DBCP database connection pool technology

DBCP is a Java connection pool project on Apache and a connection pool component used by tomcat. Dbcp requires three separate packages: common-dbcp.jar , common-pool.jar , common-collections.jar due to the establishment of a database connection behavior is a very time-consuming and resource intensive, so the pre-established through connection pooling some of the same database connection, in memory, the application needs to establish a direct connection to the database Apply for one in the pool, and then put it back after use. dbcp does not automatically recover idle connections. DBCP has minor bugs and is generally not recommended.

Method 1: Get database information directly in Java code and establish a database connection pool.

@Test
 public  void test () throws Exception { 
    BasicDataSource source = new BasicDataSource (); // Create a database connection pool 
    source.setDriverClassName ("com.mysql.jdbc.Driver"); // Drive 
    source.setUrl ("jdbc: mysql : // localhost: 3306 / test "); // url 
    source.setUsername (" root "); // username 
    source.setPassword (" 123456 "); // password         
    Connection conn = source.getConnection (); // Get database connection 
    System.out.println (conn); // Print database connection 
}

Method 2: Obtain database information through configuration file and establish database connection pool

@Test
 public  void  throws Exception { 
        Properties pros = new Properties (); 
        InputStream is = DBCPTest. Class .getClassLoader (). GetResourceAsStream ("dbcp.properties" ); 
        pros.load (is); // Get the configuration file 
    DataSource source = BasicDataSourceFactory.createDataSource (pros); // Create a database connection pool. 
    Connection conn = source.getConnection (); // Get connection 
    System.out.println (conn); // Print connection 
}

The configuration file can be named arbitrarily: xxx.properties is usually named dbcp.properties.

driverClassName = com.mysql.jdbc.Driver 
url = jdbc: mysql: // localhost: 3306 / jdbc 
username = root 
password = 123456 

# <!-initial connection-> 
initialSize = 10 
#maximum 

number of connections maxActive = 50 

# < ! 
-Maximum idle connection-> maxIdle = 20 

# <!-Minimum idle connection-> 
minIdle = 5 

# <!-Timeout waiting time in milliseconds 6000 milliseconds / 1000 equals 60 
seconds- > maxWait = 60000 


#The format of the connection property attribute attached when the JDBC driver establishes the connection must be as follows: [property name = property;] #Note 
: The two properties "user" and "password" will be passed explicitly, so there is no need to include them here . 
connectionProperties = useUnicode = true; 

characterEncoding = gbk #Specify the auto-commit status of connections created by the connection pool. 
defaultAutoCommit = true 

#driver default specifies the read-only status of the connection created by the connection pool. 
#If the value is not set, the "setReadOnly" method will not be called. (Some drivers do not support read-only mode, such as Informix)
defaultReadOnly = 

#driver default Specifies the transaction level (TransactionIsolation) of the connection created by the connection pool. 
#Available value is one of the following: (For details, see javadoc.) NONE, READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE 
defaultTransactionIsolation = READ_UNCOMMITTED

DBCP database connection pool technology

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