java实现文件上传、下载

tomcat上传文件下载文件

首先介绍一下我们需要的环境：我用的是myeclipse8.5的java开发环境，tomcat是用的apache-tomcat-6.0.26这个版本。首先先需要准备一下使用到的

jar包

这些jar包是struts2的jar包。这些jar包是都是用于上传文件的。

注意：这里的jar包版本必须是对应的，如不是可能会tomcat下报错。所以大家最好注意一下啊。最好是用这套jar包。我将会在csdn上将项目jar包发上去。

Jar下载地址（0

分）:https://www.360docs.net/doc/204903243.html,/detail/woaixinxin123/4193113 源代码下载（10分）：

https://www.360docs.net/doc/204903243.html,/detail/woaixinxin123/4193134

开始搭建我们的项目。创建web项目名字为File。

第一步：搭建struts2框架。

1、到jar包。

2、编辑web.xml

xmlns="https://www.360docs.net/doc/204903243.html,/xml/ns/javaee"

xmlns:xsi="https://www.360docs.net/doc/204903243.html,/2001/XMLSchema-instance"

xsi:schemaLocation="https://www.360docs.net/doc/204903243.html,/xml/ns/javaee

https://www.360docs.net/doc/204903243.html,/xml/ns/javaee/web-app_2_5.xsd">

struts2

org.apache.struts2.dispatcher.ng.filter.StrutsPrepa reAndExecuteFilter

struts2

/*

index.jsp

3、添加struts.xml

"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"

"https://www.360docs.net/doc/204903243.html,/dtds/struts-2.0.dtd">

4、启动tomcat测试。

配置完成的tomcat提示。

第二步：编写首页

代码：

<%@page language="java"import="java.util.*" pageEncoding="utf-8"%>

<%@taglib uri="/struts-tags"prefix="s"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.get ServerPort()+path+"/";

%>

第三部：编写action

代码：

package file.action;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

import java.util.List;

import com.opensymphony.xwork2.ActionSupport;

public class UploadAction extends ActionSupport {

/**

*

*/

//上传文件的路径地址（文件夹提前创建）

private static final String PATH= "D:\\apache-tomcat-6.0.26\\webapps\\uploadFiles\\";

private static final long serialVersionUID = 1L;

private List upload;

public List getUpload() {

return upload;

public void setUpload(List upload) {

this.upload = upload;

}

public List getUploadFileName() {

return uploadFileName;

}

public void setUploadFileName(List uploadFileName) { this.uploadFileName = uploadFileName;

}

private List uploadFileName;

public String execute() throws Exception{

//判断文件是否为空

if(upload!=null){

//循环遍历文件

for(int i=0;i

//取到文件流

InputStream is=new FileInputStream(upload.get(i));

//创建文件输出流

OutputStream os=new FileOutputStream(PATH+uploadFileName.get(i));

//缓存字节

byte buffer[]=new byte[1024];

//缓存字节大小

int count=0;

//写文件

while((count=is.read(buffer))>0){

os.write(buffer,0,count);

}

//关闭流

os.close();

is.close();

}

}else{

return INPUT;

}

return SUCCESS;

}

第四部：配置struts.xml

"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"

"https://www.360docs.net/doc/204903243.html,/dtds/struts-2.0.dtd">

/success.jsp

/input.jsp

第五步：创建缺省页面

Success.jsp

<%@ page language="java"import="java.util.*" pageEncoding="utf-8"%>

上传成功

Input.jsp

<%@page language="java"import="java.util.*" pageEncoding="utf-8"%>

文件为空，不能上传

上传文件测试：

启动tomcat添加File 打开浏览器输入网址

查看文件是否在：

确认，而且数据都对。

文件下载：

为区别开下载的类型下载区分为文件、图片、视频、音频、四类。定义文件读写的常用方法：

package file.download;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

public class FileUtils {

/**

* 计算机目录

*/

private String SDPA TH;

public String getSDPA TH() {

return SDPA TH;

}

public FileUtils(String path) {

//得到当前外部存储设备的目录

// /SDCARD

this.SDPA TH =path;

}

/**

* 在SD卡上创建文件

*

* @throws IOException

*/

public File creatSDFile(String fileName) throws IOException { File file = new File(SDPA TH + fileName);

file.createNewFile();

return file;

}

/**

* 在SD卡上创建目录

*

* @param dirName

*/

public File creatSDDir(String dirName) {

File dir = new File(SDPA TH + dirName);

dir.mkdirs();

return dir;

}

/**

* 判断SD卡上的文件夹是否存在

*/

public boolean isFileExist(String fileName){

File file = new File(SDPA TH + fileName);

return file.exists();

}

/**

* 将一个InputStream里面的数据写入到SD卡中

*/

public File write2SDFromInput(String path,String fileName,InputStream input){ File file = null;

OutputStream output = null;

try{

creatSDDir(path);

file = creatSDFile(path + fileName);

output = new FileOutputStream(file);

byte buffer [] = new byte[1];

while((input.read(buffer)) != -1){

output.write(buffer);

}

output.flush();

}

catch(Exception e){

e.printStackTrace();

}

finally{

try{

output.close();

}

catch(Exception e){

e.printStackTrace();

}

}

return file;

}

}

实现下载的工具类

package file.download;

import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import https://www.360docs.net/doc/204903243.html,.HttpURLConnection;

import https://www.360docs.net/doc/204903243.html,.MalformedURLException;

import https://www.360docs.net/doc/204903243.html,.URL;

public class HttpDownloadUtil {

private String path =null ;

private URL url = null;

public HttpDownloadUtil(String path) {

super();

this.path = path;

}

/**

* 根据URL下载文件，前提是这个文件当中的内容是文本，函数的返回值就是文件当中的内容

* 1.创建一个URL对象

* 2.通过URL对象，创建一个HttpURLConnection对象

* 3.得到InputStram

* 4.从InputStream当中读取数据

* @param urlStr

* @return

*/

public String download(String urlStr) {

StringBuffer sb = new StringBuffer();

String line = null;

BufferedReader buffer = null;

try {

// 创建一个URL对象

url = new URL(urlStr);

// 创建一个Http连接

HttpURLConnection urlConn = (HttpURLConnection) url

.openConnection();

// 使用IO流读取数据

buffer = new BufferedReader(new InputStreamReader(urlConn

.getInputStream()));

while ((line = buffer.readLine()) != null) {

sb.append(line);

}

} catch (Exception e) {

e.printStackTrace();

} finally {

try {

buffer.close();

} catch (Exception e) {

e.printStackTrace();

}

}

return sb.toString();

}

/**

* 该函数返回整形-1：代表下载文件出错0：代表下载文件成功1：代表文件已经存在

*/

public int downFile(String urlStr, String path, String fileName) {

InputStream inputStream = null;

try {

FileUtils fileUtils = new FileUtils(this.path);

if (fileUtils.isFileExist(path + fileName)) {

return 1;

} else {

inputStream = getInputStreamFromUrl(urlStr);

File resultFile = fileUtils.write2SDFromInput(path,fileName, inputStream);

if (resultFile == null) {

return -1;

}

}

} catch (Exception e) {

e.printStackTrace();

return -1;

} finally {

try {

inputStream.close();

} catch (Exception e) {

e.printStackTrace();

}

}

return 0;

}

/**

* 根据URL得到输入流

*

* @param urlStr

* @return

* @throws MalformedURLException

* @throws IOException

*/

public InputStream getInputStreamFromUrl(String urlStr)

throws MalformedURLException, IOException {

url = new URL(urlStr);

HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();

InputStream inputStream = urlConn.getInputStream();

return inputStream;

}

}

实现下载分类的助手类：

package file.download;

public class HttpDownloader{

private String path ;

/**

*

* @param path 计算机路径

*/

public HttpDownloader(String path) {

super();

this.path = path;

}

public String getUrl() {

return url;

}

public void setUrl(String url) {

this.url = url;

}

private String url ;

public boolean downloadOther(String url) {

String phonepath = "download/";

return this.down(phonepath,url);

}

/**

* 获取文件名称以及文件类型

*

* @param pathandname

* @return

*/

private String getFileName(String pathandname) {

int start = pathandname.trim().lastIndexOf("/");

int end = https://www.360docs.net/doc/204903243.html,stIndexOf("");

if (start != -1 && end != -1) {

return pathandname.substring(start + 1, end);

} else {

return null;

}

}

/**

*

* @param phonepath

* @param url

* @return

*/

private boolean down(String phonepath,String url){ HttpDownloadUtil hdutil = new HttpDownloadUtil(this.path);

// 获取文件名称和类型

String filename = getFileName(url);

int result = hdutil.downFile(url, phonepath, filename);

if(result ==0 ){

return true;

}else if(result==1){

System.out.println("文件已存在！");

}

return false;

}

下载测试：

第一步：将tomcat里放入一张图片我们用我们上传的文件路径然后新建一个文件夹叫做images 放进一张图片

首先用浏览器访问这张图片

浏览区确认可以访问到

下载测试

package file.download.test;

import file.download.HttpDownloader;

public class DownloadTest {

/**

* @param args

*/

public static void main(String[] args) {

//下载储存路径

String path = "c:\\Users\\ytzn\\Desktop\\";

//下载地址

String url = "http://localhost:8888/uploadFiles/images/bizhi.jpg";

HttpDownloader hdl = new HttpDownloader(path);

//下载类型

if(hdl.downloadOther(url)){

System.out.println("下载成功！");

}else{

System.out.println("下载失败！");

}

}

}

结果:

整个项目浏览

大家若有疑问请联系本人QQ:26048853200