java - Android 中 java.lang.String 类型的值无法转换为 JSONArray(转发)

Question

我重新发布此内容是因为我找不到该问题的解决方案...

这里有错误

org.json.JSONException:Value <!DOCTYPE of type java.lang.String cannot be converted to JSONArray

这是 JSON 输出:

[{"name":"Muhaimin","address":"Sylhet","bgroup":"o+"}]

这里是类代码:

entpackage com.example.blood;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import android.os.Bundle;
import android.os.StrictMode;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.widget.TextView;
import android.widget.Toast;

@SuppressLint("NewApi")
public class MainActivity extends Activity {

TextView resultView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
StrictMode.enableDefaults();
resultView=(TextView) findViewById(R.id.result);
getData();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

public void getData()
{
 String result="";
 InputStream isr=null;
 try{
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost=new HttpPost("http://10.0.2.2/blood/index.php");
    httppost.setHeader("Content-Type", "application/json");
     httppost.setHeader("Accept", "JSON");
    HttpResponse response=httpclient.execute(httppost);
    HttpEntity entity=response.getEntity();
    isr=entity.getContent();
  }catch(Exception e){
    String err=e.toString();
    resultView.setText("Could not connect to database"+err);
    Log.e("error", err);
  }

try{
    BufferedReader reader=new BufferedReader(new InputStreamReader(isr,"iso-8859-1"),8);
    StringBuilder sb=new StringBuilder();
    String line=null;
    while((line = reader.readLine()) != null){
        sb.append(line + "\n");
    }
    isr.close();

    result=sb.toString();
   }catch(Exception e){
    String err2=e.toString();
    resultView.setText("Error coverting result"+err2);
    Log.e("error", err2);
  }
  try{
    String s="";
    JSONArray jArray=new JSONArray(result);

    for(int i=0;i<jArray.length();i++){
        JSONObject json=jArray.getJSONObject(i);
        s= s + 
                "Name :"+json.getString("name")+"\n"+
                "Blood Group :"+json.getString("bgroup")+"\n" +
                "Address :"+json.getString("address")+"\n\n";
    }
    resultView.setText(s);
  }catch(Exception e){
    String err1=e.toString();
    resultView.setText("xxx"+err1);
    Log.e("error", err1);
 }
 }

}

这是 php 代码:

  <?php
$con=mysql_connect("localhost","root","","BloodDB");
mysql_select_db("BloodDB",$con);

$result=mysql_query("SELECT name,address,bgroup FROM tbl_blood_donor");

while($row=mysql_fetch_assoc($result))
{
    $output[]=$row;
}
print(json_encode($output));
mysql_close($con);
 ?>

现在如何解决这个问题。我在本地主机工作。提前致谢

Answer 1

您的问题不在 JSON 中，也不在 JSONArray 中，因此如果您遇到此异常，则意味着 JSONArray 的字符串不符合您的预期。打印该行“JSONArray jArray=new JSONArray(result);”之前的字符串结果和字符串长度。您可以使用下面的打印消息Log.d("我的字符串", "字符串结果:["+ result + "] 其长度为:"+ result.length());

请注意，我使用了下面的代码，它工作正常

String str = "[{\"name\":\"Muhaimin\",\"address\":\"Sylhet\",\"bgroup\":\"o+\"}]";
    try {
        JSONArray json = new JSONArray(str);
        Log.d(TAG, "Json value :" + json);
        Log.d(TAG, "Json value :" +    json.getJSONObject(0).getString("bgroup"));
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

结果:Json值:[{"bgroup":"o+","address":"Sylhet","name":"Muhaimin"}]

Json 值:o+