使用httpclient实现上传下载（javaWeb系统数据传输http实现）

目的：项目被拆分为两个javaWeb项目，实现项目之间数据传输以及上传、下载功能。 

前台展示项目A，后台提供数据支持项目B

题外话：

两个javaWeb传输之间使用json比较方便，如果恰好使用SpringMVC，配置相关JSON转换工具(功能很强大非常好用)，在

@Controller层

加上@ResponseBody自动将返回值转化成json格式

<mvc:annotation-driven content-negotiation-manager="contentNegotiationManager">
<mvc:message-converters register-defaults="true">
<!-- 将StringHttpMessageConverter的默认编码设为UTF-8 -->
<bean class="org.springframework.http.converter.StringHttpMessageConverter">
<constructor-arg value="UTF-8" />
</bean>
<!-- 将Jackson2HttpMessageConverter的默认格式化输出设为true -->
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="prettyPrint" value="true"/>
<property name="objectMapper">
<bean class="com.fasterxml.jackson.databind.ObjectMapper">
<property name="dateFormat">
<bean class="java.text.SimpleDateFormat">
<constructor-arg type="java.lang.String" value="yyyy-MM-dd HH:mm:ss" />
</bean>
</property>
</bean>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>

<!-- REST中根据URL后缀自动判定Content-Type及相应的View -->
<bean id="contentNegotiationManager" class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">
<property name="ignoreAcceptHeader" value="true" />
<property name="defaultContentType" value="application/json" />
<property name="mediaTypes" >
<value>
json=application/json
xml=application/xml
</value>
</property>
</bean>

<!-- jsp配置视图解析 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/page/"/>
<property name="suffix" value=".jsp"/>
</bean>

进入正题：

上传代码： A调用上传工具类(最头疼的问题就是文件名乱码)

/**
     * 文件上传
     * @param is
     * @param fileName
     * @param url
     * @return
     */
    public static String uploadFile(InputStream is ,String fileName ,String url){
        String result = null;
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(url);
        //防止文件名乱码
        InputStreamBody fileis = new InputStreamBody(is,ContentType.create("text/plain", Consts.UTF_8),fileName);
        HttpEntity reqEntity = null;
        HttpResponse responses = null;
        try {
            //BROWSER_COMPATIBLE 设置浏览器为兼容模式  随便设置编码防止乱码
            reqEntity = MultipartEntityBuilder.create().setMode(HttpMultipartMode.BROWSER_COMPATIBLE)
                    .addPart("Filedata", fileis).setCharset(CharsetUtils.get("utf-8")).build();
            httppost.setEntity(reqEntity);
            // 如果需要登陆加上sessionId
            httppost.addHeader(new BasicHeader("Cookie", "sessionId=" + clientUser.getSessionId()));
            responses = httpclient.execute(httppost);
            HttpEntity entity = responses.getEntity();
            if(entity != null){
                result = EntityUtils.toString(entity, Charset.forName("utf-8"));
            }
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return result;
    }

B使用SpringMvc方便得到传入的文件。

@RequestMapping(value="/upload",method=RequestMethod.POST)
@ResponseBody
public ModelMap upload(MultipartRequest request){

ModelMap model = new ModelMap();
MultipartFile file = request.getFile("Filedata");

String realName= null;
realName = new Date().getTime() + "_" +file.getOriginalFilename();

File targetFile = new File(UPLOAD_PATH, realName);
if (!targetFile.exists()) {
targetFile.mkdirs();
}
              //生成文件<pre name="code" class="java">               file.transferTo(targetFile);

return model;}

------------------------------------------------------------------------------------

下载

A调用下载  上代码

/**
* 文件下载
* @param url
* @param fileName
* @return
*/
public static InputStream fileDownload(String url,String fileName){
CloseableHttpClient  httpclient = new HttpUtils().buildHttpClient();
HttpPost httppost = new HttpPost(url);
StringEntity sEntity = new StringEntity(fileName, Charset.forName("utf-8"));
//		BasicNameValuePair basicNameValuePair = new BasicNameValuePair("fileName",fileName);
//		List<NameValuePair> list = new ArrayList<NameValuePair>();
//		list.add(basicNameValuePair);
//		UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(list, Charset.forName("utf-8"));
//   	httppost.setEntity(formEntity);
httppost.setEntity(sEntity);

httppost.addHeader(new BasicHeader("Cookie", "sessionId=" + clientUser.getSessionId()));
httppost.addHeader("Content-Type", "application/xml;charset=utf-8");
try {
CloseableHttpResponse responses = httpclient.execute(httppost);
HttpEntity entity = responses.getEntity();
InputStream content = entity.getContent();
return content;
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

return null;
}

B服务端代码：屏蔽了response.set部分代码，不然会报一个奇怪的错，无法解决。

    @RequestMapping(value="/fileDownload",method=RequestMethod.POST)
    @ResponseBody
    public void fileDownload(HttpServletRequest request,HttpServletResponse response){
// getXmlContent获取流传输的文件名,当然也可以使用request.getAttribute获取文件名，需要httpclient做一些设置
        String fileName = getXmlContent(request).trim();
        System.out.println("开始下载文件....."  + fileName);
        try {
            File file = new File(DOWNLOAD_PATH + fileName);
            if(!file.exists() ||  !file.isFile()){
                System.out.println("文件不存在。。" + fileName );
                return;
            }
            //response.setCharacterEncoding("utf-8");
            //response.setContentType("multipart/form-data");
            //response.setHeader("Content-Disposition", "attachment;fileName=" + fileName);
            InputStream inputStream = new FileInputStream(file);
            OutputStream os = response.getOutputStream();
            byte[] b = new byte[1024];
            int length;
            while ((length = inputStream.read(b)) > 0) {
                os.write(b, 0, length);
            }
//            Long filelength = file.length();
//            byte[] b = new byte[filelength.intValue()];
//            inputStream.read(b);
//            os.write(b, 0, filelength.intValue());
            inputStream.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

如果服务端A的下载文件为中文名，需要转码

try {
fileName =  new String(fileName.getBytes("iso8859-1"),"UTF-8");
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
}