我的应用程序所做的就是从第一个活动中获取一个字符串，然后在第二个活动中使用它从mysql数据库中获取下载链接。
下载活动.java
package com.example.telugump3;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URLEncoder;
import java.util.ArrayList;
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.app.Activity;
import android.app.DownloadManager;
import android.app.DownloadManager.Query;
import android.app.DownloadManager.Request;
import android.app.ProgressDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
public class DownloadActivity extends Activity{
Activity context;
HttpPost httppost;
StringBuffer buffer;
HttpResponse response;
HttpClient httpclient;
ProgressDialog pd;
CustomAdapter adapter;
ListView listProduct;
ArrayList<String> records;
String mname;
String sText;
private long enqueue;
private DownloadManager dm;
protected void onCreate(Bundle savedInstanceState) {
//TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.download_activity);
context=this;
records=new ArrayList<String>();
listProduct=(ListView)findViewById(R.id.product_list);
adapter=new CustomAdapter(context, R.layout.thirdlist_item,R.id.pro_name, records);
listProduct.setAdapter(adapter);
Intent iin= getIntent();
Bundle b = iin.getExtras();
if(b!=null)
{
mname =(String) b.getString("song_name");
System.out.print(mname);
}
listProduct.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position, long id){
String sText = ((TextView) v.findViewById(R.id.pro_name)).getText().toString();
}
});
BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
long downloadId = intent.getLongExtra(
DownloadManager.EXTRA_DOWNLOAD_ID, 0);
Query query = new Query();
query.setFilterById(enqueue);
Cursor c = dm.query(query);
if (c.moveToFirst()) {
int columnIndex = c
.getColumnIndex(DownloadManager.COLUMN_STATUS);
if (DownloadManager.STATUS_SUCCESSFUL == c
.getInt(columnIndex)) {
ImageView view = (ImageView) findViewById(R.id.imageView);
String uriString = c
.getString(c
.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
view.setImageURI(Uri.parse(uriString));
}
}
}
}
};
registerReceiver(receiver, new IntentFilter(
DownloadManager.ACTION_DOWNLOAD_COMPLETE));
}
public void onClick(View view) {
dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
Request request = new Request(
Uri.parse(sText));
enqueue = dm.enqueue(request);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
//create a LayoutTransition object
return true;
}
public void onStart(){
super.onStart();
//execute background task
BackTask bt=new BackTask();
bt.execute();
}
//background process to make a request to server and list product information
private class BackTask extends AsyncTask<Void,Void,Void>{
protected void onPreExecute(){
super.onPreExecute();
pd = new ProgressDialog(context);
pd.setTitle("Retrieving data");
pd.setMessage("Please wait.");
pd.setCancelable(true);
pd.setIndeterminate(true);
pd.show();
}
protected Void doInBackground(Void...params){
InputStream is=null;
String result="";
try{
records.clear();
String query = URLEncoder.encode(mname, "utf-8");
httpclient=new DefaultHttpClient();
httppost= new HttpPost("http://necrecords.16mb.com/getsongslist.php?password="+query);
response=httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
if(pd!=null)
pd.dismiss(); //close the dialog if error occurs
Log.e("ERROR",e.getMessage());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"utf-8"),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("ERROR", "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);
String record=json_data.getString("link")+"__"+json_data.getInt("test");
records.add(record);
}
}
catch(Exception e){
Log.e("ERROR", "Error pasting data "+e.toString());
}
return null;
}
protected void onPostExecute(Void result){
if(pd!=null) pd.dismiss(); //close dialog
adapter.notifyDataSetChanged(); //notify the ListView to get new records
}
public void showDownload(View view) {
Intent i = new Intent();
i.setAction(DownloadManager.ACTION_VIEW_DOWNLOADS);
startActivity(i);
}
}
}
logcat
03-23 22:20:51.423: E/IMGSRV(19723): :0: PVRDRMOpen: TP3, ret = 37
03-23 22:20:51.423: E/IMGSRV(19723): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:51.423: E/IMGSRV(19723): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:51.423: E/IMGSRV(19723): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:52.133: E/IMGSRV(19734): :0: PVRDRMOpen: TP3, ret = 37
03-23 22:20:52.133: E/IMGSRV(19734): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:52.133: E/IMGSRV(19734): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:52.133: E/IMGSRV(19734): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:52.313: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 51
03-23 22:20:52.343: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 47
03-23 22:20:52.373: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 54
03-23 22:20:52.403: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:52.433: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 56
03-23 22:20:52.443: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 62
03-23 22:20:52.713: E/Save(902): com.android.launcher3.Workspace$$Icicle.
03-23 22:20:52.713: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 47
03-23 22:20:53.243: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 50
03-23 22:20:53.443: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 47
03-23 22:20:54.413: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 51
03-23 22:20:54.823: E/lights(565): [LED] open path fail.
03-23 22:20:55.083: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 55
03-23 22:20:55.113: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 56
03-23 22:20:55.153: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 70
03-23 22:20:55.183: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 33
03-23 22:20:55.493: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 47
03-23 22:20:55.743: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 47
03-23 22:20:55.953: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 50
03-23 22:20:56.893: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 40
03-23 22:20:56.923: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 54
03-23 22:20:56.973: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 69
03-23 22:20:57.313: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 47
03-23 22:20:57.343: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 37
03-23 22:20:57.523: E/ERROR(19684): Error pasting data org.json.JSONException: Value null of type org.json.JSONObject$1 cannot be converted to JSONArray
03-23 22:20:57.573: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 38
03-23 22:20:57.783: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 50
03-23 22:20:59.653: E/lights(565): [LED] open path fail.
03-23 22:21:00.033: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 40
03-23 22:21:00.043: E/IMGSRV(186): :0: PVRDRMOpen: TP3, ret = 47
我想做的…
1） 由于我不知道如何将json数据转换为字符串，所以我将其作为一个数组并在ListView中使用。当我点击ListView时，我会得到字符串形式的下载链接。
String sText = ((TextView) v.findViewById(R.id.pro_name)).getText().toString();
现在我可以使用sText使用Android默认下载管理器下载所需的文件。但是ListView并没有被创建。Logcat显示"无法转换为json数组"。我已使用此链接获取数据。http://necrecords.16mb.com/getlink.php?password=acchata%20mucchata
使用下面的代码，它将解析并为您提供正确的值。
new AsyncTask<Void, Void, Void>(){
@Override
protected Void doInBackground(Void... params) {
try {
String result = callWebService("http://necrecords.16mb.com/getlink.php?password=acchata%20mucchata");
JSONArray resArray = new JSONArray(result);
for (int i=0; i<resArray.length();i++){
JSONObject res = resArray.getJSONObject(i);
String link = res.getString("link");
String test = res.getString("test");
Log.v("result ==== ", link + " , " + test);
}
}
catch (Exception e){
e.printStackTrace();
}
return null;
}
}.execute();
public String callWebService(String urlvalue) throws Exception {
System.setProperty("http.keepAlive", "false");
URL u = new URL(urlvalue);
URLConnection conn = u.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(
conn.getInputStream()));
StringBuffer buffer = new StringBuffer();
String inputLine;
while ((inputLine = in.readLine()) != null)
buffer.append(inputLine);
in.close();
// System.out.println(buffer.toString());
return buffer.toString();
}
根据您的代码更新
package com.example.telugump3;
import android.app.Activity;
import android.app.DownloadManager;
import android.app.DownloadManager.Query;
import android.app.DownloadManager.Request;
import android.app.ProgressDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import com.xavient.kwickhelp.testappstack.R;
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 java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.ArrayList;
public class DownloadActivity extends Activity{
Activity context;
HttpPost httppost;
StringBuffer buffer;
HttpResponse response;
HttpClient httpclient;
ProgressDialog pd;
CustomAdapter adapter;
ListView listProduct;
ArrayList<String> records;
String mname;
String sText;
private long enqueue;
private DownloadManager dm;
protected void onCreate(Bundle savedInstanceState) {
//TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.download_activity);
context=this;
records=new ArrayList<String>();
listProduct=(ListView)findViewById(R.id.product_list);
adapter=new CustomAdapter(context, R.layout.thirdlist_item,R.id.pro_name, records);
listProduct.setAdapter(adapter);
Intent iin= getIntent();
Bundle b = iin.getExtras();
if(b!=null)
{
mname =(String) b.getString("song_name");
System.out.print(mname);
}
listProduct.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position, long id){
String sText = ((TextView) v.findViewById(R.id.pro_name)).getText().toString();
}
});
BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
long downloadId = intent.getLongExtra(
DownloadManager.EXTRA_DOWNLOAD_ID, 0);
Query query = new Query();
query.setFilterById(enqueue);
Cursor c = dm.query(query);
if (c.moveToFirst()) {
int columnIndex = c
.getColumnIndex(DownloadManager.COLUMN_STATUS);
if (DownloadManager.STATUS_SUCCESSFUL == c
.getInt(columnIndex)) {
ImageView view = (ImageView) findViewById(R.id.imageView);
String uriString = c
.getString(c
.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
view.setImageURI(Uri.parse(uriString));
}
}
}
}
};
registerReceiver(receiver, new IntentFilter(
DownloadManager.ACTION_DOWNLOAD_COMPLETE));
}
public void onClick(View view) {
dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
Request request = new Request(
Uri.parse(sText));
enqueue = dm.enqueue(request);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
//create a LayoutTransition object
return true;
}
@Override
public void onStart(){
super.onStart();
//execute background task
new BackTask().execute();
}
//background process to make a request to server and list product information
private class BackTask extends AsyncTask<Void,Void,Void>{
protected void onPreExecute(){
super.onPreExecute();
pd = new ProgressDialog(context);
pd.setTitle("Retrieving data");
pd.setMessage("Please wait.");
pd.setCancelable(true);
pd.setIndeterminate(true);
pd.show();
}
protected Void doInBackground(Void...params){
//parse json data
try{
String result = callWebService("http://necrecords.16mb.com/getlink.php?password=acchata%20mucchata");
JSONArray jArray =new JSONArray(result);
JSONArray resArray = new JSONArray(result);
for (int i=0; i<resArray.length();i++){
JSONObject res = resArray.getJSONObject(i);
String link = res.getString("link");
String test = res.getString("test");
String record = link+"__"+test;
Log.v("result ==== ", link + " , " + test);
records.add(record);
}
}
catch(Exception e){
Log.e("ERROR", "Error pasting data "+e.toString());
}
return null;
}
protected void onPostExecute(Void result){
if(pd!=null) pd.dismiss(); //close dialog
adapter.notifyDataSetChanged(); //notify the ListView to get new records
}
public void showDownload(View view) {
Intent i = new Intent();
i.setAction(DownloadManager.ACTION_VIEW_DOWNLOADS);
startActivity(i);
}
}
public String callWebService(String urlvalue) throws Exception {
System.setProperty("http.keepAlive", "false");
URL u = new URL(urlvalue);
URLConnection conn = u.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(
conn.getInputStream()));
StringBuffer buffer = new StringBuffer();
String inputLine;
while ((inputLine = in.readLine()) != null)
buffer.append(inputLine);
in.close();
// System.out.println(buffer.toString());
return buffer.toString();
}
}