本文介绍了Android应用程序连接到外部数据库（phpMyAdmin的）使用JSON的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想我的Android应用程序连接到外部数据库。我在我的phpmyadmin数据库中的表'产品'。当我尝试打开我的应用程序的活动 AllProductsActivity ，这将粉碎，并显示一个错误。
我用调试模式下运行应用程序，并发现它会死时运行到code Log.d（所有产品，json.toString（））; 上的行129 的和的JSONObject的值 JSON是空的
我新写的应用程序，我真的感到绝望现在。这将是感激，如果你可以提供帮助。谢谢大家。
FYI：程序首先进入 AllProductsActivity.java 然后调用 JSONParser.java 和 EditProductActivity.java 。的布局 AllProductsActivity.java 是 list_item.xml 和 EditProductActivity.java布局是 edit_product.xml 。假设用户可以选择从 LIST_ITEM 选项，并转到页关于
以下是错误：
03-17 17：17：54.003 1821年至1821年/ com.google.andriod.gms.example.hongkongmedicalapp I /编舞：跳过70帧！
该应用程序可能会做它的主线程的工作太多了。
03-17 17：17：54.963 1821年至1835年/ com.google.andriod.gms.example.hongkongmedicalapp E / JSON解析器：错误解析数据org.json.JSONException：在字符输入0结束
03-17 17：17：54.963 1821年至1835年/ com.google.andriod.gms.example.hongkongmedicalapp W / dalvikvm：主题ID = 11：螺纹未捕获的异常退出（组= 0x40a71930）
03-17 17：17：55.203 1821年至1835年/ com.google.andriod.gms.example.hongkongmedicalapp E / AndroidRuntime：致命的异常：AsyncTask的＃1
了java.lang.RuntimeException：执行doInBackground发生错误（）
在android.os.AsyncTask $ 3.done（AsyncTask.java:299）
在java.util.concurrent.FutureTask.finishCompletion（FutureTask.java:352）
在java.util.concurrent.FutureTask.setException（FutureTask.java:219）
在java.util.concurrent.FutureTask.run（FutureTask.java:239）
在android.os.AsyncTask $ SerialExecutor $ 1.run（AsyncTask.java:230）
在java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1080）
在java.util.concurrent.ThreadPoolExecutor中的$ Worker.run（ThreadPoolExecutor.java:573）
在java.lang.Thread.run（Thread.java:856）
显示java.lang.NullPointerException：产生的原因
在com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:129)
在com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:102)
在android.os.AsyncTask $ 2.call（AsyncTask.java:287）
在java.util.concurrent.FutureTask.run（FutureTask.java:234）
在android.os.AsyncTask $ SerialExecutor $ 1.run（AsyncTask.java:230）
在java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1080）
在java.util.concurrent.ThreadPoolExecutor中的$ Worker.run（ThreadPoolExecutor.java:573）
在java.lang.Thread.run（Thread.java:856）
03-17 17：17：56.093 1821年至1821年/ com.google.andriod.gms.example.hongkongmedicalapp I /编舞：跳过57帧！该应用程序可能会做太多的工作
03-17 17：17：56.473 1821年至1821年/ com.google.andriod.gms.example.hongkongmedicalapp I /编舞：跳过33帧！该应用程序可能会做它的主线程的工作太多了。
03-17 17：17：57.173 1821年至1821年/ com.google.andriod.gms.example.hongkongmedicalapp I /编舞：跳过73帧！该应用程序可能会做它的主线程的工作太多了。
03-17 17：17：58.083 1821年至1821年/ com.google.andriod.gms.example.hongkongmedicalapp E /窗口管理器：活动com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity已泄漏窗口com.android.internal。 policy.impl.PhoneWindow $ {DecorView VE 40db1fe0 .... - [R ..... ID 0,0-729,192}，最初这里加入
android.view.WindowLeaked：活动com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity渗漏窗口com.android.internal.policy.impl.PhoneWindow $ {DecorView VE 40db1fe0 .... - [R ..... ID 0,0-729,192}，最初这里加入
在android.view.ViewRootImpl＆LT;＆初始化GT;（ViewRootImpl.java:354）
在android.view.WindowManagerGlobal.addView（WindowManagerGlobal.java:216）
在android.view.WindowManagerImpl.addView（WindowManagerImpl.java:69）
在android.app.Dialog.show（Dialog.java:281）
在com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity$LoadAllProducts.on$p$pExecute(AllProductsActivity.java:114)
在android.os.AsyncTask.executeOnExecutor（AsyncTask.java:586）
在android.os.AsyncTask.execute（AsyncTask.java:534）
在com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity.onCreate(AllProductsActivity.java:57)
在android.app.Activity.performCreate（Activity.java:5104）
在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1080）
在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2144）
在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2230）
在android.app.ActivityThread.access $ 600（ActivityThread.java:141）
在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1234）
在android.os.Handler.dispatchMessage（Handler.java:99）
在android.os.Looper.loop（Looper.java:137）
在android.app.ActivityThread.main（ActivityThread.java:5041）
在java.lang.reflect.Method.invokeNative（本机方法）
在java.lang.reflect.Method.invoke（Method.java:511）
在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:793）
在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:560）
在dalvik.system.NativeStart.main（本机方法）
下面是AllProductActivity.Java的code：
包com.google.andriod.gms.example.hongkongmedicalapp;进口android.app.ListActivity;
进口android.app.ProgressDialog;
进口android.content.Intent;
进口android.os.AsyncTask;
进口android.os.Bundle;
进口android.util.Log;
进口android.view.View;
进口android.widget.AdapterView;
进口android.widget.AdapterView.OnItemClickListener;
进口android.widget.ListAdapter;
进口android.widget.ListView;
进口android.widget.SimpleAdapter;
进口android.widget.TextView;进口org.apache.http.NameValuePair;
进口org.json.JSONArray;
进口org.json.JSONException;
进口org.json.JSONObject;进口的java.util.ArrayList;
进口的java.util.HashMap;
进口的java.util.List;公共类AllProductsActivity扩展ListActivity { //进度对话框
私人ProgressDialog pDialog; //创建JSON解析器对象
JSONParser jParser =新JSONParser（）; ArrayList的＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;产品列表; // URL获得所有产品清单
私人静态字符串url_all_products =http://101.78.175.101:21280/android_connect/get_all_products.php; // JSON节点名称
私有静态最后弦乐TAG_SUCCESS =成功;
私有静态最后弦乐TAG_PRODUCTS =产品;
私有静态最后弦乐TAG_PID =PID;
私有静态最后弦乐TAG_NAME =名; //产品JSONArray
JSONArray产品= NULL; @覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.all_products）; //为哈希映射的ListView
产品列表=新的ArrayList＆LT;＆HashMap的LT;字符串，字符串＆GT;＆GT;（）; //装载产品在后台线程
新LoadAllProducts（）执行（）; //获取列表视图
ListView控件LV = getListView（）; //在选课单品
//启动编辑产品屏幕
lv.setOnItemClickListener（新OnItemClickListener（）{ @覆盖
公共无效onItemClick（适配器视图＆LT;＆GT;母公司，观景，INT位置，长的id）{
//从选定的ListItem得到的值
字符串的pid =（（的TextView）view.findViewById（R.id.pid））的getText（）的toString（）。 //开始新意图
在意向=新意图（getApplicationContext（），EditProductActivity.class）;
//发送到PID下一个活动
in.putExtra（TAG_PID，PID）; //开始新的活动，期待一些回响应
startActivityForResult（在100）;
}
}）; } //从编辑产品的活动响应
@覆盖
保护无效的onActivityResult（INT申请code，INT结果code，意图数据）{
super.onActivityResult（要求code，结果code，数据）;
//如果结果code 100
如果（结果code == 100）{
//如果结果code 100接收
//意味着用户编辑/删除产品
//重新载入该画面
意向意图= getIntent（）;
完（）;
startActivity（意向）;
} } / **
*背景异步任务以通过HTTP请求负载的所有产品
* * /
类LoadAllProducts扩展的AsyncTask＆LT;字符串，字符串，字符串＆GT; { / **
*启动后台线程显示进度对话框之前
* * /
@覆盖
在preExecute保护无效（）{
super.on preExecute（）;
pDialog =新ProgressDialog（AllProductsActivity.this）;
pDialog.setMessage（加载产品请稍候......）;
pDialog.setIndeterminate（假）;
pDialog.setCancelable（假）;
pDialog.show（）; } / **
*让所有的产品网址
* * /
保护字符串doInBackground（字符串参数... args）{
//大厦参数
清单＆LT;＆的NameValuePair GT; PARAMS =新的ArrayList＆LT;＆的NameValuePair GT;（）;
// URL从获取JSON字符串
JSONObject的JSON = jParser.makeHtt prequest（url_all_products，GET，则params）; //检查JSON效应初探日志的猫
//当我使用调试模式，我发现程序在这条线上和JSON的JSONObject的价值死者为空
Log.d（所有产品，json.toString（））; 尝试{
//检查成功TAG
INT成功= json.getInt（TAG_SUCCESS）; 如果（成功== 1）{
发现//产品
//获取产品阵列
产品= json.getJSONArray（TAG_PRODUCTS）; //产品通过所有循环
的for（int i = 0; I＆LT; products.length（）;我++）{
JSONObject的C = products.getJSONObject（I） //存储在变量中的每个JSON项目
字符串ID = c.getString（TAG_PID）;
字符串名称= c.getString（TAG_NAME）; //创建新的HashMap
HashMap的＆LT;字符串，字符串＆GT;地图=新的HashMap＆LT;字符串，字符串＆GT;（）; //将每个子节点的HashMap键=＆GT;值
map.put（TAG_PID，身份证）;
map.put（TAG_NAME，名）; //添加HashList到ArrayList的
productsList.add（地图）;
}
}其他{ }
}赶上（JSONException E）{
e.printStackTrace（）;
} 返回null;
} / **
*在完成后台任务之后辞退进度对话框
* ** /
保护无效onPostExecute（字符串FILE_URL）{
//让所有的产品后，关闭该对话框
pDialog.dismiss（）; //从后台线程更新界面
runOnUiThread（新的Runnable（）{
公共无效的run（）{
/ **
*更新解析JSON数据到ListView控件
* * /
ListAdapter适配器=新SimpleAdapter（
AllProductsActivity.this，产品列表，R.layout.list_item，新的String [] {TAG_PID，TAG_NAME}，新的INT [] {R.id.pid，R.id.name}）;
//更新列表视图
setListAdapter（适配器）;
}
}）; } }
}
下面是EditProductActivity.java的code
包com.google.andriod.gms.example.hongkongmedicalapp;进口android.app.Activity;
进口android.app.ProgressDialog;
进口android.content.Intent;
进口android.graphics.Bitmap;
进口android.os.AsyncTask;
进口android.os.Bundle;
进口android.os.StrictMode;
进口android.util.Log;
进口android.widget.Button;
进口android.widget.EditText;
进口android.widget.TextView;进口org.apache.http.NameValuePair;
进口org.apache.http.message.BasicNameValuePair;
进口org.json.JSONArray;
进口org.json.JSONException;
进口org.json.JSONObject;进口的java.util.ArrayList;
进口的java.util.List;公共类EditProductActivity延伸活动{ TextView的txtName的;
TextView的txtPrice;
TextView的txtDesc;
TextView的txtUses;
TextView的txtSide;
TextView的TXT precau;
TextView的txtinterac;
TextView的txtoverdose;
串PID; //进度对话框
私人ProgressDialog pDialog;// JSON节点名称
私有静态最后弦乐TAG_SUCCESS =成功;
私有静态最后弦乐TAG_PRODUCT =产品;
私有静态最后弦乐TAG_PID =PID;
私有静态最后弦乐TAG_NAME =名;
私有静态最后弦乐TAG_PRICE =价格;
私有静态最后弦乐TAG_DESCRIPTION =说明;
私有静态最后弦乐TAG_USES =使用;
私有静态最后弦乐TAG_SIDEEFFECTS =sideeffects;
私有静态最后弦乐TAG_ preCAUTIONS =precauctions
私有静态最后弦乐TAG_INTERACTIONS =互动;
私有静态最后弦乐TAG_OVERDOSE =过量; @覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.edit_product）;
如果（android.os.Build.VERSION.SDK_INT＆GT; 9）{
。StrictMode.ThreadPolicy政策=新StrictMode.ThreadPolicy.Builder（）permitAll（）建（）;
StrictMode.setThreadPolicy（政策）;
} //获取来自意图产品的详细信息
意向I = getIntent（）; //从意图获取产品ID（PID）
PID = i.getStringExtra（TAG_PID）; //获取在后台线程完整的产品细节
GetProductDetails dproductdetail =新GetProductDetails（）;
dproductdetail.execute（）; } / **
*背景异步任务以获得完整的产品细节
* * /
类GetProductDetails扩展的AsyncTask＆LT;字符串，字符串，字符串＆GT; {
// JSON解析器类
JSONParser jsonParser =新JSONParser（）;
/ **
*启动后台线程显示进度对话框之前
* * /
@覆盖
在preExecute保护无效（）{
super.on preExecute（）;
pDialog =新ProgressDialog（EditProductActivity.this）;
pDialog.setMessage（装载产品的详细信息，请稍候...）;
pDialog.setIndeterminate（假）;
pDialog.setCancelable（真）;
pDialog.show（）;
} / **
*获取产品的详细信息在后台线程
* * /
保护字符串doInBackground（字符串... PARAMS）{ //从后台线程更新界面
runOnUiThread（新的Runnable（）{
公共无效的run（）{
//检查成功标记
诠释成功;
尝试{
//大厦参数
清单＆LT;＆的NameValuePair GT; PARAMS =新的ArrayList＆LT;＆的NameValuePair GT;（）;
params.add（新BasicNameValuePair（PID，PID））; //通过HTTP请求获得产品的详细信息
//注意产品的详细信息URL会使用GET请求
JSONObject的JSON = jsonParser.makeHtt prequest（http://101.78.175.101:21280/android_connect/get_product_details.php，GET，则params）; //检查你的日志，JSON响应
Log.d（单一产品详细信息，json.toString（））; // JSON的成功标签
成功= json.getInt（TAG_SUCCESS）;
如果（成功== 1）{
//成功接收产品的详细信息
JSONArray productObj = json.getJSONArray（TAG_PRODUCT）; // JSON数组 //从JSON数组的第一个产品对象
的JSONObject产物= productObj.getJSONObject（0）; //与本产品的PID发现
//编辑文本
txtName的=（的TextView）findViewById（R.id.inputName）;
txtPrice =（的TextView）findViewById（R.id.inputPrice）;
txtDesc =（的TextView）findViewById（R.id.inputDesc）;
txtUses =（的TextView）findViewById（R.id.inputuses）;
txtSide =（的TextView）findViewById（R.id.inputsideeffects）;
TXT precau =（的TextView）findViewById（R.id.input precautions）;
txtinterac =（的TextView）findViewById（R.id.inputinteractions）;
txtoverdose =（的TextView）findViewById（R.id.inputoverdose）;
//在显示的EditText产品数据
txtName.setText（product.getString（TAG_NAME））;
txtPrice.setText（product.getString（TAG_PRICE））;
txtDesc.setText（product.getString（TAG_DESCRIPTION））;
txtUses.setText（product.getString（TAG_USES））;
txtSide.setText（product.getString（TAG_SIDEEFFECTS））;
TXT precau.setText（product.getString（TAG_ preCAUTIONS））;
txtinterac.setText（product.getString（TAG_INTERACTIONS））;
txtoverdose .setText（product.getString（TAG_OVERDOSE））; }其他{
//产品具有pid未找到
}
}赶上（JSONException E）{
e.printStackTrace（）;
}
}
}）; 返回null;
} / **
*在完成后台任务之后辞退进度对话框
* ** /
保护无效onPostExecute（字符串FILE_URL）{
//关闭该对话框一旦得了所有细节
pDialog.dismiss（）;
}
}}
下面是JSONParser.java的code
包com.google.andriod.gms.example.hongkongmedicalapp;进口android.util.Log;进口org.apache.http.HttpEntity;
进口org.apache.http.Htt presponse;
进口org.apache.http.NameValuePair;
进口org.apache.http.client.ClientProtocolException;
进口org.apache.http.client.entity.UrlEn codedFormEntity;
进口org.apache.http.client.methods.HttpGet;
进口org.apache.http.client.methods.HttpPost;
进口org.apache.http.client.utils.URLEn codedUtils;
进口org.apache.http.impl.client.DefaultHttpClient;
进口org.json.JSONException;
进口org.json.JSONObject;进口java.io.BufferedReader中;
进口java.io.IOException异常;
进口的java.io.InputStream;
进口java.io.InputStreamReader中;
进口java.io.UnsupportedEncodingException;
进口的java.util.List;公共类JSONParser { 静态InputStream为= NULL;
静态的JSONObject jObj = NULL;
静态JSON字符串=; //构造
公共JSONParser（）{ } //函数得到JSON的网址
//通过HTTP POST或GET mehtod
公众的JSONObject makeHtt prequest（URL字符串，字符串的方法，列表与LT;＆的NameValuePair GT; PARAMS）{ //使HTTP请求
尝试{ //检查请求的方法
如果（方法==POST）{
//请求方法是POST
// defaultHttpClient
DefaultHttpClient的HttpClient =新DefaultHttpClient（）;
HttpPost httpPost =新HttpPost（URL）;
httpPost.setEntity（新UrlEn codedFormEntity（PARAMS））; HTT presponse HTT presponse = httpClient.execute（httpPost）;
HttpEntity httpEntity = HTT presponse.getEntity（）;
是= httpEntity.getContent（）; }否则如果（方法==GET）{
//请求方法是GET
DefaultHttpClient的HttpClient =新DefaultHttpClient（）;
字符串中的paramString = URLEn codedUtils.format（参数，可以UTF-8）;
网址+ =？ +中的paramString;
HTTPGET HTTPGET =新HTTPGET（URL）; HTT presponse HTT presponse = httpClient.execute（HTTPGET）;
HttpEntity httpEntity = HTT presponse.getEntity（）;
是= httpEntity.getContent（）;
}
}赶上（UnsupportedEncodingException五）{
e.printStackTrace（）;
}赶上（ClientProtocolException E）{
e.printStackTrace（）;
}赶上（IOException异常五）{
e.printStackTrace（）;
} 尝试{
读者的BufferedReader =新的BufferedReader（新的InputStreamReader（
是，ISO-8859-1），8）;
StringBuilder的SB =新的StringBuilder（）;
串线= NULL;
而（（行= reader.readLine（））！= NULL）{
sb.append（行+\\ n）;
}
is.close（）;
JSON = sb.toString（）;
}赶上（例外五）{
Log.e（缓冲区错误，错误转换结果+ e.toString（））;
} //尝试分析字符串到一个JSON对象
尝试{
jObj =新的JSONObject（JSON）;
}赶上（JSONException E）{
Log.e（JSON解析器，错误分析数据+ e.toString（））;
} //返回JSON字符串
返回jObj; }
}
我的PHP脚本get_product_details：
＆LT; PHP/ *
*继code将得到单品细节
*一个产品是由产品id标识（PID）
* ///数组JSON响应
$响应=阵列（）;
//其中包括DB连接类
require_once __DIR__。 /db_connect.php';//连接到数据库
$ DB =新DB_CONNECT（）;//检查数据后
如果（使用isset（$ _ GET [PID]））{
$ PID = $ _GET ['PID']; //从产品表中的产品
$结果= mysql_query（SELECT * FROM产品WHERE PID = $ PID）; 如果（！空（$结果））{
//检查空结果
如果（mysql_num_rows（$结果）大于0）{ $结果= mysql_fetch_array（$结果）; $产品=阵列（）;
$产品[PID] = $结果[PID];
$产品[名称] = $结果[名称];
$产品[价格] = $结果[价格];
$产品[说明] = $结果[描述];
$产品[使用] = $结果[利用];
$产品[sideeffects] = $结果[sideeffects];
$产品[precauctions] = $结果[precauctions];
$产品[互动] = $结果[互动];
$产品[过量] = $结果[用药过量];
$产品[created_at] = $结果[created_at];
$产品[的updated_at] = $结果[的updated_at];
//成功
$响应[成功] = 1; //用户节点
$响应[产品] =阵列（）; array_push（$响应[产品]，$产品）; //呼应JSON响应
回声json_en code（$响应）;
}其他{
//没有产品找到
$响应[成功] = 0;
$响应[消息] =没有产品找到了; //回声没有用户JSON
回声json_en code（$响应）;
}
}其他{
//没有产品找到
$响应[成功] = 0;
$响应[消息] =没有产品找到了; //回声没有用户JSON
回声json_en code（$响应）;
}
}其他{
//必填字段缺失
$响应[成功] = 0;
$响应[消息] =必填字段（s）是失踪; //呼应JSON响应
回声json_en code（$响应）;
}
？＆GT;
解决方案
我认为错误的主要原因是，您的服务器不返回JSON。
我试图打开在浏览器中，不幸的是，我得到了一个空白页。
有关有效的JSON它应该至少返回 {} 。
您可以手动验证JSON这个流行的工具
所以，首先，你必须让你的服务器返回有效JSON，然后我们可以看到，如果一切工作正常。
I'm trying to connect my android application to an external database. I have a table 'products' in my phpmyadmin database. when I try to open the activity AllProductsActivity in my app, it will crush and show an error.
I have used debug mode to run the app and find that it will dead when runs to the code Log.d("All Products: ", json.toString()); on line 129 and the value of JSONObject json is null.
I am new to write app and I really feel desperate right now. It would be thankful if you can help. thank you to everyone.
FYI:The program first goes to AllProductsActivity.java and then it calls JSONParser.java and EditProductActivity.java. The layout of the AllProductsActivity.java is list_item.xml and the layout of EditProductActivity.java is edit_product.xml. User suppose can choose the option from the list_item and go to regarding page.
Below is the error:
03-17 17:17:54.003 1821-1821/com.google.andriod.gms.example.hongkongmedicalapp I/Choreographer﹕ Skipped 70 frames!
The application may be doing too much work on its main thread.
03-17 17:17:54.963 1821-1835/com.google.andriod.gms.example.hongkongmedicalapp E/JSON Parser﹕ Error parsing data org.json.JSONException: End of input at character 0 of
03-17 17:17:54.963 1821-1835/com.google.andriod.gms.example.hongkongmedicalapp W/dalvikvm﹕ threadid=11: thread exiting with uncaught exception (group=0x40a71930)
03-17 17:17:55.203 1821-1835/com.google.andriod.gms.example.hongkongmedicalapp E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
at java.util.concurrent.FutureTask.run(FutureTask.java:239)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
Caused by: java.lang.NullPointerException
at com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:129)
at com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity$LoadAllProducts.doInBackground(AllProductsActivity.java:102)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask.run(FutureTask.java:234)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
03-17 17:17:56.093 1821-1821/com.google.andriod.gms.example.hongkongmedicalapp I/Choreographer﹕ Skipped 57 frames! The application may be doing too much work on its
03-17 17:17:56.473 1821-1821/com.google.andriod.gms.example.hongkongmedicalapp I/Choreographer﹕ Skipped 33 frames! The application may be doing too much work on its main thread.
03-17 17:17:57.173 1821-1821/com.google.andriod.gms.example.hongkongmedicalapp I/Choreographer﹕ Skipped 73 frames! The application may be doing too much work on its main thread.
03-17 17:17:58.083 1821-1821/com.google.andriod.gms.example.hongkongmedicalapp E/WindowManager﹕ Activity com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{40db1fe0 V.E..... R.....ID 0,0-729,192} that was originally added here
android.view.WindowLeaked: Activity com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{40db1fe0 V.E..... R.....ID 0,0-729,192} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:354)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:216)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
at android.app.Dialog.show(Dialog.java:281)
at com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity$LoadAllProducts.onPreExecute(AllProductsActivity.java:114)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at android.os.AsyncTask.execute(AsyncTask.java:534)
at com.google.andriod.gms.example.hongkongmedicalapp.AllProductsActivity.onCreate(AllProductsActivity.java:57)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
Below is the code of AllProductActivity.Java:
package com.google.andriod.gms.example.hongkongmedicalapp;
import android.app.ListActivity;
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.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class AllProductsActivity extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
// url to get all products list
private static String url_all_products = "http://101.78.175.101:21280/android_connect/get_all_products.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "products";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
// products JSONArray
JSONArray products = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_products);
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
// Get listview
ListView lv = getListView();
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
// getting values from selected ListItem
String pid = ((TextView) view.findViewById(R.id.pid)).getText().toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),EditProductActivity.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
}
// Response from Edit Product Activity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// if result code 100
if (resultCode == 100) {
// if result code 100 is received
// means user edited/deleted product
// reload this screen again
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllProducts extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllProductsActivity.this);
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
//When I use debug mode, I find the program dead on this line and the value of JSONObject json is null
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
productsList.add(map);
}
} else {
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
AllProductsActivity.this, productsList,R.layout.list_item, new String[] { TAG_PID,TAG_NAME},new int[] { R.id.pid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}
}
Below is the code of EditProductActivity.java
package com.google.andriod.gms.example.hongkongmedicalapp;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
public class EditProductActivity extends Activity {
TextView txtName;
TextView txtPrice;
TextView txtDesc;
TextView txtUses;
TextView txtSide;
TextView txtPrecau;
TextView txtinterac;
TextView txtoverdose;
String pid;
// Progress Dialog
private ProgressDialog pDialog;
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCT = "product";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
private static final String TAG_PRICE = "price";
private static final String TAG_DESCRIPTION = "description";
private static final String TAG_USES = "uses";
private static final String TAG_SIDEEFFECTS = "sideeffects";
private static final String TAG_PRECAUTIONS= "precauctions";
private static final String TAG_INTERACTIONS = "interactions";
private static final String TAG_OVERDOSE = "overdose";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.edit_product);
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
// getting product details from intent
Intent i = getIntent();
// getting product id (pid) from intent
pid = i.getStringExtra(TAG_PID);
// Getting complete product details in background thread
GetProductDetails dproductdetail = new GetProductDetails();
dproductdetail.execute();
}
/**
* Background Async Task to Get complete product details
* */
class GetProductDetails extends AsyncTask<String, String, String> {
// JSON parser class
JSONParser jsonParser = new JSONParser();
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(EditProductActivity.this);
pDialog.setMessage("Loading product details. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
/**
* Getting product 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 product details by making HTTP request
// Note that product details url will use GET request
JSONObject json = jsonParser.makeHttpRequest("http://101.78.175.101:21280/android_connect/get_product_details.php", "GET", params);
// check your log for json response
Log.d("Single Product Details", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// successfully received product details
JSONArray productObj = json.getJSONArray(TAG_PRODUCT); // JSON Array
// get first product object from JSON Array
JSONObject product = productObj.getJSONObject(0);
// product with this pid found
// Edit Text
txtName = (TextView) findViewById(R.id.inputName);
txtPrice = (TextView) findViewById(R.id.inputPrice);
txtDesc = (TextView) findViewById(R.id.inputDesc);
txtUses = (TextView) findViewById(R.id.inputuses);
txtSide = (TextView) findViewById(R.id.inputsideeffects);
txtPrecau = (TextView) findViewById(R.id.inputprecautions);
txtinterac= (TextView) findViewById(R.id.inputinteractions);
txtoverdose = (TextView) findViewById(R.id.inputoverdose);
// display product data in EditText
txtName.setText(product.getString(TAG_NAME));
txtPrice.setText(product.getString(TAG_PRICE));
txtDesc.setText(product.getString(TAG_DESCRIPTION));
txtUses.setText(product.getString(TAG_USES));
txtSide.setText(product.getString(TAG_SIDEEFFECTS));
txtPrecau.setText(product.getString(TAG_PRECAUTIONS));
txtinterac.setText(product.getString(TAG_INTERACTIONS));
txtoverdose .setText(product.getString(TAG_OVERDOSE));
}else{
// product 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();
}
}
}
Below is the code of JSONParser.java
package com.google.andriod.gms.example.hongkongmedicalapp;
import android.util.Log;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
My php script get_product_details:
<?php
/*
* Following code will get single product details
* A product is identified by product id (pid)
*/
// array for JSON response
$response = array();
// include db connect class
require_once __DIR__ . '/db_connect.php';
// connecting to db
$db = new DB_CONNECT();
// check for post data
if (isset($_GET["pid"])) {
$pid = $_GET['pid'];
// get a product from products table
$result = mysql_query("SELECT *FROM products WHERE pid = $pid");
if (!empty($result)) {
// check for empty result
if (mysql_num_rows($result) > 0) {
$result = mysql_fetch_array($result);
$products = array();
$products["pid"] = $result["pid"];
$products["name"] = $result["name"];
$products["price"] = $result["price"];
$products["description"] = $result["description"];
$products["uses"] = $result["uses"];
$products["sideeffects"] = $result["sideeffects"];
$products["precauctions"] = $result["precauctions"];
$products["interactions"] = $result["interactions"];
$products["overdose"] = $result["overdose"];
$products["created_at"] = $result["created_at"];
$products["updated_at"] = $result["updated_at"];
// success
$response["success"] = 1;
// user node
$response["products"] = array();
array_push($response["products"], $products);
// echoing JSON response
echo json_encode($response);
} else {
// no product found
$response["success"] = 0;
$response["message"] = "No product found";
// echo no users JSON
echo json_encode($response);
}
} else {
// no product found
$response["success"] = 0;
$response["message"] = "No product found";
// echo no users JSON
echo json_encode($response);
}
} else {
// required field is missing
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";
// echoing JSON response
echo json_encode($response);
}
?>
解决方案
I think that the main reason of error is that your server doesn't return json.
I tried to open http://101.78.175.101:21280/android_connect/get_all_products.php in the browser, and, unfortunately, I got an empty page.
For valid JSON it should return at least {}.
You can manually validate JSON with this popular tool http://jsonlint.com/
So, firstly, you have to make your server return valid JSON, and then we can see if everything else is working fine.
这篇关于Android应用程序连接到外部数据库（phpMyAdmin的）使用JSON的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！