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java:java [2022/07/26 06:58] – [org.hibernate.connection.C3P0ConnectionProvider with c3p0 connection pool] adminjava:java [2024/05/31 05:22] (current) – [Random in Java] admin
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 // so add 1 to make it inclusive // so add 1 to make it inclusive
 ThreadLocalRandom.current().nextInt(min, max + 1); ThreadLocalRandom.current().nextInt(min, max + 1);
 +</code>
 +==== Md5 ====
 +<code java>
 +import java.util.HashMap;
 +import java.security.MessageDigest;
 +public static String md5(String original) {
 +    try{
 +        MessageDigest md = MessageDigest.getInstance("MD5");
 +        md.update(original.getBytes());
 +        byte[] digest = md.digest();
 +        StringBuffer sb = new StringBuffer();
 +        for (byte b : digest) {
 +            sb.append(String.format("%02x", b & 0xff));
 +        }
 +        return sb.toString();
 +    }catch(Exception e){
 +        return "";
 +    }
 +}
 </code> </code>
 ==== Java Reflection ==== ==== Java Reflection ====
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   * **Atomic variables** have features that minimize synchronization and help avoid memory consistency errors.   * **Atomic variables** have features that minimize synchronization and help avoid memory consistency errors.
   * **ThreadLocalRandom** (in JDK 7) provides **efficient generation of pseudorandom numbers from multiple threads**.   * **ThreadLocalRandom** (in JDK 7) provides **efficient generation of pseudorandom numbers from multiple threads**.
-=== Executor Interfaces === + 
-=== Thread pools ===+==== Thread pools ==== 
 +{{:java:thread-pool-tasks.png|}}
 refer:  refer: 
-  * https://docs.oracle.com/javase/tutorial/essential/concurrency/pools.html +  * https://www.baeldung.com/thread-pool-java-and-guava
-  * http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ThreadPoolExecutor.html+
   * http://howtodoinjava.com/2012/10/20/how-to-use-blockingqueue-and-threadpoolexecutor-in-java   * http://howtodoinjava.com/2012/10/20/how-to-use-blockingqueue-and-threadpoolexecutor-in-java
 +  * http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ThreadPoolExecutor.html
 Thread pools address two different problems:  Thread pools address two different problems: 
   * They usually provide improved performance when **executing large numbers of asynchronous tasks**, due to reduced per-task invocation overhead   * They usually provide improved performance when **executing large numbers of asynchronous tasks**, due to reduced per-task invocation overhead
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   * {{:java:pooling.jpg|}}   * {{:java:pooling.jpg|}}
  
-==== Hibernate connection pooling and mysql connection timeout ==== +==== Default Hibernate connection pooling ==== 
-Below are basic steps config for connections in Hibernate(each connection in MySQL was a session in Hibernate):+Below are basic steps config for connections in Hibernate(each connection in MySQL was a session in Hibernate)(refer: https://docs.jboss.org/hibernate/stable/core.old/reference/en/html/configuration-hibernatejdbc.html):
   - Config max connections in MySQL:   - Config max connections in MySQL:
     * config temporary in MySQL Admin console:<code sql>     * config temporary in MySQL Admin console:<code sql>
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 } }
 </code> </code>
-==== c3p0 connection pool==== 
 Most important Hibernate JDBC properties:<code xml> Most important Hibernate JDBC properties:<code xml>
 <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
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