cvc-complex-type.2.4.c: 通配符的匹配很全面, 但无法找到元素 'context:property-placeholder' 的声明

spring在启动时获取不到引入的外部资源文件获取不到，出现这种情况的原因是在spring.xml配置的头部beans中存在问题，首先需要添加xmlns:context的命名空间，然后需要在schemaLocation中添加context的xsd。

添加好xsd之后重新运行测试类检查资源文件引入是否成功以及数据库是否连接成功

public class TestConnection {
    public static void main(String[] args) throws Exception {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("config/spring.xml");
        DataSource dataSource = (DataSource) ctx.getBean("dataSource");
        System.out.println(dataSource.getConnection());
    }
}

运行结果如下

Tue Jan 02 11:30:59 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
Tue Jan 02 11:30:59 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
Tue Jan 02 11:30:59 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
com.mchange.v2.c3p0.impl.NewProxyConnection@dd0c991 [wrapping: com.mysql.jdbc.JDBC4Connection@5f16132a]