CN1317638C - Loading method of driving program for database - Google Patents

Abstract

The present invention relates to a loading method of a JAVA database driver, wherein the driver manager accepts and processes the request for establishing a database connection sent by a client, and uses a standard method provided by JAVA to find the required database driver, if Find and then establish connection with the database with this database driver; It is characterized in that, if can not find required database driver, then by carrying out the following steps: A. then send loading database to database driver loader by the driver program manager The driver's request; B. The database driver loader looks for the required database driver on the local machine or the network server, and if it finds the required database driver, it returns it to the driver manager; C. Use all The found database driver establishes a connection to the database. By adopting the method of the present invention, the programmer has more choices besides the standard loading method.

Description

How to load the database driver

technical field

The invention relates to database technology, more specifically, to a loading method of a database driver.

Background technique

JDBC (Java Database Connectivity, that is, JAVA database connection) is composed of a set of classes and interfaces written in the Java language. JDBC uses a specification for connecting different databases. Its purpose is to allow various database developers to provide Java programmers with standard databases. Access classes and interfaces, so the application is quite extensive. When programmers apply JDBC, they often bind the database driver with their own program, that is, specify in CLASSPATH (class path), or their own program and database driver together form a jar file (a type defined for JAVA Compressed file extension, this file compression format adopts the ZIP standard). This method has the following disadvantages:

(1), if a jar file is formed, the whole program will have a huge "volume", and the JDBC driver provided by the database developer often accounts for a large proportion in the program package;

(2) The database driver may be fixed in the program and cannot be modified or is inconvenient to modify;

(3) It is cumbersome to modify things in CLASSPATH;

(4) The version cannot be easily upgraded with the database driver provided by the database developer;

(5), cannot provide the mechanism of centralized management database driver.

Of course, programmers can put the database driver in the JAVA extension directory (usually in the ext directory) to achieve the purpose of separating the program and the database driver, but the loading of the database driver is still not flexible enough to achieve unified management The purpose of the database driver.

Contents of the invention

The technical problem to be solved by the present invention is to provide a loading method of a database driver for the above-mentioned defects of the prior art, which enables programmers to have more choices besides the standard loading method.

The technical solution adopted by the present invention to solve the technical problem is: a loading method of a JAVA database driver, wherein the driver manager accepts and processes the request for establishing a database connection sent by the client, and adopts the standard provided by JAVA Method searches for the required database driver, if found then establishes connection with database with this database driver; It is characterized in that, if can not find required database driver, then by performing the following steps: A, then by described The program manager sends a request for loading the database driver to the database driver loader; B, the database driver loader searches for the required database driver on the local machine or the network server, if the required database driver is found, Then return it to the driver manager; C, establish a connection with the database with the found database driver.

In the method of the present invention, the compressed file of the database driver can be stored on the local machine, and the database driver loader can search for the required database driver on the local machine. Now, in the step B, according to the driver name in the request sent by the driver manager, each entry point of the compressed file is searched, if the compressed file of the required database driver is found, then Decompress the compressed file, and define classes (i.e. register classes with the JAVA virtual machine, and establish the correspondence between class names and class bytes), then return the decompressed and defined database driver to the driver manager; An exception is returned if a required database driver cannot be found in the entry points of all compressed files.

In the method of the present invention, the compressed file of the database driver can also be stored in the database driver file server, and the database driver loader can find the required database driver from the database driver file server through the network. program. At this time, in the step B, according to the driver program name in the request sent by the driver program manager, the database driver program loader sends the database driver program required for searching to the database driver program file server The request of the database driver program file server is searched in the stored compressed file, and if found, a success message is returned to the database driver program loader, and the found file is attached to the message body and sent to the database the driver loader, which returns it to the driver manager;

If the database driver file server cannot find the required database driver in the stored compressed file, then return a failure message to the database driver loader; The program manager returned exception information.

It can be seen that compared with the prior art, the method of the present invention is more flexible in loading the database driver, because the directory where the driver is stored is configurable, and it is more possible to load the database driver through the network to achieve unified management of the database driver. Purpose. Method of the present invention has following characteristics:

(1), the main program and the database driver are separated, avoiding the defect that the main program is too large due to the "volume" of the database driver;

(2), easy to configure, the driver class can be configured, and it is easy to provide users with a graphical configuration interface;

(3) It is very easy to upgrade the database driver, as long as the configuration file is modified, the program can be replaced with a suitable driver, without modifying the program package or modifying the CLASSPATH;

(4) Easy to manage, providing a simple centralized management mode of the database driver - multiple clients can download and load the driver from one place, and a separate server manages the update of the driver.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is a schematic diagram for realizing the method of the present invention;

Fig. 2 is the flow chart that utilizes method of the present invention to establish connection with data;

Fig. 3 is the flowchart of searching database driver;

Fig. 4 is a schematic diagram of the communication interaction between the database loader and the database driver file server in the present invention.

Detailed ways

The principle of the method of the present invention is as shown in Figure 1, the UML standard that this figure adopts, wherein each Chinese frame is connected to a corresponding English frame through a dotted line, and the content in the English frame is translated into Chinese. For implementing the method of the present invention, some following modules need to be provided:

1. The database driver loader (FlexDriverLoader), used to find the database driver in the compressed file of the specified database driver;

2. The database driver manager (FlexDriverManager) is used to provide the database according to the specified database driver, URL (uniform resource location mark: the representation method used to specify the location of information on the WWW service program of the Internet), user name and password. Connection;

3. The database driver file server (DriverClassFileServer), which is used to manage JDBC drivers of various databases, responds to the request of the database driver loader, and provides the function of downloading the driver;

4. Configurator (DriverConfig): used to read the configuration, which can implement text configuration or XML (Extended Markup Language) configuration, and specify the driver for the database driver loader, and can specify multiple compressed files;

5. Client program (Client): used to call the driver manager to obtain a database connection.

In the present invention, driver program loader can realize two kinds of search driver mode, and specific mode is as follows: the one is the standard class loading method that Java provides, promptly searches for driver in CLASSPATH (class path) by Class.forName () method The second is the class loading method provided by the database driver manager, and the "database driver loader" cooperates with the "database driver file server" to complete the task of searching and loading the driver.

As shown in Figure 2, the use of these two methods is sequential in the present invention, and the standard class loading method provided by Java is given priority. If the method cannot find the database driver, the database driver manager will be used Provided class loading methods.

Therefore, the present invention actually expands the Java database class loading method, and provides a more flexible database driver loading method for customers.

Regarding the class loading method provided by the database driver manager, from the structure in Figure 1, two methods can be formed by the cooperation of the "database driver loader" and the "database driver file server". One is the local database The loading method of the driver; the second is the loading method of the network database driver. The workflows of the two schemes are described below respectively.

1. Loading method of local database driver

The loading method of the so-called local database driver means that the database driver is stored on the local machine (local), and the database driver loader is responsible for completing the local search and loading of the database driver. The specific process is shown in Figure 3:

1. The driver manager accepts and processes the request to establish a database connection.

Among them, the customer can directly specify a database driver to establish a connection, instead of just providing the DriverManager as JDK (JAVA Development Kit) only provides the URL and login user password information to establish a database connection. Here, the database connection is established The work is done by a static method named getConnection(), and the parameters of the method are:

String driver driver class name

String url The url information of the database

String user database user name

String password password information

After the database driver manager accepts the request, it will send a request to the database driver loader to load the database driver.

2. The database driver loader accepts and processes the request to load the database driver.

Among them, the database driver loader searches the database driver from the compressed file according to the class to be loaded. The search process is completed by the lookFile (find file) method, and the flow of the LookFile method is shown in Figure 3. Before searching, you must set the compressed file of the database driver to be searched. The work of setting is completed by the addDriverFile() method. If the required database driver cannot be found locally, a 'ClassNotFoundException' (exception that the class cannot be found ) for detection of anomalies.

After the database driver loader finishes loading, it will return the loaded classes to the driver manager.

3. The driver manager returns a database connection to the client.

When implementing the above three steps, since no network operation is involved, the configuration of the database driver file server can be ignored. First, configure the location information of the driver in the configuration file or other places (such as command line, input box, etc.), that is, the location of the database driver; the configuration class object (configurator) will read the information of the driver and provide The driver loader adds the corresponding driver resources. Then, the client program calls the "getConnection" method of the driver manager to obtain a database connection, which requires the following information: driver class name, URL, user name, and password. For example, the client program can be written like this:

String driver="com.sybase.jdbc2.jdbc.SybDriver";

String url="jdbc:sybase:Tds:10.40.99.1:5000/billdb";

String user="sa";

String password=〃〃;

Connection conn=

FlexDriverManager.getConnection(driver, url, user, password);

If the connection is successful, return the database connection to the client program application; if it fails, throw an exception for the client program to detect and process.

Second, the loading method of the network database driver

The loading method of the so-called network database driver means that the database driver is stored on the database driver file server, and the database driver file server cooperates with the database driver loader to complete the network search of the database driver (search on the server) and Loaded work. The difference between this method and the "local database driver loading method" is that the database driver loader and the database driver file server must perform some network operations to complete the task of searching. The following is just an introduction to the process of how to complete the network operation between the database driver loader and the database driver file server, and other processes are the same as the "Loading method of the local database driver". Among them, the database driver loader and the database driver file server communicate through the HTTP 1.0 protocol, as shown in Figure 4, the communication process is as follows:

1. The database driver loader sends a request to the database driver file server to find a certain database driver class.

2. The database driver file server searches in the configured driver compressed file according to the request, and returns a successful message if found, and attaches the class file in the message body and sends it to the database driver loader; if no corresponding class, a failure message is returned to the database driver loader.

3. After the database driver loader completes the loading work, it will return the loaded class to the driver manager; if no class that can be loaded is found, an exception of ClassNotFoundException will be thrown for detection.

When implementing the above steps, the process is slightly more complicated than loading the database driver locally because it involves network operations, as follows:

(1) The database driver file server configures the service listening port, and configures the database driver compressed package or driver class directory to be managed by the server.

(2) Start the database driver file server, the command line is as follows:

Java FlexClassFileServer,

You can use a browser to verify whether the database driver file server has started successfully.

Suppose the IP address of the machine where the database driver file server is located is: 10.40.57.4, the port is set to 8898, and the following database driver compressed packages are managed:

Sybase JDBC driver package: jconn2.jar

Oracle's JDBC driver package: 816classes12.zip

After entering http://10.40.57.4:8898/SybVersion.class in the browser, if a download prompt appears, it means that the database driver file server has started successfully. Note that each class should have a complete package name when testing, for example: http://10.40.57.4:8898/oracle.JDBC.driver.OracleSql.class can be successful, but if it is written as http://10.40.57.4:8898 /OracleSql.class will fail. If there is no download prompt, it means that the database driver file server has not been started, or the startup is wrong, or the test itself is wrong (such as not entering the correct class name and package name). The following process can only be continued after the database driver file server is started successfully, otherwise it is meaningless.

(3) Configure the location information of the driver program in the local configuration file or other places (such as the command line, or the input box, etc.), including the IP address and the listening port of the database driver file server.

(4) The client program calls the "getConnection" method of the driver manager to obtain the database connection, which requires the following information: driver class name, URL, user name, password. If the connection is obtained successfully, the database connection is returned to the client program application. If it fails, an exception will be thrown for the client program to detect and process.

When the method of the invention is applied in the billing inquiry system, the effect is good, the inquiry program can be separated from the database driver program, and the database driver program can be upgraded conveniently.

Claims (6)

1, a kind of stowage of JAVA database device, wherein, by driver manager accept and handle that the client sent set up the database connection requests, and the standard method of adopting JAVA to provide searches required database device, if find then connect with this database device and database; It is characterized in that, if can not find required database device, then by carrying out following steps:

A, the request of sending the loading of databases driver by described driver manager to the database device loading bin;

B, described database-driven loading bin are searched required database device on this machine or the webserver, if find required database device, then it is turned back to described driver manager;

C, use the database device and the database that are found to connect.

2, method according to claim 1 is characterized in that, the compressed file of database device can be left on this machine, searches required database device by described database device loading bin on this machine.

3, method according to claim 2, it is characterized in that, in described step B, database device name in the request of sending according to described driver manager, each entrance of compressed file is searched,, then the file that finds is carried out decompress(ion) if find the file of required database device, and the definition class, return the database device of decompress(ion) and definition then to described driver manager; If in all compressed file entrances, can not find required database device, then return abnormal information.

4, method according to claim 3 is characterized in that, the operation of described definition class comprises to JAVA virtual machine registration class, and sets up the corresponding relation of class name and class byte.

5, method according to claim 1, it is characterized in that, the compressed file of database device can be left in the database device file server, search required database device by network from described database device file server by described database device loading bin.

6, method according to claim 5, it is characterized in that, in described step B, driver name in the request of sending according to described driver manager, described database device loading bin sends the request of searching required database device to described database device file server; Described database device file server is searched in stored compressed file, if find then return success message and give described database device loading bin, and the file that finds is attached to sends to described database device loading bin in the message body, again it is turned back to described driver manager;

If described database device file server can not find required database device in stored compressed file, then return failed message and give described database device loading bin; Described database device loading bin returns abnormal information to described driver manager again.

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