为什么使用下面的代码，我试图通过使用JSON解析器的数据库来创建登录和注册表单，但是运行后出现错误，其日志中出现以下错误：
07-15 01:55:47.400: E/JSON(1661): <HTML></HTML>
07-15 01:55:47.400: E/JSON Parser(1661): Error parsing data org.json.JSONException: Value <HTML>< of type java.lang.String cannot be converted to JSONObject
07-15 01:55:47.400: W/dalvikvm(1661): threadid=1: thread exiting with uncaught exception (group=0xa6289288)
07-15 01:55:47.404: E/AndroidRuntime(1661): FATAL EXCEPTION: main
07-15 01:55:47.404: E/AndroidRuntime(1661): java.lang.NullPointerException
07-15 01:55:47.404: E/AndroidRuntime(1661): at com.example.androidhive.RegisterActivity$1.onClick(RegisterActivity.java:64)
07-15 01:55:47.404: E/AndroidRuntime(1661): at android.view.View.performClick(View.java:4084)
07-15 01:55:47.404: E/AndroidRuntime(1661): at android.view.View$PerformClick.run(View.java:16966)
07-15 01:55:47.404: E/AndroidRuntime(1661): at android.os.Handler.handleCallback(Handler.java:615)
07-15 01:55:47.404: E/AndroidRuntime(1661): at android.os.Handler.dispatchMessage(Handler.java:92)
07-15 01:55:47.404: E/AndroidRuntime(1661): at android.os.Looper.loop(Looper.java:137)
07-15 01:55:47.404: E/AndroidRuntime(1661): at android.app.ActivityThread.main(ActivityThread.java:4745)
07-15 01:55:47.404: E/AndroidRuntime(1661): at java.lang.reflect.Method.invokeNative(Native Method)
07-15 01:55:47.404: E/AndroidRuntime(1661): at java.lang.reflect.Method.invoke(Method.java:511)
07-15 01:55:47.404: E/AndroidRuntime(1661): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
07-15 01:55:47.404: E/AndroidRuntime(1661): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-15 01:55:47.404: E/AndroidRuntime(1661): at dalvik.system.NativeStart.main(Native Method)
如果我的代码有问题，也许可以在完整的代码之后帮助我证明我的代码合理，包含错误：
<?php
/**
* Database config variables
*/
define("DB_HOST", "localhost");
define("DB_USER", "root");
define("DB_PASSWORD", "");
define("DB_DATABASE", "android_api");
?>
DB_Connect.php
<?php
class DB_Connect {
// constructor
function __construct() {
}
// destructor
function __destruct() {
// $this->close();
}
// Connecting to database
public function connect() {
require_once 'include/config.php';
// connecting to mysql
$con = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);
// selecting database
mysql_select_db(DB_DATABASE);
// return database handler
return $con;
}
// Closing database connection
public function close() {
mysql_close();
}
}
?>
<?php
class DB_Functions {
private $db;
//put your code here
// constructor
function __construct() {
require_once 'DB_Connect.php';
// connecting to database
$this->db = new DB_Connect();
$this->db->connect();
}
// destructor
function __destruct() {
}
/**
* Storing new user
* returns user details
*/
public function storeUser($name, $email, $password) {
$uuid = uniqid('', true);
$hash = $this->hashSSHA($password);
$encrypted_password = $hash["encrypted"]; // encrypted password
$salt = $hash["salt"]; // salt
$result = mysql_query("INSERT INTO users(unique_id, name, email, encrypted_password, salt, created_at) VALUES('$uuid', '$name', '$email', '$encrypted_password', '$salt', NOW())");
// check for successful store
if ($result) {
// get user details
$uid = mysql_insert_id(); // last inserted id
$result = mysql_query("SELECT * FROM users WHERE uid = $uid");
// return user details
return mysql_fetch_array($result);
} else {
return false;
}
}
/**
* Get user by email and password
*/
public function getUserByEmailAndPassword($email, $password) {
$result = mysql_query("SELECT * FROM users WHERE email = '$email'") or die(mysql_error());
// check for result
$no_of_rows = mysql_num_rows($result);
if ($no_of_rows > 0) {
$result = mysql_fetch_array($result);
$salt = $result['salt'];
$encrypted_password = $result['encrypted_password'];
$hash = $this->checkhashSSHA($salt, $password);
// check for password equality
if ($encrypted_password == $hash) {
// user authentication details are correct
return $result;
}
} else {
// user not found
return false;
}
}
/**
* Check user is existed or not
*/
public function isUserExisted($email) {
$result = mysql_query("SELECT email from users WHERE email = '$email'");
$no_of_rows = mysql_num_rows($result);
if ($no_of_rows > 0) {
// user existed
return true;
} else {
// user not existed
return false;
}
}
/**
* Encrypting password
* @param password
* returns salt and encrypted password
*/
public function hashSSHA($password) {
$salt = sha1(rand());
$salt = substr($salt, 0, 10);
$encrypted = base64_encode(sha1($password . $salt, true) . $salt);
$hash = array("salt" => $salt, "encrypted" => $encrypted);
return $hash;
}
/**
* Decrypting password
* @param salt, password
* returns hash string
*/
public function checkhashSSHA($salt, $password) {
$hash = base64_encode(sha1($password . $salt, true) . $salt);
return $hash;
}
}
?>
或者可能是我的Android项目中出现了以下错误，其代码如下：
import java.util.HashMap;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHandler extends SQLiteOpenHelper {
// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "android_api";
// Login table name
private static final String TABLE_LOGIN = "login";
// Login Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_EMAIL = "email";
private static final String KEY_UID = "uid";
private static final String KEY_CREATED_AT = "created_at";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_LOGIN_TABLE = "CREATE TABLE " + TABLE_LOGIN + "("
+ KEY_ID + " INTEGER PRIMARY KEY,"
+ KEY_NAME + " TEXT,"
+ KEY_EMAIL + " TEXT UNIQUE,"
+ KEY_UID + " TEXT,"
+ KEY_CREATED_AT + " TEXT" + ")";
db.execSQL(CREATE_LOGIN_TABLE);
}
// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOGIN);
// Create tables again
onCreate(db);
}
/**
* Storing user details in database
* */
public void addUser(String name, String email, String uid, String created_at) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_NAME, name); // Name
values.put(KEY_EMAIL, email); // Email
values.put(KEY_UID, uid); // Email
values.put(KEY_CREATED_AT, created_at); // Created At
// Inserting Row
db.insert(TABLE_LOGIN, null, values);
db.close(); // Closing database connection
}
/**
* Getting user data from database
* */
public HashMap<String, String> getUserDetails(){
HashMap<String,String> user = new HashMap<String,String>();
String selectQuery = "SELECT * FROM " + TABLE_LOGIN;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// Move to first row
cursor.moveToFirst();
if(cursor.getCount() > 0){
user.put("name", cursor.getString(1));
user.put("email", cursor.getString(2));
user.put("uid", cursor.getString(3));
user.put("created_at", cursor.getString(4));
}
cursor.close();
db.close();
// return user
return user;
}
/**
* Getting user login status
* return true if rows are there in table
* */
public int getRowCount() {
String countQuery = "SELECT * FROM " + TABLE_LOGIN;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
int rowCount = cursor.getCount();
db.close();
cursor.close();
// return row count
return rowCount;
}
/**
* Re crate database
* Delete all tables and create them again
* */
public void resetTables(){
SQLiteDatabase db = this.getWritableDatabase();
// Delete All Rows
db.delete(TABLE_LOGIN, null, null);
db.close();
}
}
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
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, List<NameValuePair> params) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
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();
Log.e("JSON", json);
} 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;
}
}
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONObject;
import android.content.Context;
public class UserFunctions {
private JSONParser jsonParser;
private static String loginURL = "http://10.0.2.2/android_login_api/";
private static String registerURL = "http://10.0.2.2/android_login_api/";
private static String login_tag = "login";
private static String register_tag = "register";
// constructor
public UserFunctions(){
jsonParser = new JSONParser();
}
/**
* function make Login Request
* @param email
* @param password
* */
public JSONObject loginUser(String email, String password){
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("tag", login_tag));
params.add(new BasicNameValuePair("email", email));
params.add(new BasicNameValuePair("password", password));
JSONObject json = jsonParser.getJSONFromUrl(loginURL, params);
// return json
// Log.e("JSON", json.toString());
return json;
}
/**
* function make Login Request
* @param name
* @param email
* @param password
* */
public JSONObject registerUser(String name, String email, String password){
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("tag", register_tag));
params.add(new BasicNameValuePair("name", name));
params.add(new BasicNameValuePair("email", email));
params.add(new BasicNameValuePair("password", password));
// getting JSON Object
JSONObject json = jsonParser.getJSONFromUrl(registerURL, params);
// return json
return json;
}
/**
* Function get Login status
* */
public boolean isUserLoggedIn(Context context){
DatabaseHandler db = new DatabaseHandler(context);
int count = db.getRowCount();
if(count > 0){
// user logged in
return true;
}
return false;
}
/**
* Function to logout user
* Reset Database
* */
public boolean logoutUser(Context context){
DatabaseHandler db = new DatabaseHandler(context);
db.resetTables();
return true;
}
}
您在RegisterActivity上遇到了NullPointerException，请发布此类，以便我们为您提供帮助。
E/AndroidRuntime(1661): FATAL EXCEPTION: main
07-15 01:55:47.404: E/AndroidRuntime(1661): java.lang.NullPointerException
07-15 01:55:47.404: E/AndroidRuntime(1661): at com.example.androidhive.RegisterActivity$1.onClick(RegisterActivity.java:64)