[collection]struts download Action

BlueO2 — Wed, 07 Dec 2005 09:21:00 GMT

虽然struts上传下载文件很简单，但是封装一下还是好地。
/*
* $Id: DownloadAction.java 164530 2005-04-25 03:11:07Z niallp $
*
* Copyright 2004-2005 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.apache.struts.actions;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

/**
* This is an abstract base class that minimizes the amount of special coding
* that needs to be written to download a file. All that is required to use
* this class is to extend it and implement the getStreamInfo()
* method so that it returns the relevant information for the file (or other
* stream) to be downloaded. Optionally, the getBufferSize()
* method may be overridden to customize the size of the buffer used to
* transfer the file.
*
* @since Struts 1.2.6
*/
public abstract class DownloadAction extends Action {

/**
* If the getBufferSize() method is not overridden, this is
* the buffer size that will be used to transfer the data to the servlet
* output stream.
*/
protected static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

/**
* Returns the information on the file, or other stream, to be downloaded
* by this action. This method must be implemented by an extending class.
*
* @param mapping The ActionMapping used to select this instance.
* @param form The optional ActionForm bean for this request (if any).
* @param request The HTTP request we are processing.
* @param response The HTTP response we are creating.
*
* @return The information for the file to be downloaded.
*
* @throws Exception if an exception occurs.
*/
protected abstract StreamInfo getStreamInfo(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response)
throws Exception;

/**
* Returns the size of the buffer to be used in transferring the data to
* the servlet output stream. This method may be overridden by an extending
* class in order to customize the buffer size.
*
* @return The size of the transfer buffer, in bytes.
*/
protected int getBufferSize() {
return DEFAULT_BUFFER_SIZE;
}

/**
* Process the specified HTTP request, and create the corresponding HTTP
* response (or forward to another web component that will create it).
* Return an ActionForward instance describing where and how
* control should be forwarded, or null if the response has
* already been completed.
*
* @param mapping The ActionMapping used to select this instance.
* @param form The optional ActionForm bean for this request (if any).
* @param request The HTTP request we are processing.
* @param response The HTTP response we are creating.
*
* @throws Exception if an exception occurs.
*/
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {

StreamInfo info = getStreamInfo(mapping, form, request, response);
String contentType = info.getContentType();
InputStream stream = info.getInputStream();

try {
response.setContentType(contentType);
copy(stream, response.getOutputStream());
} finally {
if (stream != null) {
stream.close();
}
}

// Tell Struts that we are done with the response.
return null;
}

/**
* Copy bytes from an InputStream to an
* OutputStream.
*
* @param input The InputStream to read from.
* @param output The OutputStream to write to.
*
* @return the number of bytes copied
*
* @throws IOException In case of an I/O problem
*/
public int copy(InputStream input, OutputStream output)
throws IOException {
byte[] buffer = new byte[getBufferSize()];
int count = 0;
int n = 0;
while (-1 != (n = input.read(buffer))) {
output.write(buffer, 0, n);
count += n;
}
return count;
}

/**
* The information on a file, or other stream, to be downloaded by the
* DownloadAction.
*/
public static interface StreamInfo {

/**
* Returns the content type of the stream to be downloaded.
*
* @return The content type of the stream.
*/
public abstract String getContentType();

/**
* Returns an input stream on the content to be downloaded. This stream
* will be closed by the DownloadAction.
*
* @return The input stream for the content to be downloaded.
*/
public abstract InputStream getInputStream() throws IOException;
}

/**
* A concrete implementation of the StreamInfo interface which
* simplifies the downloading of a file from the disk.
*/
public static class FileStreamInfo implements StreamInfo {

/**
* The content type for this stream.
*/
private String contentType;

/**
* The file to be downloaded.
*/
private File file;

/**
* Constructs an instance of this class, based on the supplied
* parameters.
*
* @param contentType The content type of the file.
* @param file The file to be downloaded.
*/
public FileStreamInfo(String contentType, File file) {
this.contentType = contentType;
this.file = file;
}

/**
* Returns the content type of the stream to be downloaded.
*
* @return The content type of the stream.
*/
public String getContentType() {
return this.contentType;
}

/**
* Returns an input stream on the file to be downloaded. This stream
* will be closed by the DownloadAction.
*
* @return The input stream for the file to be downloaded.
*/
public InputStream getInputStream() throws IOException {
FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis);
return bis;
}
}

/**
* A concrete implementation of the StreamInfo interface which
* simplifies the downloading of a web application resource.
*/
public static class ResourceStreamInfo implements StreamInfo {

/**
* The content type for this stream.
*/
private String contentType;

/**
* The servlet context for the resource to be downloaded.
*/
private ServletContext context;

/**
* The path to the resource to be downloaded.
*/
private String path;

/**
* Constructs an instance of this class, based on the supplied
* parameters.
*
* @param contentType The content type of the file.
* @param context The servlet context for the resource.
* @param path The path to the resource to be downloaded.
*/
public ResourceStreamInfo(String contentType, ServletContext context,
String path) {
this.contentType = contentType;
this.context = context;
this.path = path;
}

/**
* Returns the content type of the stream to be downloaded.
*
* @return The content type of the stream.
*/
public String getContentType() {
return this.contentType;
}

/**
* Returns an input stream on the resource to be downloaded. This stream
* will be closed by the DownloadAction.
*
* @return The input stream for the resource to be downloaded.
*/
public InputStream getInputStream() throws IOException {
return context.getResourceAsStream(path);
}
}
}

BlueO2 2005-12-07 17:21 发表评论

Struts ActionForm->BO转换方式总结

BlueO2 — Sat, 08 Oct 2005 07:40:00 GMT

也算是Struts in Action的读书笔记吧~~~
1 实现业务层接口
public class ArticleForm extends ActionForm implements ArticleBean{
//...
}
调用ArticleBean articleBean = (ArticleBean)form;
articleModel.update(articleBean.getKey(),articleBean);
2 手动初始化
ArticleForm aForm = (ArticleForm)form;
ArticleBean aBean = new ArticleBean(aFrom.getxxxx..,.,.,.);
4 提供工厂方法
ActionForm中封装此方法
public ArticleBean getArticleBean(){
ArticleBean aBean = new ArticleBean(
this.getXXXX,
this.getXXXX,
......
)
}
5 传递Map对象
用BeanUtils包或者手动产生于ActionForm
public Map describe(){
map = new HashMap();
map.add("xx",this.getXXX());
map.add("xx",this.getXX());
//......
}
6 反射传递数据
写于action
BeanUtils.copyProperties(myBusinessBean,myActionForm);
//Business Object's somemethod
BeanUtils.copyProperties(myActionForm,myBusinessBean);

BlueO2 2005-10-08 15:40 发表评论

打破神话

BlueO2 — Sat, 08 Oct 2005 04:13:00 GMT

我什么时候也起这么恶心的题目了，可能和某些同志混久了，也喜欢抓眼球了。言归正传，banq老爷子(这么叫挺可爱的)，就是jdon创始的那个banq，其实我一直有些佩服有些BS的复杂情绪看待这样一个人，banq技术上确实有几下，起码不是只会吵架的人，能研究些东西，但是，看他吵架和写东西确实不是很舒服，总是感觉什么东西都是他banq的最好，他的jdonframework比spring先进阿，HiveMind框架的思想他早就有啊之类的……翻翻帖子，看看gigix robbin怎么和banq结的梁子，有时候不禁喷饭。但是似乎所有大牛都有个特点，什么东西都要评头品足，我就纳闷，世界上有这样的人么？什么东西都研究的明明白白的。今天好不容易闲了，去jdon看看热闹，看有人吵架每(这心里够bt)，结果看到banq解答的struts问题的帖子，sigh，要是普通人我早就反驳了，可是因为是banq，我又再次翻出来以前看的资料和源码才敢指出:banq,u r wrong.而且是很基础的很本质的错误。问题如下：
感觉Struts标签太繁琐了，想用 struts+velocity ,但是页面如果没有html:form等struts标签，页面的form elements 是否能赋值到formbean中，formbean中的validate方法是否还有效。
banq的理解：
当然不会有效。每个字段实际是通过：
"ACTIONFORM名称" propert=""
其中name很重要，指定了使用哪个ActionForm。
俺给个解答，也请指出不足和理解上的偏颇：
name:The attribute name of the bean whose properties are consulted when rendering the current value of this input field. If not specified, the bean associated with the form tag we are nested within is utilized.
Any JavaBean can be used with the Struts JSP tags to populate a control. But to provide automatic validation of the input, Struts uses its own JavaBean subclass,called the ActionForm.
The ActionForm solution
The Struts solution to HTTP parameter handling is to transform the input fields into JavaBean properties. When a property on the ActionForm matches a parameter in the request, the framework automatically sets the property to the value of the parameter. A Struts developer can work with a trusty JavaBean and leave the HTTP rigmarole to the framework.To harvest request parameters, all the Struts developer needs to do is provide an ActionForm with JavaBean properties that match the names of the HTTP parameters. The rest is automatic.
具体如何automatic解析，ActionForm如何被控制，有空再写，毕竟struts研究的系列心得才进行了很少篇blog，现在忙着webwork2 hibernate spring

BlueO2 2005-10-08 12:13 发表评论

BlogJava-Colorful Day-随笔分类-MVC Framework

[collection]struts download Action

Struts ActionForm->BO转换方式总结

打破神话