Android:如何在不强制关闭的情况下处理try catch中的错误
当我运行asynctask以连接到HTTP服务器时,我希望在它无法连接到服务器时显示错误消息。相反,应用程序会在出现错误时强制关闭,而不会显示错误消息。我想在发生错误时显示错误消息,而不是崩溃,但它只是在body description alert dialog中显示带有消息error(e.getMessage())的警报对话框 下面是我的代码:Android:如何在不强制关闭的情况下处理try catch中的错误,android,Android,当我运行asynctask以连接到HTTP服务器时,我希望在它无法连接到服务器时显示错误消息。相反,应用程序会在出现错误时强制关闭,而不会显示错误消息。我想在发生错误时显示错误消息,而不是崩溃,但它只是在body description alert dialog中显示带有消息error(e.getMessage())的警报对话框 下面是我的代码: private String downloadUrl(String strUrl) throws IOException { String d
private String downloadUrl(String strUrl) throws IOException {
String data = "";
InputStream iStream = null;
try {
URL url = new URL(strUrl);
HttpURLConnection urlConnection = (HttpURLConnection) url
.openConnection();
urlConnection.connect();
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(
iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
br.close();
} catch (IOException e) {
Log.d(TAG, e.getMessage());
ErrorDialog(e.getMessage());
}
return data;
}
private class DownloadTask extends AsyncTask<String, Integer, String> {
String data = null;
@Override
protected String doInBackground(String... url) {
try {
data = downloadUrl(url[0]);
} catch (IOException e) {
Log.d(TAG, e.getMessage());
ErrorDialog(e.getMessage());
}
return data;
}
@Override
protected void onPostExecute(String result) {
if (result != null && result.length() < 0) {
ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
listViewLoaderTask.execute(result);
}
}
}
private void ErrorDialog(String Description) {
AlertDialog.Builder alertDialog = new AlertDialog.Builder(
ListCategoryActivity.this);
alertDialog.setTitle("You get Error...");
alertDialog.setMessage(Description);
alertDialog.setIcon(R.drawable.ic_warning);
alertDialog.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
alertDialog.show();
}
谢谢。如日志所示:
RuntimeException:无法在尚未创建的线程内创建处理程序
调用Looper.prepare()
因为您试图从AsyncTask的doInBackground显示AlertDialog,而我们无法从doInBackground方法更新UI元素。将代码更改为在doInBackground中处理执行:
String strcatcherror="";
@Override
protected String doInBackground(String... url) {
try {
data = downloadUrl(url[0]);
strcatcherror="";
} catch (IOException e) {
Log.d(TAG, e.getMessage());
strcatcherror=e.getMessage();
}
return data;
}
@Override
protected void onPostExecute(String result) {
if(!strcatcherror.equals("")){
if (result != null && result.length() < 0) {
ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
listViewLoaderTask.execute(result);
}
}
else{
// show error message here
ErrorDialog(strcatcherror);
}
}
字符串strcatcherror=“”;
@凌驾
受保护的字符串doInBackground(字符串…url){
试一试{
数据=下载url(url[0]);
strcatcherror=“”;
}捕获(IOE异常){
Log.d(标记,例如getMessage());
strCachError=e.getMessage();
}
返回数据;
}
@凌驾
受保护的void onPostExecute(字符串结果){
如果(!strCachError.equals(“”){
if(result!=null&&result.length()<0){
ListViewLoaderTask ListViewLoaderTask=新建ListViewLoaderTask();
listViewLoaderTask.execute(结果);
}
}
否则{
//在此处显示错误消息
错误对话框(strcatcherror);
}
}
您不能在doInBackground()内调用警报对话
因此,另一种方法是将全局变量(如XYZ)放置在Asyc类中,并将e.getMessage()设置为catch块中的变量XYZ。检查该变量是否为空并执行ErrorDialog(XYZ);在onPostExecute()方法中
希望它能对您有所帮助。将对话框与UI线程分开运行。只需尝试以下方法:
私有类下载任务扩展了异步任务{
字符串数据=null;
@凌驾
受保护的字符串doInBackground(字符串…url){
试一试{
数据=下载url(url[0]);
}捕获(IOE异常){
Log.d(标记,例如getMessage());
runOnUiThread(新的Runnable(){
公开募捐{
ErrorDialog(例如getMessage());
}
});
}
}
返回数据;
}
@凌驾
受保护的void onPostExecute(字符串结果){
if(result!=null&&result.length()<0){
ListViewLoaderTask ListViewLoaderTask=新建ListViewLoaderTask();
listViewLoaderTask.execute(结果);
}
}
}
您不能直接从doinbackground()显示警报对话框。您需要从runOnUIThread()调用它,或者从postExecute()调用它,或者向活动处理程序发送消息。Urlconnection具有setTimeout方法。 使用SocketTimeOutException捕捉它(它将被抛出回调用方)。
举杯庆祝。检查AndroidManifest.xml文件作为INTERNETHi的权限谢谢回复,仍然不起作用,我认为下载URL中的问题通过回答Grishu解决了;解决了这个问题,但在此之前,我移动字符串downloadUrl来尝试asyntask DownloadTask。我删除了方法字符串downloadurl。谢谢兄弟,我给了你真实的答案和一票。
01-23 11:58:36.909: D/HaichalLog(5776): failed to connect to
/192.168.103.121 (port 80): connect failed: ENETUNREACH (Network is unreachable)
String strcatcherror="";
@Override
protected String doInBackground(String... url) {
try {
data = downloadUrl(url[0]);
strcatcherror="";
} catch (IOException e) {
Log.d(TAG, e.getMessage());
strcatcherror=e.getMessage();
}
return data;
}
@Override
protected void onPostExecute(String result) {
if(!strcatcherror.equals("")){
if (result != null && result.length() < 0) {
ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
listViewLoaderTask.execute(result);
}
}
else{
// show error message here
ErrorDialog(strcatcherror);
}
}
ErrorDialog(e.getMessage());
private class DownloadTask extends AsyncTask<String, Integer, String> {
String data = null;
@Override
protected String doInBackground(String... url) {
try {
data = downloadUrl(url[0]);
} catch (IOException e) {
Log.d(TAG, e.getMessage());
runOnUiThread(new Runnable(){
public void run() {
ErrorDialog(e.getMessage());
}
});
}
}
return data;
}
@Override
protected void onPostExecute(String result) {
if (result != null && result.length() < 0) {
ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
listViewLoaderTask.execute(result);
}
}
}