SSH问题解决办法之重定向问题

问题1：Cannot create a session after the response has been committed

问题2：Cannot call sendError() after the response has been committed

• 以下是报错代码

2015-5-29 10:31:44 org.apache.catalina.core.ApplicationDispatcher invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: Cannot create a session after the response has been committed
    at org.apache.catalina.connector.Request.doGetSession(Request.java:2882)
    at org.apache.catalina.connector.Request.getSession(Request.java:2316)
    at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:898)
    at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:229)
    at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:571)
    at org.apache.catalina.core.ApplicationHttpRequest.getSession(ApplicationHttpRequest.java:516)
    at javax.servlet.http.HttpServletRequestWrapper.getSession(HttpServletRequestWrapper.java:238)
    at org.apache.jasper.runtime.PageContextImpl._initialize(PageContextImpl.java:146)
    at org.apache.jasper.runtime.PageContextImpl.initialize(PageContextImpl.java:125)
    at org.apache.jasper.runtime.JspFactoryImpl.internalGetPageContext(JspFactoryImpl.java:112)
    at org.apache.jasper.runtime.JspFactoryImpl.getPageContext(JspFactoryImpl.java:65)
    at org.apache.jsp.index_jsp._jspService(index_jsp.java:54)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:605)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:544)
    at org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:161)
    at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)
    at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:373)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:277)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:133)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:142)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:166)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:485)
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1008
)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:619)

2015-5-29 10:31:44 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet [default] in context with path [/MiniBank] threw exception
java.lang.IllegalStateException: Cannot call sendError() after the response has been committed
    at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:451)
    at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:771)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:506)
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1008)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:619)

首先，采用的是SSH三框架搭建的服务端，需求是在页面上输出一段文字或者HTML代码或者JSON数据等等，当然了我们这里是输出一段文字。

疑惑点

1.是不是我们在操作的时候DAO层把session关闭导致的？

在这里我把DAO层的代码贴出来：

    /**
 * 查询所有记录
 * 
 * @param classez
 * 实体类
 * @return 数据表中所有记录，list类型
 */
@SuppressWarnings("rawtypes")
public List hqlList(Class classez) {
// 定义list
        List list = null;
// 获取session
        Session session = getSession();
// HQL语句
        String hql = "from " + classez.getName();
// 执行
try {
            list = session.createQuery(hql).list();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            session.close();
        }
return list;
    }

大家可以看到我的session是关闭了的。

session.close();

可能大家会想这是不是出现我们根本问题的所在呢？其实不是。
这里我们做个测试，把session.close();注释掉，再次运行程序。

    /**
 * 查询所有记录
 * 
 * @param classez
 * 实体类
 * @return 数据表中所有记录，list类型
 */
@SuppressWarnings("rawtypes")
public List hqlList(Class classez) {
// 定义list
        List list = null;
// 获取session
        Session session = getSession();
// HQL语句
        String hql = "from " + classez.getName();
// 执行
try {
            list = session.createQuery(hql).list();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
//session.close();注释掉
        }
return list;
    }

修改DAO层代码：

//session.close();

错误依旧存在：

2015-5-29 11:04:03 org.apache.catalina.core.ApplicationDispatcher invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: Cannot create a session after the response has been committed
//省略更多报错代码

2015-5-29 11:04:03 org.apache.catalina.core.ApplicationDispatcher invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: Cannot create a session after the response has been committed
//省略更多报错代码

由此可见，报错并不是DAO层session引起的。

2.是不是我们的配置文件导致的？

我们去网上查阅资料发现，网上有各种各样的解决办法，比如说为Struts2添加过滤器、Spring配置、web.xml配置等等。经过测试都不行，都不是根本原因。

以下贴出完整的代码从DAO层到service层再到action

• BaseDao

public class BaseDao extends HibernateDaoSupport {
/**
 * 查询所有记录
 * 
 * @param classez
 * 实体类
 * @return 数据表中所有记录，list类型
 */
@SuppressWarnings("rawtypes")
public List hqlList(Class classez) {
// 定义list
        List list = null;
// 获取session
        Session session = getSession();
// HQL语句
        String hql = "from " + classez.getName();
// 执行
try {
            list = session.createQuery(hql).list();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            session.close();
        }
return list;
    }
}

• RoiDao
  注意这里是面向接口编程的，所以可能和大家有点不一样，但是程序整个实现的过程是一样的。大家照着我的写，或者自己修改一下代码即可。

//注意这是个接口
public interface RoiDao {
/**
 * 获取所有数据记录
 * 
 * @return 所有数据记录
 */
@SuppressWarnings("rawtypes")
public List roiAll();
}

实现类：

public class RoiDaoImpl extends BaseDao implements RoiDao {

// 获取所有数据记录
@SuppressWarnings("rawtypes")
@Override
public List roiAll() {
return hqlList(Roi.class);
    }

}

• RoiService
  接口:

public interface RoiService {

/**
 * 获取所有数据记录
 * 
 * @return 所有数据记录
 */
@SuppressWarnings("rawtypes")
public List roiAll();
}

实现类：

public class RoiServiceImpl implements RoiService {
private RoiDao roiDao = null;

public RoiDao getRoiDao() {
return roiDao;
    }

public void setRoiDao(RoiDao roiDao) {
this.roiDao = roiDao;
    }

// 获取所有数据
@SuppressWarnings("rawtypes")
@Override
public List roiAll() {
return roiDao.roiAll();
    }
}

在写web层的时候，我们先写一个BaseAction，所有Action的基类。
- BaseAction

/**
 * 操作Servlet API
 * 
 * @author y1笑而过
 * 
 */
public class BaseAction {
// 获取HTTPrequest
public HttpServletRequest getHttpRequest() {
return ServletActionContext.getRequest();
    }

// 获取request对象
public Map<String, Object> getRequest() {
// 通过ActionContext得到request
return (Map<String, Object>) ActionContext.getContext().get("request");
    }

// 获取response对象
public HttpServletResponse getResponse() {
// 通过ServletActionContext得到response
        HttpServletResponse response = ServletActionContext.getResponse();
// 设置响应头与字符编码
        response.setContentType("text/html;charset=utf-8");
        response.setCharacterEncoding("utf-8");
return response;
    }

// 获取session对象
public Map<String, Object> getSession() {
return ActionContext.getContext().getSession();
    }

// 获取Application对象
public Map<String, Object> getApplication() {
return ActionContext.getContext().getApplication();
    }

// 输出
public void outMessage(Object object) {
try {
            PrintWriter out = getResponse().getWriter();
            out.print(object);
            out.flush();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

• RoiAction

public class RoiAction extends BaseAction {
private Roi roi = null;

public Roi getRoi() {
return roi;
    }

public void setRoi(Roi roi) {
this.roi = roi;
    }

private RoiService roiService = null;

public RoiService getRoiService() {
return roiService;
    }

public void setRoiService(RoiService roiService) {
this.roiService = roiService;
    }

public String roiAll() {
// 获取所有数据记录
        List<Roi> rois = roiService.roiAll();
        outMessage("123");
// 页面跳转
if (rois != null) {
return "roiAll";
        }
return "fail";
    }
}

• applicationContext.xml

    <!-- 省略自动生成代码 -->

<!-- 实体类 -->
<bean id="roi" class="com.scp.entity.Roi"></bean>

<!-- DAO层 -->
<bean id="baseDao" class="com.scp.dao.Impl.BaseDao">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
<bean id="roiDao" class="com.scp.dao.Impl.RoiDaoImpl">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>

<!-- Service层 -->
<bean id="roiService" class="com.scp.service.Impl.RoiServiceImpl">
<property name="roiDao" ref="roiDao"></property>
</bean>

<!-- Action层 -->
<bean id="roiAction" class="com.scp.web.RoiAction">
<property name="roi" ref="roi"></property>
<property name="roiService" ref="roiService"></property>
</bean>

• struts.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<package name="default" extends="struts-default">
<!-- 利率信息表 -->
<action name="roiAction" class="roiAction">
<result name="roiAll">/index.jsp</result>
<result name="fail">/index.jsp</result>
</action>
</package>
</struts>    

• 工程结构图
  
  当然了，大家的工程名不一定和我的一样，但是呢图中黄色高亮区域内容一定要有。【后面我们会讲解此次问题的解决办法】

3.是不是out.close导致的？

刚开始在网上搜索相关问题的时候看到这样一个解决办法，经过测试，这也不是导致出错的原因。

解决办法

• 解决办法1：
  首先我们要知道出现此次问题的原因是因为我们在Response输出响应后才创建Session的。
(因为那时候服务器已经将数据发送到客户端了，即：就无法发送Session ID 了)
你只需要在你的程序中将创建访问Session的语句【request.getSession()】提前至Response输出数据之前就好了。
例如改成下面的写法OK：
ServletOutputStream ut = response.getOutputStream();
// 最好这样紧挨着 response.getOutputStream()
HttpSession seesion = request.getSession();
seesion.setAttribute("xxx", rand);
// 输出数据
out.print("hello");
out.close();
  这个是网上的解决办法。
• 解决办法2：

public String roiAll() {
// 获取所有数据记录
        List<Roi> rois = roiService.roiAll();
        outMessage("123");
// 页面跳转
if (rois != null) {
return "roiAll";
        }
return "fail";
    }

大家发现了没有，我们在Action里面写的时候有个Struts的映射，即返回一个字符串对应struts.xml对应的网页。这个动作是重定向！！！问题就在这，也就是说我们在向网页输出一段文字的时候，网页同时做了重定向操作！我们的需求是向网页输出一段文字，不需要重定向操作，那么我们就可以修改action里面的代码了，如下：

public void roiTest(){
        outMessage("向页面输出字符");
    }

可以看到，我们将返回值改为了void，只需要向页面写数据，不需要跳转就可以这样写。当然了，有些是需要页面跳转的，那么我们也可以手动书写页面跳转代码即可。

在地址栏中输入localhost:8080/MiniBank/roiAction!roiTest.action重新运行一下我们的程序，发现没有报错，程序运行正常！


y1笑而过的CSDN博客
y1笑而过的博客园
y1笑而过的新浪博客
y1笑而过的安卓巴士博客
y1笑而过的51CTO技术博客