我正在构建一个复杂的应用程序，但是我遇到了一个孤立的问题。我的Android应用程序类UserPage.java应该能够从网页中获取字符串，然后将其传递到布局并相应地显示它。
UserPage.java
package com.example.ams;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.List;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
public class UserPage extends Activity {
HttpPost httppost;
StringBuffer buffer;
HttpResponse response;
HttpClient httpclient;
List<NameValuePair> nameValuePairs;
ProgressDialog dialog = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.userpage);
String json = getStudents();
//System.out.println(json);
TextView datazer = (TextView) findViewById(R.id.data);
datazer.setText(json);
}
public String getStudents(){
HttpResponse response = null;
//String classID = "CSD2334";
try {
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI("http://localhost:8080/de.vogella.jersey.first/resources/hello/ids/CSD2334"));
response = client.execute(request);
System.out.println(response.toString());
} catch (URISyntaxException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return response.toString();
}
}
布局-userpage.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<TextView
android:id="@+id/data"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
从网络上获取的内容
[{"student_id":3,"student_name":"Dite Gashi","w1mo":"1","w1tue":"0","w1wed":0,"w1thu":0,"w1fri":1},{"student_id":4,"student_name":"Vullnet Dyla","w1mo":"2","w1tue":"2","w1wed":1,"w1thu":0,"w1fri":0},{"student_id":5,"student_name":"Edon Ymeri","w1mo":"0","w1tue":"0","w1wed":0,"w1thu":0,"w1fri":2},{"student_id":6,"student_name":"Ilir Kelmendi","w1mo":"2","w1tue":"0","w1wed":2,"w1thu":0,"w1fri":0}]
我遇到的错误非常普遍，我似乎无法在任何地方找到信息
03-30 17:36:15.074: E/AndroidRuntime(1458): FATAL EXCEPTION: main
03-30 17:36:15.074: E/AndroidRuntime(1458): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ams/com.example.ams.UserPage}: android.os.NetworkOnMainThreadException
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.ActivityThread.access$600(ActivityThread.java:123)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.os.Handler.dispatchMessage(Handler.java:99)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.os.Looper.loop(Looper.java:137)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.ActivityThread.main(ActivityThread.java:4424)
03-30 17:36:15.074: E/AndroidRuntime(1458): at java.lang.reflect.Method.invokeNative(Native Method)
03-30 17:36:15.074: E/AndroidRuntime(1458): at java.lang.reflect.Method.invoke(Method.java:511)
03-30 17:36:15.074: E/AndroidRuntime(1458): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-30 17:36:15.074: E/AndroidRuntime(1458): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-30 17:36:15.074: E/AndroidRuntime(1458): at dalvik.system.NativeStart.main(Native Method)
03-30 17:36:15.074: E/AndroidRuntime(1458): Caused by: android.os.NetworkOnMainThreadException
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
03-30 17:36:15.074: E/AndroidRuntime(1458): at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
03-30 17:36:15.074: E/AndroidRuntime(1458): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
03-30 17:36:15.074: E/AndroidRuntime(1458): at java.net.InetAddress.getAllByName(InetAddress.java:220)
03-30 17:36:15.074: E/AndroidRuntime(1458): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
03-30 17:36:15.074: E/AndroidRuntime(1458): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
03-30 17:36:15.074: E/AndroidRuntime(1458): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
03-30 17:36:15.074: E/AndroidRuntime(1458): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
03-30 17:36:15.074: E/AndroidRuntime(1458): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
03-30 17:36:15.074: E/AndroidRuntime(1458): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
03-30 17:36:15.074: E/AndroidRuntime(1458): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
03-30 17:36:15.074: E/AndroidRuntime(1458): at com.example.ams.UserPage.getStudents(UserPage.java:44)
03-30 17:36:15.074: E/AndroidRuntime(1458): at com.example.ams.UserPage.onCreate(UserPage.java:31)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.Activity.performCreate(Activity.java:4465)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
03-30 17:36:15.074: E/AndroidRuntime(1458): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
03-30 17:36:15.074: E/AndroidRuntime(1458): ... 11 more
03-30 17:36:15.363: I/dalvikvm(1458): threadid=3: reacting to signal 3
03-30 17:36:15.434: I/dalvikvm(1458): Wrote stack traces to '/data/anr/traces.txt'
03-30 17:36:15.814: I/dalvikvm(1458): threadid=3: reacting to signal 3
03-30 17:36:15.834: I/dalvikvm(1458): Wrote stack traces to '/data/anr/traces.txt'
任何帮助或指示，我们将不胜感激，
d
最佳答案
您正在主线程上运行http调用，这会导致错误。
response = client.execute(request);
上面的代码应在新线程上运行。
您应该具有以下内容：
new Thread( new Runnable() {
@Override
public void run() {
HttpResponse response = null;
//String classID = "CSD2334";
try {
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI("http://localhost:8080/de.vogella.jersey.first/resources/hello/ids/CSD2334"));
response = client.execute(request);
System.out.println(response.toString());
} catch (URISyntaxException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return response.toString();
}
}).start();
如果要更新UI组件，则应将代码运行到：
runOnUiThread(new Runnable() {
@Override
public void run() {
// runs on the UI thread so update UI here
}
});
您应该阅读有关threads on android的更多信息