文件上传和下载12-15讲

文件上传和下载12-15讲明天看～

对URL的字符进行解码：java.net.URLDecoder

public static String decode(String s, String enc) throws UnsupportedEncodingException

参数：

s

- 要解码的

String

enc

- 所支持的字符编码的名称。 返回： 新解码的

String

enctype="multipart/form-data" 上传文件必须设置：默认是：enctype="application/x-www-form-urlencoded"下载准备：commons-fileupload-1.2.1 和commons-io-1.4引入包得到文件的路径时候，有的浏览器是传的所有的路径，有的是传的最后的文件名。要注意，按通用的方法写。

@SuppressWarnings("unchecked")
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//文件的工厂类org.apache.commons.fileupload.disk.DiskFileItemFactory;
DiskFileItemFactory factory = new DiskFileItemFactory();
//目录设为当前根目录，我的是WebRoot
factory.setRepository(new File(request.getRealPath("/")));
//设置文件的大小。超过写到本地缓存中， 默认10240
factory.setSizeThreshold(5 * 1024 * 1024);//5M
//org.apache.commons.fileupload.servlet.ServletFileUpload;
ServletFileUpload fileUpload = new ServletFileUpload(factory);
// org.apache.commons.fileupload.FileItem;
List<FileItem> list = null;
try {
list = fileUpload.parseRequest(request);
for (FileItem fileItem : list) {
if (fileItem.isFormField()) {//普通的字段
request.setAttribute(fileItem.getFieldName(), fileItem
.getString());
} else {//是文件
String name = fileItem.getFieldName();
System.out.println(name);
String value = fileItem.getName();
int start = value.lastIndexOf("//");
//不同的浏览器可能是不同的值，我们只取文件名
String filename = value.substring(start + 1);
request.setAttribute(name, filename);
fileItem
.write(new File(request.getRealPath("/"), filename));
/*OutputStream out = new FileOutputStream(new File(request.getRealPath("/"),filename));
InputStream is =fileItem.getInputStream();
byte[] buff= new byte[1024];
int length=0;
while((length=is.read(buff))>0){
out.write(buff, 0, length);
}
out.close();
is.close();*/
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
request.getRequestDispatcher("result.jsp").forward(request, response);
}

都是自己实现的，struts2中单个的文件可以这样获取 private File file;
private String fileFileName;//file-FileName固定的
private String fileContentType;//file-ContentType固定的 org.apache.struts2.interceptor.FileUploadInterceptor

InputStream is = new FileInputStream(file);
String root = ServletActionContext.getRequest().getRealPath("/upload");
File fileto = new File(root,this.getFileFileName());
OutputStream out = new FileOutputStream(fileto);
byte[] buff = new byte[1024];
int length=0;
while((length=is.read(buff))>0){
out.write(buff, 0, length);
}
out.close();
is.close();
return SUCCESS;

若对于多个文件则可以定义为 private List<File> file;
private List<String> fileFileName;
private List<String> fileContentType;存的时候循环遍历

for (int i=0;i<file.size();++i) {
InputStream is = new FileInputStream(file.get(i));
String root = ServletActionContext.getRequest().getRealPath(
"/upload");
File fileto = new File(root, this.getFileFileName().get(i));
OutputStream out = new FileOutputStream(fileto);
byte[] buff = new byte[1024];
int length = 0;
while ((length = is.read(buff)) > 0) {
out.write(buff, 0, length);
}
out.close();
is.close();
}

第15讲：接上一讲多个文件上传按钮:function addmore(){
var mo=document.getElementById("more");
var br = document.createElement("br");
var input = document.createElement("input");
var button= document.createElement("input");
input.type="file";
input.name="file";
button.type="button";
button.value="移除";
button.onclick=function(){
mo.removeChild(br);
mo.removeChild(input);
mo.removeChild(button);

}
mo.appendChild(br);
mo.appendChild(input);
mo.appendChild(button);
}看org.apache.struts2.interceptor.FileUploadInterceptor代码设置属性 protected static final Log log = LogFactory.getLog(FileUploadInterceptor.class);
private static final String DEFAULT_DELIMITER = ",";
private static final String DEFAULT_MESSAGE = "no.message.found"; protected Long maximumSize;//限制大小
protected String allowedTypes;//允许的文件类型
protected Set allowedTypesSet = Collections.EMPTY_SET;允许的文件类型参照tomcat下的conf下的web.xml如：<mime-mapping>
<extension>ppt</extension>
<mime-type>application/vnd.ms-powerpoint</mime-type>
</mime-mapping>则struts.xm：<interceptor-ref name="fileUpload">
<param name="maximumSize">20480000</param>
<param name="allowedTypes">application/vnd.ms-powerpoint</param>
</interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>默认的defaultStack要设置错误的信息的key在代码中也有，用自己的信息，在message文件中替换就行了配置文件：

<action name="download" class="com.test.action.DownLoadAction">
<result name="success" type="stream">
<param name="contentType">
application/vnd.ms-powerpoint
</param><!-- 下载文件的类型 -->
<param name="contentDisposition">filename="test.ppt"</param><!-- 显示的文件名 -->
<param name="inputName">downFile</param><!-- action中的get方法 -->
</result>
</action>

action内容

import java.io.InputStream;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class DownLoadAction extends ActionSupport {

public InputStream getDownFile() {
return ServletActionContext.getServletContext().getResourceAsStream(
"/upload/CoreJava基础.ppt");
}
@Override
public String execute() throws Exception {
return SUCCESS;
}
}

会报这个错：java.net.SocketException: Connection reset by peer: socket write error大体搜了下。没有解释的好的。貌似是个bug