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java自行下载文件代码 java下载怎么写
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Java中文件下载该怎么写代码求高手指导
if (upfile.exists()) {
bytes = FileUtils.readFileToByteArray(upfile);
response.setContentType("application/x-download");
String agent = request.getHeader("USER-AGENT");//用户代理
// 防止中文文件名乱码
if (null != agent -1 != agent.indexOf("MSIE")) {
String codedfilename = StringUtils.replace(URLEncoder.encode(fileName, "UTF-8"), "+", "%20");
response.setHeader("Content-Disposition", "attachment;filename=" + codedfilename);
} else if (null != agent -1 != agent.indexOf("Mozilla")) {
String codedfilename = MimeUtility.encodeText(fileName, "UTF-8", "B");
response.setHeader("Content-Disposition", "attachment;filename=" + codedfilename);
} else {
response.setHeader("Content-Disposition", "attachment;filename=" + fileName);
}
response.setContentLength(bytes.length);
response.getOutputStream().write(bytes);
}
相关问答
Q1: 求一个Java实现自动下载的源代码
您好，这样的：
/**
*
*/
package com.b510.base.bean.install;
import java.io.File;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* @author hongten(hongtenzone@foxmail.com)
* @date 2013-2-24
*/
@SuppressWarnings("unchecked")
public class BeanUtils {
//公共部分
private static final String RT_1 = "\r\n";
private static final String RT_2 = RT_1+RT_1;
private static final String BLANK_1 =" ";
private static final String BLANK_4 =" ";
private static final String BLANK_8 =BLANK_4 + BLANK_4;
//注释部分
private static final String ANNOTATION_AUTHOR_PARAMTER = "@author ";
private static final String ANNOTATION_AUTHOR_NAME = "hongten(hongtenzone@foxmail.com)";
private static final String ANNOTATION_AUTHOR = ANNOTATION_AUTHOR_PARAMTER + ANNOTATION_AUTHOR_NAME;
private static final String ANNOTATION_DATE = "@date ";
private static final String ANNOTATION = "/**"+RT_1+BLANK_1+"*"+BLANK_1+ANNOTATION_AUTHOR +RT_1+BLANK_1+"*"+BLANK_1+ANNOTATION_DATE +getDate()+RT_1+BLANK_1+"*/"+RT_1;
//文件 地址
//private static final String BEAN_PATH = "com/b510/base/bean";
private static final String DAO_PATH = "com/b510/base/dao";
private static final String DAO_IMPL_PATH = "com/b510/base/dao/impl";
private static final String SERVICE_PATH = "com/b510/base/service";
private static final String SERVICE_IMPL_PATH = "com/b510/base/service/impl";
//包名
private static final String BEAN_URL = "com.b510.base.bean";
private static final String DAO_URL = "com.b510.base.dao";
private static final String DAO_IMPL_URL = "com.b510.base.dao.impl";
private static final String SERVICE_URL = "com.b510.base.service";
private static final String SERVICE_IMPL_URL = "com.b510.base.service.impl";
//基本类名称
private static final String BASE_DAO_NAME = DAO_URL + ".BaseDao";
private static final String ABSTRACT_BASE_DAO_IMPL_NAME = DAO_IMPL_URL + ".AbstractBaseDaoImpl";
private static final String BASE_SERVICE_NAME = SERVICE_URL + ".BaseService";
private static final String ABSTRACT_BASE_SERVICE_IMPL_NAME = SERVICE_IMPL_URL + ".AbstractBaseServiceImpl";
/**
* 创建bean的Daobr
*
* @param c
* @throws Exception
*/
public void createBeanDao(Class c) throws Exception {
String cName = c.getName();
String fileName = System.getProperty("user.dir") + "/src/" + DAO_PATH
+ "/" + getLastChar(cName) + "Dao.java";
File f = new File(fileName);
FileWriter fw = new FileWriter(f);
fw.write("package "+DAO_URL+";"+RT_2+ANNOTATION+"public interface " +
getLastChar(cName) + "Dao extends "+BASE_DAO_NAME+" " + cName + " {"+RT_2+"}");
fw.flush();
fw.close();
showInfo(fileName);
}
/**
* 创建bean的Dao的实现类
* @param c
* @throws Exception
*/
public void createBeanDaoImpl(Class c) throws Exception{
String cName = c.getName();
String fileName = System.getProperty("user.dir") + "/src/" + DAO_IMPL_PATH
+ "/" + getLastChar(cName) + "DaoImpl.java";
File f = new File(fileName);
FileWriter fw = new FileWriter(f);
fw.write("package "+DAO_IMPL_URL+";"+RT_2+ANNOTATION+"public class " +
getLastChar(cName) + "DaoImpl extends "+ABSTRACT_BASE_DAO_IMPL_NAME+"" +
cName + " implements "+DAO_URL+"."+getLastChar(cName)+"Dao{"+RT_2+"}");
fw.flush();
fw.close();
showInfo(fileName);
}
/**
* 创建bean的service
* @param c
* @throws Exception
*/
public void createBeanService(Class c) throws Exception{
String cName = c.getName();
String fileName = System.getProperty("user.dir") + "/src/" + SERVICE_PATH
+ "/" + getLastChar(cName) + "Service.java";
File f = new File(fileName);
FileWriter fw = new FileWriter(f);
fw.write("package "+SERVICE_URL+";"+RT_2+ANNOTATION+"public interface " +
getLastChar(cName) + "Service extends "+BASE_SERVICE_NAME+""+ cName +"{"+RT_2+"}");
fw.flush();
fw.close();
showInfo(fileName);
}
/**
* 创建bean的service的实现类
* @param c
* @throws Exception
*/
public void createBeanServiceImpl(Class c) throws Exception{
String cName = c.getName();
String fileName = System.getProperty("user.dir") + "/src/" + SERVICE_IMPL_PATH
+ "/" +getLastChar(cName)+"ServiceImpl.java";
File f = new File(fileName);
FileWriter fw = new FileWriter(f);
fw.write("package "+SERVICE_IMPL_URL+";"+RT_2+ANNOTATION+"public class "
+ getLastChar(cName) + "ServiceImpl extends "+ABSTRACT_BASE_SERVICE_IMPL_NAME+""+ cName
+ " implements "+SERVICE_URL+"."+getLastChar(cName)+"Service{"+RT_2+BLANK_4
+"private "+DAO_URL+"."+getLastChar(cName)+"Dao "+getLowercaseChar(getLastChar(cName))
+"Dao;"+RT_2+BLANK_4+"public void set"+getLastChar(cName)+"Dao("+DAO_URL+"."+getLastChar(cName)+"Dao "
+getLowercaseChar(getLastChar(cName))+"Dao){"+RT_1+BLANK_8+"this."+getLowercaseChar(getLastChar(cName))+"Dao = "
+getLowercaseChar(getLastChar(cName))+"Dao;"+RT_1+BLANK_4+"}"+RT_2+BLANK_4+"@Override"+RT_1+BLANK_4
+"public "+DAO_URL+"."+"BaseDao"+BEAN_URL+"."+getLastChar(cName)+" getBaseDao(){"+RT_1+BLANK_8
+"return "+getLowercaseChar(getLastChar(cName))+"Dao;"+RT_1+BLANK_4+"}"+RT_2+"}");
fw.flush();
fw.close();
showInfo(fileName);
}
/**
* 获取路径的最后面字符串br
* 如：br
* codestr = "com.b510.base.bean.User"/codebr
* code return "User";code
* @param str
* @return
*/
public String getLastChar(String str) {
if ((str != null) (str.length() 0)) {
int dot = str.lastIndexOf('.');
if ((dot -1) (dot (str.length() - 1))) {
return str.substring(dot + 1);
}
}
return str;
}
/**
* 把第一个字母变为小写br
* 如：br
* codestr = "UserDao";/codebr
* codereturn "userDao";/code
* @param str
* @return
*/
public String getLowercaseChar(String str){
return str.substring(0,1).toLowerCase()+str.substring(1);
}
/**
* 显示信息
* @param info
*/
public void showInfo(String info){
System.out.println("创建文件："+ info+ "成功！");
}
/**
* 获取系统时间
* @return
*/
public static String getDate(){
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
return simpleDateFormat.format(new Date());
}
}
Q2: java 代码实现下载.doc文件
%@ page contentType="text/html; charset=gb2312" %
%@ page import="java.io.*"%
%!
public String toUtf8String(String s)
{
StringBuffer sb = new StringBuffer();
for (int i=0;is.length();i++) {
char c = s.charAt(i);
if (c = 0 c = 255) {
sb.append(c);
} else {
byte[] b;
try {
b = Character.toString(c).getBytes("utf-8");
} catch (Exception ex) {
System.out.println(ex);
b = new byte[0];
}
for (int j = 0; j b.length; j++) {
int k = b[j];
if (k 0) k += 256;
sb.append("%" + Integer.toHexString(k).
toUpperCase());
}
}
}
return sb.toString();
}
%
%
String filename=new String(request.getParameter("filename").getBytes("ISO8859-1"),"GBK");
String dirName="D:/我.doc";
java.io.File ff=null;
String dd=dirName+System.getProperties().getProperty("file.separator")+filename;
try{
ff=new java.io.File(dd);
}
catch(Exception e){
System.out.println(e.getMessage());
e.printStackTrace();
}
if (ff!=nullff.exists()ff.isFile())
{
long filelength = ff.length();
InputStream inStream=new FileInputStream(dd);
//设置输出的格式
response.reset();
response.setContentType("application/x-msdownload");
response.setContentLength((int)filelength);
response.addHeader("Content-Disposition","attachment; filename=\"" + toUtf8String(filename) + "\"");
//循环取出流中的数据
byte[] b = new byte[100];
int len;
while((len=inStream.read(b)) 0)
response.getOutputStream().write(b,0,len);
inStream.close();
out.clear();
out = pageContext.pushBody();
}
%
：a href="d.jsp"aa/a
上面的那个是用流写的 但是也可以用超链接下载
你写上文件的路径就可以了
Q3: java 写一个action 能实现点击事件后浏览器能自动下载xml文件的功能！！急
方法一:调用浏览器下载文件
下面Action里的代码可以用调用浏览器进行下载xml文件
import java.awt.Desktop;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.URI;
import javax.swing.JButton;
import javax.swing.JFrame;
public class DownLoadDemo extends JFrame {
JButton jb;
public DownLoadDemo() {
jb = new JButton("Download");
jb.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
try {
String path = "网络xml的地址";
URI uri = new URI(path);
Desktop.getDesktop().browse(uri);
} catch (Exception e1) {
e1.printStackTrace();
}
}
});
add(jb);
setTitle("调用浏览器下载");
setBounds(380, 380,230,80);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
public static void main(String[] args) {
new DownLoadDemo();
}
}
当时上述下载方式,可能会弹出提示,比如保存位置等.
方法二:使用IO和net下载文件.这种方式没有调用浏览器,下载过程,不会弹出提示灯
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.Date;
public class DownLoadDemo {
public static void main(String[] args) throws Exception {
String str = "XML的网络地址";
URL url = new URL(str);
URLConnection urlconn = url.openConnection();
urlconn.connect();
InputStream is = urlconn.getInputStream();
FileOutputStream fos = new FileOutputStream("qq.exe");
byte[] buf = new byte[4096];
int length = 0;
//System.out.println("开始下载时间："+new Date());
while((length=is.read(buf))!=-1){
fos.write(buf, 0, length);
}
fos.close();
is.close();
//System.out.println("下载完成时间："+new Date());
}
}
Q4: jsp中怎么利用java需要将在oracle数据库中存在的pdf，doc等文件下载下来。最好有代码
首先你要明确一个概念java自行下载文件代码，数据库中是不可能存这些文件java自行下载文件代码的java自行下载文件代码，存java自行下载文件代码的最多是这些文件对应的地址，是String类型的数据。
在这基础上来看这些代码。注意标注的1234：
//获取网站部署路径(通过ServletContext对象)，用于确定下载文件位置，从而实现下载
String path = servletContext.getRealPath("/");
//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型
response.setContentType("multipart/form-data");
//2.设置文件头：最后一个参数是设置下载文件名(假如我们叫a.pdf)
response.setHeader("Content-Disposition", "attachment;fileName="+"a.pdf");
ServletOutputStream out;
//通过文件路径获得File对象(假如此路径中有一个download.pdf文件)
File file = new File(path + "download/" + "download.pdf");
try {
FileInputStream inputStream = new FileInputStream(file);
//3.通过response获取ServletOutputStream对象(out)
out = response.getOutputStream();
int b = 0;
byte[] buffer = new byte[512];
while (b != -1){
b = inputStream.read(buffer);
//4.写到输出流(out)中
out.write(buffer,0,b);
}
inputStream.close();
out.close();
out.flush();
} catch (IOException e) {
e.printStackTrace();
}
Q5: Java文件下载怎么实现的
下载就很简单了
把你要下载的文件做成超级链接，可以不用任何组件
比如说
下载一个word文档
a href="名称.doc"名称.doc/a
路径你自己写
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URI;
import java.net.URL;
import java.util.Random;
/**
*
* 实现了下载的功能*/
public class SimpleTh {
public static void main(String[] args){
// TODO Auto-generated method stub
//String path = "倩女幽魂.mp3";//MP3下载的地址
String path ="";
try {
new SimpleTh().download(path, 3); //对象调用下载的方法
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static String getFilename(String path){//获得文件的名字
return path.substring(path.lastIndexOf('/')+1);
}
public void download(String path,int threadsize) throws Exception//下载的方法
{//参数 下载地址，线程数量
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();//获取HttpURLConnection对象
conn.setRequestMethod("GET");//设置请求格式，这里是GET格式
conn.setReadTimeout(5*1000);//
int filelength = conn.getContentLength();//获取要下载文件的长度
String filename = getFilename(path);
File saveFile = new File(filename);
RandomAccessFile accessFile = new RandomAccessFile(saveFile, "rwd");
accessFile.setLength(filelength);
accessFile.close();
int block = filelength%threadsize ==0?filelength/threadsize:filelength/threadsize+1;
for(int threadid = 0;threadid=threadsize;threadid++){
new DownloadThread(url,saveFile,block,threadid).start();
}
}
private final class DownloadThread extends Thread{
private URL url;
private File saveFile;
private int block;//每条线程下载的长度
private int threadid;//线程id
public DownloadThread(URL url,File saveFile,int block,int threadid){
this.url = url;
this.saveFile= saveFile;
this.block = block;
this.threadid = threadid;
}
@Override
public void run() {
//计算开始位置的公式：线程id*每条线程下载的数据长度=？
//计算结束位置的公式：（线程id+1）*每条线程下载数据长度-1=？
int startposition = threadid*block;
int endposition = (threadid+1)*block-1;
try {
try {
RandomAccessFile accessFile = new RandomAccessFile(saveFile, "rwd");
accessFile.seek(startposition);//设置从什么位置写入数据
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("GET");
conn.setReadTimeout(5*1000);
conn.setRequestProperty("Range","bytes= "+startposition+"-"+endposition);
InputStream inStream = conn.getInputStream();
byte[]buffer = new byte[1024];
int len = 0;
while((len = inStream.read(buffer))!=-1){
accessFile.write(buffer, 0, len);
}
inStream.close();
accessFile.close();
System.out.println("线程id："+threadid+"下载完成");
} catch (FileNotFoundException e) {
e.printStackTrace();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
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