我有独立的java客户端使用httpURLconnection类将xml数据发送到http servlet。但是数据以不可打印的字符格式显示。
对于模拟，我一直在尝试发送简单的字符串，但它仍然以不可打印的格式出现。
我编写了以下客户端代码来与servlet进行通信，
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URL;
public class HttpClient implements IClient {
private static IClient client = null;
private HttpURLConnection httpConn = null;
private OutputStream output = null;
private InputStream input = null;
private OutputStreamWriter out = null;
private HttpClient() {
}
public static IClient getHttpClient() {
if (client == null) {
client = new HttpClient();
}
return client;
}
@Override
public void connect(String urlString) throws IOException {
URL url = new URL(urlString);
httpConn = (HttpURLConnection) url.openConnection();
initConnection();
httpConn.connect();
output = httpConn.getOutputStream();
input = httpConn.getInputStream();
System.out.println("Connection Response:" + httpConn.getResponseCode());
}
@Override
public void sendFile(File file) throws IOException {
// BufferedOutputStream bos = new BufferedOutputStream(output);
// InputStream fis = new FileInputStream(file);
// int bytesRead = 0;
// byte[] buffer = new byte[8192];
// while ((bytesRead = fis.read(buffer, 0, 8192)) != -1) {
// bos.write(buffer, 0, bytesRead);
// System.out.println("write:"+buffer);
// }
// bos.close();
// fis.close();
OutputStreamWriter out = new OutputStreamWriter(output, "UTF-16");
out.write("test me");
}
@Override
public boolean isConnected() {
return httpConn != null ? true : false;
}
@Override
public void close() {
httpConn.disconnect();
}
private void initConnection() throws ProtocolException {
httpConn.setDoOutput(true);
httpConn.setDoInput(true);
httpConn.setRequestMethod("POST");
httpConn.setUseCaches(false);
httpConn.setRequestProperty("Content-Type",
"text/xml; charset=\"UTF-16\"");
httpConn.setRequestProperty("Connection", "Keep-Alive");
}
private static byte[] getBytesFromFile(File file) throws IOException {
InputStream is = new FileInputStream(file);
System.out.println("\nDEBUG: FileInputStream is " + file);
// Get the size of the file
long length = file.length();
System.out.println("DEBUG: Length of " + file + " is " + length + "\n");
/*
* You cannot create an array using a long type. It needs to be an int
* type. Before converting to an int type, check to ensure that file is
* not loarger than Integer.MAX_VALUE;
*/
if (length > Integer.MAX_VALUE) {
System.out.println("File is too large to process");
return null;
}
// Create the byte array to hold the data
byte[] bytes = new byte[(int) length];
// Read in the bytes
int offset = 0;
int numRead = 0;
while ((offset < bytes.length)
&& ((numRead = is.read(bytes, offset, bytes.length - offset)) >= 0)) {
offset += numRead;
}
// Ensure all the bytes have been read in
if (offset < bytes.length) {
throw new IOException("Could not completely read file "
+ file.getName());
}
return bytes;
}
}
和servlet代码如下，
import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class XMLServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doPost(req, resp);
}
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
System.out.println("=========inside doPost=========");
// BufferedInputStream bis = new BufferedInputStream(req.getInputStream());
// OutputStream fos = new FileOutputStream("test.xml");
// int bytesRead = 0;
// byte[] buffer = new byte[8192];
// while ((bytesRead = bis.read(buffer, 0, 8192)) != -1) {
// System.out.println("read:"+buffer);
// fos.write(buffer, 0, bytesRead);
// }
// fos.close();
// bis.close();
//
req.setCharacterEncoding("UTF-16");
InputStreamReader isr = new InputStreamReader(req.getInputStream(),"UTF-16");
char[] data = new char[10];
isr.read(data);
System.out.println(data);
for (char c : data) {
System.out.println(c);
}
}
}
请帮助我摆脱这个问题。
答案 0 :(得分：2)
我认为你过于复杂了。我只是写了类似的东西，它接受任何文件并通过HTTP将它传递给servlet。请记住：所有数据都是二进制（包括文本文件） - 句点。由给定的应用程序来解释该二进制数据。例如，notepad.exe只读取一组二进制数据并尝试使用ASCII标准对其进行格式化。因此，知道这一点，只需使用原始流读取文件，将连接的mime类型设置为application / octet-stream并通过“PUT”方法发送。 servlet代码应该使用请求中的原始InputStream读取文件，并在其空间中创建相应的文件。
从客户端代码：
URL url = new URL(urlString);
HttpURLConnection cnx = (HttpURLConnection)url.openConnection();
cnx.setRequestMethod("PUT");
cnx.setRequestProperty("Content-Type", "application/octet-stream");
// optional request property
cnx.setRequestProperty("filename", filename);
cnx.setDoOutput(true);
cnx.connect();
BufferedInputStream fileIn =
new BufferedInputStream(new FileInputStream(fileName), BUFFER_SIZE);
BufferedOutputStream out =
new BufferedOutputStream(cnx.getOutputStream(), BUFFER_SIZE);
byte[] bytes = new byte[BUFFER_SIZE];
int bytesRead;
while((bytesRead = fileIn.read(bytes)) != -1){
out.write(bytes, 0, bytesRead);
}
就是这样。
现在是servlet代码....
public void doPut(HttpServletRequest request, HttpServletResponse response){
String filename = (String)request.getHeader("filename");
StringBuilder fullPath = new StringBuilder(100);
ServletContext ctxt = getServletContext();
fullPath.append(ctxt.getRealPath(""))
.append("uploads\\").append(filename);
File f = new File(fullPath.toString());
f.createNewFile();
InputStream in = request.getInputStream();
BufferedOutputStream fileOut =
new BufferedOutputStream(new FileOutputStream(f));
byte[] bytes = new byte[BUFFER_SIZE];
int bytesRead;
while((bytesRead = in.read(bytes)) != -1){
fileOut.write(bytes, 0, bytesRead);
}
fileOut.flush();
fileOut.close();
response.setStatus(HttpServletResponse.SC_CREATED);
}
答案 1 :(得分：1)
使用http方法将文件上传到服务器有两种主要方法：
使用PUT方法上传文件。这允许您一次将一个文件放到服务器上。 PUT方法易于实现，但您无法使用PUT方法从html表单上传文件（例如，在网络浏览器中上传表单）。
使用POST方法上传文件。这更复杂，但大多数网站使用此文件将文件上传到服务器。您可以根据请求进行多个文件上传。这就是我要谈的内容。
注意：除非您以某种方式对其进行编码，否则GET不会用于文件上传。
使用URLConnection上传文件不是直截了当的，需要您在“multipart form”中准备数据。当然，你不应该自己做。有许多库可以为您处理此问题，例如： HttpClient。如果你真的想使用URLConnection，我会参考之前关于“How to use java.net.URLConnection to fire and handle HTTP requests”的问题
以下是使用HttpClient上传文件的代码。它是从HttpClient示例代码中简化而来的。
import java.io.File;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.multipart.FilePart;
import org.apache.commons.httpclient.methods.multipart.MultipartRequestEntity;
import org.apache.commons.httpclient.methods.multipart.Part;
import org.apache.commons.httpclient.params.HttpMethodParams;
public class MultipartFileUploadApp {
public static void main(String[] args) {
String targetURL = "http://localhost:8080/yourserver/upload";
File targetFile = new File("/path/to/your/file.txt");
PostMethod filePost = new PostMethod(targetURL);
filePost.getParams().setBooleanParameter(HttpMethodParams.USE_EXPECT_CONTINUE, false);
try {
System.out.println("Uploading " + targetFile.getName() + " to " + targetURL);
// add more parts you want to upload multiple files.
Part[] parts = {new FilePart(targetFile.getName(), targetFile)};
filePost.setRequestEntity(new MultipartRequestEntity(parts, filePost.getParams()));
HttpClient client = new HttpClient();
client.getHttpConnectionManager().getParams().setConnectionTimeout(5000);
int status = client.executeMethod(filePost);
if (status == HttpStatus.SC_OK) {
System.out.println("Upload complete, response=" + filePost.getResponseBodyAsString());
} else {
System.out.println("Upload failed, response=" + HttpStatus.getStatusText(status));
}
} catch (Exception ex) {
System.out.println("Error: " + ex.getMessage());
ex.printStackTrace();
} finally {
filePost.releaseConnection();
}
}
}
对于服务器端，您必须解析多部分表单请求。当然，有一些库可以帮到你。这是我正在使用的snipplet
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class CommonsFileUploadServlet extends HttpServlet {
private static final String TMP_DIR_PATH = "c:\\tmp";
private File tmpDir;
private static final String DESTINATION_DIR_PATH = "c:\\tmp\\files";
private File destinationDir;
public void init(ServletConfig config) throws ServletException {
super.init(config);
tmpDir = new File(TMP_DIR_PATH);
if (!tmpDir.isDirectory()) {
throw new ServletException(TMP_DIR_PATH + " is not a directory");
}
//String realPath = getServletContext().getRealPath(DESTINATION_DIR_PATH);
destinationDir = new File(DESTINATION_DIR_PATH);
if (!destinationDir.isDirectory()) {
throw new ServletException(DESTINATION_DIR_PATH + " is not a directory");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();
response.setContentType("text/plain");
out.println("<h1>Servlet File Upload Example using Commons File Upload</h1>");
out.println();
DiskFileItemFactory fileItemFactory = new DiskFileItemFactory();
/*
*Set the size threshold, above which content will be stored on disk.
*/
fileItemFactory.setSizeThreshold(1 * 1024 * 1024); //1 MB
/*
* Set the temporary directory to store the uploaded files of size above threshold.
*/
fileItemFactory.setRepository(tmpDir);
ServletFileUpload uploadHandler = new ServletFileUpload(fileItemFactory);
try {
/*
* Parse the request
*/
List items = uploadHandler.parseRequest(request);
out.println("Count : " + items.size());
Iterator itr = items.iterator();
while (itr.hasNext()) {
FileItem item = (FileItem) itr.next();
/*
* Handle Form Fields.
*/
if (item.isFormField()) {
out.println("Field = " + item.getFieldName() + ", Value = " + item.getString());
} else {
//Handle Uploaded files.
out.println("Field Name = " + item.getFieldName()
+ ", File Name = " + item.getName()
+ ", Content type = " + item.getContentType()
+ ", File Size = " + item.getSize());
/*
* Write file to the ultimate location.
*/
File file = new File(destinationDir, item.getName());
item.write(file);
}
}
out.close();
} catch (FileUploadException ex) {
log("Error encountered while parsing the request", ex);
} catch (Exception ex) {
log("Error encountered while uploading file", ex);
}
}
}
答案 2 :(得分：0)
我有独立的java客户端使用httpURLconnection类将xml数据发送到http servlet。但是数据以不可打印的字符格式显示。
我能理解。您将数据作为UTF-16发送，但XML文件本身可能不会以UTF-16保存。您需要使用与保存的XML文件相同的字符编码。这通常是UTF-8。
对于模拟，我一直在尝试发送简单的字符串，但它仍然以不可打印的格式出现。
我不明白。它应该像在代码中那样正常工作。可能你没有正确测试它。