java 代码实现读取Properties文件中的数据库配置信息

野性酷女 2023-10-18 18:04 50阅读 0赞

实例1:

import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    import java.util.Properties; 
    public class JDBC {
    	 private static Properties pro=new Properties();
    	
    	 static{
    		 try {
    			//getClassLoader()  动态加载类到JVM 中
    	pro.load(new FileReader(JDBC.class.getClassLoader()
    			.getResource("jdbc.properties").getPath()));
    		 } catch (FileNotFoundException e) {
    			 e.printStackTrace();
    		 } catch (IOException e) {
    			 e.printStackTrace();
    		 }
    		}
    	 
    	 
    		public static Connection getConnection() {
    			Connection conn=null;
    			try {
    			Class.forName(pro.getProperty("Drivername"));
    				conn=DriverManager.getConnection(
    						pro.getProperty("url"), 
    						pro.getProperty("username"), 
    						pro.getProperty("password"));
    			} catch (Exception e) {
    				e.printStackTrace();
    			}		
    			return conn;		
    		}
    		 		
    }

实例2:

import java.io.IOException;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    import java.util.Properties;
    public class JDBC2 {
    	
    	public static String driverClassName;
    	public static String url;
    	public static String username;
    	public static String password;
    
    	static {
    		Properties properties = new Properties();
    		try {
    			properties.load(JDBC2.class.getClassLoader().getResourceAsStream("jdbc.properties"));
    			driverClassName=properties.getProperty("Drivername");
    			url=properties.getProperty("url");
    			username=properties.getProperty("username");
    			password=properties.getProperty("password");
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    
    	public static Connection getconnection() {
    		Connection conn = null;
    		try {
    			Class.forName(driverClassName);
    			conn = DriverManager.getConnection(url, username, password);
    		} catch (Exception e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		return conn;
    
    	} 
    }

实例3:

import java.io.IOException;
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    import java.util.Properties;
    import org.apache.commons.dbcp2.BasicDataSource;
    import org.apache.commons.dbcp2.BasicDataSourceFactory;
    
    public class JDBC3 {
    	private static BasicDataSource dataSource;
    	static {
    		Properties properties = new Properties();
    		InputStream inputStream = JDBC3.class.getClassLoader().getResourceAsStream("jdbc.properties");
    		try {
    			properties.load(inputStream);
    			inputStream.close();
    			dataSource = BasicDataSourceFactory.createDataSource(properties);
    			
    		} catch (IOException e) {
    			e.printStackTrace();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    	
    	public static Connection getconnection() throws SQLException{
    		return dataSource.getConnection();
    	}
    }

注意如果如下错误，解决方案：导入 commons-logging的jar包

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0xvb2tpbmdUb21vcnJvdw_size_16_color_FFFFFF_t_70][] 注意如果如下错误，解决方案：导入 commons-pool2的jar包

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0xvb2tpbmdUb21vcnJvdw_size_16_color_FFFFFF_t_70 1][] 即使用下面依赖中的三个jar包：

<dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-pool2</artifactId>
        <version>2.6.2</version>
    </dependency>
            
    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>1.2</version>
    </dependency>
            
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-dbcp2</artifactId>
        <version>2.6.0</version>
    </dependency>

jdbc.properties 文件如下：

Drivername=com.mysql.jdbc.Driver
    url=jdbc:mysql://127.0.0.1:3306/shujuku
    username=root
    password=123456

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