我正在尝试更多地了解MySQL并使用Java(在Android上)从我的WAMS服务器上的数据库中访问和检索信息.我的应用程序的设置方式是它有一个初始登录屏幕,它也抓取登录用户名的“uid”(来自不同的表)并存储它.
登录后(功能正常 – 我设置了一个显示检索到的用户名和登录用户的uid的Toast通知),它将进入一个新的屏幕(dashboard.xml),该屏幕具有TextView字段设置以显示检索到的数据(来自下面发布的表格)与存储的“uid”相关联.这是我试图从中提取数据的表：
现在,我已经设置了一个PHP文件,该文件向我的数据库查询与特定“uid”相关联的行.我已使用HTML表单测试了此文件.
$connect = MysqL_connect($dbhost, $dbuser, $dbpass) or die("connection error");
MysqL_select_db($dbdb)or die("database selection error");
//Retrieve the User ID
$uid = $_POST['uid'];
//Query
$query = MysqL_query("SELECT * FROM node WHERE uid='$uid' AND type='goal'");
//store # of rows returned
$num_rows = MysqL_num_rows($query);
if ($num_rows >= 1) {
while($results=MysqL_fetch_assoc($query)) {
//Store the returned data into a variable
$output = $results;
//encode the returned data in JSON format
echo json_encode($output);
}
MysqL_close();
}
{“nid”:”1″,”vid”:”1″,”type”:”goal”,”language”:””,”title”:”test”,”uid”:”1″,”status”:”1″,”created”:”1342894493″,”changed”:”1342894493″,”comment”:”2″,”promote”:”1″,”moderate”:”0″,”sticky”:”1″,”tnid”:”0″,”translate”:”0″}
{“nid”:”2″,”vid”:”2″,”type”:”goal”,”language”:””,”title”:”test2″,”uid”:”1″,”status”:”1″,”created”:”1342894529″,”changed”:”1342894529″,”comment”:”2″,”promote”:”1″,”moderate”:”0″,”sticky”:”1″,”tnid”:”0″,”translate”:”0″}
{“nid”:”5″,”vid”:”5″,”type”:”goal”,”language”:””,”title”:”run”,”uid”:”1″,”status”:”1″,”created”:”1343506987″,”changed”:”1343506987″,”comment”:”2″,”promote”:”1″,”moderate”:”0″,”sticky”:”1″,”tnid”:”0″,”translate”:”0″}
{“nid”:”9″,”vid”:”9″,”type”:”goal”,”language”:””,”title”:”run to the
hills”,”uid”:”1″,”status”:”1″,”created”:”1343604338″,”changed”:”1343605100″,”comment”:”2″,”promote”:”0″,”moderate”:”0″,”sticky”:”0″,”tnid”:”0″,”translate”:”0″}
现在,我已经编写了一些设置httppost的android代码,并且应该检索我的数据库表中的“titles”.我知道这是错的(显然因为它不起作用)但我对下一步做什么很困惑.
import java.io.BufferedReader;
import java.io.IOException;
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.apache.http.message.BasicNameValuePair;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class Dashboard extends Activity implements OnClickListener {
// variable declarations
String uid = "1";
// create textview to display retrieved data
TextView display;
HttpClient httpclient;
HttpPost httppost;
HttpResponse httpresponse;
httpentity httpentity;
ArrayList<NameValuePair> resultArray;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dashboard);
display = (TextView) findViewById(R.id.test);
// initialize HttpClient
httpclient = new DefaultHttpClient();
// initialize HttpPost
httppost = new HttpPost("http://192.168.1.112/android/fetch.PHP");
try {
// Create new List
List<NameValuePair> resultList = new ArrayList<NameValuePair>();
resultList.add(new BasicNameValuePair("uid", uid));
httppost.setEntity(new UrlEncodedFormEntity(resultList));
httpresponse = httpclient.execute(httppost);
httpentity = httpresponse.getEntity();
InputStream instream = entity.getContent();
try {
// store incoming stream in an array
JSONArray jArray = new JSONArray(streamToString(instream));
JSONObject jData = null;
for (int i = 0; i < jArray.length(); i++) {
jData = jArray.getJSONObject(i);
String goals = jData.getString("title");
display.setText(goals);
}
//} catch (JSONException e) {
//Toast.makeText(this, "No entries found", Toast.LENGTH_LONG).show();
} catch (Exception e) {
Toast.makeText(this, e.toString(), Toast.LENGTH_LONG)
.show();
}
} catch (Exception e) {
e.printstacktrace();
Notifications error = new Notifications();
error.userPassErrorDialog();
}
}
private static String streamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printstacktrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printstacktrace();
}
}
return sb.toString();
}
public void onClick(View v) {
// Todo Auto-generated method stub
}
}
在Android模拟器中测试时出现以下错误：
任何帮助或建议将不胜感激.
解决方法:
在您的Android应用中,您需要一个JSONArray：
// store incoming stream in an array
JSONArray jArray = new JSONArray(streamToString(instream));
但是,在PHP文件中,您只输出多个单独的JSON对象而不是实际数组.我认为,您应首先从PHP数组中收集数据库中的所有项目,然后编码并仅输出一次.
我的PHP技能有点生锈,但我希望这个有用：
//store # of rows returned
$num_rows = MysqL_num_rows($query);
if ($num_rows >= 1) {
$output = array();
while($results = MysqL_fetch_assoc($query)) {
// append row to output
$output[] = results
}
MysqL_close(); // shouldn't that be outside the if block?
//encode the returned data in JSON format
echo json_encode($output);
}
我希望输出就像这样(也许没有缩进)：
[
{"nid":"1","vid":"1","type":"goal","language":"","title":"test","uid":"1","status":"1","created":"1342894493","changed":"1342894493","comment":"2","promote":"1","moderate":"0","sticky":"1","tnid":"0","translate":"0"},
{"nid":"2","vid":"2","type":"goal","language":"","title":"test2","uid":"1","status":"1","created":"1342894529","changed":"1342894529","comment":"2","promote":"1","moderate":"0","sticky":"1","tnid":"0","translate":"0"},
{"nid":"5","vid":"5","type":"goal","language":"","title":"run","uid":"1","status":"1","created":"1343506987","changed":"1343506987","comment":"2","promote":"1","moderate":"0","sticky":"1","tnid":"0","translate":"0"},
{"nid":"9","vid":"9","type":"goal","language":"","title":"run to the hills","uid":"1","status":"1","created":"1343604338","changed":"1343605100","comment":"2","promote":"0","moderate":"0","sticky":"0","tnid":"0","translate":"0"}
]
