从 MySql 获取 JSON 数据

Question

我已经使用 JSON 创建了一个数据库和 php 文件：

= Connection Established - Database selected 
[{"latitude":"43222121","longitude":"2112212","description":"O masina rosie cu farurile stinse."},{"latitude":"33211322","longitude":"3211313","description":null}]

我正在使用只有一个 TextView 的 XML。 这是课程：

public class ConnectMySql extends Activity {

 TextView httpStuff;
 HttpClient client;
 JSONObject json;
 final static String URL = "http://79.114.48.119/RadarsMySql.php";

 @Override
 protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    httpStuff = (TextView) findViewById(R.id.tvHttp);
    client = new DefaultHttpClient();
    new Read().execute("latitude");
}


public JSONObject lastTweet(String username) throws ClientProtocolException, IOException,JSONException{
    StringBuilder url = new StringBuilder(URL);
    url.append(username);

    HttpGet get = new HttpGet(url.toString());
    HttpResponse r = client.execute(get);
    int status = r.getStatusLine().getStatusCode();
    //if(status == 200){
        HttpEntity e = r.getEntity();
        String data = EntityUtils.toString(e);
        JSONArray timeline = new JSONArray(data);
        JSONObject last = timeline.getJSONObject(0);
        return last;

    //}else{ 
        //Toast.makeText(ConnectMySql.this, "error", Toast.LENGTH_LONG);
        //return null;

    //}
}

public class Read extends AsyncTask<String, Integer, String>{

    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub
        try {
            json = lastTweet("");
            return json.getString(params[0]);
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        httpStuff.setText(result);
    }

}

}

我遵循了一个从 Tweeter 获取数据的教程，它可以工作，但在我的网站上却没有。

谁能帮助我，提供有用的建议，甚至更好地告诉我我做错了什么？

这是我放 Log.i-thing 后的 logcat：

05-05 19:44:07.109: W/System.err(717): org.json.JSONException: Expected literal value at character 0 of =

05-05 19:44:07.109: W/System.err(717):      

05-05 19:44:07.109: W/System.err(717):    Connection Established - Database selected[{"latitude":"43222121","longitude":"2112212","description":"O masina rosie cu farurile stinse."},{"latitude":"33211322","longitude":"3211313","description":null}]
05-05 19:44:07.109: W/System.err(717):  at org.json.JSONTokener.syntaxError(JSONTokener.java:446)
05-05 19:44:07.109: W/System.err(717):  at org.json.JSONTokener.readLiteral(JSONTokener.java:281)
05-05 19:44:07.109: W/System.err(717):  at org.json.JSONTokener.nextValue(JSONTokener.java:107)
05-05 19:44:07.109: W/System.err(717):  at org.json.JSONArray.<init>(JSONArray.java:87)
05-05 19:44:07.109: W/System.err(717):  at org.json.JSONArray.<init>(JSONArray.java:103)
05-05 19:44:07.109: W/System.err(717):  at com.project.radars.ConnectMySql.lastTweet(ConnectMySql.java:53)
05-05 19:44:07.119: W/System.err(717):  at com.project.radars.ConnectMySql$Read.doInBackground(ConnectMySql.java:71)
05-05 19:44:07.130: W/System.err(717):  at com.project.radars.ConnectMySql$Read.doInBackground(ConnectMySql.java:1)
05-05 19:44:07.130: W/System.err(717):  at android.os.AsyncTask$2.call(AsyncTask.java:185)
05-05 19:44:07.130: W/System.err(717):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
05-05 19:44:07.130: W/System.err(717):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
05-05 19:44:07.130: W/System.err(717):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
05-05 19:44:07.130: W/System.err(717):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
05-05 19:44:07.130: W/System.err(717):  at java.lang.Thread.run(Thread.java:1096)

Answer 1

你的问题来了：我已经连接到你的网站并收到了这个字符串：

= Connection Established - Database selected[{"latitude":"43222121","longitude":"2112212","description":"O masina rosie cu farurile stinse."},{"latitude":"33211322","longitude":"3211313","description":null}]

但是，您尝试在 JSONArray 中加载它，这当然会失败，因为 = Connection Established - Database selected 前缀不是任何合法 json 数组的一部分。

您需要先截断此前缀，然后才能解析数组。最好的选择是从 php 代码中删除前缀（我很确定您手动添加以记录）。但是，如果这对您来说很困难，您可以在 java 端进行。在解析json数组前添加如下一行：

String data = EntityUtils.toString(e);
data = data.substring(data.indexOf("["));