JavaWeb-JDBC eight-legged essay, JSBC uses stored procedures, stored functions, and handles CLOB/BLOB types

1.jdbc summary (template, eight-legged essay):

try{ a. Import the driver package and load the specific driver class Class.forName("specific driver class"); b. Establish a connection with the database connection = DriverManager.getConnection(...); c. Get the object of operating the database through the connection (Statement\preparedStatement\callablestatement)           stmt = connection.createStatement(); d.(Query) processing result set rs = pstmt.executeQuery() while(rs.next()){ rs.getXxx(..) ;} }catch (ClassNotFoundException e) {...} catch(SQLException e) {... } catch(Exception e) {... } finally {     //The opening sequence is opposite to the closing sequence     if(rs!=null)rs.close ()     if(stmt!=null) stmt.close();     if(connection!=null)connection.close(); }

- In jdbc, except Class.forName() throws ClassNotFoundException, all other methods throw SQLException

2.CallableStatement: call stored procedures, stored functions

connection.prepareCall(参数：存储过程或存储函数名)

Parameter format:
stored procedure (return without return value, replace with out parameter):
    {call stored procedure name (parameter list)}
stored function (with return value return):
    {? = Call stored function name (parameter list)}

Stored procedure:

create or replace procedure addTwoNum ( num1  in number,num2  in number,result out number )  -- 1 + 2 ->3
as
begin
    result := num1+num2 ;
end ;

Emphasize:
If you access the database through sqlplus, you only need to open: OracleServiceSID
to access data through other programs (sqldevelop, navicate, JDBC), you need to open: OracleServiceSID, XxxListener

Steps for JDBC to call a stored procedure:

a. Generate the object that calls the stored procedure (CallableStatement) cstmt = connection.prepareCall( "..." );
b. Process the output parameter value through setXxx() cstmt.setInt(1, 30);
c. Through registerOutParameter(.. .) Process output parameter type
d.cstmt.execute() execute
e. Accept output value (return value) getXxx()

JDBC call storage function:

create or replace function addTwoNumfunction (num1 in number,num2 in number) - 1 + 2 
return number
as
    result number;    
begin
    result := num1+num2;
    return result;
end;
/
JDBC calling a stored function: the difference between calling a stored procedure :
When calling, pay attention to the parameters: "{? = call addTwoNumfunction (?,?) }"

3. Handling CLOB/BLOB types

Processing slightly larger data:
    
a. Storage path E:\JDK_API_zh_CN.CHM
    stores the file path through JDBC, and then processes it according to IO operations.
    For example: JDBC stores the E:\JDK_API_zh_CN.CHM file as a string "E:\JDK_API_zh_CN.CHM"
        Obtain from the database : 1. Obtain the path "E:\JDK_API_zh_CN.CHM" 2.IO    

b.
    CLOB: large text data (novel -> data)
    BLOB: binary

clob: large text data character stream Reader Writer
storage
1. First pass the pstmt? to replace the novel content (placeholder)
2. Then pass pstmt.setCharacterStream(2, reader, (int)file.length()); to the previous step of? Replace with a novel stream, note that the third parameter needs to be of type Int

Take:
1. Pass Reader reader = rs.getCharacterStream("NOVEL"); Save the data of type cloc into the Reader object
2. Just output the Reader through Writer.

blob: Binary byte stream InputStream OutputStream
and CLOB steps are basically the same, the difference: setBinaryStream(...) getBinaryStream(...)