HttpUrlConnection Post使浏览器下载Java代理中的响应JSON

我正在调用AlfrescoWebscripts，它返回JSON。我使用GET请求来实现这一点，所有这些请求都可以完美地工作。但是，如果我发布一个文件，Alfresco服务器会正确地接收该文件并返回一个JSON响应，但这次响应会导致浏览器提示下载，而不是让Javascript处理回调

现在，所有这些调用都通过一个使用HttpUrlConnection的“自制”反向代理（见下文）。此代理将所有调用路由到另一台主机上运行的Alfresco。其他一切都可以正常工作（PNG、文本、html、GET请求，甚至身份验证）。在GET和POST响应中，内容类型都是“application/json；charset=UTF-8”

非常感谢您的回复

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.codec.binary.Base64;

public class ReverseProxy extends GenericServlet{

public static final String SERVER_URL = "serverURL";
protected String serverURL;
protected boolean debug;

public ReverseProxy(){
}

public void init(ServletConfig config) throws ServletException {
    super.init(config);
    debug = Boolean.valueOf(config.getInitParameter("debug")).booleanValue();
    serverURL = config.getInitParameter("serverURL");
    if(serverURL == null){
        throw new ServletException("ReverseProxy servlet initialization parameter 'serverURL' not defined");
    }
}

public void service(ServletRequest req, ServletResponse resp) throws ServletException, IOException {
    InputStream inputStream;
    OutputStream outputStream;
    Exception exception;
    if(debug){System.out.println("ReverseProxy.service()");}
    HttpServletRequest request;
    HttpServletResponse response;
    try{
        request = (HttpServletRequest)req;
        response = (HttpServletResponse)resp;
    }
    catch(ClassCastException e){
        throw new ServletException("non-HTTP request or response");
    }
    String method = request.getMethod();
    StringBuffer urlBuffer = new StringBuffer();
    urlBuffer.append(serverURL);
    urlBuffer.append(request.getServletPath());
    if(request.getPathInfo() != null)
        urlBuffer.append(request.getPathInfo());
    if(request.getQueryString() != null){
        urlBuffer.append('?');
        urlBuffer.append(request.getQueryString());
    }
    URL url = new URL(urlBuffer.toString());

    //pass authentication
    String user=null, password=null;

    Set entrySet = req.getParameterMap().entrySet();
    Map headers = new HashMap();
    for ( Object anEntrySet : entrySet ) {
        Map.Entry header = (Map.Entry) anEntrySet;
        String key = (String) header.getKey();
        String value = ((String[]) header.getValue())[0];
        if ("user".equals(key)) {
            user = value;
        } else if ("password".equals(key)) {
            password = value;
        }else {
            headers.put(key, value);
        }
    }

    String userpass = null;
    if (user != null && userpass!=null) {
        userpass = user+":"+password;
    }
    String auth = request.getHeader("Authorization");
    if(auth != null){
        if (auth.toUpperCase().startsWith("BASIC ")){
            String userpassEncoded = auth.substring(6);
            userpass = new String(Base64.decodeBase64(userpassEncoded.getBytes()));
        }
    }

    String digest=null;
    if (userpass!=null) {
        if(debug){System.out.println("ReverseProxy found userpass:" + userpass);}
        digest = "Basic " + new String(Base64.encodeBase64((userpass).getBytes()));
    }
    else{
        if(debug){System.out.println("ReverseProxy found no auth credentials");}
    }

    //do connection
    HttpURLConnection connection = null;
    connection = (HttpURLConnection) url.openConnection();
    if (digest != null) {connection.setRequestProperty("Authorization", digest);}

    connection.setRequestMethod(method);
    connection.setDoInput(true);

    if(method.equals("POST")){
        if(request.getHeader("Content-Type") != null){
            if(debug){System.out.println("ReverseProxy Content-Type: " + request.getHeader("Content-Type"));}
            if(debug){System.out.println("ReverseProxy Content-Length: " + request.getHeader("Content-Length"));}
            if(request.getHeader("Content-Type").indexOf("multipart/form-data") != -1){
                connection.setRequestProperty("Content-Type", request.getHeader("Content-Type"));
                connection.setRequestProperty("Content-Length", request.getHeader("Content-Length"));
            }
        }
        connection.setDoOutput(true);
    }
    if(debug){
        System.out.println((new StringBuilder()).append("ReverseProxy: URL=").append(url).append(" method=").append(method).toString());
    }

    //set headers
    Set headersSet = headers.entrySet();
    for ( Object aHeadersSet : headersSet ) {
        Map.Entry header = (Map.Entry) aHeadersSet;
        connection.setRequestProperty((String) header.getKey(), (String) header.getValue());
    }

    connection.connect();
    inputStream = null;
    outputStream = null;
    try{
        if(method.equals("POST")){
            javax.servlet.ServletInputStream servletInputStream = request.getInputStream();
            outputStream = connection.getOutputStream();
            copy(servletInputStream, outputStream);
        }
        response.setContentLength(connection.getContentLength());
        response.setContentType(connection.getContentType());
        if(debug){System.out.println("ReverseProxy Connection Content-Type: " + connection.getContentType());}
        response.setCharacterEncoding(connection.getContentEncoding());
        String cacheControl = connection.getHeaderField("Cache-Control");
        if(cacheControl != null){
            response.setHeader("Cache-Control", cacheControl);
        }
        int responseCode = connection.getResponseCode();
        response.setStatus(responseCode);

        if(responseCode == 401){
            response.setHeader("WWW-Authenticate", "Basic realm=\"Login Required\"");
        }

        for( Iterator i = connection.getHeaderFields().entrySet().iterator() ; i.hasNext() ;){
            Map.Entry mapEntry = (Map.Entry)i.next();
            if(mapEntry.getKey()!=null){
                response.setHeader(mapEntry.getKey().toString(), ((List)mapEntry.getValue()).get(0).toString());
            }
        }

        //if(debug){System.out.println("ReverseProxy Connection Content-Disposition: " + connection.getHeaderField("Content-Disposition"));}

        if(debug){System.out.println((new StringBuilder()).append("ReverseProxy: response code '").append(responseCode).append("' from ").append(url).toString());}
        if (responseCode == 200 || responseCode == 201) {
            inputStream = connection.getInputStream();
        }
        else{
            inputStream = connection.getErrorStream();
        }

        javax.servlet.ServletOutputStream servletOutputStream = response.getOutputStream();
        copy(inputStream, servletOutputStream);
    }
    catch(IOException ex){
        if(debug)
            ex.printStackTrace();
        throw ex;
    }
    finally{
        //if(inputStream == null) goto _L0; else goto _L0
        //break;
    }
    if(inputStream != null){
        inputStream.close();
    }
    if(outputStream != null){
        outputStream.close();
    } 
    inputStream.close();
    if(outputStream != null){
        outputStream.close();
    }
    //throw exception;
}

public long copy(InputStream input, OutputStream output) throws IOException{
    byte buffer[] = new byte[4096];
    long count = 0L;
    for(int n = 0; -1 != (n = input.read(buffer));){
        output.write(buffer, 0, n);
        count += n;
    }

    output.flush();
    if(debug)
        System.err.println((new StringBuilder()).append("copy ").append(count).append(" bytes").toString());
    return count;
}

---

}

我想问题更多的是在客户端，或者是您的误解。当文件的内容类型为

application/json

时，如果浏览器提示下载文件，这是正确的行为，因为浏览器本身不知道如何处理它。浏览器只能显示与至少

text/*

或

image/*

的内容类型匹配的所有内容

通常，JSON响应将由JavaScript在内部处理，JavaScript可以完美地处理内容类型为

application/JSON

的Axical响应。您可以通过将其更改为

text/plain

或

text/javascript

来测试它，您将看到浏览器将显示它（因为它匹配

text/*

）。但是对于JSON，正确的内容类型确实是

application/JSON

。保持原样，使用正确的工具下载/打开JSON；）

已解决（根据我的评论）

---

如果请求是从Javascript发送的XmlHttpRequest，那么“application/json”内容类型将被理解，并且不会进行下载。GET和POST请求都是如此。如果上传文件，JQuery、ExtJS等库会创建一个设置为“application/x-www-form-urlencoded”的隐藏表单并发布（所有这些都不需要用户交互）。这意味着响应是由浏览器解释的，而不是Javascript。解决这个问题的唯一方法是将返回的JSON的内容类型设置为“text/html”（而不是“text/plain”，否则浏览器会尝试添加标记）。

。如果请求是从Javascript发送的XMLHTTPREQUEST，那么“application/json”内容类型将被理解，并且不会进行下载。GET和POST请求都是如此。如果上传文件，JQuery、ExtJS等库会创建一个设置为“application/x-www-form-urlencoded”的隐藏表单并发布（所有这些都不需要用户交互）。这意味着响应是由浏览器解释的，而不是Javascript。解决此问题的唯一方法是将内容类型设置为“text/html”（而不是“text/plain”，否则浏览器会尝试添加标记）。“…使用“application/x-www-form-urlencoded”设置创建一个隐藏表单并发布…”您还可以自己创建Ajax调用，并将其设置为“application/json”。但不管是json还是x-www-form-urlencoded，至少对我来说都是有效的。不过，我确实用自己的ajax代码创建了表单。您应该接受这个答案，将其从未回答问题列表中删除。