当我点击登录按钮时，我的申请人关闭......为什么会这样？这是什么解决方案？
我的Login_Menu活动如下： -
package com.campuspro.start;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Login_Menu extends Activity {
EditText usname;
EditText pass;
TextView tv;
HttpClient client;
HttpPost post;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.login_lay);
tv=(TextView) findViewById(R.id.login_stat_tv);
usname=(EditText)findViewById(R.id.uname);
pass=(EditText)findViewById(R.id.pass);
Button login=(Button)findViewById(R.id.login_but);
Button cancel=(Button)findViewById(R.id.cancel_but);
client = new DefaultHttpClient();
String url="http://10.0.2.2:7001/proj/login.jsp";
post = new HttpPost(url);
login.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
new login().execute("");
}
});
cancel.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
usname.getText().clear();
pass.getText().clear();
}
});
}
private class login extends AsyncTask<String, Void, JSONObject>{
ProgressDialog dialog = ProgressDialog.show(Login_Menu.this, "", "Authenticating, Please wait...");
@Override
protected JSONObject doInBackground(String... params) {
// TODO Auto-generated method stub
Log.i("thread", "Doing Something...");
//authentication operation
try{
List<NameValuePair> pairs = new ArrayList<NameValuePair>();
pairs.add(new BasicNameValuePair("username",usname.getText().toString()));
pairs.add(new BasicNameValuePair("password",pass.getText().toString()));
post.setEntity(new UrlEncodedFormEntity(pairs));
HttpResponse response = client.execute(post);
int status=response.getStatusLine().getStatusCode();
if(status == 200)
{
HttpEntity e=response.getEntity();
String data=EntityUtils.toString(e);
JSONObject last=new JSONObject(data);
return last;
}
}
catch(Exception e)
{
e.printStackTrace();
}
return null;
}
protected void onPreExecute(){
//dialog.dismiss();
Log.i("thread", "Started...");
dialog.show();
}
protected void onPostExecute(JSONObject result){
Log.i("thread", "Done...");
String name;
try {
name = result.getString("status");
if(dialog!=null)
dialog.dismiss();
if(name.equalsIgnoreCase("yes")){
tv.setText("user found");
Intent myIntent=new Intent("com.campuspro.start.MYMENU");
startActivity(myIntent);
}else{
tv.setText("No User Found, please try again!");
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}}
我的login.jsp页面如下......
<%@page contentType="text/html; charset=UTF-8"%>
<%@page import="org.json.simple.JSONObject"%>
<%@page import="java.util.*,java.sql.*"%>
<%!
Connection con;
PreparedStatement ps;
ResultSet rs;
String x,y;
%>
<%
Class.forName("oracle.jdbc.driver.OracleDriver");
con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","pro","pro");
x=request.getParameter("username");
y=request.getParameter("password");
ps=con.prepareStatement("select * from login_stud where uname=? and pass=?");
ps.setString(1,x);
ps.setString(2,y);
rs=ps.executeQuery();
JSONObject obj=new JSONObject();
if(rs.next())
{
obj.put("status","yes");
out.print(obj);
}
else
{
obj.put("status","no");
out.print(obj);
}
out.flush();
%>
这是我的日志猫......
04-15 23:42:06.449: I/thread(276): Started...
04-15 23:42:06.460: I/thread(276): Doing Something...
04-15 23:42:07.950: D/dalvikvm(276): GC_FOR_MALLOC freed 3284 objects / 170544 bytes in 156ms
04-15 23:42:10.469: I/thread(276): Done...
04-15 23:42:10.469: D/AndroidRuntime(276): Shutting down VM
04-15 23:42:10.469: W/dalvikvm(276): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
04-15 23:42:10.509: E/AndroidRuntime(276): FATAL EXCEPTION: main
04-15 23:42:10.509: E/AndroidRuntime(276): java.lang.NullPointerException
04-15 23:42:10.509: E/AndroidRuntime(276): at com.campuspro.start.Login_Menu$login.onPostExecute(Login_Menu.java:117)
04-15 23:42:10.509: E/AndroidRuntime(276): at com.campuspro.start.Login_Menu$login.onPostExecute(Login_Menu.java:1)
04-15 23:42:10.509: E/AndroidRuntime(276): at android.os.AsyncTask.finish(AsyncTask.java:417)
04-15 23:42:10.509: E/AndroidRuntime(276): at android.os.AsyncTask.access$300(AsyncTask.java:127)
04-15 23:42:10.509: E/AndroidRuntime(276): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
04-15 23:42:10.509: E/AndroidRuntime(276): at android.os.Handler.dispatchMessage(Handler.java:99)
04-15 23:42:10.509: E/AndroidRuntime(276): at android.os.Looper.loop(Looper.java:123)
04-15 23:42:10.509: E/AndroidRuntime(276): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-15 23:42:10.509: E/AndroidRuntime(276): at java.lang.reflect.Method.invokeNative(Native Method)
04-15 23:42:10.509: E/AndroidRuntime(276): at java.lang.reflect.Method.invoke(Method.java:521)
04-15 23:42:10.509: E/AndroidRuntime(276): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-15 23:42:10.509: E/AndroidRuntime(276): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-15 23:42:10.509: E/AndroidRuntime(276): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
这是根本原因：
Intent myIntent=new Intent("com.campuspro.start.MYMENU");
startActivity(myIntent);
应该是这样的：
Intent myIntent=new Intent(Login_Menu.this, MYMENU.class);
startActivity(myIntent);
答案 1 :(得分：0)
应用程序强制关闭，因为Android清单文件中未提及MYMENU活动。
启动意图时没有出现这样的错误。
在androidmanifest.xml中声明活动的过程是：
<activity
android:name=".ActivityName"
android:label="@string/app_name"
>
<intent-filter>
<action android:name="com.campuspro.start.ACTIVITYNAME" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
谢谢