我正在尝试编写代码，以便我的android应用程序可以查询MySQL数据库，然后检索JSON中的数据然后解析。然后我想获取数据并将其插入到SQLite上的应用程序的本地数据库中。我希望这些数据也能以设定的频率更新。
这是JSON数组和HTTP Get协议活动。
package com.connector;
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.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.LinearLayout;
import android.widget.TextView;
public class whitehat extends Activity {
/** Called when the activity is first created. */
TextView txt;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Create a crude view - this should really be set via the layout resources
// but since its an example saves declaring them in the XML.
LinearLayout rootLayout = new LinearLayout(getApplicationContext());
txt = new TextView(getApplicationContext());
rootLayout.addView(txt);
setContentView(rootLayout);
// Set the text and call the connect function.
txt.setText("Connecting...");
//call the method to run the data retreival
txt.setText(getServerData(KEY_121));
}
public static final String KEY_121 = "http://xx.xx.xxx.xxx/hellomysql/mysqlcon.php"; //i use my real ip here
private String getServerData(String returnString) {
InputStream is = null;
String result = "";
//the year data to send
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("publisher","Penguin Books UK"));
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(KEY_121);
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,"iso-8859-1"),8);
StringBuilder sb = new StringBuilder();
String line = null;
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());
}
//parse json data
try{
JSONArray jArray = new JSONArray(result);
for(int i=0;i<jArray.length();i++){
JSONObject json_data = jArray.getJSONObject(i);
Log.i("log_tag","id: "+json_data.getInt("id")+
", isbn: "+json_data.getString("isbn")+
", title: "+json_data.getString("title")+
", publisher: "+json_data.getString("publisher")
);
//Get an output to the screen
returnString += "\n\t" + jArray.getJSONObject(i);
}
}catch(JSONException e){
Log.e("log_tag", "Error parsing data "+e.toString());
}
return returnString;
}
}
以下两项是与数据库相关的活动。
package com.example.database;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_ISBN = "isbn";
public static final String KEY_TITLE = "title";
public static final String KEY_PUBLISHER = "publisher";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "books";
private static final String DATABASE_TABLE = "titles";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE =
"create table titles (_id integer primary key autoincrement, "
+ "isbn text not null, title text not null, "
+ "publisher text not null);";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(DATABASE_CREATE); }
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
Log.w(TAG, "Upgrading database from version " + oldVersion
+ " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS titles");
onCreate(db);
}
}
//---opens the database---
public DBAdapter open() throws SQLException
{
db = DBHelper.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
DBHelper.close();
}
//---insert a title into the database---
public long insertTitle(String isbn, String title, String publisher)
{
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_ISBN, isbn);
initialValues.put(KEY_TITLE, title);
initialValues.put(KEY_PUBLISHER, publisher);
return db.insert(DATABASE_TABLE, null, initialValues);
}
//---deletes a particular title---
public boolean deleteTitle(long rowId)
{
return db.delete(DATABASE_TABLE, KEY_ROWID +
"=" + rowId, null) > 0;
}
//---retrieves all the titles---
public Cursor getAllTitles()
{
return db.query(DATABASE_TABLE, new String[] {
KEY_ROWID,
KEY_ISBN,
KEY_TITLE,
KEY_PUBLISHER},
null,
null,
null,
null,
null);
}
//---retrieves a particular title---
public Cursor getTitle(long rowId) throws SQLException
{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {
KEY_ROWID,
KEY_ISBN,
KEY_TITLE,
KEY_PUBLISHER
},
KEY_ROWID + "=" + rowId,
null,
null,
null,
null,
null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
//---updates a title---
public boolean updateTitle(long rowId, String isbn,
String title, String publisher)
{
ContentValues args = new ContentValues();
args.put(KEY_ISBN, isbn);
args.put(KEY_TITLE, title);
args.put(KEY_PUBLISHER, publisher);
return db.update(DATABASE_TABLE, args,
KEY_ROWID + "=" + rowId, null) > 0;
}
}
第二个是：
public class DatabaseActivity extends Activity {
DBAdapter db;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
db = new DBAdapter(this);
System.out.println("bool1");
insert();
disAll();
//update();
//dis(3);
//del(5);
}
private void update(){
db.open();
if (db.updateTitle(1,
"0470285818",
"C# 2008 Programmer's Reference",
"Wrox Press"))
Toast.makeText(this, "Update successful.",
Toast.LENGTH_LONG).show();
else
Toast.makeText(this, "Update failed.",
Toast.LENGTH_LONG).show();
//-------------------
//---retrieve the same title to verify---
Cursor c = db.getTitle(1);
if (c.moveToFirst())
DisplayTitle(c);
else
Toast.makeText(this, "No title found",
Toast.LENGTH_LONG).show();
//-------------------
db.close();
}
private void insert(){
db.open();
long id;
id = db.insertTitle(
"0470285819",
"Teach yourself Java",
"Wrox");
id = db.insertTitle(
"047017661y",
"Professional Windows 07 Gadgets Programming",
"Wrox");
System.out.println("bool211");
db.close();
}
private void disAll(){
db.open();
/*Cursor c = db.getAllTitles();
if (c.moveToFirst())
{
do {
System.out.println("bool2");
DisplayTitle(c);
} while (c.moveToNext());
}
else
System.out.println("boo3l");*/
try{
Cursor c = db.getAllTitles();
if (c.moveToFirst())
{
do {
System.out.println("bool2");
DisplayTitle(c);
} while (c.moveToNext());
}
}catch(Exception e){
System.out.println(e);
}
db.close();
}
private void dis( int j){
db.open();
Cursor c = db.getTitle(j);
if (c.moveToFirst())
DisplayTitle(c);
else
Toast.makeText(this, "No title found",
Toast.LENGTH_LONG).show();
db.close();
}
private void del( int j){
db.open();
if (db.deleteTitle(j))
Toast.makeText(this, "Delete successful.",
Toast.LENGTH_LONG).show();
else
Toast.makeText(this, "Delete failed.",
Toast.LENGTH_LONG).show();
db.close();
}
public void DisplayTitle(Cursor c)
{
System.out.println("bool");
Toast.makeText(this,
"id: " + c.getString(0) + "\n" +
"ISBN: " + c.getString(1) + "\n" +
"TITLE: " + c.getString(2) + "\n" +
"PUBLISHER: " + c.getString(3),
Toast.LENGTH_LONG).show();
}
}
如果有人能够提供帮助，我们将不胜感激。
答案 0 :(得分：1)
你的getServerData方法将返回一个JSONString。在你的getServerData方法中，你有一个Log语句，它实际上是在解析JSONObject。您可以在dbAdapter类中调用insertTitle而不是记录它。
要完成这项工作，你必须做一些改变。 Ur DBAdapter构造函数应该如下所示
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
this.db=DBHelper.getWritableDatabase();
}
Ur create语句应该如下所示。你从服务器获取id。所以没有必要将id作为自动增量。
private static final String DATABASE_CREATE =
"create table titles (_id integer primary key , "
+ "isbn text not null, title text not null, "
+ "publisher text not null);";
Ur insertTitle应该是这样的。同样改变你的更新和其他方法。
public long insertTitle(String _id,String isbn, String title, String publisher)
{
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_ID, _id);
initialValues.put(KEY_ISBN, isbn);
initialValues.put(KEY_TITLE, title);
initialValues.put(KEY_PUBLISHER, publisher);
return db.insert(DATABASE_TABLE, null, initialValues);
}
但请确保在for循环外创建dbAdapter对象。希望这会有所帮助