CentOS 7 Shell脚本编程第九讲 read命令简单介绍

测试代码

sqlSessionFactory.openSession(false).getMapper(StudentMapper.class).findStudentById(id)
核心方法：org.apache.ibatis.session.Configuration#getMapper

  public T getMapper(Class type, SqlSession sqlSession) {

    //从Mybatis初始化过程中绑定的名称空间和接口类，获取接口工厂
    final MapperProxyFactory mapperProxyFactory = (MapperProxyFactory) knownMappers.get(type);
    if (mapperProxyFactory == null) {
      throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
    }
    try {
        //生成接口代理类
      return mapperProxyFactory.newInstance(sqlSession);
    } catch (Exception e) {
      throw new BindingException("Error getting mapper instance. Cause: " + e, e);
    }
  }
动态代理工厂

public class MapperProxyFactory {

  private final Class mapperInterface;
  private final Map methodCache = new ConcurrentHashMap();

  public MapperProxyFactory(Class mapperInterface) {
    this.mapperInterface = mapperInterface;
  }

  public Class getMapperInterface() {
    return mapperInterface;
  }

  public Map getMethodCache() {
    return methodCache;
  }

  @SuppressWarnings("unchecked")
  protected T newInstance(MapperProxy mapperProxy) {
    //JDK动态代理
    return (T) Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[] { mapperInterface }, mapperProxy);
  }

  public T newInstance(SqlSession sqlSession) {
    final MapperProxy mapperProxy = new MapperProxy(sqlSession, mapperInterface, methodCache);
    return newInstance(mapperProxy);
  }
}
动态代理对象：MapperProxy

 [@Override](https://my.oschina.net/u/1162528)
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    try {
      if (Object.class.equals(method.getDeclaringClass())) {
        return method.invoke(this, args);
      } else if (isDefaultMethod(method)) {
        return invokeDefaultMethod(proxy, method, args);
      }
    } catch (Throwable www.ylouyi3.com) {
      throw ExceptionUtil.unwrapThrowable(t);
    }
    final MapperMethod mapperMethod = cachedMapperMethod(method);
    return mapperMethod.execute(sqlSession, args);
  }
sql操作

 public Object execute(SqlSession sqlSession, Object[] args) {
    Object result;
    switch (command.getType()) {
      case INSERT: {
      Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.insert(command.getName(), param));
        break;
      }
      case UPDATE: {
        Object param =www.qwert888.com method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.update(command.getName(), param));
        break;
      }
      case DELETE: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.delete(command.getName(), param));
        break;
      }
      case SELECT:
        if (method.returnsVoid() && method.hasResultHandler()) {
          executeWithResultHandler(sqlSession, args);
          result = null;
        } else if (method.returnsMany()) {
          result = executeForMany(sqlSession, args);
        } else if (method.returnsMap()) {
          result = executeForMap(sqlSession, args);
        } else if (method.returnsCursor()) {
          result = executeForCursor(sqlSession, args);
        } else {
          Object param = method.convertArgsToSqlCommandParam(args);
          result = sqlSession.selectOne(command.getName(), param);
        }
        break;
      case FLUSH:
        result = sqlSession.flushStatements();
        break;
      default:
        throw new BindingException("Unknown execution method for: " + command.getName());
    }
    if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid()) {
      throw new BindingException("Mapper method '" + command.getName() 
          + " attempted to return null from a method with a primitive return type (" + method.getReturnType() + ").");
    }
    return result;
  }
org.apache.ibatis.binding.MapperMethod#executeForMany

  private Object executeForMany(SqlSession sqlSession, Object[] args) {
    List result;
    Object param = method.convertArgsToSqlCommandParam(args);
    if (method.hasRowBounds()) {
      RowBounds rowBounds = method.extractRowBounds(args);
      result = sqlSession.selectList(command.getName(), param, rowBounds);
    } else {
      result = sqlSession.selectList(command.getName(), param);
    }
    // issue #510 Collections & arrays support
    if (!method.getReturnType().isAssignableFrom(result.getClass())) {
      if (method.getReturnType(www.gouyiflb.cn/).isArray()) {
        return convertToArray(result);
      } else {
        return convertToDeclaredCollection(sqlSession.getConfiguration(), result);
      }
    }
    return result;
  }

//具体的操作通过Executor操作，本质底层也是JDBC操作，只是通过configuration配置按照业务进行数据转换
[@Override](https://my.oschina.net/u/1162528)
  public List selectList(String statement, Object parameter, RowBounds rowBounds) {
    try {
      MappedStatement ms = configuration.getMappedStatement(statement);
      return executor.query(ms, wrapCollection(parameter), rowBounds, Executor.NO_RESULT_HANDLER);
    } catch (Exception e) {
      throw ExceptionFactory.wrapException(www.yongxinzaixian.cn"Error querying database.  Cause: " + e, e);
    } finally {
      ErrorContext.instance().reset();
    }

[root@promote ~]# 
[root@promote ~]# bash testreadv1.0.sh 
please input name: www
name is : www
#第二次等待5秒未输入内容
[root@promote ~]# bash testreadv1.0.sh 
please input name:www.mhylpt.com www
input error...
#思考问题如何清除错误输出内容到下一行，本次操作实际输入www未按回车键
[root@promote ~]# www
[root@promote ~]# 
#-s 不前台显示输入内容
[root@promote ~]# cat testreadv1.1.sh 
#!/bin/bash
read  -s  -p "please input password:" passwd
echo -e "\npassword is :$passwd"
exit 0
[root@promote ~]#