Java 无法从JSON获取响应
我是android新手。在下面的代码中,我试图做的是向一个php文件发送一个http请求,json从中获得响应。在php文件中,我试图显示从A开始的城市名称。每当我运行代码时,我都会遇到以下错误:Java 无法从JSON获取响应,java,php,android,json,Java,Php,Android,Json,我是android新手。在下面的代码中,我试图做的是向一个php文件发送一个http请求,json从中获得响应。在php文件中,我试图显示从A开始的城市名称。每当我运行代码时,我都会遇到以下错误:“org.json.jsonexception value doctype类型java.lang.string无法转换为jsonarray”。所有这些都没有帮助,或者我无法理解那里给出的解决方案。 这是我的Java代码 MainActivity.java package com.list; impor
“org.json.jsonexception value doctype类型java.lang.string无法转换为jsonarray
”。所有这些都没有帮助,或者我无法理解那里给出的解决方案。
这是我的Java代码MainActivity.java
package com.list;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
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.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.net.ParseException;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
JSONArray jArray;
String result = null;
InputStream is = null;
StringBuilder sb=null;
int ct_id;
String ct_name;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textview1 = (TextView)findViewById(R.id.textView1);
textview1.setText("Erqem");
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://10.0.2.2/city.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection"+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"UTF-8"),8);
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line="0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
//paring data
try{
jArray = new JSONArray(result);
JSONObject json_data = new JSONObject();
json_data=null;
for(int i=0;i<jArray.length();i++){
json_data = jArray.getJSONObject(i);
ct_id=json_data.getInt("CITY_ID");
ct_name=json_data.getString("CITY_NAME");
textview1.setText(ct_name);
}
}
catch(JSONException e1){
Toast.makeText(getBaseContext(), "No City Found"+e1.toString() ,Toast.LENGTH_LONG).show();
Log.e("log_tag", "Error converting result "+e1.getMessage() );
} catch (ParseException e1) {
e1.printStackTrace();
}
}
}
package.com.list;
导入java.io.BufferedReader;
导入java.io.InputStream;
导入java.io.InputStreamReader;
导入java.util.ArrayList;
导入org.apache.http.HttpEntity;
导入org.apache.http.HttpResponse;
导入org.apache.http.NameValuePair;
导入org.apache.http.client.HttpClient;
导入org.apache.http.client.entity.UrlEncodedFormEntity;
导入org.apache.http.client.methods.HttpPost;
导入org.apache.http.impl.client.DefaultHttpClient;
导入org.json.JSONArray;
导入org.json.JSONException;
导入org.json.JSONObject;
导入android.app.Activity;
导入android.net.ParseException;
导入android.os.Bundle;
导入android.util.Log;
导入android.widget.TextView;
导入android.widget.Toast;
公共类MainActivity扩展了活动{
杰索纳雷·贾雷;
字符串结果=null;
InputStream=null;
StringBuilder sb=null;
int ct_id;
字符串ct_名称;
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView textview1=(TextView)findViewById(R.id.textview1);
textview1.setText(“Erqem”);
ArrayList nameValuePairs=新的ArrayList();
//http post
试一试{
HttpClient HttpClient=新的DefaultHttpClient();
HttpPost HttpPost=新的HttpPost(“http://10.0.2.2/city.php");
setEntity(新的UrlEncodedFormEntity(nameValuePairs));
HttpResponse response=httpclient.execute(httppost);
HttpEntity=response.getEntity();
is=entity.getContent();
}捕获(例外e){
e(“Log_标记”,“http连接错误”+e.toString());
}
//将响应转换为字符串
试一试{
BufferedReader reader=新的BufferedReader(新的InputStreamReader(is,“UTF-8”),8;
sb=新的StringBuilder();
sb.append(reader.readLine()+“\n”);
字符串行=“0”;
而((line=reader.readLine())!=null){
sb.追加(第+行“\n”);
}
is.close();
结果=sb.toString();
}捕获(例外e){
Log.e(“Log_标记”,“错误转换结果”+e.toString());
}
//配对数据
试一试{
jArray=新的JSONArray(结果);
JSONObject json_data=new JSONObject();
json_data=null;
对于(int i=0;i可能您使用的地址不正确,请尝试10.0.2.2:8080/city.php您应该在尝试解析之前记录您得到的响应,并检查得到的结果。您是否尝试从emulator浏览器运行url?您尝试解析的输出是什么?请使用更新您的问题it@WarrenFaith因为我是新来的android。你能更详细地解释一下你的观点吗?如果我是一个赌徒(我不是),我会说你收到的是服务器返回的错误消息,而不是json。记录你的响应,就像@WarrenFaith所说的。此外,你的代码会使任何现代(4.x+)崩溃Android设备出现NetworkOnMainThreadException。非常感谢;我在这个小问题上浪费了这么长时间。
<?php
header('Content-type=application/json; charset=utf-8');
mysql_connect("","root","");
mysql_select_db("Deal");
$sql=mysql_query("select * from CITY where CITY_NAME like 'A%'");
while($row=mysql_fetch_assoc($sql))
$output[]=$row;
print(json_encode($output));
mysql_close();
?>