javajson上传文件
A. 关于 java在后台传一个json数据到前台的问题
从你传的json来看，你传回的sessionModel仅仅是一个字符串，并不是包含对象的结构体，所以你取不到类成员的，如果sessionModel是一个对象，那么相应的字符串应该类似如下结构
{“model”:{"sessionModel":{"id":"1","name","lz"}}}
B. java如何实现文件上传和下载的功能
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.jspsmart.upload.*;
import net.sf.json.JSONObject;
import action.StudentAction;
public class UploadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
boolean result=true;
SmartUpload mySmartUpload=new SmartUpload();
mySmartUpload.initialize(this.getServletConfig(), request,response);
mySmartUpload.setTotalMaxFileSize(50*1024*1024);//大小限制
mySmartUpload.setAllowedFilesList("doc,docx");//后缀名限制
try {
mySmartUpload.upload();
com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
myFile.saveAs("/file/"+1+".doc");//保存目录
} catch (SmartUploadException e) {
e.printStackTrace();result=false;
}
//*****************************//
response.setContentType("text/html;charset=UTF-8");
response.setHeader("Cache-Control","no-cache");
PrintWriter out = response.getWriter();
out.print(result);
out.flush();
out.close();
}
}
//我这是ajax方式的，不想这样,把//**********************//以下部分修改就行了
//需要SmartUpload组件，去网上下个就行了，也有介绍的
C. java后台post方法上传文件
/** * 执行post请求并将返回内容转为json格式返回 */public static JsonObject doPost(String url, JsonObject message)throws WeiXinException {JsonObject jo = null;PrintWriter out = null;InputStream in = null;try {if (url.startsWith("https")){//https方式提交需要SSLContext sc = SSLContext.getInstance("SSL");sc.init(null, new TrustManager[] { new TrustAnyTrustManager() },new java.security.SecureRandom());URL console = new URL(url);HttpsURLConnection conn = (HttpsURLConnection) console.openConnection();conn.setSSLSocketFactory(sc.getSocketFactory());conn.setHostnameVerifier(new TrustAnyHostnameVerifier());conn.connect();in = conn.getInputStream();}else{in = new URL(url).openStream();}// 打开和URL之间的连接URLConnection conn = new URL(url).openConnection();// 设置通用的请求属性conn.setRequestProperty("accept", "*/*");conn.setRequestProperty("connection", "Keep-Alive");conn.setRequestProperty("user-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");// 发送POST请求必须设置如下两行conn.setDoOutput(true);conn.setDoInput(true);// 获取URLConnection对象对应的输出流out = new PrintWriter(conn.getOutputStream());// 发送请求参数out.print(message.toString());// flush输出流的缓冲out.flush();// POST请求out.flush();out.close();in = conn.getInputStream();jo = JSON.parse(getContext(in));doExeption(jo);} catch (MalformedURLException e) {e.printStackTrace();} catch (ProtocolException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} catch (KeyManagementException e) {e.printStackTrace();} catch (NoSuchAlgorithmException e) {e.printStackTrace();} finally {if (out != null) {out.flush();out.close();}if (in != null ){try {in.close();} catch (IOException e) {e.printStackTrace();}}}return jo;}
D. 使用ajaxFileUpload这个控件上传文件，返回json数据出错
用这个东西返回的data其实与一般ajax返回的不同，因为它本身就是一个模拟ajax的操作，所以只不过是对用iframe的onload事件对返回的response进行截取......
E. 能用json传递文件吗
Java里面可以用BASE64Encoder，BASE64Decoder，这是sun.misc包里面的，一般是不公开的Android 里面没有用过，不过有个android.util.Base64，你可以使试一试encodeToString（）decode（）方法
F. java后台怎样传json格式的数据
通过 JSONObject类就可以了
首先 你把这几个包 下下来 放到你项目。如果有就不要下了：
1.commons-lang.jar
2.commons-beanutils.jar
3.commons-collections.jar
4.commons-logging.jar
5.ezmorph.jar
6.json-lib-2.2.2-jdk15.jar
像你这种是数据形式 就通过 JSONArray 如：
JSONArray datasJson = JSONArray.fromObject(datas);最好把datas toString 一下