一.概述
1.一个servlet上传文件，构造参数为HttpServletRequest，可以通过此参数获取请求信息
获取上传文件的编码类型：如UTF-8获取上传文件的内容类型：servlet上传文件以"multipart/"开始获取上传文件的大小获取上传文件的输入流
二.RequestContext
抽象访问文件上传所需的请求信息。
// 1.2.1
package org.apache.commons.fileupload;
import java.io.InputStream;
import java.io.IOException;
/**
* 抽象访问文件上传所需的请求信息。
* 对于可以由FileUpload处理的每种类型的请求（如servlet和portlet），都应该实现这种互操作。
*
* @since FileUpload 1.1
*/
public interface RequestContext {
/**
* 返回请求的字符编码。
* @return The character encoding for the request.
*/
String getCharacterEncoding();
/**
* 获取请求的内容类型。
* @return The content type of the request.
*/
String getContentType();
/**
* 获取请求的内容长度。
* @return The content length of the request.
*/
int getContentLength();
/**
* 获取请求的输入流。
* @return The input stream for the request.
* @throws IOException if a problem occurs.
*/
InputStream getInputStream() throws IOException;
}
三.ServletRequestContext
// 1.2.1
package org.apache.commons.fileupload.servlet;
import java.io.InputStream;
import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.fileupload.RequestContext;
/**
* Provides access to the request information needed for a request made to an HTTP servlet.
*
* 提供对HTTP servlet请求所需的请求信息的访问。
*
* @since FileUpload 1.1
*
*/
public class ServletRequestContext implements RequestContext {
/**
* The request for which the context is being provided.
* 提供上下文的请求。
*/
private HttpServletRequest request;
/**
* Construct a context for this request.
* @param request The request to which this context applies.
*/
public ServletRequestContext(HttpServletRequest request) {
this.request = request;
}
public String getCharacterEncoding() {
return request.getCharacterEncoding();
}
public String getContentType() {
return request.getContentType();
}
public int getContentLength() {
return request.getContentLength();
}
/**
* 从请求对象中获取上传文件的输入流
*
*/
public InputStream getInputStream() throws IOException {
return request.getInputStream();
}
public String toString() {
return "ContentLength=" + this.getContentLength() + ", ContentType=" + this.getContentType();
}
}
3.一个实例截图
