java实现文件上传

zoukankan html css js c++ java

java实现文件上传
最近自己在做一个小系统玩的时候涉及到了文件的上传，于是在网上找到Java上传文件的方案，最后确定使用common-fileupload实现上传操作。
- 需求说明
用户添加页面有一个“上传”按钮，点击按钮弹出上传界面，上传完成后关闭上传界面。
- 所需Jar包
commons.fileupload-1.2.0.jar、commons.logging-1.1.1.jar、commons.beanutils-1.8.0.jar、commons.collections-3.2.0.jar、commons.io-1.4.0.jar、commons.lang-2.1.0.jar
- 实现效果
- 代码实现
首先编写核心代码，Javascript打开上传页面，并且从上传页获取返回参数，最后数据返回给回调函数callback：
Js代码

/**

* 跳转到上传页

* functionId:功能ID

* fileType:文件类型

* maxSize:文件容量上限

* callback:回调函数，返回三个参数：文件真名、文件存放名和文件大小

*/

function openUpload(functionId,fileType,maxSize,callback){

    var url = root+"/CommonController.jhtml?method=goFileUpload&";

    if(functionId!=null){

        url = url + "functionId="+functionId+"&";

    }

    if(fileType!=null){

        url = url + "fileType="+fileType+"&";

    }

    if(maxSize!=null){

        url = url + "maxSize="+maxSize;

    }

    var win = window.showModalDialog(url,"","dialogWidth:300px;dialogHeight:150px;scroll:no;status:no");

    if(win != null){

        var arrWin = win.split(",");

        callback(arrWin[0],arrWin[1],arrWin[2]);

    }

}
```
/**
 * 跳转到上传页
 * functionId:功能ID
 * fileType:文件类型
 * maxSize:文件容量上限
 * callback:回调函数，返回三个参数：文件真名、文件存放名和文件大小
 */
function openUpload(functionId,fileType,maxSize,callback){
	var url = root+"/CommonController.jhtml?method=goFileUpload&";
	if(functionId!=null){
		url = url + "functionId="+functionId+"&";
	}
	if(fileType!=null){
		url = url + "fileType="+fileType+"&";
	}
	if(maxSize!=null){
		url = url + "maxSize="+maxSize;
	}
	var win = window.showModalDialog(url,"","dialogWidth:300px;dialogHeight:150px;scroll:no;status:no");
	if(win != null){
		var arrWin = win.split(",");
		callback(arrWin[0],arrWin[1],arrWin[2]);
	}
}
```
用户添加页面相关代码，点击“上传”按钮时调用上面的核心js代码，并且获取返回值
Html代码

<script>

.......



function openUpload_(){

    openUpload(null,'JPG,GIF,JPEG,PNG','5',callback);

}



/**

* 回调函数,获取上传文件信息

* realName真实文件名

* saveName文件保存名

* maxSize文件实际大小

*/

function callback(realName,saveName,maxSize){

    $("#photo_").val(saveName);

    //回调后其它操作

}

</script>



<tr>

            <td>头像：</td>

            <td>

                <input type="hidden" name="photo" id="photo_"></input>

                <input type="button" onclick="openUpload_()" value="上传"/>

            </td>

        </tr>
```
<script>
.......

function openUpload_(){
	openUpload(null,'JPG,GIF,JPEG,PNG','5',callback);
}

/**
 * 回调函数,获取上传文件信息
 * realName真实文件名
 * saveName文件保存名
 * maxSize文件实际大小
 */
function callback(realName,saveName,maxSize){
	$("#photo_").val(saveName);
	//回调后其它操作
}
</script>

<tr>
			<td>头像：</td>
			<td>
				<input type="hidden" name="photo" id="photo_"></input>
				<input type="button" onclick="openUpload_()" value="上传"/>
			</td>
		</tr>
```
文件上传的JSP代码，需要注意的是在head标签内添加<base target="_self">以防止页面跳转时弹出新窗口，用户选择指定文件，点击上传时就提交表单访问指定后台代码
Html代码

<%@ include file="/WEB-INF/jsp/header.jsp" %>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">

<meta http-equiv="pragma" content="no-cache" />

<base target="_self">

<title>文件上传</title>

</head>

<body>

    <h5>文件上传</h5><hr/>

    <form id="file_upload_id" name="file_upload_name" action="<%=root%>/CommonController.jhtml?method=doFileUpload" method="post" enctype="multipart/form-data">

        <input type="hidden" name="functionId" value="${functionId}"/>

        <input type="hidden" name="fileType" value="${fileType}"/>

        <input type="hidden" name="maxSize" value="${maxSize}"/>

        <div><input type="file" name="file_upload"/></div>

        <c:if test="${maxSize!=null}">

            <div style="font: 12">文件最大不能超过${maxSize}MB</div>

        </c:if>

        <c:if test="${fileType!=null}">

            <div style="font: 12">文件格式必须是：${fileType}</div>

        </c:if>

        <div><input type="submit" value="上传"/></div>

    </form>

</body>

</html>
```
<%@ include file="/WEB-INF/jsp/header.jsp" %>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<meta http-equiv="pragma" content="no-cache" />
<base target="_self">
<title>文件上传</title>
</head>
<body>
	<h5>文件上传</h5><hr/>
	<form id="file_upload_id" name="file_upload_name" action="<%=root%>/CommonController.jhtml?method=doFileUpload" method="post" enctype="multipart/form-data">
		<input type="hidden" name="functionId" value="${functionId}"/>
		<input type="hidden" name="fileType" value="${fileType}"/>
		<input type="hidden" name="maxSize" value="${maxSize}"/>
		<div><input type="file" name="file_upload"/></div>
		<c:if test="${maxSize!=null}">
			<div style="font: 12">文件最大不能超过${maxSize}MB</div>
		</c:if>
		<c:if test="${fileType!=null}">
			<div style="font: 12">文件格式必须是：${fileType}</div>
		</c:if>
		<div><input type="submit" value="上传"/></div>
	</form>
</body>
</html>
```
CommonController目前有两个方法，一个是跳转到上传页面的方法，一个是执行上传操作的方法doFileUpload，上传方法运行的大概逻辑是：首先获取页面的请求参数，fileType用于限制上传文件格式，

maxSize用于限制上传文件最大值，随后创建上传目录上传即可。
Java代码

public class CommonController extends BaseController {

    Log log = LogFactory.getLog(CommonController.class);



    Properties fileUploadPro = null;

    public CommonController(){

        fileUploadPro = PropertiesUtil.getPropertiesByClass("fileupload.properties");

    }





    @Override

    public ModeAndView init(HttpServletRequest request,

            HttpServletResponse response) throws ServletException, IOException {



        return null;

    }



    /**

     * 跳转到文件上传页

     * @param request

     * @param response

     * @return

     * @throws ServletException

     * @throws IOException

     */

    public ModeAndView goFileUpload(HttpServletRequest request,

            HttpServletResponse response) throws ServletException, IOException {

        String functionId = request.getParameter("functionId");

        String fileType = request.getParameter("fileType");

        String maxSize = request.getParameter("maxSize");

        ModeAndView mav = new ModeAndView("/WEB-INF/jsp/common/fileUpload.jsp");



        if(functionId!=null && !"".equals(functionId.trim())){

            mav.addObject("functionId", functionId);

        }

        if(fileType!=null && !"".equals(fileType.trim())){

            mav.addObject("fileType", fileType);

        }

        if(maxSize!=null && !"".equals(maxSize.trim())){

            mav.addObject("maxSize", maxSize);

        }

        return mav;

    }



    /**

     * 上传文件

     * @param request

     * @param response

     * @return

     * @throws ServletException

     * @throws IOException

     */

    @SuppressWarnings("unchecked")

    public ModeAndView doFileUpload(HttpServletRequest request,

            HttpServletResponse response) throws ServletException, IOException {

        //获取并解析文件类型和支持最大值

        String functionId = request.getParameter("functionId");

        String fileType = request.getParameter("fileType");

        String maxSize = request.getParameter("maxSize");



        //临时目录名

        String tempPath = fileUploadPro.getProperty("tempPath");

        //真实目录名

        String filePath = fileUploadPro.getProperty("filePath");



        FileUtil.createFolder(tempPath);

        FileUtil.createFolder(filePath);



        DiskFileItemFactory factory = new DiskFileItemFactory();

        //最大缓存

        factory.setSizeThreshold(5*1024);

        //设置临时文件目录

        factory.setRepository(new File(tempPath));

        ServletFileUpload upload = new ServletFileUpload(factory);

        if(maxSize!=null && !"".equals(maxSize.trim())){

            //文件最大上限

            upload.setSizeMax(Integer.valueOf(maxSize)*1024*1024);

        }



        try {

            //获取所有文件列表

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

            for (FileItem item : items) {

                if(!item.isFormField()){

                    //文件名

                    String fileName = item.getName();



                    //检查文件后缀格式

                    String fileEnd = fileName.substring(fileName.lastIndexOf(".")+1).toLowerCase();

                    if(fileType!=null && !"".equals(fileType.trim())){

                        boolean isRealType = false;

                        String[] arrType = fileType.split(",");

                        for (String str : arrType) {

                            if(fileEnd.equals(str.toLowerCase())){

                                isRealType = true;

                                break;

                            }

                        }

                        if(!isRealType){

                            //提示错误信息:文件格式不正确

                            super.printJsMsgBack(response, "文件格式不正确!");

                            return null;

                        }

                    }



                    //创建文件唯一名称

                    String uuid = UUID.randomUUID().toString();

                    //真实上传路径

                    StringBuffer sbRealPath = new StringBuffer();

                    sbRealPath.append(filePath).append(uuid).append(".").append(fileEnd);

                    //写入文件

                    File file = new File(sbRealPath.toString());

                    item.write(file);

                    //上传成功，向父窗体返回数据:真实文件名,虚拟文件名,文件大小

                    StringBuffer sb = new StringBuffer();

                    sb.append("window.returnValue='").append(fileName).append(",").append(uuid).append(".").append(fileEnd).append(",").append(file.length()).append("';");

                    sb.append("window.close();");

                    super.printJsMsg(response, sb.toString());

                    log.info("上传文件成功,JS信息："+sb.toString());

                }//end of if

            }//end of for



        }catch (Exception e) {

            //提示错误:比如文件大小

            super.printJsMsgBack(response, "上传失败,文件大小不能超过"+maxSize+"M!");

            log.error("上传文件异常!",e);

            return null;

        }



        return null;

    }

}
```
public class CommonController extends BaseController {
	Log log = LogFactory.getLog(CommonController.class);
	
	Properties fileUploadPro = null;
	public CommonController(){
		fileUploadPro = PropertiesUtil.getPropertiesByClass("fileupload.properties");
	}
	
	
	@Override
	public ModeAndView init(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		
		return null;
	}
	
	/**
	 * 跳转到文件上传页
	 * @param request
	 * @param response
	 * @return
	 * @throws ServletException
	 * @throws IOException
	 */
	public ModeAndView goFileUpload(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		String functionId = request.getParameter("functionId");
		String fileType = request.getParameter("fileType");
		String maxSize = request.getParameter("maxSize");
		ModeAndView mav = new ModeAndView("/WEB-INF/jsp/common/fileUpload.jsp");
		
		if(functionId!=null && !"".equals(functionId.trim())){
			mav.addObject("functionId", functionId);
		}
		if(fileType!=null && !"".equals(fileType.trim())){
			mav.addObject("fileType", fileType);
		}
		if(maxSize!=null && !"".equals(maxSize.trim())){
			mav.addObject("maxSize", maxSize);
		}
		return mav;
	}
	
	/**
	 * 上传文件
	 * @param request
	 * @param response
	 * @return
	 * @throws ServletException
	 * @throws IOException
	 */
	@SuppressWarnings("unchecked")
	public ModeAndView doFileUpload(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		//获取并解析文件类型和支持最大值
		String functionId = request.getParameter("functionId");
		String fileType = request.getParameter("fileType");
		String maxSize = request.getParameter("maxSize");
		
		//临时目录名
		String tempPath = fileUploadPro.getProperty("tempPath");
		//真实目录名
		String filePath = fileUploadPro.getProperty("filePath");
		
		FileUtil.createFolder(tempPath);
		FileUtil.createFolder(filePath);
		
		DiskFileItemFactory factory = new DiskFileItemFactory();
		//最大缓存
		factory.setSizeThreshold(5*1024);
		//设置临时文件目录
		factory.setRepository(new File(tempPath));
		ServletFileUpload upload = new ServletFileUpload(factory);
		if(maxSize!=null && !"".equals(maxSize.trim())){
			//文件最大上限
			upload.setSizeMax(Integer.valueOf(maxSize)*1024*1024);
		}
		
		try {
			//获取所有文件列表
			List<FileItem> items = upload.parseRequest(request);
			for (FileItem item : items) {
				if(!item.isFormField()){
					//文件名
					String fileName = item.getName();
					
					//检查文件后缀格式
					String fileEnd = fileName.substring(fileName.lastIndexOf(".")+1).toLowerCase();
					if(fileType!=null && !"".equals(fileType.trim())){
						boolean isRealType = false;
						String[] arrType = fileType.split(",");
						for (String str : arrType) {
							if(fileEnd.equals(str.toLowerCase())){
								isRealType = true;
								break;
							}
						}
						if(!isRealType){
							//提示错误信息:文件格式不正确
							super.printJsMsgBack(response, "文件格式不正确!");
							return null;
						}
					}
					
					//创建文件唯一名称
					String uuid = UUID.randomUUID().toString();
					//真实上传路径
					StringBuffer sbRealPath = new StringBuffer();
					sbRealPath.append(filePath).append(uuid).append(".").append(fileEnd);
					//写入文件
					File file = new File(sbRealPath.toString());
					item.write(file);
					//上传成功，向父窗体返回数据:真实文件名,虚拟文件名,文件大小
					StringBuffer sb = new StringBuffer();
					sb.append("window.returnValue='").append(fileName).append(",").append(uuid).append(".").append(fileEnd).append(",").append(file.length()).append("';");
					sb.append("window.close();");
					super.printJsMsg(response, sb.toString());
					log.info("上传文件成功,JS信息："+sb.toString());
				}//end of if
			}//end of for
			
		}catch (Exception e) {
			//提示错误:比如文件大小
			super.printJsMsgBack(response, "上传失败,文件大小不能超过"+maxSize+"M!");
			log.error("上传文件异常!",e);
			return null;
		}
		
		return null;
	}
}
```
至此一个文件上传即已实现，而且能够基本满足不同模块的上传通用性，我还留着个functionId参数用于以后针对不同模块上传文件到不同目录。
2018年7月28日，绝望到明白人活着只能靠自己； 2018年7月29日，告诉她一切，还对我不离不弃。从此，走技术路线，改变生活。
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原文地址：https://www.cnblogs.com/outlooking/p/4234621.html