小编Cyr*_*ith的帖子

我在android培训中心网站上看到了这段代码:

boolean hasExternalStoragePrivateFile() {
    // Get path for the file on external storage.  If external
    // storage is not currently mounted this will fail.
    File file = new File(getExternalFilesDir(null), "DemoFile.jpg");
    if (file != null) {
        return file.exists();
    }
    return false;
}

这是否意味着在Android上new File()可以返回null？

http://developer.android.com/reference/android/content/Context.html#getExternalFilesDir(java.lang.String)

我有Spring JPA,Hibernate,MySQL的问题.我有一个实体(Nom.java)和存储库(公共接口NomRepository扩展JpaRepository).它们被创建并注入很好.

问题在于,当我试图通过存储库的save方法保存记录时,spring抱怨"Table"不存在".实际上我没有在MySQL中看到这个表.你已经尝试了不同的hibernate.hbm2ddl.auto值,但它没有帮助.

我使用无XML配置BTW.

这是配置文件:

package ru.interosite.awp.config;

import java.util.Properties;
import javax.sql.DataSource;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;

@Configuration
@ComponentScan("ru.interosite.awp")
@EnableAutoConfiguration
public class AppConfiguration {

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://localhost:3306/awp");
        dataSource.setUsername("root");
        dataSource.setPassword("password");
        return dataSource;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter) {
        LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
        lef.setPersistenceUnitName("my_pu");
        lef.setPackagesToScan("ru.interosite.awp.data");
        lef.setDataSource(dataSource);
        lef.setJpaVendorAdapter(jpaVendorAdapter);
        lef.setJpaProperties(getJpaProperties());
        return lef;
    }

    @Bean
    public JpaVendorAdapter jpaVendorAdapter() …