用接口的方法就报空指针 , 到最后发现竟然是接口的实例是空指针
private DBDao dbdao ;
private TUser t ;public DBDao getDbdao() {
return dbdao;
}
public void setDbdao(DBDao dbdao) {
this.dbdao = dbdao;
}public String queryUser(){
System.out.println(t.getUsername());
System.out.println(dbdao);
list = dbdao.seleteByUsernameAndPassword(t);
if(list!=null && list.size()>0)
{
return "success";
}
else
return "fail";
}list = dbdao.seleteByUsernameAndPassword(t);此行出现空指针
System.out.println(dbdao); 此行打印nullapplication.xml 配置有
<bean id="dbdao" class="impl.DB" autowire="byName">
<property name="sessionFactory" ref="sessionFactory">
</property>
</bean>到底是怎么回事 超级郁闷啊
private DBDao dbdao ;
private TUser t ;public DBDao getDbdao() {
return dbdao;
}
public void setDbdao(DBDao dbdao) {
this.dbdao = dbdao;
}public String queryUser(){
System.out.println(t.getUsername());
System.out.println(dbdao);
list = dbdao.seleteByUsernameAndPassword(t);
if(list!=null && list.size()>0)
{
return "success";
}
else
return "fail";
}list = dbdao.seleteByUsernameAndPassword(t);此行出现空指针
System.out.println(dbdao); 此行打印nullapplication.xml 配置有
<bean id="dbdao" class="impl.DB" autowire="byName">
<property name="sessionFactory" ref="sessionFactory">
</property>
</bean>到底是怎么回事 超级郁闷啊
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你这个DAO对象要在配置文件里说明引用到你调用的类
假设吧:
<bean id="Test" class="com.test.ABC">
<property name="dbdao">
<ref local="dbdao"/>
</property>
</bean><bean id="dbdao" class="impl.DB" autowire="byName">
<property name="sessionFactory" ref="sessionFactory">
</property>
</bean>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<bean id="dataSource"
class="org.apache.commons.dbcp.BasicDataSource">
<property name="driverClassName"
value="com.mysql.jdbc.Driver">
</property>
<property name="url" value="jdbc:mysql://localhost:3336/wjn"></property>
<property name="username" value="root"></property>
<property name="password" value="g"></property>
</bean>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource">
<ref bean="dataSource" />
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">
org.hibernate.dialect.MySQLDialect
</prop>
</props>
</property>
<property name="mappingResources">
<list>
<value>entity/TUser.hbm.xml</value>
<value>entity/TInfo.hbm.xml</value></list>
</property>
</bean>
<bean id="dbdao" class="impl.DB" autowire="byName">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
<bean id="userAction" class="action.UserAction" autowire="byName">
<property name="dbdao" ref="dbdao">
</property>
</bean>
</beans>这个是完整的APPLICATION.XML
DBDao 这个类 开头不能由 2个大写字母组成
改为DbDao 就能通过了
别忘了修改配置文件和 spring中的bean的id名字
public DBDao getDbdao() {
return dbdao;
}
public void setDbdao(DBDao dbdao) {
this.dbdao = dbdao;
}
你这个代码是些在action中的么?
是的话,那么你将action交给 spring来管理了么?
配置 plugin了么
<bean id="dbdao" class="impl.DB" autowire="byName">
<property name="sessionFactory" ref="sessionFactory"> </property>
</bean> <bean id="userAction" class="action.UserAction" autowire="byName">
<property name="dbdao" ref="dbdao">
</property>
</bean> 这个就是了吧?
配置Spring监听器。在web.xml文件中增加如下内容:<listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener>
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd"><struts>
<constant name="struts.objectFactory" value="spring"></constant> <package name="sshv" extends="struts-default">
<action name="user" class="action.UserAction">
<result name="success" type="velocity">/showuser.htm</result>
<result name="fail" type="velocity">/error.htm</result>
<result name="showuser" type="velocity">/showuser.htm</result>
<result name="add_suc" type="velocity">/login.htm</result>
</action>
</package>
</struts>WEB.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>applicationContext*.xml</param-value>
</context-param>
<filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<welcome-file-list>
<welcome-file>login.htm</welcome-file>
</welcome-file-list>
</web-app>
郁闷了 你们说的我都弄了啊 ..
System.out.println(t.getUsername()); 这个可以打印值的
public DBDao getDBDao() {
return dBDao;
} public void setDBDao(DBDao dao) {
dBDao = dao;
}
这个帖子来做 唯一不同的是我用的是myeclipse 6.5
也是实例接口的时候出空指针异常 . 不知道怎么回事
忘得解
<action name="user" class="action.UserAction">
<result name="success" type="velocity">/showuser.htm </result>
<result name="fail" type="velocity">/error.htm </result>
<result name="showuser" type="velocity">/showuser.htm </result>
<result name="add_suc" type="velocity">/login.htm </result>
</action>
改成
<action name="user" class="userAction">
<result name="success" type="velocity">/showuser.htm </result>
<result name="fail" type="velocity">/error.htm </result>
<result name="showuser" type="velocity">/showuser.htm </result>
<result name="add_suc" type="velocity">/login.htm </result>
</action>