在Tapestry中使用redirect-after-post模式控制表单提交-技术开发专区

在Tapestry中使用redirect-after-post模式控制表单提交

作者：tapestry 编辑： ITPUB实习编辑 2006-12-07 17:12

【IT168技术文档】
Tapestry中表单的提交有很多问题，刷新导致表单的重复提交、臭名昭著的dirty form warning、显示不友好的URL等，这些都可以使用redirect-after-post模式来避免，也就是post表单之后将页面redirect一下，这样地址栏显示的就是redirect之后的页面，刷新的也将是这个页面，而且redirect之后的页面一般为Page页面，可以使用friendlyUrl来显示友好的url。要使用这个模式，不得不提到一个ILink接口，T4中可接受的listener方法中一个方法签名是这样的:

java 代码

public ILink listenerMethod(Parameter parameter);

这个方法的返回值为ILink，如果T4侦测到是这个返回值的话，将自动redirect到ILink指定的页面。而且ILink可以为纯页面的Link也可以是带有参数的Link。纯页面Link也就是page service生成的link，带参数的link为external service生成的link，具体link的生成代码如下：

java 代码

@InjectObject("engine-service:page")

  public abstract IEngineService getPageService();

       public ILink getPageLink(String pageName) ...{

           return getPageService().getLink(false, pageName);

  }


      @InjectObject("engine-service:external")

  public abstract IEngineService getExternalService();

       public ILink getExternalLink(String pageName, Object[] parameters) ...{

     ExternalServiceParameter esp = new ExternalServiceParameter(pageName,

            parameters);

     return getExternalService().getLink(false, esp);

  }

将上述方法放入到你的项目中自定义的MyBasePage（继承Tapestry的BasePage）中，然后让你的页面类继承MyBasePage，这样就可以使用上述方法了。

这样在页面提交时可以如下调用java 代码

public ILink onDelete(Long id)...{

//your code to delete object   

return getPageLink(getPageName());//删除后重新redirect到本页面   

}

当然如果这个页面带参数，例如catgoryId=1，则代码如下：

public ILink onDelete(Long id)...{

//your code to delete object   

return getExternalLink(getPageName(),new Object[]...{categoryId});
//删除后重新redirect到本页面,并带一个参数   

}

上述方式通过继承来实现方法调用，感觉不是很好，我们可以利用Tapestry的易扩展特性来扩展它，首先想到的就是注释方式来注入，例如我想实现如下注入java 代码

@InjectPageLink（“Home“）

Public abstract ILink getHomeLink();

@InjectExternalLink（“Category“）

Public abstract ILink getCategoryLink(Long categoryId);

这样即去掉了页面的继承，也显得比较直接。
【IT168技术文档】
首先是定义注释类java 代码

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;



@Target( ...{ ElementType.METHOD })

@Retention(RetentionPolicy.RUNTIME)

public @interface InjectPageLink ...{

    String value();

}

然后写注释的worker类

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.hivemind.Location;
import org.apache.hivemind.service.BodyBuilder;
import org.apache.hivemind.service.MethodSignature;
import org.apache.tapestry.annotations.AnnotationUtils;
import org.apache.tapestry.annotations.MethodAnnotationEnhancementWorker;    
  import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.enhance.EnhancementOperation;
import org.apache.tapestry.spec.IComponentSpecification;

public class InjectPageLinkAnnotationWorker implements 
               MethodAnnotationEnhancementWorker ...{
public void performEnhancement(EnhancementOperation op,
                        IComponentSpecification spec, 
                         Method method, Location location) ...{
if (!method.getReturnType().equals(ILink.class)) throw new 
                ApplicationRuntimeException(
"InjectPage annotation must return ILink");
InjectPageLink injectPageLink = method.getAnnotation(InjectPageLink.class);
String pageName = injectPageLink.value();
BodyBuilder builder = new BodyBuilder();
 builder.begin();
builder.addln(
"return getPage().getRequestCycle().getInfrastructure().getServiceMap().getService(  
           org.apache.tapestry.Tapestry.PAGE_SERVICE).getLink(false,\"{0}\");",pageName);
builder.end();
op.addMethod(Modifier.PUBLIC, new MethodSignature(method), 
     builder.toString(), location);
if (isGetter(method))
op.claimReadonlyProperty(AnnotationUtils.getPropertyName(method));
}
boolean isGetter(Method method) ...{
return method.getName().startsWith("get") && method.getParameterTypes().length == 0;   
}
}

External的同样两个类java 代码

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;



@Target( ...{ ElementType.METHOD })

@Retention(RetentionPolicy.RUNTIME)

public @interface InjectExternalLink ...{

    String value();

}

【IT168技术文档】
Work类

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.hivemind.Location;
import org.apache.hivemind.service.BodyBuilder;
import org.apache.hivemind.service.MethodSignature;
import org.apache.tapestry.Tapestry;    
  import org.apache.tapestry.annotations.AnnotationUtils;
import org.apache.tapestry.annotations.MethodAnnotationEnhancementWorker;    
  import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.enhance.EnhancementOperation;
import org.apache.tapestry.spec.IComponentSpecification;

public class InjectExternalLinkAnnotationWorker implements           
     MethodAnnotationEnhancementWorker ...{
public void performEnhancement(EnhancementOperation op,IComponentSpecification spec, 
 Method method, Location location) ...{
if (!method.getReturnType().equals(ILink.class))
throw new ApplicationRuntimeException(
"injectExternalLink annotation must return ILink");                
 InjectExternalLink injectExternalLink = method.getAnnotation(InjectExternalLink.class);  
String pageName = injectExternalLink.value();
BodyBuilder builder = new BodyBuilder();
builder.begin();
Class[] parameterTypes = method.getParameterTypes();
int paramCount = Tapestry.size(parameterTypes);
if (paramCount > 0) ...{
if (parameterTypes[0].isArray()) ...{

builder.addln(
"return getPage().getRequestCycle().getInfrastructure().getServiceMap().getService(
     org.apache.tapestry.Tapestry.EXTERNAL_SERVICE).getLink(
     false, new org.apache.tapestry.engine.ExternalServiceParameter(\"{0}\",$1));"
         ,pageName);    
     } else ...{
builder.addln(
"java.lang.Object[] params = new java.lang.Object0}];",paramCount);
for (int i = 0; i < paramCount; i++) ...{
builder.add("params[{0}] = ", i);
if (parameterTypes[i].isPrimitive())
builder.add("($w) ");  // Parameter $0 is this, so $1 is the first real parameter.   
builder.addln("${0};", i + 1);
}
builder.addln(
"return getPage().getRequestCycle().getInfrastructure().getServiceMap().getService(
                org.apache.tapestry.Tapestry.EXTERNAL_SERVICE).getLink(false, 
             new org.apache.tapestry.engine.ExternalServiceParameter(\"{0}\",params));"
                  ,pageName);
     }           
   }
builder.end();
op.addMethod(Modifier.PUBLIC, new MethodSignature(method), builder.toString(),location);  
 if (isGetter(method))
op.claimReadonlyProperty(AnnotationUtils.getPropertyName(method));        }
boolean isGetter(Method method) ...{           
  return method.getName().startsWith("get")&& method.getParameterTypes().length == 0;
 }
 }

类写好了，然后就是贡献到Tapestry中xml 代码

<module id="your.model.annotation" version="1.0.0" package="your.package.annotations">

     <contribution configuration-id="tapestry.annotation.MethodWorkers">

      <worker annotation="InjectPageLink" 
           object="instance:InjectPageLinkAnnotationWorker"/>

      <worker annotation="InjectExternalLink" 
           object="instance:InjectExternalLinkAnnotationWorker"/>

    <!--</span-->contribution>

<!--</span-->module>

好了将你的module放入项目hivemodule.Xml作为子module。

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