Java AsyncTask崩溃，原因是NetworkonMainThreadException

当我试图转到另一个页面时，我的应用程序崩溃，这是错误代码

        01-05 18:49:25.976: E/AndroidRuntime(7596): FATAL EXCEPTION: main
01-05 18:49:25.976: E/AndroidRuntime(7596): android.os.NetworkOnMainThreadException
01-05 18:49:25.976: E/AndroidRuntime(7596):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1144)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:670)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:509)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at com.example.splashscreentwo.JSONParser.makeHttpRequest(JSONParser.java:62)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at com.example.splashscreentwo.EmployeePayslip$GetEmployeeDetails$1.run(EmployeePayslip.java:127)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at android.os.Handler.handleCallback(Handler.java:730)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at android.os.Handler.dispatchMessage(Handler.java:92)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at android.os.Looper.loop(Looper.java:137)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at android.app.ActivityThread.main(ActivityThread.java:5493)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at java.lang.reflect.Method.invokeNative(Native Method)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at java.lang.reflect.Method.invoke(Method.java:525)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
01-05 18:49:25.976: E/AndroidRuntime(7596):     at dalvik.system.NativeStart.main(Native Method)

我并不真正理解代码，也不确定是什么导致了问题，下面是我的java类

        package com.example.splashscreentwo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;


import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.telephony.SmsManager;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;

public class EmployeePayslip extends Activity {

    private ProgressDialog pDialog;
    String pid;
    TextView employeeName;
    TextView Desc;
    TextView txtCreatedAt;

    // Creating JSON Parser object
    JSONParser jParser = new JSONParser();
    JSONArray payslip = null;
    ArrayList<HashMap<String, String>> payslipList;

    // url to get all fulltime employees list
    private static String url_payslip = "http://rollit.sg/FYP/ExportPayslip.php";
    private static final String url_employees_details = "http://rollit.sg/FYP/get_employees_details.php";

    private static final String TAG_SUCCESS = "success";
    private static final String TAG_PAYSLIP = "payslip";
    private static final String TAG_PID = "pid";
    private static final String TAG_NAME = "name";
    private static final String TAG_PAYSLIPNO = "payslipno";
    private static final String TAG_NETSALARY = "netsalary";
    private static final String TAG_ISSUEDATE = "issuedate";
    private static final String TAG_STARTOFPAYSLIP = "startofpayslip";
    private static final String TAG_ENDOFPAYSLIP = "endofpayslip";
    private static final String TAG_TYPEOFALLOWANCE = "typeofallowance";
    private static final String TAG_ALLOWANCEAMT = "allowanceamt";
    private static final String TAG_ALLOWANCEDATE = "allowancedate";
    private static final String TAG_AVAILABLEALLOWANCE = "availableallowance";
    private static final String TAG_TYPEOFDEDUCTION = "typeofdeduction";
    private static final String TAG_DEDUCTIONAMT = "deductionamt";
    private static final String TAG_DEDUCTIONDATE = "deductiondate";
    private static final String TAG_AGREEDOVERTIMERATE = "agreedovertimerate";
    private static final String TAG_OVERTIMERATE = "overtimerate";
    private static final String TAG_STARTOFOVERTIMEPERIOD = "startofovertimeperiod";
    private static final String TAG_ENDOFOVERTIMEPERIOD = "endofovertimeperiod";
    private static final String TAG_BASICSALARY = "basicsalary";
    private static final String TAG_EXTRAPAYMENT = "extrapayment";

    private static final String TAG_EMPLOYEE = "employ";
    private static final String TAG_SALARY = "pay";
    private static final String TAG_DESCRIPTION = "description";




    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.employeepayslip);




     payslipList = new ArrayList<HashMap<String, String>>();

     // Loading all fulltime employees in Background Thread
     // getting employee details from intent
     Intent i = getIntent();

     // getting employee id (pid) from intent
     pid = i.getStringExtra(TAG_PID);


     new GetEmployeeDetails().execute();

    }
    class GetEmployeeDetails extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(EmployeePayslip.this);
            pDialog.setMessage("Loading employees details. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        /**
         * Getting employee details in background thread
         * */
        protected String doInBackground(String... params) {

            // updating UI from Background Thread
             runOnUiThread(new Runnable() {
                 public void run() {
                     // Check for success tag
                     int success;
                     try {
                         // Building Parameters
                         List<NameValuePair> params = new ArrayList<NameValuePair>();
                         params.add(new BasicNameValuePair("pid", pid));

                         // getting employee details by making HTTP request
                         // Note that employee details url will use GET request
                         JSONObject json = jParser.makeHttpRequest(
                                 url_employees_details, "GET", params);

                         // check your log for json response
                         Log.d("Employee Details", json.toString());

                         // json success tag
                         success = json.getInt(TAG_SUCCESS);
                         if (success == 1) {
                             // successfully received employee details
                             JSONArray employeeObj = json
                                     .getJSONArray(TAG_EMPLOYEE); // JSON Array

                             // get first employee object from JSON Array
                             JSONObject employee = employeeObj.getJSONObject(0);

                             // employee with this pid found
                             // Edit Text
                             employeeName = (TextView) findViewById(R.id.employeeName);

                             Desc = (TextView) findViewById(R.id.department);

                             // display employee data in EditText
                             employeeName.setText(employee.getString(TAG_NAME));

                             Desc.setText(employee.getString(TAG_DESCRIPTION));

                         }else{
                             // employee with pid not found
                         }
                     } catch (JSONException e) {
                         e.printStackTrace();
                     }
                 }
             });

            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog once got all details
            pDialog.dismiss();
        }
    }
}

package com.example.two；
导入java.util.ArrayList；
导入java.util.HashMap；
导入java.util.List；
导入org.apache.http.NameValuePair；
导入org.apache.http.message.BasicNameValuePair；
导入org.json.JSONArray；
导入org.json.JSONException；
导入org.json.JSONObject；
导入android.app.Activity；
导入android.app.ProgressDialog；
导入android.content.Intent；
导入android.net.Uri；
导入android.os.AsyncTask；
导入android.os.Bundle；
导入android.telephony.smsmsmanager；
导入android.util.Log；
导入android.view.view；
导入android.widget.Button；
导入android.widget.ImageButton；
导入android.widget.TextView；
导入android.widget.Toast；
公共类EmployeePayslip扩展活动{
私人对话；
串pid；
TextView employeeName；
文本视图描述；
TextView txtCreatedAt；
//创建JSON解析器对象
JSONParser jParser=新的JSONParser（）；
JSONArray工资单=空；
ArrayList工资列表；
//获取所有全职员工列表的url
私有静态字符串url_工资单=”http://rollit.sg/FYP/ExportPayslip.php";
私有静态最终字符串url\u employees\u details=”http://rollit.sg/FYP/get_employees_details.php";
私有静态最终字符串标记_SUCCESS=“SUCCESS”；
私有静态最终字符串标记\u PAYSLIP=“PAYSLIP”；
私有静态最终字符串标记_PID=“PID”；
私有静态最终字符串标记_NAME=“NAME”；
私有静态最终字符串标记\u PAYSLIPNO=“PAYSLIPNO”；
私有静态最终字符串标记\u NETSALARY=“NETSALARY”；
私有静态最终字符串标记_ISSUEDATE=“ISSUEDATE”；
私有静态最终字符串标记\u startoffayslip=“startoffayslip”；
私有静态最终字符串标记；
私有静态最终字符串标记\u TYPEOFALLOWANCE=“TYPEOFALLOWANCE”；
私有静态最终字符串标记\u ALLOWANCEAMT=“ALLOWANCEAMT”；
私有静态最终字符串标记\u ALLOWANCEDATE=“ALLOWANCEDATE”；
私有静态最终字符串标记\u AvailableLowance=“AvailableLowance”；
私有静态最终字符串标记\u typeofdecision=“typeofdecision”；
私有静态最终字符串标记_declareonamt=“declareonamt”；
私有静态最终字符串标记_declareondate=“declareondate”；
私有静态最终字符串标记_AGREEDOVERTIMERATE=“AGREEDOVERTIMERATE”；
私有静态最终字符串标记_OVERTIMERATE=“OVERTIMERATE”；
私有静态最终字符串标记\u startofavertimeperiod=“startofavertimeperiod”；
私有静态最终字符串标记_endofVertimePeriod=“endofVertimePeriod”；
私有静态最终字符串标记\u BASICSALARY=“BASICSALARY”；
私有静态最终字符串标记_EXTRAPAYMENT=“EXTRAPAYMENT”；
私有静态最终字符串TAG_EMPLOYEE=“EMPLOYEE”；
私有静态最终字符串TAG_SALARY=“pay”；
私有静态最终字符串标记_DESCRIPTION=“DESCRIPTION”；
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.EmployeePaysslip）；
payslipList=newarraylist（）；
//在后台线程中加载所有全职员工
//从intent获取员工详细信息
Intent i=getIntent（）；
//从intent获取员工id（pid）
pid=i.getStringExtra（标签\ pid）；
新建GetEmployeeDetails（）.execute（）；
}
类GetEmployeeDetails扩展了AsyncTask{
/**
*在启动后台线程显示进度对话框之前
* */
@凌驾
受保护的void onPreExecute（）{
super.onPreExecute（）；
pDialog=新建进度对话框（employeepaysslip.this）；
pDialog.setMessage（“正在加载员工详细信息。请稍候…”）；
pDialog.setUndeterminate（假）；
pDialog.setCancelable（真）；
pDialog.show（）；
}
/**
*在后台线程中获取员工详细信息
* */
受保护的字符串doInBackground（字符串…参数）{
//从后台线程更新UI
runOnUiThread（新的Runnable（）{
公开募捐{
//检查成功标签
成功；
试一试{
//建筑参数
List params=new ArrayList（）；
参数添加（新的BasicNameValuePair（“pid”，pid））；
//通过发出HTTP请求获取员工详细信息
//请注意，员工详细信息url将使用GET请求
JSONObject json=jParser.makeHttpRequest(
url_员工_详细信息，“获取”，参数）；
//检查日志中的json响应
Log.d（“员工详细信息”，json.toString（））；
//json成功标记
success=json.getInt（TAG_success）；
如果（成功==1）{
//已成功接收员工详细信息
JSONArray employeeObj=json
.getJSONArray（TAG_EMPLOYEE）；//JSON数组
//从JSON数组中获取第一个employee对象
JSONObject employee=employeeObj.getJSONObject（0）；
//找到具有此pid的员工
//编辑文本
employeeName=（TextView）findViewById（R.id.employeeName）；
Desc=（TextView）findViewById（R.id.department）；
//在EditText中显示员工数据
employeeName.setText（employee.getString（标记
 runOnUiThread(new Runnable() {
             public void run() {

employeeName = (TextView) findViewById(R.id.employeeName);
Desc = (TextView) findViewById(R.id.department);