让我们看一下工作的截图,以便更好地理解问题:
- 我已经上传第一个列表项的图像到服务器 [i.e:-
Thumbnail 1.png
],见下图:
- 我使用 Localhost 在 myfile 文件夹下上传了图片:
- 当我向下滚动
ListView
时,得到这个 - 真正的痛苦来了,如您所见Thumbnail 7
,我没有点击在上面:
- 当我再次向上滚动
ListView
时,得到这样的东西 - 这让我很恼火,对于Thumbnail 2
,我做到了不要碰那个:
我认为这足以
向您解释,什么我正在尝试做什么,正在发生什么以及在哪里我有问题
现在轮到你告诉我解决方案了,我该如何解决这个问题?
一些解释:
我已经将第一个列表项的图像上传到服务器(并且根据我的要求,我的图像状态为“已上传”并且上传按钮现在已禁用)但是当我向下/向上滚动 ListView 时,它显示了其中的任何一个项目上传的列表不是我上传的列表(我主要注意到可见的列表项)并重置最初上传到服务器的第一个列表项的状态...
所以在这里我只想使我最初上传的那个特定项目的上传状态稳定...而不是任何可见项目(那些还没有上传)
只影响 ListView ,服务器没有任何反应(只获取我上传的一张图片)
MainActivity.java:-
public class MainActivity extends Activity {
static ListView lstView;
private Handler handler = new Handler();;
static List <String> ImageList;
String strPath;
int position ;
static File f;
File newFile;
static File[] files ;
static File file ;
ViewHolder holder;
View v ;
String fileName;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/*** Get Images from SDCard ***/
ImageList = getSD();
// ListView and imageAdapter
lstView = (ListView) findViewById(R.id.listView);
lstView.setAdapter(new ImageAdapter(this));
}
private List <String> getSD()
{
List <String> it = new ArrayList <String>();
File f = new File ("/mnt/sdcard/mydata/");
File[] files = f.listFiles ();
for (int i = 0; i <files.length; i++)
{
File file = files[i];
Log.d("Count",file.getPath());
it.add (file.getPath());
}
return it;
}
static class ViewHolder {
public ViewHolder(View convertView) {
// TODO Auto-generated constructor stub
}
TextView textName;
ImageView thumbnail;
TextView textStatus;
Button btnUpload;
}
public class ImageAdapter extends BaseAdapter
{
public ImageAdapter(Context c)
{
}
public int getCount() {
// TODO Auto-generated method stub
return ImageList.size();
}
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
// Avoid unneccessary calls to findViewById() on each row, which is expensive!
holder = null;
if (convertView == null) {
convertView = getLayoutInflater().inflate(R.layout.adapter_main, null);
holder = new ViewHolder(convertView);
// Create a ViewHolder and store references to the children views
holder.textName = (TextView) convertView.findViewById(R.id.textName);
holder.thumbnail = (ImageView) convertView.findViewById(R.id.thumbnail);
holder.btnUpload = (Button) convertView.findViewById(R.id.btnUpload);
holder.textStatus = (TextView) convertView.findViewById(R.id.textStatus);
// The tag can be any Object, this just happens to be the ViewHolder
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
strPath = ImageList.get(position).toString();
// Get File Name
fileName = strPath.substring( strPath.lastIndexOf('/')+1, strPath.length() );
file = new File(strPath);
@SuppressWarnings("unused")
long length = file.length();
holder.textName.setText(fileName);
final BitmapFactory.Options options = new BitmapFactory.Options();
Bitmap bm = BitmapFactory.decodeFile(strPath,options);
holder.thumbnail.setImageBitmap(bm);
//btnUpload
holder.btnUpload.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Upload
startUpload(position);
}
});
return convertView;
}
}
// Upload
public void startUpload(final int position) {
Runnable runnable = new Runnable() {
public void run() {
handler.post(new Runnable() {
public void run() {
v = lstView.getChildAt(position - lstView.getFirstVisiblePosition());
holder = (ViewHolder) v.getTag();
holder.btnUpload.setEnabled(false);
new UploadFileAsync().execute(String.valueOf(position));
}
});
}
};
new Thread(runnable).start();
}
// Async Upload
public class UploadFileAsync extends AsyncTask<String, Void, Void> {
String resServer;
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(String... params) {
// TODO Auto-generated method stub
position = Integer.parseInt(params[0]);
int bytesRead, bytesAvailable, bufferSize;
byte[] buffer;
int maxBufferSize = 1 * 1024 * 1024;
int resCode = 0;
String resMessage = "";
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
// File Path
String strSDPath = ImageList.get(position).toString();
// Upload to PHP Script
String strUrlServer = "http://10.0.2.2/uploadFile.php";
try {
/** Check file on SD Card ***/
File file = new File(strSDPath);
if(!file.exists())
{
resServer = "{\"StatusID\":\"0\",\"Message\":\"Please check path on SD Card\"}";
return null;
}
FileInputStream fileInputStream = new FileInputStream(new File(strSDPath));
URL url = new URL(strUrlServer);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("Content-Type",
"multipart/form-data;boundary=" + boundary);
DataOutputStream outputStream = new DataOutputStream(conn
.getOutputStream());
outputStream.writeBytes(twoHyphens + boundary + lineEnd);
outputStream
.writeBytes("Content-Disposition: form-data; name=\"filUpload\";filename=\""
+ strSDPath + "\"" + lineEnd);
outputStream.writeBytes(lineEnd);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// Read file
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
while (bytesRead > 0) {
outputStream.write(buffer, 0, bufferSize);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
}
outputStream.writeBytes(lineEnd);
outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
// Response Code and Message
resCode = conn.getResponseCode();
if(resCode == HttpURLConnection.HTTP_OK)
{
InputStream is = conn.getInputStream();
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int read = 0;
while ((read = is.read()) != -1) {
bos.write(read);
}
byte[] result = bos.toByteArray();
bos.close();
resMessage = new String(result);
}
Log.d("resCode=",Integer.toString(resCode));
Log.d("resMessage=",resMessage.toString());
fileInputStream.close();
outputStream.flush();
outputStream.close();
resServer = resMessage.toString();
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
protected void onPostExecute(Void unused) {
statusWhenFinish(position,resServer);
}
}
// When Upload Finish
@SuppressWarnings("unused")
protected void statusWhenFinish(int position, String resServer) {
/*** Default Value ***/
String strStatusID = "0" ;
String strError = "" ;
try {
JSONObject c = new JSONObject(resServer);
strStatusID = c.getString("StatusID");
strError = c.getString("Message");
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// prepare Status
if(strStatusID.equals("0"))
{
// When update Failed
holder.textStatus.setText("Failed");
holder.btnUpload.setEnabled(true);
}
else
{
holder.textStatus.setText("Uploaded");
holder.btnUpload.setEnabled(false);
}
}
}
最佳答案
引入如下结构:
/**
* Introduce a class with below attributes to hold a state of each row in single
* element
*
*/
public class MyData {
/* Image url or path of image in single row */
private String images;
/* anme of image in single row */
private String name;
/* status ID of image in single row */
private String statusID;
/* message of image in single row */
private String message;
// Generate getters and setter
public String getImages() {
return images;
}
public void setImages(String images) {
this.images = images;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getStatusID() {
return statusID;
}
public void setStatusID(String statusID) {
this.statusID = statusID;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
添加了适当的注释以理解代码。
//MyDataList是arrylist ArrayList(),需要在构造函数中初始化这个数据结构
public View getView(int position, View convertView, ViewGroup parent) {
MyData fields = MyDataList.get(position);
}
编辑:
我已经编辑了上面发布的代码,请看下面的代码我是如何使用 MyData 设置状态的
package com.example.trial;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
public class MainActivity extends Activity {
static ListView lstView;
private Handler handler = new Handler();;
static List<MyData> ImageList;
String strPath;
int position;
File newFile;
ViewHolder holder;
View v;
String fileName;
ImageAdapter mAdapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/*** Get Images from SDCard ***/
ImageList = getSD();
// ListView and imageAdapter
lstView = (ListView) findViewById(R.id.listView);
mAdapter = new ImageAdapter(this);
lstView.setAdapter(mAdapter);
}
private List<MyData> getSD() {
List<MyData> it = new ArrayList<MyData>();
String root_sd = Environment.getExternalStorageDirectory().toString();
File f = new File(root_sd + "/Download");
File[] files = f.listFiles();
for (int i = 0; i < files.length; i++) {
File file = files[i];
Log.d("Count", file.getPath());
MyData data = new MyData();
data.setImages(file.getPath());
data.setStatusEnable(true);
it.add(data);
}
return it;
}
static class ViewHolder {
public ViewHolder(View convertView) {
// TODO Auto-generated constructor stub
}
TextView textName;
ImageView thumbnail;
TextView textStatus;
Button btnUpload;
}
public class ImageAdapter extends BaseAdapter {
public ImageAdapter(Context c) {
}
public int getCount() {
// TODO Auto-generated method stub
return ImageList.size();
}
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
public View getView(final int position, View convertView,
ViewGroup parent) {
// Avoid unneccessary calls to findViewById() on each row, which is
// expensive!
holder = null;
if (convertView == null) {
convertView = getLayoutInflater().inflate(
R.layout.adapter_main, null);
holder = new ViewHolder(convertView);
// Create a ViewHolder and store references to the children
// views
holder.textName = (TextView) convertView
.findViewById(R.id.textName);
holder.thumbnail = (ImageView) convertView
.findViewById(R.id.thumbnail);
holder.btnUpload = (Button) convertView
.findViewById(R.id.btnUpload);
holder.textStatus = (TextView) convertView
.findViewById(R.id.textStatus);
// The tag can be any Object, this just happens to be the
// ViewHolder
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.btnUpload.setEnabled(ImageList.get(position)
.isStatusEnable());
holder.textStatus.setText(ImageList.get(position).getMessage());
strPath = ImageList.get(position).getImages().toString();
// Get File Name
fileName = strPath.substring(strPath.lastIndexOf('/') + 1,
strPath.length());
File file = new File(strPath);
@SuppressWarnings("unused")
long length = file.length();
holder.textName.setText(fileName);
final BitmapFactory.Options options = new BitmapFactory.Options();
Bitmap bm = BitmapFactory.decodeFile(strPath, options);
holder.thumbnail.setImageBitmap(bm);
// btnUpload
holder.btnUpload.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Upload
startUpload(position);
}
});
return convertView;
}
}
// Upload
public void startUpload(final int position) {
Runnable runnable = new Runnable() {
public void run() {
handler.post(new Runnable() {
public void run() {
v = lstView.getChildAt(position
- lstView.getFirstVisiblePosition());
holder = (ViewHolder) v.getTag();
synchronized (this) {
ImageList.get(position).setStatusEnable(false);
mAdapter.notifyDataSetChanged();
}
new UploadFileAsync().execute(String.valueOf(position));
}
});
}
};
new Thread(runnable).start();
}
// Async Upload
public class UploadFileAsync extends AsyncTask<String, Void, Void> {
String resServer;
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(String... params) {
position = Integer.parseInt(params[0]);
int bytesRead, bytesAvailable, bufferSize;
byte[] buffer;
int maxBufferSize = 1 * 1024 * 1024;
int resCode = 0;
String resMessage = "";
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
// File Path
String strSDPath = ImageList.get(position).getImages().toString();
// Upload to PHP Script
String strUrlServer = "http://mymasterpeice.comxa.com/uploadFile.php";
try {
/** Check file on SD Card ***/
File file = new File(strSDPath);
if (!file.exists()) {
resServer = "{\"StatusID\":\"0\",\"Message\":\"Please check path on SD Card\"}";
return null;
}
FileInputStream fileInputStream = new FileInputStream(new File(
strSDPath));
URL url = new URL(strUrlServer);
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("Content-Type",
"multipart/form-data;boundary=" + boundary);
DataOutputStream outputStream = new DataOutputStream(
conn.getOutputStream());
outputStream.writeBytes(twoHyphens + boundary + lineEnd);
outputStream
.writeBytes("Content-Disposition: form-data; name=\"filUpload\";filename=\""
+ strSDPath + "\"" + lineEnd);
outputStream.writeBytes(lineEnd);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// Read file
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
while (bytesRead > 0) {
outputStream.write(buffer, 0, bufferSize);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
}
outputStream.writeBytes(lineEnd);
outputStream.writeBytes(twoHyphens + boundary + twoHyphens
+ lineEnd);
// Response Code and Message
resCode = conn.getResponseCode();
if (resCode == HttpURLConnection.HTTP_OK) {
InputStream is = conn.getInputStream();
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int read = 0;
while ((read = is.read()) != -1) {
bos.write(read);
}
byte[] result = bos.toByteArray();
bos.close();
resMessage = new String(result);
}
Log.d("resCode=", Integer.toString(resCode));
Log.d("resMessage=", resMessage.toString());
fileInputStream.close();
outputStream.flush();
outputStream.close();
resServer = resMessage.toString();
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
protected void onPostExecute(Void unused) {
statusWhenFinish(position, resServer);
}
}
// When Upload Finish
@SuppressWarnings("unused")
protected void statusWhenFinish(int position, String resServer) {
/*** Default Value ***/
String strStatusID = "0";
String strError = "";
try {
JSONObject c = new JSONObject(resServer);
strStatusID = c.getString("StatusID");
strError = c.getString("Message");
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// // prepare Status
if (strStatusID.equals("0")) {
// When update Failed
ImageList.get(position).setMessage("Failed");
ImageList.get(position).setStatusEnable(true);
mAdapter.notifyDataSetChanged();
} else {
ImageList.get(position).setMessage("Uploded");
ImageList.get(position).setStatusEnable(false);
mAdapter.notifyDataSetChanged();
}
}
/**
* Introduce a class with below attributes to hold a state of each row in
* single element
*
*/
public class MyData {
/* Image url or path of image in single row */
private String images;
/* anme of image in single row */
private String name;
/* status ID of image in single row */
private String statusID;
/* message of image in single row */
private String message;
private boolean statusEnable;
public boolean isStatusEnable() {
return statusEnable;
}
public void setStatusEnable(boolean statusEnable) {
this.statusEnable = statusEnable;
}
// Generate getters and setter
public String getImages() {
return images;
}
public void setImages(String images) {
this.images = images;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getStatusID() {
return statusID;
}
public void setStatusID(String statusID) {
this.statusID = statusID;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
}
关于android - 如何保存和恢复ListView的滚动位置和状态,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29114729/