memchache 将对象序列化后保存 memcahce将值序列化成字节数组,然后存储到缓存中。 如下例,我们将user对象序列化到文件a.txt中,同时将user保存到缓存中,通过比较文件和缓存中的值 发现,两者是一样的。 public class User implements Serializable { priv
memchache 将对象序列化后保存
memcahce将值序列化成字节数组,然后存储到缓存中。
如下例,我们将user对象序列化到文件a.txt中,同时将user保存到缓存中,通过比较文件和缓存中的值
发现,两者是一样的。
<code class=" hljs java"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">User</span> <span class="hljs-keyword">implements</span> <span class="hljs-title">Serializable</span>{</span> <span class="hljs-keyword">private</span> String name; <span class="hljs-keyword">private</span> String address; <span class="hljs-keyword">public</span> <span class="hljs-title">User</span>(String name, String address) { <span class="hljs-keyword">super</span>(); <span class="hljs-keyword">this</span>.name = name; <span class="hljs-keyword">this</span>.address = address; } }</code>
<code class=" hljs cs"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span>(String[] args) throws InterruptedException, ExecutionException, FileNotFoundException, IOException { MemcachedClient mcc = <span class="hljs-keyword">null</span>; <span class="hljs-keyword">try</span>{ <span class="hljs-comment">// 本地连接 Memcached 服务</span> mcc = <span class="hljs-keyword">new</span> MemcachedClient(<span class="hljs-keyword">new</span> InetSocketAddress(<span class="hljs-string">"127.0.0.1"</span>, <span class="hljs-number">11211</span>)); System.<span class="hljs-keyword">out</span>.println(<span class="hljs-string">"Connection to server sucessful."</span>); }<span class="hljs-keyword">catch</span>(Exception ex){ System.<span class="hljs-keyword">out</span>.println( ex.getMessage() ); } User u = <span class="hljs-keyword">new</span> User(<span class="hljs-string">"junwang"</span>,<span class="hljs-string">"qingdao city"</span>); ObjectOutputStream oos = <span class="hljs-keyword">new</span> ObjectOutputStream(<span class="hljs-keyword">new</span> FileOutputStream(<span class="hljs-keyword">new</span> File(<span class="hljs-string">"a.txt"</span>)) ); oos.writeObject(u); Future fo = mcc.<span class="hljs-keyword">set</span>(<span class="hljs-string">"myuser"</span>, <span class="hljs-number">5</span>*<span class="hljs-number">60</span>*<span class="hljs-number">1000</span>, u); <span class="hljs-comment">// 查看存储状态</span> System.<span class="hljs-keyword">out</span>.println(<span class="hljs-string">"set status:"</span> + fo.<span class="hljs-keyword">get</span>()); <span class="hljs-comment">// 输出值</span> System.<span class="hljs-keyword">out</span>.println(<span class="hljs-string">"myuser value in cache - "</span> + mcc.<span class="hljs-keyword">get</span>(<span class="hljs-string">"myuser"</span>)); <span class="hljs-comment">// 关闭连接</span> mcc.shutdown(); }</code>
查看源代码
查看源代码,可以发现正是将对象序列化,然后保存。证明了我们上述的猜想。
<code class=" hljs cs">BaseSerializingTranscoder.java <span class="hljs-keyword">protected</span> <span class="hljs-keyword">byte</span>[] <span class="hljs-title">serialize</span>(Object o) { <span class="hljs-keyword">if</span> (o == <span class="hljs-keyword">null</span>) { <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> NullPointerException(<span class="hljs-string">"Can't serialize null"</span>); } <span class="hljs-keyword">byte</span>[] rv=<span class="hljs-keyword">null</span>; ByteArrayOutputStream bos = <span class="hljs-keyword">null</span>; ObjectOutputStream os = <span class="hljs-keyword">null</span>; <span class="hljs-keyword">try</span> { bos = <span class="hljs-keyword">new</span> ByteArrayOutputStream(); os = <span class="hljs-keyword">new</span> ObjectOutputStream(bos); os.writeObject(o); os.close(); bos.close(); rv = bos.toByteArray(); } <span class="hljs-keyword">catch</span> (IOException e) { <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> IllegalArgumentException(<span class="hljs-string">"Non-serializable object"</span>, e); } <span class="hljs-keyword">finally</span> { CloseUtil.close(os); CloseUtil.close(bos); } <span class="hljs-keyword">return</span> rv; } </code>
结论
值的存储,都是序列化成字节数组,然后保存

The main role of MySQL in web applications is to store and manage data. 1.MySQL efficiently processes user information, product catalogs, transaction records and other data. 2. Through SQL query, developers can extract information from the database to generate dynamic content. 3.MySQL works based on the client-server model to ensure acceptable query speed.

The steps to build a MySQL database include: 1. Create a database and table, 2. Insert data, and 3. Conduct queries. First, use the CREATEDATABASE and CREATETABLE statements to create the database and table, then use the INSERTINTO statement to insert the data, and finally use the SELECT statement to query the data.

MySQL is suitable for beginners because it is easy to use and powerful. 1.MySQL is a relational database, and uses SQL for CRUD operations. 2. It is simple to install and requires the root user password to be configured. 3. Use INSERT, UPDATE, DELETE, and SELECT to perform data operations. 4. ORDERBY, WHERE and JOIN can be used for complex queries. 5. Debugging requires checking the syntax and use EXPLAIN to analyze the query. 6. Optimization suggestions include using indexes, choosing the right data type and good programming habits.

MySQL is suitable for beginners because: 1) easy to install and configure, 2) rich learning resources, 3) intuitive SQL syntax, 4) powerful tool support. Nevertheless, beginners need to overcome challenges such as database design, query optimization, security management, and data backup.

Yes,SQLisaprogramminglanguagespecializedfordatamanagement.1)It'sdeclarative,focusingonwhattoachieveratherthanhow.2)SQLisessentialforquerying,inserting,updating,anddeletingdatainrelationaldatabases.3)Whileuser-friendly,itrequiresoptimizationtoavoidper

ACID attributes include atomicity, consistency, isolation and durability, and are the cornerstone of database design. 1. Atomicity ensures that the transaction is either completely successful or completely failed. 2. Consistency ensures that the database remains consistent before and after a transaction. 3. Isolation ensures that transactions do not interfere with each other. 4. Persistence ensures that data is permanently saved after transaction submission.

MySQL is not only a database management system (DBMS) but also closely related to programming languages. 1) As a DBMS, MySQL is used to store, organize and retrieve data, and optimizing indexes can improve query performance. 2) Combining SQL with programming languages, embedded in Python, using ORM tools such as SQLAlchemy can simplify operations. 3) Performance optimization includes indexing, querying, caching, library and table division and transaction management.

MySQL uses SQL commands to manage data. 1. Basic commands include SELECT, INSERT, UPDATE and DELETE. 2. Advanced usage involves JOIN, subquery and aggregate functions. 3. Common errors include syntax, logic and performance issues. 4. Optimization tips include using indexes, avoiding SELECT* and using LIMIT.


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