要在java对数据库做任何操作,第一件事当然是获取数据库连接,笔者是通过配置文件的形式加载数据库信息的,配置文件名为db.properties,内容如下 driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/customermanage username=root password=root
要在java对数据库做任何操作,第一件事当然是获取数据库连接,笔者是通过配置文件的形式加载数据库信息的,配置文件名为db.properties,内容如下
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/customermanage
username=root
password=root
ps:properties中的内容均为键值对形式,不需要用到引号
接下来是DBUtil类,获取配置,得到连接
<code class=" hljs java"><span class="hljs-keyword">package</span> com.cherry.utils; <span class="hljs-keyword">import</span> java.sql.Connection; <span class="hljs-keyword">import</span> java.sql.DriverManager; <span class="hljs-keyword">import</span> java.sql.PreparedStatement; <span class="hljs-keyword">import</span> java.sql.ResultSet; <span class="hljs-keyword">import</span> java.sql.SQLException; <span class="hljs-keyword">import</span> java.util.Properties; <span class="hljs-keyword">import</span> java.util.ResourceBundle; <span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">DBUtils</span> {</span> <span class="hljs-keyword">static</span> String driver; <span class="hljs-keyword">static</span> String url; <span class="hljs-keyword">static</span> String username; <span class="hljs-keyword">static</span> String password; <span class="hljs-keyword">static</span> { <span class="hljs-keyword">try</span> { <span class="hljs-comment">// Class.forName("com.mysql.jdbc.Driverr");</span> <span class="hljs-comment">// DriverManager.getConnection("jdbc:mysql://localhost:3306/customermanage",</span> <span class="hljs-comment">// "root", "root");</span> ResourceBundle rb = ResourceBundle.getBundle(<span class="hljs-string">"db"</span>); driver = rb.getString(<span class="hljs-string">"driver"</span>); Class.forName(driver); url = rb.getString(<span class="hljs-string">"url"</span>); username = rb.getString(<span class="hljs-string">"username"</span>); password = rb.getString(<span class="hljs-string">"password"</span>); } <span class="hljs-keyword">catch</span> (ClassNotFoundException e) { e.printStackTrace(); } } <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> Connection <span class="hljs-title">getConn</span>() <span class="hljs-keyword">throws</span> SQLException { <span class="hljs-keyword">return</span> DriverManager.getConnection(url, username, password); } <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">releaseRes</span>(ResultSet rs, PreparedStatement ps, Connection conn) <span class="hljs-keyword">throws</span> SQLException { <span class="hljs-keyword">if</span> (rs != <span class="hljs-keyword">null</span>) { rs.close(); } <span class="hljs-keyword">if</span> (ps != <span class="hljs-keyword">null</span>) { ps.close(); } <span class="hljs-keyword">if</span> (conn != <span class="hljs-keyword">null</span>) { conn.close(); } } } </code>
先说说批处理操作类
<code class=" hljs avrasm">package <span class="hljs-keyword">com</span><span class="hljs-preprocessor">.cherry</span><span class="hljs-preprocessor">.batch</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.sql</span><span class="hljs-preprocessor">.Connection</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.sql</span><span class="hljs-preprocessor">.PreparedStatement</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.sql</span><span class="hljs-preprocessor">.SQLException</span><span class="hljs-comment">;</span> import <span class="hljs-keyword">com</span><span class="hljs-preprocessor">.cherry</span><span class="hljs-preprocessor">.utils</span><span class="hljs-preprocessor">.DBUtils</span><span class="hljs-comment">;</span> public class BatchSQL { public static void main(String[] args) throws SQLException { Connection conn= DBUtils<span class="hljs-preprocessor">.getConn</span>()<span class="hljs-comment">;</span> String sql=<span class="hljs-string">"insert into des value(?,?)"</span><span class="hljs-comment">;</span> PreparedStatement ps=conn<span class="hljs-preprocessor">.prepareStatement</span>(sql)<span class="hljs-comment">;</span> for ( int i=<span class="hljs-number">0</span><span class="hljs-comment">;i<10000 ;i++) {</span> ps<span class="hljs-preprocessor">.setString</span>(<span class="hljs-number">1</span>, <span class="hljs-string">"name"</span>+i)<span class="hljs-comment">;</span> ps<span class="hljs-preprocessor">.setString</span>(<span class="hljs-number">2</span>, <span class="hljs-string">"des"</span>+i)<span class="hljs-comment">;</span> ps<span class="hljs-preprocessor">.addBatch</span>()<span class="hljs-comment">;</span> if(i%<span class="hljs-number">100</span>==<span class="hljs-number">0</span>){ ps<span class="hljs-preprocessor">.executeBatch</span>()<span class="hljs-comment">;</span> ps<span class="hljs-preprocessor">.clearBatch</span>()<span class="hljs-comment">;</span> } } } } </code>
再看大文本或图片类型的存储
<code class=" hljs avrasm">package <span class="hljs-keyword">com</span><span class="hljs-preprocessor">.cherry</span><span class="hljs-preprocessor">.batch</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.io</span><span class="hljs-preprocessor">.File</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.io</span><span class="hljs-preprocessor">.FileInputStream</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.io</span><span class="hljs-preprocessor">.FileReader</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.io</span><span class="hljs-preprocessor">.Reader</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.sql</span><span class="hljs-preprocessor">.Connection</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.sql</span><span class="hljs-preprocessor">.PreparedStatement</span><span class="hljs-comment">;</span> import java<span class="hljs-preprocessor">.util</span><span class="hljs-preprocessor">.UUID</span><span class="hljs-comment">;</span> import <span class="hljs-keyword">com</span><span class="hljs-preprocessor">.cherry</span><span class="hljs-preprocessor">.utils</span><span class="hljs-preprocessor">.DBUtils</span><span class="hljs-comment">;</span> public class TextSQL { public static void main(String[] args) { try { Connection connection = DBUtils<span class="hljs-preprocessor">.getConn</span>()<span class="hljs-comment">;</span> String sql = <span class="hljs-string">"insert into des values(?,?)"</span><span class="hljs-comment">;</span> PreparedStatement ps = connection<span class="hljs-preprocessor">.prepareStatement</span>(sql)<span class="hljs-comment">;</span> ps<span class="hljs-preprocessor">.setString</span>(<span class="hljs-number">1</span>, UUID<span class="hljs-preprocessor">.randomUUID</span>()<span class="hljs-preprocessor">.toString</span>())<span class="hljs-comment">;</span> File file = new File(<span class="hljs-string">"f://test.txt"</span>)<span class="hljs-comment">;</span> Reader reader = new FileReader(file)<span class="hljs-comment">;</span> //这里不一定要强转,看你的mysql驱动版本,总之不转不行就转个试试 ps<span class="hljs-preprocessor">.setCharacterStream</span>(<span class="hljs-number">2</span>, reader, (int)file<span class="hljs-preprocessor">.length</span>())<span class="hljs-comment">;</span> ps<span class="hljs-preprocessor">.executeUpdate</span>()<span class="hljs-comment">;</span> } catch (Exception e) { e<span class="hljs-preprocessor">.printStackTrace</span>()<span class="hljs-comment">;</span> } } } </code>
另外,注意导包,这里所有的数据库操作类所导的都是java.sql下的,想想也知道,面向接口编程的Java君,肯定是使用sql包的(普适性),因为mysql/sqlserver/orcale这些都是实现类,用他们肯定不合适。

MySQLoffersvariousstorageengines,eachsuitedfordifferentusecases:1)InnoDBisidealforapplicationsneedingACIDcomplianceandhighconcurrency,supportingtransactionsandforeignkeys.2)MyISAMisbestforread-heavyworkloads,lackingtransactionsupport.3)Memoryengineis

Common security vulnerabilities in MySQL include SQL injection, weak passwords, improper permission configuration, and unupdated software. 1. SQL injection can be prevented by using preprocessing statements. 2. Weak passwords can be avoided by forcibly using strong password strategies. 3. Improper permission configuration can be resolved through regular review and adjustment of user permissions. 4. Unupdated software can be patched by regularly checking and updating the MySQL version.

Identifying slow queries in MySQL can be achieved by enabling slow query logs and setting thresholds. 1. Enable slow query logs and set thresholds. 2. View and analyze slow query log files, and use tools such as mysqldumpslow or pt-query-digest for in-depth analysis. 3. Optimizing slow queries can be achieved through index optimization, query rewriting and avoiding the use of SELECT*.

To monitor the health and performance of MySQL servers, you should pay attention to system health, performance metrics and query execution. 1) Monitor system health: Use top, htop or SHOWGLOBALSTATUS commands to view CPU, memory, disk I/O and network activities. 2) Track performance indicators: monitor key indicators such as query number per second, average query time and cache hit rate. 3) Ensure query execution optimization: Enable slow query logs, record and optimize queries whose execution time exceeds the set threshold.

The main difference between MySQL and MariaDB is performance, functionality and license: 1. MySQL is developed by Oracle, and MariaDB is its fork. 2. MariaDB may perform better in high load environments. 3.MariaDB provides more storage engines and functions. 4.MySQL adopts a dual license, and MariaDB is completely open source. The existing infrastructure, performance requirements, functional requirements and license costs should be taken into account when choosing.

MySQL uses a GPL license. 1) The GPL license allows the free use, modification and distribution of MySQL, but the modified distribution must comply with GPL. 2) Commercial licenses can avoid public modifications and are suitable for commercial applications that require confidentiality.

The situations when choosing InnoDB instead of MyISAM include: 1) transaction support, 2) high concurrency environment, 3) high data consistency; conversely, the situation when choosing MyISAM includes: 1) mainly read operations, 2) no transaction support is required. InnoDB is suitable for applications that require high data consistency and transaction processing, such as e-commerce platforms, while MyISAM is suitable for read-intensive and transaction-free applications such as blog systems.

In MySQL, the function of foreign keys is to establish the relationship between tables and ensure the consistency and integrity of the data. Foreign keys maintain the effectiveness of data through reference integrity checks and cascading operations. Pay attention to performance optimization and avoid common errors when using them.


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