我如何使用 AsyncTask 在 android 中发送 httppost？
How do i send a httppost in android using AsyncTask?
我正在尝试使用 httppost 将数据存储在数据库中。我发现在主线程中尝试这样做会导致崩溃，所以我尝试使用 AsyncTask.
这是我创建的 AsyncTask 代码
public class PostData extends AsyncTask<String, Void, String> {
protected String doInBackground(String... params){
// get zero index of nameValuePairs and use that to post
String result = "fail";
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://www.name.com/Script.php");
// Add your data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
Log.d("1", "nope");
nameValuePairs.add(new BasicNameValuePair("id", params[0]));
Log.d("2", "nope");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
Log.d("3", "nope");
// Execute HTTP Post Request
HttpResponse response = httpclient.execute(httppost);
Log.d("4", "nope");
Log.i("postData", response.getStatusLine().toString());
result="got it";
}
catch (Exception e){
Log.d("lol","lool");
}
finally{}
return result;
}
}
我最近才开始android所以我对AsyncTask很陌生。
这是我尝试使用此 class
的代码
public class HomePage extends ActionBarActivity {
PostData postD;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
}
//Connect to other activities
public void aboutPage(View view) throws IOException {
//Intent intent = new Intent(this, AboutPage.class);
//startActivity(intent);
postD.doInBackground("1111");
}
我得到了新的错误
01-30 18:13:44.592 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/art﹕ Not late-enabling -Xcheck:jni (already on)
01-30 18:13:44.962 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/OpenGLRenderer﹕ Render dirty regions requested: true
01-30 18:13:45.003 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/﹕ HostConnection::get() New Host Connection established 0xa6853600, tid 1921
01-30 18:13:45.033 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/Atlas﹕ Validating map...
01-30 18:13:45.110 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/﹕ HostConnection::get() New Host Connection established 0xa6853740, tid 1942
01-30 18:13:45.130 1921-1942/com.example.user2013.mobileapplicationcustomerversion I/OpenGLRenderer﹕ Initialized EGL, version 1.4
01-30 18:13:45.169 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/OpenGLRenderer﹕ Enabling debug mode 0
01-30 18:13:45.216 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/EGL_emulation﹕ eglSurfaceAttrib not implemented
01-30 18:13:45.216 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6805440, error=EGL_SUCCESS
01-30 18:13:48.461 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Choreographer﹕ Skipped 78 frames! The application may be doing too much work on its main thread.
01-30 18:13:49.128 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/EGL_emulation﹕ eglSurfaceAttrib not implemented
01-30 18:13:49.128 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6805440, error=EGL_SUCCESS
01-30 18:13:49.828 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Choreographer﹕ Skipped 36 frames! The application may be doing too much work on its main thread.
01-30 18:13:51.004 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/AndroidRuntime﹕ Shutting down VM
--------- beginning of crash
01-30 18:13:51.004 1921-1921/com.example.user2013.mobileapplicationcustomerversion E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.user2013.mobileapplicationcustomerversion, PID: 1921
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View.onClick(View.java:4007)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View.onClick(View.java:4002)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method \'java.lang.String com.example.user2013.mobileapplicationcustomerversion.PostData.doInBackground(java.lang.String[])\' on a null object reference
at com.example.user2013.mobileapplicationcustomerversion.HomePage.aboutPage(HomePage.java:41)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View.onClick(View.java:4002)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
01-30 18:14:00.311 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Process﹕ Sending signal. PID: 1921 SIG: 9
这里：
postD.doInBackground("1111");
您正在使用 class 对象调用 doInBackground 方法，该对象也将在主 ui 线程上工作。
要在后台线程中 运行 doInBackground 您需要使用 AsyncTask.execute 方法启动 AsyncTask。这样做：
public void aboutPage(View view) throws IOException {
postD=new PostData();
postD.execute("1111");
}
查看更多关于 AsyncTask
我正在尝试使用 httppost 将数据存储在数据库中。我发现在主线程中尝试这样做会导致崩溃，所以我尝试使用 AsyncTask.
这是我创建的 AsyncTask 代码
public class PostData extends AsyncTask<String, Void, String> {
protected String doInBackground(String... params){
// get zero index of nameValuePairs and use that to post
String result = "fail";
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://www.name.com/Script.php");
// Add your data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
Log.d("1", "nope");
nameValuePairs.add(new BasicNameValuePair("id", params[0]));
Log.d("2", "nope");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
Log.d("3", "nope");
// Execute HTTP Post Request
HttpResponse response = httpclient.execute(httppost);
Log.d("4", "nope");
Log.i("postData", response.getStatusLine().toString());
result="got it";
}
catch (Exception e){
Log.d("lol","lool");
}
finally{}
return result;
}
}
我最近才开始android所以我对AsyncTask很陌生。
这是我尝试使用此 class
public class HomePage extends ActionBarActivity {
PostData postD;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_page);
}
//Connect to other activities
public void aboutPage(View view) throws IOException {
//Intent intent = new Intent(this, AboutPage.class);
//startActivity(intent);
postD.doInBackground("1111");
}
我得到了新的错误
01-30 18:13:44.592 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/art﹕ Not late-enabling -Xcheck:jni (already on)
01-30 18:13:44.962 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/OpenGLRenderer﹕ Render dirty regions requested: true
01-30 18:13:45.003 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/﹕ HostConnection::get() New Host Connection established 0xa6853600, tid 1921
01-30 18:13:45.033 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/Atlas﹕ Validating map...
01-30 18:13:45.110 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/﹕ HostConnection::get() New Host Connection established 0xa6853740, tid 1942
01-30 18:13:45.130 1921-1942/com.example.user2013.mobileapplicationcustomerversion I/OpenGLRenderer﹕ Initialized EGL, version 1.4
01-30 18:13:45.169 1921-1942/com.example.user2013.mobileapplicationcustomerversion D/OpenGLRenderer﹕ Enabling debug mode 0
01-30 18:13:45.216 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/EGL_emulation﹕ eglSurfaceAttrib not implemented
01-30 18:13:45.216 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6805440, error=EGL_SUCCESS
01-30 18:13:48.461 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Choreographer﹕ Skipped 78 frames! The application may be doing too much work on its main thread.
01-30 18:13:49.128 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/EGL_emulation﹕ eglSurfaceAttrib not implemented
01-30 18:13:49.128 1921-1942/com.example.user2013.mobileapplicationcustomerversion W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6805440, error=EGL_SUCCESS
01-30 18:13:49.828 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Choreographer﹕ Skipped 36 frames! The application may be doing too much work on its main thread.
01-30 18:13:51.004 1921-1921/com.example.user2013.mobileapplicationcustomerversion D/AndroidRuntime﹕ Shutting down VM
--------- beginning of crash
01-30 18:13:51.004 1921-1921/com.example.user2013.mobileapplicationcustomerversion E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.user2013.mobileapplicationcustomerversion, PID: 1921
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View.onClick(View.java:4007)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View.onClick(View.java:4002)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method \'java.lang.String com.example.user2013.mobileapplicationcustomerversion.PostData.doInBackground(java.lang.String[])\' on a null object reference
at com.example.user2013.mobileapplicationcustomerversion.HomePage.aboutPage(HomePage.java:41)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View.onClick(View.java:4002)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
01-30 18:14:00.311 1921-1921/com.example.user2013.mobileapplicationcustomerversion I/Process﹕ Sending signal. PID: 1921 SIG: 9
这里：
postD.doInBackground("1111");
您正在使用 class 对象调用 doInBackground 方法，该对象也将在主 ui 线程上工作。
要在后台线程中 运行 doInBackground 您需要使用 AsyncTask.execute 方法启动 AsyncTask。这样做：
public void aboutPage(View view) throws IOException {
postD=new PostData();
postD.execute("1111");
}
查看更多关于 AsyncTask