utils 中 @Value 返回为null

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
/**
 * @Title: JDBCUtils.java
 * @Description: 
 * @author  zhangkai
 * @date 2020年4月3日上午9:56:32
 * @see  [相关类/方法]
 * @since  [产品/模块版本]
 */
@Component
public class JDBCUtils {

	
	private static  String user;
	private static String password;
	private static String url;
	private static String driver;

	/**
	 * 功能：用于获取连接
	 * 
	 * @return Connection连接对象 @ throws Exception
	 *
	 */
	public Connection getConnection() {
		// 获取连接
		try {
			Class.forName(driver);
			return DriverManager.getConnection(url, user, password);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	/**
	 * 功能：释放资源 通用的释放资源方法，无用参数留null
	 * 
	 * @param connection
	 * @param statement
	 *            PreparedStatement是其子类，使用多态，也可引用
	 * @param resultSet
	 */
	public void close(Connection connection, Statement statement, ResultSet resultSet) {
		// 使用try-catch方式处理异常，免去调用者再次处理
		try {
			if (connection != null) {
				connection.close();
			}
			if (statement != null) {
				statement.close();
			}
			if (resultSet != null) {
				resultSet.close();
			}
		} catch (SQLException e) {
			// 编译时异常转为运行时异常
			throw new RuntimeException(e);
		}
	}

	public int toUpdateDelStatus(String tableName) throws Exception {
		Connection connection = null;
		Statement statement = null;
		int i = 0;
		try {
			String sql = "UPDATE " + tableName + " SET del_status = '1' ";
			connection = this.getConnection();
			statement = connection.createStatement();
			i = statement.executeUpdate(sql);

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			this.close(connection, statement, null);
			return i;
		}
	}
	@Value("${spring.datasource.master.username}")
	public  void setUser(String users) {
		user = users;
	}
	@Value("${spring.datasource.master.username}")
	public  void setPassword(String passwords) {
		password = passwords;
	}
	@Value("${spring.datasource.master.jdbc-url}")
	public  void setUrl(String urls) {
		url = urls;
	}
	@Value("${spring.datasource.master.driver-class-name}")
	public  void setDriver(String drivers) {
		driver = drivers;
	}

}

 需要注意 ：

　　1>类上面需要@component　　

　　2>需要编写set 方法

查考文章：https://blog.csdn.net/mononoke111/article/details/81088472#commentBox