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Enterprise Library2.0(1):Data Access Application Block学

WBOY
WBOYoriginal
2016-06-07 15:42:461020parcourir

Data Access Application Block 提供了通用的数据访问的功能,随着 2.0 版本的推出有了很大变化。 一.改进 在 DAAB1.1 里面我们知道 Database 方法返回或者创建一个 DBCommandWrapper 对象,而在 DAAB2.0 里面移除了 DBCommandWrapper 类,用 ADO.NET2.0 里

Enterprise Library2.0(1):Data Access Application Block学

Data Access Application Block提供了通用的数据访问的功能,随着2.0版本的推出有了很大变化。

一.改进

DAAB1.1里面我们知道Database方法返回或者创建一个DBCommandWrapper对象,而在DAAB2.0里面移除了DBCommandWrapper类,用ADO.NET2.0里面的DBCommand类代替实现类似的功能,这样使得DAAB跟我们的.NET类库的结合更加紧密,回忆一下我们在1.1里面用DBCommandWrapper来访问数据时的代码:

Enterprise Library2.0(1):Data Access Application Block学Database db = DatabaseFactory.CreateDatabase();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学DBCommandWrapper dbCommand 
= db.GetStoredProcCommandWrapper("GetProductsByCategory");
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学dbCommand.AddInParameter(
"CategoryID", DbType.Int32, Category);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学DataSet productDataSet 
= db.ExecuteDataSet(dbCommand);

而用了新的DBCommand类之后则变成了:

Enterprise Library2.0(1):Data Access Application Block学Database db = DatabaseFactory.CreateDatabase();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学DbCommand dbCommand 
= db.GetStoredProcCommand("GetProductsByCategory"); 
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学db.AddInParameter(dbCommand, 
"CategoryID", DbType.Int32, Category);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学DataSet productDataSet 
= db.ExecuteDataSet(dbCommand);

数据库连接字符串在我们基于数据库的开发永远是少不了的,但是在DAAB1.1下,它所使用的字符串跟我们在.NET类库中使用的连接字符串却是不能共享的,它们分别保存在不同的位置。而在2.0Data Access Application Block使用了ADO.NET2.0里面配置区,这样带来的一个好处是连接字符串可以在Application Block和自定义的.NET类之间共享使用该配置区,如:

Enterprise Library2.0(1):Data Access Application Block学connectionStrings>
Enterprise Library2.0(1):Data Access Application Block学        
add
Enterprise Library2.0(1):Data Access Application Block学            
name="DataAccessQuickStart" 
Enterprise Library2.0(1):Data Access Application Block学            providerName
="System.Data.SqlClient"
Enterprise Library2.0(1):Data Access Application Block学            connectionString
="server=(local)\SQLEXPRESS;database=EntLibQuickStarts;Integrated Security=true" />
Enterprise Library2.0(1):Data Access Application Block学
connectionStrings>

.NET2.0下,泛型编程已经成为了一个核心,而2.0版的DAAB中也新增了一个GenericDatabase对象。DAAB中虽然已经包含了SqlDatabaseOrcaleDatabase,但是如果我们需要使用其他的像DB2等数据库时,就需要用到GenericDatabase,它可以用于任何.NET类库中的数据提供者,包括OdbcProviderOleDbProvider

二.使用示例

DAAB2.0的配置非常简单,主要有以下几方面的配置:

配置连接字符串

Enterprise Library2.0(1):Data Access Application Block学

配置默认数据库

Enterprise Library2.0(1):Data Access Application Block学

添加相关的命名空间:

Enterprise Library2.0(1):Data Access Application Block学using Microsoft.Practices.EnterpriseLibrary.Data;
Enterprise Library2.0(1):Data Access Application Block学
using System.Data;

使用Data Access Application Block进行数据的读取和操作,一般分为三步:

1.创建Database对象

2.提供命令参数,如果需要的话

3.执行命令

下面分别看一下DataAccessQuickStart中提供的一些例子:

执行静态的SQL语句

Enterprise Library2.0(1):Data Access Application Block学public string GetCustomerList()
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学
// 创建Database对象
Enterprise Library2.0(1):Data Access Application Block学
Database db = DatabaseFactory.CreateDatabase();
Enterprise Library2.0(1):Data Access Application Block学
// 使用SQL语句创建DbCommand对象
Enterprise Library2.0(1):Data Access Application Block学
string sqlCommand = "Select CustomerID, Name, Address, City, Country, PostalCode " +
Enterprise Library2.0(1):Data Access Application Block学    
"From Customers";
Enterprise Library2.0(1):Data Access Application Block学DbCommand dbCommand 
= db.GetSqlStringCommand(sqlCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学StringBuilder readerData 
= new StringBuilder();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学
// 调用ExecuteReader方法
Enterprise Library2.0(1):Data Access Application Block学
using (IDataReader dataReader = db.ExecuteReader(dbCommand))
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学    
while (dataReader.Read())
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学    
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学        
// Get the value of the 'Name' column in the DataReader
Enterprise Library2.0(1):Data Access Application Block学
        readerData.Append(dataReader["Name"]);
Enterprise Library2.0(1):Data Access Application Block学        readerData.Append(Environment.NewLine);
Enterprise Library2.0(1):Data Access Application Block学    }

Enterprise Library2.0(1):Data Access Application Block学}

Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学
return readerData.ToString();
Enterprise Library2.0(1):Data Access Application Block学}

执行存储过程并传递参数,返回DataSet

Enterprise Library2.0(1):Data Access Application Block学public DataSet GetProductsInCategory(int Category)
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学    
// Create the Database object, using the default database service. The
Enterprise Library2.0(1):Data Access Application Block学    
// default database service is determined through configuration.
Enterprise Library2.0(1):Data Access Application Block学
    Database db = DatabaseFactory.CreateDatabase();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
string sqlCommand = "GetProductsByCategory";
Enterprise Library2.0(1):Data Access Application Block学    DbCommand dbCommand 
= db.GetStoredProcCommand(sqlCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Retrieve products from the specified category.
Enterprise Library2.0(1):Data Access Application Block学
    db.AddInParameter(dbCommand, "CategoryID", DbType.Int32, Category);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// DataSet that will hold the returned results        
Enterprise Library2.0(1):Data Access Application Block学
    DataSet productsDataSet = null;
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    productsDataSet 
= db.ExecuteDataSet(dbCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Note: connection was closed by ExecuteDataSet method call 
Enterprise Library2.0(1):Data Access Application Block学

Enterprise Library2.0(1):Data Access Application Block学    
return productsDataSet;
Enterprise Library2.0(1):Data Access Application Block学}

利用DataSet更新数据

Enterprise Library2.0(1):Data Access Application Block学public int UpdateProducts()
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学    
// Create the Database object, using the default database service. The
Enterprise Library2.0(1):Data Access Application Block学    
// default database service is determined through configuration.
Enterprise Library2.0(1):Data Access Application Block学
    Database db = DatabaseFactory.CreateDatabase();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    DataSet productsDataSet 
= new DataSet();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
string sqlCommand = "Select ProductID, ProductName, CategoryID, UnitPrice, LastUpdate " +
Enterprise Library2.0(1):Data Access Application Block学        
"From Products";
Enterprise Library2.0(1):Data Access Application Block学    DbCommand dbCommand 
= db.GetSqlStringCommand(sqlCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
string productsTable = "Products";
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Retrieve the initial data
Enterprise Library2.0(1):Data Access Application Block学
    db.LoadDataSet(dbCommand, productsDataSet, productsTable);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Get the table that will be modified
Enterprise Library2.0(1):Data Access Application Block学
    DataTable table = productsDataSet.Tables[productsTable];
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Add a new product to existing DataSet
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学
    DataRow addedRow = table.Rows.Add(new object[] Enterprise Library2.0(1):Data Access Application Block学{DBNull.Value, "New product"1125});
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Modify an existing product
Enterprise Library2.0(1):Data Access Application Block学
    table.Rows[0]["ProductName"= "Modified product";
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Establish our Insert, Delete, and Update commands
Enterprise Library2.0(1):Data Access Application Block学
    DbCommand insertCommand = db.GetStoredProcCommand("AddProduct");
Enterprise Library2.0(1):Data Access Application Block学    db.AddInParameter(insertCommand, 
"ProductName", DbType.String, "ProductName", DataRowVersion.Current);
Enterprise Library2.0(1):Data Access Application Block学    db.AddInParameter(insertCommand, 
"CategoryID", DbType.Int32, "CategoryID", DataRowVersion.Current);
Enterprise Library2.0(1):Data Access Application Block学    db.AddInParameter(insertCommand, 
"UnitPrice", DbType.Currency, "UnitPrice", DataRowVersion.Current);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    DbCommand deleteCommand 
= db.GetStoredProcCommand("DeleteProduct");
Enterprise Library2.0(1):Data Access Application Block学    db.AddInParameter(deleteCommand, 
"ProductID", DbType.Int32, "ProductID", DataRowVersion.Current);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    DbCommand updateCommand 
= db.GetStoredProcCommand("UpdateProduct");
Enterprise Library2.0(1):Data Access Application Block学    db.AddInParameter(updateCommand, 
"ProductID", DbType.Int32, "ProductID", DataRowVersion.Current);
Enterprise Library2.0(1):Data Access Application Block学    db.AddInParameter(updateCommand, 
"ProductName", DbType.String, "ProductName", DataRowVersion.Current);
Enterprise Library2.0(1):Data Access Application Block学    db.AddInParameter(updateCommand, 
"LastUpdate", DbType.DateTime, "LastUpdate", DataRowVersion.Current);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Submit the DataSet, capturing the number of rows that were affected
Enterprise Library2.0(1):Data Access Application Block学
    int rowsAffected = db.UpdateDataSet(productsDataSet, "Products", insertCommand, updateCommand,
Enterprise Library2.0(1):Data Access Application Block学                                        deleteCommand, UpdateBehavior.Standard);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
return rowsAffected;
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学}

通过ID获取记录详细信息

Enterprise Library2.0(1):Data Access Application Block学public string GetProductDetails(int productID)
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学    
// Create the Database object, using the default database service. The
Enterprise Library2.0(1):Data Access Application Block学    
// default database service is determined through configuration.
Enterprise Library2.0(1):Data Access Application Block学
    Database db = DatabaseFactory.CreateDatabase();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
string sqlCommand = "GetProductDetails";
Enterprise Library2.0(1):Data Access Application Block学    DbCommand dbCommand 
= db.GetStoredProcCommand(sqlCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Add paramters
Enterprise Library2.0(1):Data Access Application Block学    
// Input parameters can specify the input value
Enterprise Library2.0(1):Data Access Application Block学
    db.AddInParameter(dbCommand, "ProductID", DbType.Int32, productID);
Enterprise Library2.0(1):Data Access Application Block学    
// Output parameters specify the size of the return data
Enterprise Library2.0(1):Data Access Application Block学
    db.AddOutParameter(dbCommand, "ProductName", DbType.String, 50);
Enterprise Library2.0(1):Data Access Application Block学    db.AddOutParameter(dbCommand, 
"UnitPrice", DbType.Currency, 8);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    db.ExecuteNonQuery(dbCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Row of data is captured via output parameters
Enterprise Library2.0(1):Data Access Application Block学
    string results = string.Format(CultureInfo.CurrentCulture, "{0}, {1}, {2:C} ",
Enterprise Library2.0(1):Data Access Application Block学                                   db.GetParameterValue(dbCommand, 
"ProductID"),
Enterprise Library2.0(1):Data Access Application Block学                                   db.GetParameterValue(dbCommand, 
"ProductName"),
Enterprise Library2.0(1):Data Access Application Block学                                   db.GetParameterValue(dbCommand, 
"UnitPrice"));
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
return results;
Enterprise Library2.0(1):Data Access Application Block学}

XML格式返回数据

Enterprise Library2.0(1):Data Access Application Block学public string GetProductList()
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学    
// Use a named database instance that refers to a SQL Server database.
Enterprise Library2.0(1):Data Access Application Block学
    SqlDatabase dbSQL = DatabaseFactory.CreateDatabase() as SqlDatabase;
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
// Use "FOR XML AUTO" to have SQL return XML data
Enterprise Library2.0(1):Data Access Application Block学
    string sqlCommand = "Select ProductID, ProductName, CategoryID, UnitPrice, LastUpdate " +
Enterprise Library2.0(1):Data Access Application Block学        
"From Products FOR XML AUTO";
Enterprise Library2.0(1):Data Access Application Block学    DbCommand dbCommand 
= dbSQL.GetSqlStringCommand(sqlCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    XmlReader productsReader 
= null;
Enterprise Library2.0(1):Data Access Application Block学    StringBuilder productList 
= new StringBuilder();
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学    
try
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学    
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学        productsReader 
= dbSQL.ExecuteXmlReader(dbCommand);
Enterprise Library2.0(1):Data Access Application Block学
Enterprise Library2.0(1):Data Access Application Block学        
// Iterate through the XmlReader and put the data into our results.
Enterprise Library2.0(1):Data Access Application Block学
        while (!productsReader.EOF)
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学        
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学            
if (productsReader.IsStartElement())
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学            
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学                productList.Append(productsReader.ReadOuterXml());
Enterprise Library2.0(1):Data Access Application Block学                productList.Append(Environment.NewLine);
Enterprise Library2.0(1):Data Access Application Block学            }

Enterprise Library2.0(1):Data Access Application Block学        }

Enterprise Library2.0(1):Data Access Application Block学    }

Enterprise Library2.0(1):Data Access Application Block学    
finally
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学    
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学      
// Close the Reader.
Enterprise Library2.0(1):Data Access Application Block学
      if (productsReader != null)
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学      
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学          productsReader.Close();
Enterprise Library2.0(1):Data Access Application Block学      }

Enterprise Library2.0(1):Data Access Application Block学      
Enterprise Library2.0(1):Data Access Application Block学      
// Explicitly close the connection. The connection is not closed
Enterprise Library2.0(1):Data Access Application Block学      
// when the XmlReader is closed.
Enterprise Library2.0(1):Data Access Application Block学
      if (dbCommand.Connection != null)
Enterprise Library2.0(1):Data Access Application Block学Enterprise Library2.0(1):Data Access Application Block学      
Enterprise Library2.0(1):Data Access Application Block学{
Enterprise Library2.0(1):Data Access Application Block学        dbCommand.Connection.Close();
Enterprise Library2.0(1):Data Access Application Block学

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