彻底抛弃 jspSmartUpload，使用 common-fileupload 实现文件上传

字体大小: 中小 标准 ->行高大小: 标准 中 大
 就在前段时间，还在苦于找到不到合适的上传组件，虽然很早就知道了 common-fileupload，但当时却因为没有找到如何获取表单参数的方法而使用 jspSmartUpload，历尽艰辛终于找到了它的 jar，可是使用后才发现此东西对中文参数支持奇差，甚至需要修改源代码才能解决问题，可是jspSmartUpload并不是开源的项目，而且开发团队也不再对它进行更新，连官方网站都关门大吉了，情急之下使用JadClipse 反编译了它的jar包，原以为问题算是得到解决了，谁知道后来却发现获取到的参数经常出现部分中文乱码，而且还不是固定的汉字出现乱码，仔细研究加Google后才找出了规律，原来是奇数字数的中文会出现乱码，而偶数字数的则正常，阅读了源代码，终于还是没耐心阅读下去，而且看到网上还有评论说该组件有内存泄露的问题，于是才下定决定搞定common-fileupload。

于是从 http://jakarta.apache.org/commons/fileupload/ 下载到了最新版的 FileUpload 1.2，阅读了部分文档跟例子，终于找到了获取表单中参数的方法并对该组件做了进一点封装，使其更容易使用，并支持单文件上传和多文件上传两种方式，首先定义一个基类放置公共属性：

FileUploadBase.java

import java.io.File;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;

public abstract class FileUploadBase {
protected Map<String, String> parameters = new HashMap<String, String>();// 保存普通form表单域
protected String encoding = "utf-8"; // 字符编码，当读取上传表单的各部分时会用到该encoding

protected UploadFileFilter filter = null; // 文件过滤器, 默认为NULL 不过滤
/**
* The directory in which uploaded files will be stored, if stored on disk.
*/
protected int sizeThreshold = DiskFileItemFactory.DEFAULT_SIZE_THRESHOLD;

/**
*
* The maximum size permitted for the complete request, as opposed to
*
* {@link #fileSizeMax}. A value of -1 indicates no maximum.
*
*/
protected long sizeMax = -1;

/**
* The directory in which uploaded files will be stored, if stored on disk.
*/
protected File repository;

public String getParameter(String key) {
return parameters.get(key);
}

public String getEncoding() {
return encoding;
}

public void setEncoding(String encoding) {
this.encoding = encoding;
}

/**
* 获取上传文件最大的大小，单位为Byte(字节），为-1时表示无限制
* @return
*/
public long getSizeMax() {
return sizeMax;
}

/**
* 设置上传文件最大的大小，单位为Byte(字节），为-1时表示无限制
* @param sizeMax
*/
public void setSizeMax(long sizeMax) {
this.sizeMax = sizeMax;
}

public int getSizeThreshold() {
return sizeThreshold;
}

public void setSizeThreshold(int sizeThreshold) {
this.sizeThreshold = sizeThreshold;
}

/**
* Returns the directory used to temporarily store files that are larger
* than the configured size threshold.
*
* @return The directory in which temporary files will be located.
*
* @see #setRepository(java.io.File)
*
*/
public File getRepository() {
return repository;
}

/**
* Sets the directory used to temporarily store files that are larger than
* the configured size threshold.
*
* @param repository
* The directory in which temporary files will be located.
*
* @see #getRepository()
*
*/
public void setRepository(File repository) {
this.repository = repository;
}

/**
* 获取参数列表
* @return
*/
public Map<String, String> getParameters() {
return parameters;
}

/**
* 获取过滤器
* @return
*/
public UploadFileFilter getFilter() {
return filter;
}

/**
* 设置文件过滤器，不符合过滤器规则的将不被上传
* @param filter
*/
public void setFilter(UploadFileFilter filter) {
this.filter = filter;
}

/**
* 验证文件是否有效
* @param item
* @return
*/
protected boolean isValidFile(FileItem item){
return item == null || item.getName() == "" || item.getSize() == 0 || (filter != null && !filter.accept(item.getName())) ? false : true;
}
}


支持单文件上传的 SingleFileUpload 类：
SingleFileUpload.java


import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class SingleFileUpload extends FileUploadBase {
private FileItem fileItem;

/**
*
* @param request
* @throws UnsupportedEncodingException
*/
public void parseRequest(HttpServletRequest request)
throws UnsupportedEncodingException {

DiskFileItemFactory factory = new DiskFileItemFactory();

factory.setSizeThreshold(sizeThreshold);

if (repository != null)
factory.setRepository(repository);

ServletFileUpload upload = new ServletFileUpload(factory);

upload.setHeaderEncoding(encoding);

try {
List<FileItem> items = upload.parseRequest(request);

for (FileItem item : items) {
if (item.isFormField()) {
String fieldName = item.getFieldName();
String value = item.getString(encoding);
parameters.put(fieldName, value);
} else {

if (!super.isValidFile(item)) {
continue;
}

if (fileItem == null)
fileItem = item;
}
}

} catch (FileUploadException e) {
e.printStackTrace();
}
}

/**
* 上传文件, 调用该方法之前必须先调用 parseRequest(HttpServletRequest request)
* @param fileName 完整文件路径
* @throws Exception
*/
public void upload(String fileName) throws Exception {
File file = new File(fileName);
uploadFile(file);
}

/**
* 上传文件, 调用该方法之前必须先调用 parseRequest(HttpServletRequest request)
* @param parent 存储的目录
* @throws Exception
*/
public void upload(File parent) throws Exception {
if (fileItem == null)
return;

String name = fileItem.getName();
File file = new File(parent, name);
uploadFile(file);
}

private void uploadFile(File file) throws Exception{
if (fileItem == null)
return;

long fileSize = fileItem.getSize();
if (sizeMax > -1 && fileSize > super.sizeMax){
String message = String.format("the request was rejected because its size (%1$s) exceeds the configured maximum (%2$s)", fileSize, super.sizeMax);

throw new org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException(message, fileSize, super.sizeMax);
}

String name = fileItem.getName();
fileItem.write(file);
}

/**
* 获取文件信息
* 必须先调用 parseRequest(HttpServletRequest request)
* @return
*/
public FileItem getFileItem() {
return fileItem;
}
}


支持多文件上传的 MutiFileUpload 类：
MutiFileUpload.java



import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class MutiFileUpload extends FileUploadBase {

private Map<String, FileItem> files;// 保存上传的文件
 private long filesSize = 0; // 所有文件的总大小


public void parseRequest(HttpServletRequest request)
throws UnsupportedEncodingException {

files = new HashMap<String, FileItem>();

// Create a factory for disk-based file items

DiskFileItemFactory factory = new DiskFileItemFactory();

factory.setSizeThreshold(sizeThreshold);

if (repository != null)
factory.setRepository(repository);

ServletFileUpload upload = new ServletFileUpload(factory);

upload.setHeaderEncoding(encoding);

try {
List<FileItem> items = upload.parseRequest(request);

for (FileItem item : items) {
if (item.isFormField()) {
String fieldName = item.getFieldName();
String value = item.getString(encoding);
parameters.put(fieldName, value);
} else {

if (super.isValidFile(item)) {
continue;
}

String fieldName = item.getFieldName();

files.put(fieldName, item);
filesSize += item.getSize();
}
}

} catch (FileUploadException e) {
e.printStackTrace();
}
}

/**
* 上传文件, 调用该方法之前必须先调用 parseRequest(HttpServletRequest request)
* @param parent 文件存储的目录
* @throws Exception
*/
public void upload(File parent) throws Exception {
if (files.isEmpty())
return;

if (sizeMax > -1 && filesSize > super.sizeMax){
String message = String.format("the request was rejected because its size (%1$s) exceeds the configured maximum (%2$s)", filesSize, super.sizeMax);

throw new SizeLimitExceededException(message, filesSize, super.sizeMax);
}

for (String key : files.keySet()) {
FileItem item = files.get(key);
String name = item.getName();

File file = new File(parent, name);
item.write(file);
}
}

public Map<String, FileItem> getFiles() {
return files;
}

}


当然还少不了过滤器 UploadFileFilter：
UploadFileFilter.java


public interface UploadFileFilter {
/**
* 通过文件名后缀判断文件是否被接受
* @param filename 文件名，不包括路径
* @return
*/
public boolean accept(String filename);
}


这样在 Servlet 中我们就可以通过简单的代码实现文件的上传了：


SingleFileUpload upload = new SingleFileUpload();
upload.parseRequest(request);
File parent = new File("C:\\upload\\");

try {
upload.upload(parent);
}
catch(org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e){
// 文件大小超出最大值
 e.printStackTrace();
}catch (Exception e) {
e.printStackTrace();
}


相比 jspSmartUpload 我觉得 common-fileupload 有如下的优点：
1、开源；
2、Jakarta项目组的支持，开发十分活跃，而 jspSmartUpload 则已经停止开发了；
3、不需要写入文件之前即可获取到参数和文件信息，jspSmartUpload 则需要在获取之前调用 upload 方法；
4、对中文支持友好。

此文章由 http://www.ositren.com 收集整理 ,地址为: http://www.ositren.com/htmls/69127.html