java - HttpUrlConnection Post 导致浏览器下载 Java 代理中的响应 JSON

Question

我正在调用返回 JSON 的 Alfresco Webscripts。我使用 GET 请求来完成此操作，所有这些都运行良好。但是，如果我执行文件 POST，Alfresco 服务器会正​​确接收文件并发回 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使用 HttpUrlConnection 的“自制”反向代理(见下文)。该代理将所有调用路由到另一台主机上运行的 Alfresco。其他一切都工作正常(png、文本、html、GET 请求，甚至身份验证)。在 GET 和 POST 响应中，Content-Type 均为“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;
}

}

Answer 1

我想问题更多地出在客户端或者你这边的误解。如果浏览器在内容类型为 application/json 时提示下载文件，则这是正确行为，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/* 内容类型匹配的所有内容。

通常，JSON 响应由 JavaScript 内部处理，它可以完美处理内容类型为 application/json 的 ajaxical 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(因为它与 text/* 匹配) )。但对于 JSON，正确的内容类型确实是 application/json。只需保持原样并使用正确的工具下载/打开 JSON ;)