getInputStream() 上的 java.io.FileNotFoundException

Question

我正在尝试从 URL 获取输入流，连接响应代码是 200，但是当我尝试获取输入流时出现异常 FileNotFoundException，这是我的代码：

url = new URL("http://...");
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestMethod("POST");
int status = connection.getResponseCode();
if(status >= 400){
    request = new OutputStreamWriter(connection.getOutputStream());
    request.write(params);
    request.flush();
    request.close();
    String line;
    InputStreamReader isr = new InputStreamReader(connection.getInputStream());
    BufferedReader reader = new BufferedReader(isr);
    StringBuilder sb = new StringBuilder();
    while ((line = reader.readLine()) != null) {
        sb.append(line + "\n");
    }
}

堆栈跟踪：

W/System.err: java.io.FileNotFoundException: http://...
W/System.err:     at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:238)
W/System.err:     at com.apps.topinformers.sharedreading.AddGroupMembersFragment.postText(AddGroupMembersFragment.java:112)
W/System.err:     at com.apps.topinformers.sharedreading.AddGroupMembersFragment.access$000(AddGroupMembersFragment.java:26)
W/System.err:     at com.apps.topinformers.sharedreading.AddGroupMembersFragment$PostDataAsyncTask.doInBackground(AddGroupMembersFragment.java:65)
W/System.err:     at com.apps.topinformers.sharedreading.AddGroupMembersFragment$PostDataAsyncTask.doInBackground(AddGroupMembersFragment.java:55)
W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:295)
W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
W/System.err:     at java.lang.Thread.run(Thread.java:818)

有什么问题，我该如何调试？

Answer 1

连接响应码为200

不，不是。此代码中没有任何内容可以检查响应代码。 FileNotFoundException 表示响应码为 404。

NB setDoOutput(true) 将方法设置为 POST。你不需要自己设置，

Answer 2

感谢@EJP，我检查了以下回复：

url = new URL("http://...");
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestMethod("POST");

request = new OutputStreamWriter(connection.getOutputStream());
request.write(params);
request.flush();
request.close();
String line;

int status = connection.getResponseCode();
if(status < 400) {

    InputStreamReader isr = new InputStreamReader(connection.getInputStream());
    ...
} else{
    InputStreamReader isr = new InputStreamReader(connection.getErrorStream());
    ...
}

错误流显示我请求的 URL 的实现代码存在一些问题。