapper interface to customize query result mappings.
Summary:
JdbcTemplate is a template pattern implementation class in the Spring framework that provides simplified database operation methods. It encapsulates the operational details of JDBC, including resource acquisition and release, exception handling, etc. Using JdbcTemplate can improve development efficiency and reduce repetitive code writing.
