Javaweb Learning Note 8-dbutils Toolkit

In today's terms Javaweb 8th stage of learning.

dbutils Technology , Dbutils is a very common function of our database, although later use is the result of its encapsulation, but also need to master.

The usual, first use a mind map to show today's blog content.

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PS: my mind is used. XMind picture, if you are interested in my mind map and want to see you and the detailed information, please click to download

In addition: if the figure is not clear, please right-click --- opening in a new window is a lot clearer.

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A * Overview :

1* definition :

additions and deletions for encapsulation operations database .

* features :

* read operation for data table Span style= "Font-family:times New Roman", He can convert the results to list array , set java collection Easy for programmers to manipulate

b* write operations for data tables , and it became easy . ( just write the SQL statement ).

c* can use data sources , Use JNDI, database connection pooling and other technologies to optimize performance .

two * Common class :

1* Queryrunner class :

1.1* constructor Function :

* Queryrunner (): Default no parameter construction .

* Queryrunner (DataSource DS): The construction of the pass-through connection pool .

1.2* Common Methods :

* Query () method : used to perform query operations .

* Query (Connection conn, String sql, resultsethandler<t> rsh, Object ... params)

???? 1.3* query (String sql, resultsethandler<t> rsh, Object ... params)

* Update () method : used to perform additions, deletions and modifications .

* UPDATE (Connection conn, String sql, Object ... params)

???? * UPDATE (String sql, Object ... params)

Resultsethandler Interface :

2.1* Handle (ResultSet Rs) method :

used to add ResultSet conversion of result set types .

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three * Two ways of managing transactions :

1* Manually Manage Transactions :

* Queryrunner ()

* Query (Connection conn, String sql, resultsethandler<t> rsh, Object ... params)

* UPDATE (Connection conn, String sql, Object ... params)

* Tool Management Transactions :

* Queryrunner (DataSource DS)

* Query (String sql, resultsethandler<t> rsh, Object ... params)

* UPDATE (String sql, Object ... params)

Four * Resultsethandler:

through the above query statements can be found, every time to implement Resultsethandler the method is very troublesome. In fact , the Resultsethandler interface provides nine implementation classes for use, as follows:

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1* Arrayhandler: Turns the first row of data in the result set into an array of objects .

2 * Arraylisthandler: Turns each row of data in the result set into an array of objects , and store it in List in .

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Beanhandler: Encapsulates the first row of data in the result set into a corresponding JavaBean in the instance .

Beanlisthandler: Encapsulates each row of data in the result set into a corresponding JavaBean in the instance , stored in List in .

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5* Maphandler: Encapsulates the first row of data in the result set into a Map in , Key is a column name , Value is the corresponding value .

6* Maplisthandler: Encapsulates each row of data in the result set into a Map in , and then store it in List.

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7* Columnlisthandler: Stores data from a column in the result set to List in .

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8* Keyedhandler: Encapsulates each row of data in the result set into a Map in , and put these Map and save it to a Map in , its Key for the specified column .

9* Scalarhandler: Making a single value query .

Javaweb Learning Notes 8-dbutils Toolkit