TAILIEUCHUNG - HandBooks Professional Java-C-Scrip-SQL part 178

Tham khảo tài liệu 'handbooks professional java-c-scrip-sql part 178', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Java Language Integration Java programmers can write server-side classes that invoke SQL and PL SQL using standard JDBC or SQLJ calls. PL SQL programmers can call server-side Java methods by writing a PL SQL cover or call spec for Java using Oracle DDL. Server-side Java in Oracle may be faster than PL SQL for compute-intensive programs but not as nimble for database access. PL SQL is much more efficient for database-intensive routines because unlike Java it doesn t have to pay the overhead for converting SQL datatypes for use inside the stored program. Oracle programmers will want to continue to use PL SQL for programs that perform a lot of database I O and use Java for the best raw computation performance. The first step in creating a Java stored procedure JSP is writing or otherwise obtaining functional Java code. Having source code is not necessary though so you can use class libraries from third parties. The classes must however meet the following requirements Methods published to SQL and PL SQL must be declared static. PL SQL has no mechanism for instantiating non-static Java classes. The classes must not issue any GUI calls for example to AWT at runtime. If you write your own JSP and it needs to connect to the database for access to tables or stored procedures use standard JDBC and or SQLJ calls in your code. Many JDBC and SQLJ reference materials are available to provide assistance in calling SQL or PL SQL from Java but be sure to review the Oracle-specific documentation that ships with your release. Once you have the Java class in hand either in source or .class file format the next step is loading it into the database. Oracle s loadjava command-line utility is a convenient way to accomplish the load. Refer to Oracle s documentation for further assistance with loadjava. The third step is to create a call spec for the Java method specifying the AS LANGUAGE JAVA clause of the CREATE command. You may create a function or procedure cover as appropriate. .

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