Java 获取json数据的代码中有什么错误?
这段代码中的错误是什么 我想添加一个facebook页面名并获取其json数据,但有一个错误我无法发现。以下是我使用的所有文件和添加的logcat消息: PagesActivity.javaJava 获取json数据的代码中有什么错误?,java,android,json,Java,Android,Json,这段代码中的错误是什么 我想添加一个facebook页面名并获取其json数据,但有一个错误我无法发现。以下是我使用的所有文件和添加的logcat消息: PagesActivity.java package com.engahmedphp.facebookcollector; import org.json.JSONException; import org.json.JSONObject; import android.os.Bundle; import android.app.Activ
package com.engahmedphp.facebookcollector;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class PagesActivity extends Activity {
DatabaseHandler db = new DatabaseHandler(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pages);
final Button button = (Button) findViewById(R.id.addPage);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
AlertDialog.Builder alert = new AlertDialog.Builder(
PagesActivity.this);
alert.setTitle("Add New Page");
alert.setMessage("Enter Page Name OR Valid Facebook Link");
// Set an EditText view to get user input
final EditText input = new EditText(PagesActivity.this);
alert.setView(input);
alert.setPositiveButton("Ok",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
String value = input.getText().toString();
// Do something with value!
String url = "http://graph.facebook.com/"
+ value + "/?fields=picture,name";
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
// Storing each json item in variable
String name = json.getString("name");
String fid = json.getString("id");
String picture = json
.getJSONObject("picture")
.getJSONObject("data")
.getString("url");
db.addPage(name, fid, picture);
} catch (JSONException e) {
e.printStackTrace();
}
// addPageData(value);
}
});
alert.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int whichButton) {
// Canceled.
}
});
alert.show();
}
});
}
void addPageData(String pageName) {
String url = "http://graph.facebook.com/" + pageName
+ "/?fields=picture,name";
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
// Storing each json item in variable
String name = json.getString("name");
String fid = json.getString("id");
String picture = json.getJSONObject("picture")
.getJSONObject("data").getString("url");
db.addPage(name, fid, picture);
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.splash, menu);
return true;
}
}
JSONParser.java
package com.engahmedphp.facebookcollector;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
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;
}
}
LogCat
08-31 03:35:23.031: D/dalvikvm(15972): GC_FOR_ALLOC freed 39K, 6% free 2633K/2792K, paused 65ms, total 68ms
08-31 03:35:23.041: I/dalvikvm-heap(15972): Grow heap (frag case) to 3.767MB for 1136500-byte allocation
08-31 03:35:23.163: D/dalvikvm(15972): GC_FOR_ALLOC freed 2K, 5% free 3740K/3904K, paused 116ms, total 116ms
08-31 03:35:23.511: D/gralloc_goldfish(15972): Emulator without GPU emulation detected.
08-31 03:35:26.611: I/Choreographer(15972): Skipped 30 frames! The application may be doing too much work on its main thread.
08-31 03:39:40.903: D/dalvikvm(15972): GC_FOR_ALLOC freed 47K, 4% free 4013K/4180K, paused 48ms, total 81ms
08-31 03:39:40.903: I/dalvikvm-heap(15972): Grow heap (frag case) to 4.638MB for 635812-byte allocation
08-31 03:39:41.023: D/dalvikvm(15972): GC_FOR_ALLOC freed 2K, 4% free 4631K/4804K, paused 111ms, total 111ms
08-31 03:39:41.483: I/Choreographer(15972): Skipped 83 frames! The application may be doing too much work on its main thread.
08-31 03:39:48.701: D/AndroidRuntime(15972): Shutting down VM
08-31 03:39:48.701: W/dalvikvm(15972): threadid=1: thread exiting with uncaught exception (group=0x414c4700)
08-31 03:39:48.741: E/AndroidRuntime(15972): FATAL EXCEPTION: main
08-31 03:39:48.741: E/AndroidRuntime(15972): android.os.NetworkOnMainThreadException
08-31 03:39:48.741: E/AndroidRuntime(15972): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1133)
08-31 03:39:48.741: E/AndroidRuntime(15972): at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
08-31 03:39:48.741: E/AndroidRuntime(15972): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
08-31 03:39:48.741: E/AndroidRuntime(15972): at java.net.InetAddress.getAllByName(InetAddress.java:214)
08-31 03:39:48.741: E/AndroidRuntime(15972): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
08-31 03:39:48.741: E/AndroidRuntime(15972): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
08-31 03:39:48.741: E/AndroidRuntime(15972): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
08-31 03:39:48.741: E/AndroidRuntime(15972): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
08-31 03:39:48.741: E/AndroidRuntime(15972): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
08-31 03:39:48.741: E/AndroidRuntime(15972): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
08-31 03:39:48.741: E/AndroidRuntime(15972): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
08-31 03:39:48.741: E/AndroidRuntime(15972): at com.engahmedphp.facebookcollector.JSONParser.getJSONFromUrl(JSONParser.java:38)
08-31 03:39:48.741: E/AndroidRuntime(15972): at com.engahmedphp.facebookcollector.PagesActivity$1$1.onClick(PagesActivity.java:49)
08-31 03:39:48.741: E/AndroidRuntime(15972): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
08-31 03:39:48.741: E/AndroidRuntime(15972): at android.os.Handler.dispatchMessage(Handler.java:99)
08-31 03:39:48.741: E/AndroidRuntime(15972): at android.os.Looper.loop(Looper.java:137)
08-31 03:39:48.741: E/AndroidRuntime(15972): at android.app.ActivityThread.main(ActivityThread.java:5103)
08-31 03:39:48.741: E/AndroidRuntime(15972): at java.lang.reflect.Method.invokeNative(Native Method)
08-31 03:39:48.741: E/AndroidRuntime(15972): at java.lang.reflect.Method.invoke(Method.java:525)
08-31 03:39:48.741: E/AndroidRuntime(15972): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
08-31 03:39:48.741: E/AndroidRuntime(15972): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-31 03:39:48.741: E/AndroidRuntime(15972): at dalvik.system.NativeStart.main(Native Method)
您将获得
NetworkOnMainThreadException
。看见当应用程序尝试在其主(UI)线程上执行网络操作时,会引发此异常。使用AsyncTask
或在新线程内执行网络任务。有关此异常的原因,请参阅上的Android文档
在这里:
您正在主UI线程上执行与网络相关的操作。尝试在新线程中执行此操作 JSONParser在UI线程中创建HTTP连接(oneClick在UI线程中被调用),现在它被禁用了。
因此,您需要将网络代码移动到其他线程。以防您没有注意到;对于Android 3.0(蜂巢)或更高版本,网络访问的StrictMode会导致致命错误,除非您的应用程序针对的是蜂巢之前的API版本 解决这个问题的正确方法是使用Android AsyncTask进行网络访问 处理此问题的惰性方法是将检查转到: StrictMode.ThreadPolicy policy=新建StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(策略) 正如其他人所提到的,你不应该在UI线程上进行联网以使你的应用程序UI响应 试试这个
public class JsonParser extends AsyncTask<String, Void, JSONObject> {
InputStream is = null;
JSONObject jObj = null;
String json = "";
@Override
protected JSONObject doInBackground(String... params) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(params[0]);
HttpResponse httpResponse = httpClient.execute(httpPost);
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;
}
@Override
protected void onPostExecute(JSONObject json) {
try {
// Storing each json item in variable
String name = json.getString("name");
String fid = json.getString("id");
String picture = json
.getJSONObject("picture")
.getJSONObject("data")
.getString("url");
db.addPage(name, fid, picture);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
公共类JsonParser扩展了异步任务{
InputStream=null;
JSONObject jObj=null;
字符串json=“”;
@凌驾
受保护的JSONObject doInBackground(字符串…参数){
//发出HTTP请求
试一试{
//defaultHttpClient
DefaultHttpClient httpClient=新的DefaultHttpClient();
HttpPost HttpPost=新的HttpPost(参数[0]);
HttpResponse HttpResponse=httpClient.execute(httpPost);
HttpEntity HttpEntity=httpResponse.getEntity();
is=httpEntity.getContent();
}捕获(不支持的编码异常e){
e、 printStackTrace();
}捕获(客户端协议例外e){
e、 printStackTrace();
}捕获(IOE异常){
e、 printStackTrace();
}
试一试{
BufferedReader reader=新的BufferedReader(新的InputStreamReader(is,“iso-8859-1”),8;
StringBuilder sb=新的StringBuilder();
字符串行=null;
而((line=reader.readLine())!=null){
sb.追加(第+行“\n”);
}
is.close();
json=sb.toString();
}捕获(例外e){
Log.e(“缓冲区错误”,“错误转换结果”+e.toString());
}
//尝试将字符串解析为JSON对象
试一试{
jObj=新的JSONObject(json);
}捕获(JSONException e){
Log.e(“JSON解析器”,“错误解析数据”+e.toString());
}
//返回JSON字符串
返回jObj;
}
@凌驾
受保护的void onPostExecute(JSONObject json){
试一试{
//将每个json项存储在变量中
String name=json.getString(“name”);
String fid=json.getString(“id”);
字符串picture=json
.getJSONObject(“图片”)
.getJSONObject(“数据”)
.getString(“url”);
db.addPage(名称、fid、图片);
}捕获(JSONException e){
e、 printStackTrace();
}
}
}
将上述类放在活动类中,然后使用
newjsonparser().execute(url)
获取数据并更新数据库。在onclicklistener中解析json数据有问题吗??我认为这是错误的问题是,您不能在主UI线程上执行此操作。您当前可以在UI线程上执行此操作。您需要启动一个新线程,然后调用与“HTTP”相关的方法。那就跟着你的日志走吧。在新线程中执行上述操作。对不起,我不专业。。你能给我一个关于那个问题或老问题的教程吗?有两个链接。然而,你可以找到更多。还有一个不受鼓励的差劲工作,你能看看吗
public class JsonParser extends AsyncTask<String, Void, JSONObject> {
InputStream is = null;
JSONObject jObj = null;
String json = "";
@Override
protected JSONObject doInBackground(String... params) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(params[0]);
HttpResponse httpResponse = httpClient.execute(httpPost);
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;
}
@Override
protected void onPostExecute(JSONObject json) {
try {
// Storing each json item in variable
String name = json.getString("name");
String fid = json.getString("id");
String picture = json
.getJSONObject("picture")
.getJSONObject("data")
.getString("url");
db.addPage(name, fid, picture);
} catch (JSONException e) {
e.printStackTrace();
}
}
}