设计模式课程 设计模式精讲 10-2 外观模式源码解析

Posted 2020-11-12 1446358788-qq

1　　　　源码解析

1.1　　源码解析1（jdk中的JDBCUtils工具类）

1.2　　源码解析2

1.3　　源码解析3

1.4　　源码解析4

 

1　　　　源码解析

1.1　　源码解析1（jdk中的JDBCUtils工具类）

jdbc在springJDBC中的封装

 

/**
     * Close the given JDBC Connection and ignore any thrown exception.
     * This is useful for typical finally blocks in manual JDBC code.
     * @param con the JDBC Connection to close (may be {@code null})
     */
    public static void closeConnection(Connection con) {
        if (con != null) {
            try {
                con.close();
            }
            catch (SQLException ex) {
                logger.debug("Could not close JDBC Connection", ex);
            }
            catch (Throwable ex) {
                // We don‘t trust the JDBC driver: It might throw RuntimeException or Error.
                logger.debug("Unexpected exception on closing JDBC Connection", ex);
            }
        }
    }

    /**
     * Close the given JDBC Statement and ignore any thrown exception.
     * This is useful for typical finally blocks in manual JDBC code.
     * @param stmt the JDBC Statement to close (may be {@code null})
     */
    public static void closeStatement(Statement stmt) {
        if (stmt != null) {
            try {
                stmt.close();
            }
            catch (SQLException ex) {
                logger.trace("Could not close JDBC Statement", ex);
            }
            catch (Throwable ex) {
                // We don‘t trust the JDBC driver: It might throw RuntimeException or Error.
                logger.trace("Unexpected exception on closing JDBC Statement", ex);
            }
        }
    }

    /**
     * Close the given JDBC ResultSet and ignore any thrown exception.
     * This is useful for typical finally blocks in manual JDBC code.
     * @param rs the JDBC ResultSet to close (may be {@code null})
     */
    public static void closeResultSet(ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
            }
            catch (SQLException ex) {
                logger.trace("Could not close JDBC ResultSet", ex);
            }
            catch (Throwable ex) {
                // We don‘t trust the JDBC driver: It might throw RuntimeException or Error.
                logger.trace("Unexpected exception on closing JDBC ResultSet", ex);
            }
        }
    }

 

 

 

1.2　　源码解析2（mybaties应用的Configuration）

通过封装之后，我们的客户端都有这些功能，这一组接口交给客户端来访问

 

public MetaObject newMetaObject(Object object) {
    return MetaObject.forObject(object, objectFactory, objectWrapperFactory, reflectorFactory);
  }

  public ParameterHandler newParameterHandler(MappedStatement mappedStatement, Object parameterObject, BoundSql boundSql) {
    ParameterHandler parameterHandler = mappedStatement.getLang().createParameterHandler(mappedStatement, parameterObject, boundSql);
    parameterHandler = (ParameterHandler) interceptorChain.pluginAll(parameterHandler);
    return parameterHandler;
  }

  public ResultSetHandler newResultSetHandler(Executor executor, MappedStatement mappedStatement, RowBounds rowBounds, ParameterHandler parameterHandler,
      ResultHandler resultHandler, BoundSql boundSql) {
    ResultSetHandler resultSetHandler = new DefaultResultSetHandler(executor, mappedStatement, parameterHandler, resultHandler, boundSql, rowBounds);
    resultSetHandler = (ResultSetHandler) interceptorChain.pluginAll(resultSetHandler);
    return resultSetHandler;
  }

 

 

 

 

1.3　　源码解析3（在tomcat中的应用）

1.4　　源码解析4