New Java Movement: Test Driven Development 3---User Registration 3

Up to now, we have not touched on the substantive issue of user registration, that is, adding users to the database. Let's deal with this requirement now.

First you need to determine the technology used for database access. You can choose Hibernate, JPA or JDBC here. I believe that the vast majority of applications use Hibernate as the database access technology. Others may choose JPA, but we choose JDBC here. The reason is relatively simple. The underlying things seem to be more complicated, but once mastered, it is relatively easier to master because of its less content. This O-R mapping model adds many abstract concepts and details. We usually only look at the tip of the iceberg of these architectures. If you want to master the things under the iceberg, the difficulty is several orders of magnitude more difficult than directly mastering JDBC.

In addition, due to our test-driven development architecture, if we want to convert to other architectures, we can refactor the existing code. Under the guarantee of test cases, we can safely modify the code.

Okay, we first use the DAO mode to define the database access interface class UserDao. The code is as follows:

public interface UserDao {  
    public long registerUser(Map<String, Object> userInfo);  
}

Generally speaking, we use the Mysql database, so we define the Dao implementation class UserMysqlDao , the code is as follows:

public class UserMysqlDao implements UserDao {  
    @Override  
    public long registerUser(Map<String, Object> userInfo) {  
        // TODO Auto-generated method stub  
        return 0;  
    }

Of course we do not want the user to determine the database used, and then instantiate the corresponding implementation class. For this reason, we need to adopt the factory mode and introduce the DaoFactory class. The code is as follows:

public class DaoFactory {  
    public static UserDao getUserDao() {  
        UserDao dao = null;  
        switch (dbms) {  
        case "mysql":  
            dao = new UserMysqlDao();  
            break;  
        }  
        return dao;  
    }  
      
    public static String getDbms() {  
        return dbms;  
    }  
  
    public static void setDbms(String dbms) {  
        DaoFactory.dbms = dbms;  
    }  
  
    private static String dbms = "mysql";  
}

As can be seen from the above code, the caller only needs to call DaoFactory.getUserDao() to obtain the implementation class.

The following is the problem of database connection. We hope to use the database connection pool when running on application servers such as Jboss, and use DriverManager in unit testing, so we need to define a DataSource encapsulation class JdbcDs to handle the above situation. The code is as follows:

public class JdbcDs {	
	public static Connection getConnection() throws SQLException {
		Connection conn = null;
		if (iDebug <= 0) {
			conn = appDs.getConnection();
		} else {
			try {
				Class.forName("com.mysql.jdbc.Driver").newInstance();
			} catch (InstantiationException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (IllegalAccessException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (ClassNotFoundException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			Properties connectionProps = new Properties();
		    connectionProps.put("user", "root");
		    connectionProps.put("password", "yantao");
		    conn = DriverManager.getConnection(
	                   "jdbc:" + "mysql" + "://" +
	                   "localhost" +
	                   ":" + 3306 + "/XrcjDb",
	                   connectionProps);
		}
		return conn;
	}

	public static int iDebug = 1;
	public final static String APP_DS = "java:jboss/datasources/XcgDS";
	private static DataSource appDs = null; 
	static{
		if (null == appDs) {
			Properties env = new Properties();
			try {
				InitialContext ictx = new InitialContext(env);
				appDs = (DataSource)ictx.lookup(APP_DS);
			} catch (NamingException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
		}
	}
	
}

When doing unit testing, just set iDebug to 1. Otherwise the database connection pool will be used.

After all the preparation work is done, the database function development can be officially carried out.

The above is the content of the New Java Movement: Test Driven Development 3---User Registration 3. For more related content, please pay attention to the PHP Chinese website (m.sbmmt.com)!