Question

我正在使用Hibernate将项目连接到MySQL，并且hibernate.cfg.xml文件出现错误-无法解析mysql包（以及cj，jdbc等包）。

这是代码-

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        final View rootView = inflater.inflate(R.layout.fragment_menu, container, false);
        final MenuActivity menuAct = (MenuActivity) getActivity();
        final MenuViewModel viewModel = ViewModelProviders.of(this, new MenuViewModelFactory(menuAct.getApplication(), MenuActivity.ResID)).get(MenuViewModel.class);
        viewModel.getAllMenuTitles().observe(this, new Observer<String[]>() {
            @Override
            public void onChanged(String[] strings) {
                final Spinner spinner = rootView.findViewById(R.id.spinner);
                ArrayAdapter<String> adapter = new ArrayAdapter<String>(getContext(), R.layout.support_simple_spinner_dropdown_item, strings);
                adapter.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item);
                spinner.setAdapter(adapter);

                spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                    @Override
                    public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                        menuAct.removeAllTabs();
                        SubMenuViewModel vm = ViewModelProviders.of(getParentFragment(), new SubMenuViewModelFactory(menuAct.getApplication(), i)).get(SubMenuViewModel.class); //← This is the problematic getApplication() 
                        vm.getSubMenus().observe(getActivity(), new Observer<String[]>() {
                            @Override
                            public void onChanged(@Nullable String[] strings) {
                                menuAct.populateTabs(strings);
                            }
                        });
                    }

                    @Override
                    public void onNothingSelected(AdapterView<?> adapterView) {

                    }
                });
            }
        });

        return rootView;
    }

代码中的第五行是我在说的。

问题是正确地声明了依赖项，并且在我的项目合作伙伴处可以使用相同的文件。

（Spring框架）。

#update 1- 增加了依赖性

java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v4.app.FragmentActivity android.support.v4.app.Fragment.getActivity()' on a null object reference
    at android.arch.lifecycle.ViewModelProviders.checkActivity(ViewModelProviders.java:50)
    at android.arch.lifecycle.ViewModelProviders.of(ViewModelProviders.java:100)
    at com.whatamidoingwithmylife.splitbill.MenuActivity$PlaceholderFragment$1$1.onItemSelected(MenuActivity.java:198)
    at android.widget.AdapterView.fireOnSelected(AdapterView.java:944)
    at android.widget.AdapterView.dispatchOnItemSelected(AdapterView.java:933)
    at android.widget.AdapterView.-wrap1(Unknown Source:0)
    at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:898)
    at android.os.Handler.handleCallback(Handler.java:790)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6494)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:440)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

堆栈

<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="connection.url">jdbc:mysql://localhost:3306/theprocess?useUnicode=true&amp;useJDBCCompliantTimezoneShift=true&amp;useLegacyDatetimeCode=false&amp;serverTimezone=UTC</property>
    <property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
    <property name="connection.username">root</property>
    <property name="connection.password">Amit4089</property>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <!-- DB schema will be updated if needed -->
    <property name="hbm2ddl.auto">update</property>
    <mapping class="com.example.WebAppProcess20.Entities.ClientsEntity"/>
    <mapping class="com.example.WebAppProcess20.Entities.InvoicesEntity"/>
    <mapping class="com.example.WebAppProcess20.Entities.OrdersEntity"/>
    <mapping class="com.example.WebAppProcess20.Entities.OrdersitemsEntity"/>
    <mapping class="com.example.WebAppProcess20.Entities.ProductsEntity"/>
  </session-factory>
</hibernate-configuration>

` 有什么想法吗？

Answer 1

从您的帖子中看不到错误。但是请确保MySQLDialect的版本与您使用的MySQL版本兼容。

还有其他MySQLDialect适用于5.x之前的版本。然后分别有5.5版和5.7版的MySQL55Dialect和MySQL57Dialect。

Java-Hibernate.cfg.xml-无法解析文件中的驱动程序

1 个答案: