使用HttpURLConnection发送UTF-8字符串

Question

到目前为止,我已经使用以下代码片段来发送和接收JSON字符串:

static private String sendJson(String json,String url){
    HttpClient httpClient = new DefaultHttpClient();
    String responseString = "";
    try {
        HttpPost request = new HttpPost(url);
        StringEntity params =new StringEntity(json, "UTF-8");
        request.addHeader("content-type", "application/json");
        request.setEntity(params);
        HttpResponse response = httpClient.execute(request);
        HttpEntity entity = response.getEntity();
        responseString = EntityUtils.toString(entity, "UTF-8");

    }catch (Exception ex) {
        ex.printStackTrace();
        // handle exception here
    } finally {
        httpClient.getConnectionManager().shutdown();
    }
    return responseString;
}

即使json字符串包含UTF-8字符,上面的代码工作也很完美,一切正常.

出于几个原因,我不得不改变发送HTTP post请求的方式,并使用HttpURLConnection代替apache的HttpClient.这是我的代码:

static private String sendJson(String json,String url){
    String responseString = "";
    try {
        URL m_url = new URL(url);
        HttpURLConnection conn = (HttpURLConnection)m_url.openConnection();
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("content-type", "application/json");
        DataOutputStream outputStream = new DataOutputStream(conn.getOutputStream());
        outputStream.writeBytes(json);
        outputStream.flush();
        outputStream.close();

        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        StringBuilder sb = new StringBuilder();
        String line;
        while ((line = br.readLine()) != null) {
            sb.append(line+"\n");
        }
        br.close();
        responseString = sb.toString();
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return responseString;
}

此代码适用于普通英文字符,但似乎不支持json字符串中的UTF-8字符,因为它每次都失败.(当发送json到服务器时,服务器压缩说utf8无法解码某个字节,但是当从服务器接收utf8 json时我认为它确实有效,因为我设法查看特殊字符).

服务器根本没有改变,并且在以前的代码中工作正常,因此这个新代码片段的问题是100%.

知道如何修复json字符串发送所以它会支持UTF 8吗？谢谢

Answer 1

我认为问题出在这一部分:

DataOutputStream outputStream = new DataOutputStream(conn.getOutputStream());
outputStream.writeBytes(json);
outputStream.flush();
outputStream.close();

您需要将json编码为UTF-8
并发送代表UTF-8编码的字节,而不是这样做.

试试这个:

Charset.forName("UTF-8").encode(json)

看到:

Charset.encode

更简单的方法是使用例如BufferedWriter包装
OutputStreamWriter.在OutputStreamWriter知道自己的编码
,所以它会为你做的工作(的编码工作json字符串).

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(), "UTF-8"));
bw.write(json);
bw.flush();
bw.close();

Answer 2

将a写入String输出流（字节）时，需要指定编码以进行转换。一种方法是将输出流包装为OutputStreamWriter将使用UTF-8字符集进行编码的。

        conn.setRequestProperty("content-type", "application/json;  charset=utf-8");
        Writer writer = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(), "UTF-8"));
        writer.write(json);
        writer.close();

flush()如果调用，它也是可选的close()。

如peter.petrov所述，另一种选择是先将您转换String为字节（在内存中），然后将字节数组输出到输出流。

为了使它在服务器端更加明显，您可以传递content-type标头（"content-type", "application/json; charset=utf-8"）中使用的字符集。