为什么我的bean是null?
[b] servlet-context.xml [/ b]
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context" xmlns="http://www.springframework.org/schema/beans"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd"
>
<!-- <context:annotation-config/>-->
<context:component-scan base-package="by"/>
<context:property-placeholder location="classpath:database.properties"/>
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/javakava"/>
<property name="username" value="root"/>
<property name="password" value="admin"/>
</bean>
</beans>
并[b]控制器[/ B]
public class Controller extends HttpServlet {
private static final long serialVersionUID = 1L;
@Autowired private CommandFactory commandFactory;
@Override public void init(ServletConfig servletConfig)抛出ServletException {super.init(servletConfig);
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
performAction(request, response);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
performAction(request, response);
}
private void performAction(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String page = null;
String paramPage = request.getParameter(Constants.PARAM_PAGE);
try {
if (paramPage != null && !paramPage.isEmpty()) {
Command command = commandFactory.getCommand(paramPage);
page = command.execute(request);
// Commands c = Commands.valueOf(paramPage);
// Command command = c.getCommandClass().newInstance();
page = command.execute(request);
RequestDispatcher requestDispatcher = request
.getRequestDispatcher(page);
requestDispatcher.forward(request, response);
} else {
throw new IllegalAccessError(
"Error with access to class from Controller.java");
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
LoginCommand - 这是autowared TestService bean . 在IDEA,它看起来很好 . 但是在调试模式下,我的testService为null .
@Component
public class LoginCommand implements Command {
@Autowired
TestService testService;
public String execute(HttpServletRequest request) {
DaoCheckUserImpl id = new DaoCheckUserImpl();
String pass = request.getParameter(Constants.PASS);
String login = request.getParameter(Constants.LOGIN);
id.checkUser();
String userN = id.getUserN();
String userP = id.getUserP();
String userRole = id.getUserRole();
int userId = id.getUserId();
if (userN.equals(login) & userP.equals(pass) & userRole.equals("admin")) {
/*
*
* Here testService is null[/b]
*
*/
List<Test> tests = testService.getAllTests();
request.setAttribute(Constants.TESTS, tests);
User user = new User();
user.setLogin(login);
request.getSession().setAttribute(Constants.USER, user);
return Constants.MAIN_ADMIN_PAGE;
} else {
}
return Constants.ERROR_LOGIN_PAGE;
}
}
}
TestService的
@Service
public class TestService {
@Autowired
public DaoTestImpl daoTestImpl;
public List<Test> getAllTests() {
return daoTestImpl.getAllTests();
}
public Test selectTest(String idTest) {
return daoTestImpl.selectTest(idTest);
}
public void deleteTest(Test test) {
daoTestImpl.deleteTest(test);
}
[b] DaoTestImpl [/ b]
这里我使用JdbcDaoSupport,数据源注入构造函数 .
@Component
public class DaoTestImpl extends JdbcDaoSupport implements DaoTest {
@Autowired
public DaoTestImpl(DataSource dataSource) {
setDataSource(dataSource);
}
...
public List<Test> getAllTests() throws DAOException {
return getJdbcTemplate().query(("SELECT *FROM tests"), rowMapper);
}
CommandFactory
@Component
public class CommandFactory {
@Autowired
public LoginCommand loginCommand;
public Command getCommand(String paramPage) {
Commands command = Commands.valueOf(paramPage.toUpperCase());
switch (command) {
case LOGIN_COMMAND:
return loginCommand;
commands
public enum Commands { LOGIN_COMMAND
/*login_Command(LoginCommand.class),
1 回答
你如何创建LoginCommand对象?
Spring使用Autowired来注入正确的bean . 因此只有在Spring创建LoginCommand时才有效 . 如果你执行了一个新的,或者如果你使用另一个没有与Spring正确集成的框架,这可以解释你的问题(例如没有the proper configuration的Jersey 2) .
编辑:
顺便说一句,你可以使用“@Required”注释 . 这不会解决您的问题,但新的错误消息可以帮助您了解发生的事情(特别是它将有助于查看是否真的由Spring创建了LoginCommand对象,并且如果自动装配失败[我认为]因为TestService的实例找不到[包命名问题,类加载器问题等]]
您是否检查了所有组件是否都在“by”包中(在组件扫描中指定)?